eng... · mech. eng. sci. j. vol. no. pp. skopje 37 1–2 1–120 2019 Маш. инж. науч....
TRANSCRIPT
UDC 621 CODEN: MINSC5 ISSN 1857 – 5293
e: ISSN 1857 – 9191
MECHANICAL ENGINEERING SCIENTIFIC JOURNAL
МАШИНСКО ИНЖЕНЕРСТВО
НАУЧНО СПИСАНИЕ
Volume 37 Number 1–2 Skopje, 2019
Mech. Eng. Sci. J. Vol. No. pp. Skopje
37 1–2 1–120 2019 Маш. инж. науч. спис. Год. Број стр. Скопје
MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL
МАШИНСКО ИНЖЕНЕРСТВО – НАУЧНО СПИСАНИЕ
Published by Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Republic of Macedonia
Издава Машински факултет, Универзитет „Св. Кирил и Методиј” во Скопје, Република Македонија
Published twice yearly – Излегува два пати годишно
INTERNATIONAL EDITORIAL BOARD – МЕЃУНАРОДЕН УРЕДУВАЧКИ ОДБОР
Slave Armenski (Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Skopje, R. Macedonia), Aleksandar Gajić (Faculty of Mechanical Engineering, University of Belgrade, Belgrade, Serbia), Čedomir Duboka (Faculty of Mechanical Engineering, University of Belgrade, Belgrade, Serbia), Maslina Daruš (Faculty of Science and Technology, University Kebangsaan Malaysia, Bangi, Malaysia), Robert Minovski (Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Skopje, R. Macedonia), Wilfried Sihn (Institute of Management Science, Vienna University of Technology, Vienna, Austria), Ivan Juraga (Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Zagreb, Croatia), Janez Kramberger (Faculty of Mechanical Enginneering, University of Maribor, Maribor, Slovenia), Karl Kuzman (Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia), Clarisse Molad (University of Phoenix, Phoenix, Arizona, USA), Todor Neshkov (Faculty of Mechanical Engineering, Technical University of Sofia, Sofia, Bulgaria), Zlatko Petreski (Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Skopje, R. Macedonia), Miroslav Plančak (Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia), Remon Pop-Iliev (Faculty of Engineering and Applied Science, University of Ontario, Institute of Technology, Oshawa, Ontario, Canada), Predrag Popovski (Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Skopje, R. Macedonia), Dobre Runčev (Faculty of Mechanical Engineering, Ss. Cyril and Methodius University in Skopje, Skopje, R. Macedonia), Aleksandar Sedmak (Faculty of Mechanical Engineering, University of Belgrade, elgrade, Serbia), Ilija Ćosić (Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia), Rolf Steinhilper
(Faculty of Engineering Science, University of Bayreuth, Bayreuth, Germany)
Editor in Chief Одговорен уредник Assoc. Prof. Dame Dimitrovski, Ph.D. Вон. проф. д-р Даме Димитровски
Co-editor in Chief Заменик одговорен уредник Prof. Nikola Tuneski, Ph.D. Проф. д-р Никола Тунески
Assis. Prof. Filip Zdraveski, Ph.D., secretary Доц. д-р Филип Здравески, секретар
Technical editor managing Технички уредник Blagoja Bogatinoski Благоја Богатиноски
Lectors Лектура
Capie Polk Baily (English) Capie Polk Baily (англиски) Georgi Georgievski (Macedonian) Георги Георгиевски (македонски)
Proof-reader Коректор
Alena Georgievska Алена Георгиевска
UDC: "St. Kliment Ohridski" Library – Skopje УДК: НУБ „Св.. Климент Охридски“ – Скопје
Copies: 300 Тираж: 300 Price: 520 denars Цена: 520 денари
Address Адреса
Faculty of Mechanical Engineering Машински факултет (Mechanical Engineering – Scientific Journal) (Машинско инженерство – научно списание)
Editor in Chief Одговорен уредник P.O.Box 464 пошт. фах 464
MK-1001 Skopje, Republic of Macedonia МК-1001 Скопје, Република Македонија
Mech. Eng. Sci. J. is indexed/abstracted in INIS (International Nuclear Information System) www.mf.ukim.edu.mk
MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL
FACULTY OF MECHANICAL ENGINEERING, SKOPJE, REPUBLIC OF MACEDONIA
МАШИНСКО ИНЖЕНЕРСТВО – НАУЧНО СПИСАНИЕ
МАШИНСКИ ФАКУЛТЕТ, СКОПЈЕ, РЕПУБЛИКА МАКЕДОНИЈА
Mech. Eng. Sci. J. Vol. No. pp. Skopje
37 1–2 1–120 2019 Маш. инж. науч. спис. Год. Број стр. Скопје
TABLE OF CONTENTS (С О Д Р Ж И Н А)
PRODUCTION ENGINEERING
(Производно машинство)
613 – Katerina Dimovski, Gligorče Vrtanoski
DEVELOPMENT OF THE ENERGY MANAGEMENT INFORMATIVE SYSTEM
(Развој на информациски систем за управување со енергија) ....................................... 5–15
614 – Taško Smileski, Gligorče Vrtanoski
DEVELOPMENT OF INNOVATIVE BRAKE SYSTEM FOR ROLLING STOCK
(Развој на иновативен сопирачки систем за железнички превозни средства) ............ 17–27
615 – Andon Naskovski, Gligorče Vrtanoski
TOTAL PRODUCTIVE MAINTENANCE – TOOL TO IMPROVE
THE COMPANIES PERFORMANCE
(Целосно продуктивно одржување – алатка за подобрување на перформансите
на компаниите) .................................................................................................................. 29–40
616 – Elena Papazoska, Gligorče Vrtanoski
SIX SIGMA METHODOLOGY – TOOL FOR IMPROVING THE CAPABILITY
OF THE PRODUCTION PROCESS
(Mетодологијата шест сигма – алатка за подобрување на способноста
на процесот на производството)...................................................................................... 41–54
617 – Vesna Gjorčeva, Gligoče Vrtanoski
PROCESSES OPTIMIZATION AND REDUCTION OF OPERATIONAL COSTS
– CASE IN INSURANCE COMPANY
(Оптимизација на процесите и намалување на оперативните трошоци
– Случај во осигурителна компанија –) .......................................................................... 55–64
618 – Georgi Hristov, Gligorče Vrtanoski
MANAGING ORGANIZATIONAL CHANGE IN COMMUNAL PUBLIC
ENTERPRISES: – A LITERATURE REVIEW
(Управување со организациските промени во комуналните претпријатија:
Преглед на литературата–) .............................................................................................. 65–70
MECHATRONIC
(Механотроника)
619 – Simona Domazetovska, Hristijan Mickoski, Marjan Djidrov
KINEMATIC MODELLING AND ANALYSIS OF SERIAL MANIPULATOR
(Кинематско моделирање и анализа на сериски манипулатор) ................................... 71–77
620 – Maja Anačkova, Hristijan Mickoski
CAD modelling of parallel robot (tripod) in Matlab/Simulink
(CАD-моделирање на паралелен робот (трипод) во Matlab/Simulink) ........................ 79–86
ENERGY EFFICIENCY
(Енергетска ефикасност)
621 – Dame Dimitrovski, Dalibor Stojevski
LIFECYCLE COSTS COMPARATION BETWEEN DISTRICT HEATING
AND INDIVIDUAL GAS HEATING
(Споредба на трошоците во текот на работниот век на системот на централно
греење и индивидуалното греење со гас) ....................................................................... 87–91
THERMAL ENGINEERING
(Термичко инженерство)
622 – Filip Mojsovski
DRYING CONDITIONS FOR PADDY PROCESSING IN MIXED-FLOW HIGH-
CAPACITY PLANT
(Услови на сушење за третман на оризова арпа во индустриска сушилница
со комбинирано струење) ................................................................................................ 93–98
DESIGN AND CONSTRUCTION OF STRUCTURES
(Дизајн и конструкција на структури)
623 – Bojana Trajanoska, Elisaveta Dončeva, Daniela Pana, Hristijan Gjorgievski
CONCEPT FOR STUDENT GLASS PAVILION
(Концепт за студентски стаклен павилјон) .................................................................. 99–105
INDUSTRIAL DESIGN
(Индустриски дизајн)
624 – Nikola Gerasimovski, Elena Angeleska, Sofija Sidorenko
BIONIC PRINCIPLES OF SPACE OPTIMIZATION APPLIED
IN THE PRODUCT DESIGN PROCESS
(Бионички принципи за оптимизација на просторот применети
во процесотна дизајнирање) ....................................................................................... 107–115
Instruction for authors .......................................................................................................... 117–120
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1, pp. 5–15 (2019)
Number of article: 613 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: May 20, 2018 UDC: 005.5/.6:004.75]:620.91
Accepted: July 15, 2018
Original scientific paper
DEVELOPMENT OF THE ENERGY MANAGEMENT INFORMATIVE SYSTEM
Katerina Dimovski1, Gligorče Vrtanoski2
1MAKSTIL AD Skopje, Duferco Group,
16 Makedonska brigada, No. 18, 1000 Skopje, Republic of N6rth Macedonia 2Faculty of Mechanical Engineering, "Ss. Cyril and Methodius" University in Skopje,
Karpoš II bb, P.O. box 464, 1001 Skopje, Republic of N6rth Macedonia
A b s t r a c t: The Industrial Revolution initiates an era of mass production and industrialization of cities that
provides all the comforts of modern living, and thus the unconscious pollution of the planet, climate change and global
warming. According to the Goddard Institute of Space Studies (GISS) of the National Aeronautics and Space Agency,
the depths in the ozone layer and the increased carbon dioxide emissions in the air are responsible for increasing the
surface temperature of the Earth by 1 °C in the last 100 years. As temperature rises on the Earth, we face an increase
of sea level levels, a change in precipitation on a regional scale, frequent extremes in temperatures like heat waves,
droughts, floods and snowstorms. The warming is felt more on the land surface than in the sea waters, while the most
significant is the Arctic, where glaciers are starting to disintegrate, and this can lead to the eradication of some species
of flora and fauna. For the human, global warming will lead to the challenge of providing food and leaving populated
areas close to flooded areas. Many countries support the climate change convention and contribute to reducing the
impact of GTC with climate engineering, with global warming being stopped before reaching 2 °C compared to the
period before industrialization. By implementing a system for managing energy and renewable energy sources, it will
contribute to the rational utilization of energy and energy sources and the formation of a sustainable society that will
affect in future reduction of carbon dioxide emissions in the atmosphere.
Key words: EnMS – energy management system; self-sustaining facilities; management of processes;
energy efficiency; EMIS – energy management informative system
РАЗВОЈ НА ИНФОРМАЦИСКИ СИСТЕМ ЗА УПРАВУВАЊЕ СО ЕНЕРГИЈАТА
А п с т р а к т: Со индустриската револуција започнува ерата на масовно производство и индустријали-
зација на градовите, што ги овозможува сите удобности на модерното живеење, а со тоа и несвесно загадување
на планетата, климатските промени и засилување на ефектот на стаклена градина. Според Институтот Годард
за вселенски истражувања на НАСА, за зголемување на температурата на површината на Земјата за 1°C во
последните 100 години се одговорни дупките во озонската обвивка и зголемената емисија на јаглероден диок-
сид во воздухот. Со зголемување на температурата на Земјата се соочуваме и со пораснување на нивото на
водите во морињата, промена во врнежите и сушните периоди на регионално ниво, фреквентни екстреми во
температурите како топлотни бранови, суши, поплави и снежни бури. Затоплувањето се чувствува повеќе на
копнената површина отколку во морињата, а најзначајно е на Арктикот каде глечерите полека се топат, а тоа
може да доведе до исчезнување на некои видови флора и фауна. За човечката раса глобалното затоплување ќе
доведе до предизвик за обезбедување храна и до напуштање населени места блиску поплавните подрачја.
Многу земји ја поддржуваат конвенцијата за климатски промени и со климатски инженеринг го даваат својот
придонес за намалување на ефектот на стаклена градина, со што глобалното затоплување ќе биде стопирано
пред да достигне 2°C во споредба со прединдустрискиот период. Со имплементирање на системите за
менаџирање со енергенси и обновливи извори на енергија ќе се придонесе за рационално искористување на
енергијата и енергенсите и формирање на одржливо општество, што пак во иднина ќе влијае врз намалување
на емисијата на јаглероден диоксид во атмосферата.
Клучни зборови: EnMS– систем за менаџирање со енергенси; самоодржливи објекти; управување со про-
цеси; енергетска ефикасност; ЕМIS – информативен систем за менаџирање со енергенси
6 K. Dimovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 5–15 (2019)
1. INTRODUCTION
Advancement in technology used in everyday
life for transportation and manufacturing leads to
rapid increasment in energy consumption. Natural
supplies of high calorie coal are reduced day by day.
The life on this planet is not self-sustainable to sup-
port the burden of modern society, and in order not
to affect the quality of this lifestyle, it is urgent to
rationalize the usage of energy. This means saving
energy for production by implementing Energy
Management Systems (EnMS), as well as control-
ling energy consumption in real time.
EnMS will not only save energy for produc-
tion, but also will make the consumer more inde-
pendent from the supplier of energy and continuous
fluctuations and increasment on the market prices.
When building new production plants or build-
ings it is essential to incorporate energy strategy and
efficiency predictions for future energy use. In the
existing buildings and industry plants it is important
to make adjustments to incorporate energy efficient
methodologies by making investments and process
optimization that will lead to better use of energy.
The making of EnMS, the implementatiot and
successful maintenance is complicated process that
needs intradisciplinary professionals and experts in
process automation and machine engineering, as
well as sales and marketing.
2. LITERATURE REVIEW
As relatively new software tool, EnMS has
high research potential in the development and in
improving companies’ performance and productiv-
ity [1, 2, 3, 6, 9]. In the improvement of overall com-
pany business strategies, EnMS uses informations
and innovation integration for lowering the foot-
print in carbon trust of the company.
Base of this concept is energy management,
that is elaborated in numerous books, reports and re-
searches [3, 11, 12].
According to the many surveys, enough data
have been collected that can be analyzed with few
error options, leading to reliable sources of the
structure and benefits of the EnMS energy manage-
ment system. For the purpose of developing the
model / prototype of the EnMS system, a manual [4,
10, 13] for managing energy is used as a reliable
source that informs about the analysis, the technical
and economic aspects of the heating and air condi-
tioning systems, the control systems and automati-
on, lighting, air quality control, energy maintenan-
ce, control over the procurement of energy sources,
as well as for the procedure for measurement and
verification of energy savings [4, 6, 10, 13].
The researchers generally agree on the benefits
EnMS can provide. There are two types of energy
management systems. The first type is EMIS infor-
mation system for energy management monitors
and monitors energy consumption in a defined unit
(hourly, daily, monthly, etc.) [14, 15, 16] and ex-
ports reports and analyses regarding energy con-
sumption. The second type, EnMS the energy man-
agement system continuously monitors consump-
tion and allows for real-time corrective measures
that will affect consumption [17, 18, 19].
3. MODEL OF THE ENERGY MANAGEMENT
SYSTEM
In the sphere of innovation, the energy man-
agement system is one of the leading trends of the
21st century. Every facility, company and industry
that strives to protect the environment and reduce
greenhouse gas emissions as well as energy and en-
ergy savings will inevitably implement such a sys-
tem. Energy Management System (EnMS) allows
the planning and management of energy at hourly
level [7], with each information coming to the top
management of the company in the form of reports.
For successful implementation of the EnMS
system for reducing consumption, it is first neces-
sary to create an energy efficiency policy that will
be supported by all employees. Next, it is necessary
to determine the limits in which the company can
influence the consumption of energy and energy
sources. It implies whether all production units are
locally compact or have production plants in differ-
ent locations.
Subsequently, it is necessary to identify the
main consumers of energy and energy sources. In
each plant, one can determine which are the main
consumers such as electricity, oxygen, compressed
air, water and other energy sources, and each of
those consumers should be placed on the optimiza-
tion list [5, 8].
In order to achieve the desired energy and en-
ergy savings, a constant review of the results and
actions taken in the production process is required.
Minor improvements in the production process it-
self lead to major changes that are almost always in
Development of the energy management informative system 7
Маш. инж. науч. спис., 37 (1–2), 5–15 (2019)
the direction of savings in materials, energy and en-
ergy sources, and thus increased profits of the com-
pany.
With proper knowledge of the production it is
necessary to perform optimization of the process
and the plants. This is not a simple job at all. Care
should be taken not to disturb the quality of the fin-
ished product. It is necessary for the sector for com-
merce and procurement in the future to strive for en-
ergy efficient parts for which only the purchase
price will not be important, but also to include cal-
culations for energy consumption and ongoing
maintenance. If in the part of purchases focuses only
on an initially lower cost of an energy-inefficient
system, over time it will be spent much more than if
an energy-efficient part or device would be pur-
chased which would be an investment that would
soon be repaid taking the energy price who con-
sumes it.
In order to see the results of the EnMS system
for energy management, it is necessary to constantly
check the energy and energy consumption and to re-
view the possibilities for continuous improvement.
3.1. Creating a model
For the conceptualization of a model for en-
ergy and energy management, it is necessary to set
control metering devices for measurements of the
consumption of electricity at the measuring points
that provide data on consumption and on which fur-
ther calculation of the payment is made. Each of the
measuring devices is required to provide data on ac-
tive energy, reactive energy, maximum power and
power factor as characteristics of the electrical en-
ergy transmission system [21].
Appropriate exits of the measuring devices are
collected in a device called a concentrator, which
serves as a collector of output impulses from the
measuring devices. The collected impulses are con-
verted into digital data that connect to the internal
database through a computer network and are trans-
ferred to the company's main computer center, that
is to the central computer servers. Different net-
working principles for control metering devices, the
concentrator and the computer server are shown in
Figure 1.
Fig. 1. An example of a network connection to an energy management model EnMS with SCADA [21]
8 K. Dimovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 5–15 (2019)
In the case where the measuring devices are at
a great distance from the computer server, data com-
puter servers connected to a WLAN / GPRS modem
must be set up for remote reading of the values of
the measuring devices.
The creation of a model for energy manage-
ment can be created in 4 phases [21, 22]:
1. In the first phase of the development of the
model, ideas are generated from all employees
covering this issue.
2. Then, the second phase of the concept mode-
ling, which focuses on the research of the
current state, possibilities for implementation
of the envisaged system, is followed, and the
ideas for innovations from different aspects are
considered.
3. In the third phase, a completely new one can
be developed, or existing computer software
can be adapted to enable the existing measu-
rement devices to be connected, or new mete-
ring devices can be installed in pre-selected
key sites that have significant energy and ener-
gy consumption.
4. The fourth and final phase of the model pro-
vides for a correct nomination of the basic
energy and energy consumption and moni-
toring the consumption of energy and energy
sources for the current hour. To this end it is
necessary to set monitors for supervision in all
production facilities and to train persons who
will further monitor the consumption of energy
and energy sources directly from the monitor
display and will react in real time according to
the prescribed operating instructions and pro-
tocols of the company.
In order to begin with the concept of EnMS, it
is necessary to know and select the significant con-
sumers and which energy sources they use. It is nec-
essary to place on the incoming energy sources
measuring devices that will read the consumption in
real time in accordance with the rules for the energy
and energy sources at the energy market.
After the installation of the measuring devices,
the software development phase is adapted for the
needs of the dynamic process in all production
plants in the company. The software allows to mon-
itor the consumption of all energy sources that are
connected in the energy and energy sources man-
agement system EnMS.
Each system is unique and tailored according
to the production process and no single universal
EnMS system can be made.
4. OPERATIONAL USE OF THE DEVELOPED
MODEL FOR ENERGY MANAGEMENT
Real-time energy management is a modern
technology that transforms the way of utilizing and
supplying energy by continuously collecting data on
consumption and tracking past performances. These
data are analyzed using the methodology for calcu-
lation of energy consumption and as a result, opti-
mization of propulsion consumption is obtained
[20].
Sensors, measuring devices, protocols and
other equipment that provides data in the system da-
tabase (Figure 2), which then through analyses and
other services shows the performance of the object
in real time. As an output, the system can issue a
recommendation to improve performance in real
time, resulting in lower operating and service costs
and the ability to limit consumption and maintain
productivity [22].
Fig. 2. An example of connecting the energy management system EnMS [22]
4.1. Methodology for calculation of energy savings
The first step of calculation energy savings is
collection of data from the quantity of final product
produced and the energy used for its production.
The report is generated from the company's infor-
mation system (ERP). For the input parameters in
the regression analysis used for the formation of an
energy model, is the energy consumption of all ma-
chinery of the production process. As input are
Development of the energy management informative system 9
Маш. инж. науч. спис., 37 (1–2), 5–15 (2019)
taken into consideration product specifications that
affect consumption such as [22]: production activi-
ties, weather conditions, winter and summer regime
of lighting and some routine variables that are mea-
surable as shown in Table 1.
T a b l e 1
Results of the calculation of energy consumption with mathematical regression model [22]
(K0) (K1) (K2) (K3) (K4) (K5) (K6) (K7) (K8) (K9) (K10) (K11)
Production
units
Energy
(MWh)
Predicted
consumption
(MWh)
EnPI
Actual
savings
(MWh)
Sum of actual
savings (MWh)
Target
(MWh)
Target
savings
(MWh)
Cum sum of
target savings
(MWh)
Price € Savings €
Jan-15 20.200 850.320 0
Feb-15 20.469 801.359
Mar-15 20.737 806.434
Apr-15 21.006 811.509
May-15 21.274 816.583
Jun-15 21.543 821.658
Jul-15 21.811 826.733
Aug-15 22.080 831.807
Sep-15 22.349 836.882
Oct-15 22.617 841.957
Nov-15 22.886 847.031
Dec-15 21.543 852.106 0 0
Jan-16 23.423 813.250 815.189 0,03 -1.939 -1.939 809.184 -6.005 -6.005 406.625 -9.695
Feb-16 23.691 800.370 812.270 0,03 -11.900 -13.838 796.368 -15.901 -21.907 400.185 -59.498
Mar-16 23.960 808.340 809.350 0,03 -1.010 -14.849 804.298 -5.052 -26.958 404.170 -5.050
Apr-16 24.229 806.100 806.431 0,03 -331 -15.179 802.070 -4.361 -31.320 403.050 -1.653
May-16 24.497 802.111 803.511 0,03 -1.400 -16.579 798.100 -5.411 -36.730 401.056 -7.001
Jun-16 24.766 797.592 800.592 0,03 -3.000 -19.579 793.604 -6.988 -43.718 398.796 -14.999
Jul-16 25.034 787.622 797.672 0,03 -10.050 -29.630 783.684 -13.988 -57.707 393.811 -50.252
Aug-16 25.303 784.833 794.753 0,03 -9.920 -39.550 780.909 -13.844 -71.551 392.417 -49.600
Sep-16 25.571 780.340 791.834 0,03 -11.494 -51.043 776.438 -15.395 -86.946 390.170 -57.468
Oct-16 25.840 760.914 788.914 0,03 -28.000 -79.043 757.109 -31.805 -118.751 380.457 -140.000
Nov-16 26.109 765.955 785.995 0,03 -20.040 -99.083 762.125 -23.869 -142.620 382.978 -100.198
Dec-16 26.000 698.150 787.175 0,03 -89.025 -188.108 694.659 -92.516 -235.136 349.075 -445.124
Jan-17 26.000 786.756 787.175 0,03 -418 -188.526 782.823 -4.352 -239.488 393.378 -2.092
Feb-17 26.914 780.775 777.236 0,03 3.539 -184.987 776.871 -365 -239.853 390.388 17.693
Mar-17 27.183 774.794 774.317 0,04 477 -184.511 770.920 -3.397 -83.921 387.397 2.384
Apr-17 27.451 768.812 771.398 0,04 -2.585 -187.096 764.968 -6.429 -98.075 384.406 -12.926
May-17 27.720 762.831 768.478 0,04 -5.647 -192.743 759.017 -9.461 -112.229 381.415 -28.236
Jun-17 27.989 756.850 765.559 0,04 -8.709 -201.452 753.065 -12.493 -126.382 378.425 -43.545
Jul-17 28.257 750.868 762.639 0,04 -11.771 -213.223 747.114 -15.525 -140.536 375.434 -58.855
Aug-17 28.526 744.887 759.720 0,04 -14.833 -228.056 741.162 -18.557 -154.690 372.443 -74.165
Sep-17 28.794 738.905 756.800 0,04 -17.895 -245.951 735.211 -21.589 -225.951 369.453 -89.475
Oct-17 27.720 732.924 768.478 0,04 -35.554 -281.505 729.259 -39.219 -261.505 366.462 -177.770
Nov-17 24.720 726.943 801.089 0,03 -74.146 -355.651 723.308 -77.781 -350.620 363.471 -370.730
Dec-17 25.720 726.943 802.069 0,03 -75.126 -430.777 723.308 -78.761 -420.777 363.471 -375.631
Jan-18 29.869 745.123 average 384.539 -2.153.887
Feb-18 30.137 742.203
Mar-18 30.406 739.284
Apr-18 30.674 736.364
May-18 30.943 733.445
Jun-18 31.211 730.526
Jul-18 31.480 727.606
Aug-18 31.749 724.687
Sep-18 32.017 721.767
Oct-18 32.286 718.848
Nov-18 32.554 715.928
Dec-18 32.823 713.009
10 K. Dimovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 5–15 (2019)
Table 1 shows the calculated energy savings
results using the regression model in the time frame
for which the analysis is performed. In Table 1,
2015 is taken as the base year through which the im-
plementation of EnMS takes place. The next two
years, 2016 and 2017, are the years on which the
mathematical model is formed, and the predictions
are made on the basis of the planned production for
2018.
The first column (K1) represents the unit value
of the final product expressed in pieces, tons, liters,
depending on how the company calculates the final
product, while the second column (K2) represents
the amount of electricity in MWh consumed in the
production.
The predicted energy consumption (K3) is the
output of the regression analysis that is the sum of
the intersection with the coefficients multiplied by
the corresponding input parameter, as shown in the
third column (K3), and represents the frame in
which the consumption should vary. Calculated val-
ues of predicted consumption are shown in column
3 (K3) and together with the energy consumed (K2)
construct the graph shown in Figure 4.
The fourth column (K4) in Table 1 represents
the energy performance coefficient, which gives the
percentage of the expected consumption versus re-
alized consumption. The fifth column (K5) repre-
sents the real savings from the regression model and
the consumed energy where it can be noted how
much MWh are saved monthly. The sixth column
(K6) represents a cumulative amount of savings
over the period.
Target savings (K8) derrives from the mathe-
matical regression model and shows how much
MWh should be spend monthly according to the
planned production, in order to achieve the desired
savings, that in this case is 3% savings already cal-
culated in the results.
The last columns represent the savings ex-
pressed in a monetary unit, that is to say the cost of
the energy in euros (K10) and the monthly saving of
MWh expressed in euros (K11).
The difference between the anticipated (K3)
and the realized consumption (K2) is discussed fur-
ther with the team and the reasons for the specific
deviations are analyzed.
The actual savings column (K5) represents the
difference from the planned consumption (K3)
according to the mathematical model and the actual
consumption (K2) according to the measured valu-
es. The purpose of the formed model is to produce
a monthly target-savings (K8) of a certain percen-
tage (in the model of Table 1 it is 3%), which should
be regulary checked during production. This per-
centage is not fixed and is part of the company's
energy saving policies and can vary on annual basis.
To change the target savings (K8), the calculated
formula changes the predicted percentage and auto-
matically generates the monthly targeted savings
that needs to be achieved.
The last two columns (K10) and (K11) show
the monthly price of electricity expressed in euros
for a large industrial consumer.
According to the energy strategy, the company
sets annual target savings that needs to be achieved.
According to target consumption (K7) and savings
(K8), the long-term goals in line with the energy
policy are followed, the potential targets and invest-
ments for energy savings in the next year are
updated and action plans are being set up. Company
policy should aim at energy efficient maintenance
of significant energy users through maintenance
training, monitoring of critical operating parame-
ters, plan for effectively planned maintenance and
employee awareness of their impact on the energy
consumption on each significant user.
4.2. Use of the developed model
The first step of the monitoring the energy us-
age is completed with the implementation of the
EnMS system. The next step is managing energy,
which means real time monitoring and managing
consumtion of each siginificant energy user.
Every company needs to know the significant
energy users and the type of energy they use in the
production process, since the initial optimization
starts with them. The other less significant consum-
ers have a lower priority in the process of introduc-
ing energy efficiency principles [22]. For example,
in a large manufacturing industry, it is insignificant
if the lighting in the halls is completely replaced
with efficient solutions, if the motors or boilers are
inefficient, while in office facilities, lighting is an
important factor.
With the formulated regressive model for each
consumer, a consumption plan for the next year can
be determined and calculated whether the plant is
energy efficient despite of the production. From the
results obtained with the conducted mathematical
regression analysis and from the developed models
of energy performance, a plan for consumption for
the next period can be formed. For future energy
consumption forecasts according to the planned
Development of the energy management informative system 11
Маш. инж. науч. спис., 37 (1–2), 5–15 (2019)
production quantity, energy managers can choose to
set the target so it will achieve the best performance
of the previous year or choose a fixed savings of a
certain percentage. In the case of fixed savings
(K9), the percentage is entered in the creation of the
model and consumption is required to follow the
trend of the model. In case when the consumption
(K3) is less than (K8), energy savings are made
which in the real case are shown in (K9), and in case
the actual consumption (K2) is above the trend of
the model, the plant consumes more than planned,
there is a loss of energy and in that case where it is
necessary to intervene, which means corrective ac-
tion needs to be taken.
The savings resulting from Table 1 columns
(K6) and (K9) are shown in the following graph
(Figure 3) from which it can be concluded that to a
certain point the amount of target savings (K9)
(shown in red trend line) and the amount of the ac-
tual savings (K6) (shown by the blue trend line) are
followed by which period the efficiency of the plant
increases and the actual savings exceed the planned
savings [22].
The graph shown in Figure 3 refers to the sav-
ings shown in Table 1. The time period is two years,
i.e. 24 months, from 2016 to 2017 [22].
According to the data from Table 1, for the
specific mathematical regression model and analy-
sis of the consumed energy according to the produc-
tion, it can be noted that the return on the initial in-
vestment for a period of 6 months. As an initial in-
vestment, the data from Table 1 and the cost of en-
ergy with EnMS were taken.
Fig. 3. Graphic representation of the savings achieved with EnMS [22]
Fig. 4. Regressive models of calculation of consumption and future prediction [22]
12 K. Dimovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 5–15 (2019)
On the basis of the obtained results from Table
1 and the calculated consumption (K3), the regres-
sive models shown in Figure 4 are formed, where
the dashed line (shown in red) represents the predic-
ted energy consumption (K3), while the full trend
line (shown by blue color) represents the actual
consumption (K2). From the analysis of the results
and the graph, it can be noted that by January 2017
the real consumption is lower than planned, which
means that everything is in accordance with the
energy policy, the promoted energy practices and
procedures of the company are satisfied.
In the second month of 2017, it can be noted
that consumption is greater than anticipated, which
can be influenced by several factors and it is neces-
sary to consider that month specifically and directed
to the quality of operations. On the basis of this
principle, consumption prediction can be performed
when the planned quantity of product units is known
for a certain period of time [22].
5. COMPARATIVE ANALYSIS
OF THE RESULTS OBTAINED
WITH THE DEVELOPED MODEL
The energy management system is a signifi-
cant investment. While there is an opportunity for
the company to directly implement ready-made so-
lutions for EnMS, but it can also develop and adapt
software. Given the quantities produced on the final
product, the price for transmission, distribution and
balancing of the energy can be rounded up to a
monthly savings of around 10%. This entails a re-
turn on investment in less than a year [22].
With operational control in the production pro-
cess and taking into account the minimum invest-
ment for the energy management system, depending
on the dynamics of the production process, in some
industries, the investment for EnMS can also be
paid for a shorter period of operational operation. If
the user spends an average of 40 MWh (shown in
Table 2, column (K2)) with an appropriate day
ahead nomination of energy, one can significantly
affect the cost per MWh. By nominating an upper
limit on consumption in moments when the stock
exchange of energy is more expensive than the price
of the trader or the nomination of the lower limit of
consumption in the period when the price of the
stock exchange is significantly lower than the
trader, there are large variations in the cost of pro-
duction for the final product.
For industries that are dominant electricity
consumers, this model represents a negligible in-
vestment leading to large energy savings. A key role
in the success of the EnMS model is the system for
predicting the consumption or expertise of the team
working with the nomination. The members of the
team should be adequately familiar with the produc-
tion process and the dynamics of foreign exchange
markets for the electricity market, because any
wrong forecast and estimate is a loss, and any good
prediction leads to a reduction in the unit cost price
and the competitiveness of the company's market
[22].
Table 2 gives the energy consumed for the
current hour (K2), the announced energy (K3) and
(K4) and an example of the prices of electricity from
the stock exchange in two days (K5) and (K6) for
the analysis of 46th week of the year. From the data
in Table 2, it can be concluded that one precisely
predicted day is enough to pay off the investment of
the EnMS system in relation to the received cost of
consuming the consumed electricity [22].
For medium and small consumers, it may be
necessary to have a longer period of time to see the
positive effects and savings from such an advanced
model of EnMS for monitoring and managing the
consumption of energy.
Depending on the variations in the price of the
stock exchange at the hourly level as shown in Table
2, fewer can be announced, and a larger amount of
energy is taken. In that case, when the price of the
free market is lower than the trader, a reduction in
the cost per unit of MWh is taken. With the EnMS
model in these days, more than 50% of the energy
cost can be saved. But there are days when the price
of electricity on the market is greater than the one
offered by the trader. In those days it is necessary to
announce the upper limit of consumption and take a
minimum amount of energy from the free market.
Table 2 shows the data for each hour of con-
sumed energy (K1), standard consumption (K2) and
an example of two announcements of the energy
supply from a trader (K3) and (K4). The price of-
fered by the merchant is fixed for each day of the
month, while the price of electricity on the free mar-
ket varies at hourly level. Without an EnMS moni-
toring system (Table 2, Columns (K8) and (K9)),
daily nominations will be a significant challenge.
Total expressed energy consumed (K2) which
is taken to calculate one day is approximately 900
MWh. For fixed power consumption at a given
hour, different amounts of energy (K3) and (K4) can
be nominated, which will give different values in
the formation of the final energy price shown in the
columns (K8) and (K10). The same applies to the
columns (K9) and (K11) for a different value of the
Development of the energy management informative system 13
Маш. инж. науч. спис., 37 (1–2), 5–15 (2019)
free market price (K7), which on that day is signifi-
cantly higher than the price of the trader. Without
the EnMS model, there is a significant difference in
the value of the funds spent with respect to the use
of the EnMS model (Table 2, columns (K10) and
(K11)).
It is significant that using the EnMS model
saves the company's financial resources (Table 2,
Columns (K9) and (K11)) and when the team has a
poor forecast or announcement (K4).
T a b l e 2
Overview of the nomination of consumption with and without the energy management system EnMS [22]
Figure 5 shows a graphic representation of the
price of electricity for hourly production of final
product. It is significant to notice the variation in the
price of energy for the same quantity of produced
final product.
Figure 6 shows the quantity of nominated en-
ergy and real consumption of electricity hourly. The
nominated energy is charged at the price given by
the trader, while the remaining energy is taken from
the market. In days when the price of energy from
the stock is lower than that of the trader, it is desir-
able to nominate a smaller amount of energy, while
in periods when the price of the trader is lower, it is
desirable to nominate a greater amount of energy to
reduce the cost of production of a unit product.
Figure 7 shows the difference in the cost price
needed for the production of a unit product. For the
production of a single product, the price may vary
considerably. One influential factor is the price of
electricity in the market for a certain hour, then the
nomination, i.e, the amount of electricity that is
taken from the trader and the rest from the market.
The most important factor for increasing the savings
of the company is the EnMS energy management
system, which monitors the consumption in real
time and can minimize the negative effects of the
market prices. Without the developed model of
EnMS, from Figure 7 it can be easily assessed and
realized that the price of the product is twice as high.
14 K. Dimovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 5–15 (2019)
Fig. 5. Price for hourly production expressed in euros [22]
Fig. 6. The nominated and spent amount of energy expressed in MWh [22]
Fig. 7. Average price for energy on a daily basis [22]
Development of the energy management informative system 15
Маш. инж. науч. спис., 37 (1–2), 5–15 (2019)
6. CONCLUSION
With the implementation of the EnMS the
company's competitiveness and sustainability on
the market is advanced, new business benefits are
opened, energy performance improves and systema-
tic approach to consumption is introduced. The first
savings can be seen through successfully performed
operational control and investments. The most im-
portant benefit is the financial savings, but also the
reduced emission of carbon gases in the air, thereby
reducing the greenhouse effect that leads to global
climate change. A key path to successful implemen-
tation of EnMS is the believe that a change can be
made with the appropriate team and commitment
from top management and through planning, moni-
toring and verification of the action plans for saving,
which improves the energy performance of industri-
al facilities and opens new opportunities and chal-
lenges for saving.
It is necessary to see EnMS system as an con-
tinuous process, and not as a one-time project,
which when it reaches the maximum savings, it will
cease. Energy management is a cycle where there is
always an opportunity for improvement that is not
always visible, until the current period is compared
to the beginning, in order to notice the inevitable
success.
For the production of a single product, the
price may vary considerably. One influential factor
is the price on the market for a certain hour, then the
nomination, thet is to say the amount of energy
taken from the trader, and from the market. The
most important factor for increasing the savings of
the company is the EnMS energy management
system, which monitors the consumption in real
time and can minimize the negative effects of the
market.
REFERENCES
[1] Corporate Industry Program for Energy Conservation: En-
ergy Management Information Systems, Office of Energy
Efficiency of Natural Resources Canada, Ottawa, 2003.
[2] ISO 50001:2011: Energy Management Systems: Require-
ments with Guidance for Use, Bureau of Indian Standards,
New Delhi, 2011.
[3] Foundation for Community Association Research: Energy
Efficiency Best Practices, 2007.
[4] Doty, W., Turner, C., Lilburn, S.: Energy Management
Handbook, 6th edition, The Fairmont Press Inc., 2007.
[5] http://www.esightenergy.com/uk/ – access on 15.01.2017.
[6] ISO 50004:2014: Energy Management Systems, Guidance
for the Implementation, Maintenance and Improvement of
an Energy Management System, Institute for Standardiza-
tion, 2014.
[7] ESMAP: Improving Energy Efficiency in Buildings, 2014.
[8] ETSU: Introducing Information Systems for Energy Man-
agement, 1998.
[9] http://www.cisco.com/c/en/us/products/switches/energy-
management-technology/index.html – access on 20. 02.
2017.
[10] United Nation Industrial Development Organization:
Practical Guide for Implementing an Energy Management
System, Vienna, 2013.
[11] Power Guide: Sustainable Development and Energy Effi-
ciency, Legrand, 2009.
[12] DEXMA: The Complete Playbook for Financing Energy
Efficiency, Barcelona, 2016.
[13] Doty, S., Turner W. C.,: Energy Management Handbook,
8th edition, Lilburn, The Fairmont Press Inc., 2012.
[14] Закон за енергетика, Службен весник на Република
Македонија, бр. 16, 2011.
[15] Мрежни правила за пренос на електрична енергија,
МЕПСО, Скопје, 2006.
[16] Правила за пазар на електрична енергија, Службен
весник на Република Македонија бр. 16, 2011.
[17] Правила за снабдување со електрична енергија, Служ-
бен весник на Република Македонија, бр. 144, 2012.
[18] Правила за пазар на природен гас, Службен весник на
Република Македонија, бр. 16, 2011.
[19] Правила за снабдување со природен гас, Службен вес-
ник на Република Македонија бр. 16, 2011.
[20] Katiraei, F., Iravani, R., Hatziargyriou, N., Dimea, A.:
Microgrids management, IEEE Power Energy Mag., vol.
6, no. 3, pp. 54–65 (May/Jun. 2008).
[21] Хаџидаовски, И., Мијалковски, Д., Андовски, С., Ни-
кодиноска, К.: Систем за следење и менаџирање со
електичната енергија и останатите енергенси при АД
Макстил Скопје, ЗЕМАК, 2014.
[22] Димовски, К.: Придонес на системот за енергетска
ефикасност во менаџмент на развој на животен цик-
лус на производ, Магистерски труд, УКИМ, Машински
факултет, Скопје, Јуни 2018.
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 17–27 (2019)
Number of article: 614 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: May 21, 2019 UDC: 629.43-592:004.942
Accepted: July 19, 2019
Original scientific paper
DEVELOPMENT OF INNOVATIVE BRAKE SYSTEM FOR ROLLING STOCK
Taško Smileski1, Gligorče Vrtanoski2
1MSc Student at the Faculty of Mechanical Engineering, "Ss. Cyril and Methodius" University in Skopje,
Karpoš II bb, P.O. box 464, 1001 Skopje, Republic of N6rth Macedonia 2Faculty of Mechanical Engineering, “:Ss. Cyril and Methodius” University in Skopje,
P.O. Box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: In this paper is shown the importance of introducing innovative products in railway industry,
especially when it comes to products from which depends the railway traffic safety, like the brake systems. These brake
systems have the essential function of decelerating and stoping of rolling stock. Because the brake systems are a subject
of large static and dynamic loads in external conditions, the development of this type of system is a long and complex
process. In this paper is shown one part of innovative brake system development by using computer simulation.
Key words: railway; development; brake system; innovation; simulation
РАЗВОЈ НА ИНОВАТИВЕН СОПИРАЧКИ СИСТЕМ ЗА ЖЕЛЕЗНИЧКИ ПРЕВОЗНИ СРЕДСТВA
А п с т р а к т: Во трудот е прикажана важноста на воведување иновативни производи во железничката
индустрија, особено кога се работи за производи од коишто зависи безбедноста во железничкиот сообраќај
како што се сопирачките системи. Овие сопирачки системи имаат есенцијална функција за намалување на
брзината и сопирање на железничките превозни средства. Бидејќи сопирачките системи се изложени на големи
статички и динамички оптоварувања во надворешни услови, развојот на еден ваков систем претставува долг и
сложен процес. Во трудот е прикажан еден сегмент од развојот на иновативен сопирачки систем со користење
компјутерска симулација.
Клучни зборови: железница; развој; сопирачки систем; иновација; симулација
1. INTRODUCTION
Rail transport provides a very important role in
society, not only to enable large number of people
to get to work every day, but also for transport of
materials and goods. The development of rail trans-
port in recent decades goes in direction of increasing
the speed and loading capabilities of rolling stock.
This directly affects the development of brake
technology [5]. The brake system has an essential
function of reducing the speed and braking of
rolling stock for the minimum possible time [3]. The
process of braking is of great importance for the
safety of rail traffic. As railway operators focus on
the need for greater improvements in efficiency and
safety, there is still a considerable need for advan-
cements of railway brake systems [2, 6]. Several
types of brake systems are used in the railways.
Most commonly are used compressed air brake
systems, called pneumatic brake systems [1].
The development of new products contributes
to the growth of companies, affects profits and is a
key factor in business planning [8]. Innovations are
key to the survival of companies. The meaning of
the word innovation is introduction of something
new – change, while invention refers to something
that has never been made before [11]. Throughout
the world there is a popular model – from imitation
18 T. Smileski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 17–27 (2019)
to innovation, and then generating an invention
[12]. Research has shown that investment in product
development is relatively inexpensive and free from
high risk but can lead to a major competitive ad-
vantage in terms of cost savings, customer engage-
ment and increased profits in a company [4].
In the process of developing a brake system,
the most important segment is to use the most ad-
vanced softwares, methods and techniques. The si-
mulation of multi-body dynamics, together with
finite-element simulation, is one of the key methods
for design, homologation and research in the field
of railway and similar vehicles [7]. The optimal
combination of simulation tools, field trials and tes-
ting equipment can be the right way to accelerate the
introduction of innovative technologies, reduce
costs and increase safety, performance and econo-
mic competitiveness in rail transport [14]. Multi-
body dynamic simulation can replace very expen-
sive tests and measurements of the railway vehicle.
Nowadays almost every newly developed railway
vehicle has undergone a multi-body simulation. The
obtained results from the simulation will indicate
whether the brake system meets the UIC standard
criteria for the rail and whether it meets the requi-
rements of the cutomers.
2. MODEL OF BRAKE SYSTEM
2.1. Types of brake systems
From a technical point of view, there are two
main groups of brakes for rail vehicles: adhesion
and non-adhesion brakes (Figure 1).
Fig. 1. Types of brakes for rail vehicles [13]
Adhesion brakes include mechanical brakes
and dynamic brakes. Mechanical brakes are divided
into tread brakes and disc brakes. On disc brakes,
the disc can be axle-mounted or wheel-mounted.
Dynamic brakes include rotating eddy current
brakes, electrodynamic brakes and hydrodynamic
brakes.
Non-adhesion brakes include air resistance
brakes and track brakes. The second type of brakes
includes: magnetic rail brakes and linear eddy cur-
rent brakes.
Brake systems for rail vehicles can also be
classified according to the activation method in the
following categories [3]:
• pneumatic brakes.
• electrodynamic brakes.
• mechanical brakes.
• electromagnetic brakes.
Pneumatic brakes can be classified into two
types:
• vacuum brakes.
• compressed air brakes.
Development of innovative brake system for rolling stock 19
Маш. инж. науч. спис., 37 (1–2), 17–27 (2019)
From all these braking systems, the focus in
this paper is placed on pneumatic tread brake sys-
tems with compressed air.
2.2. Description of conventional brake system
for freight wagons
The conventional brake system for freight
wagons (excluding pneumatic components) consists
of these main components: brake cylinder, slack ad-
juster, pull rods, brake riggings, brake shoe holders
and brake shoes. The schematic view of this brake
system is shown in Figure 2.
The function of the brake system is achieved
by applying pressure in the brake cylinder (1) from
which the generated force is transfered through
brake riggings (3) and slack adjuster (2) onto the
brake shoe holders (4). From the brake shoe holders,
the brake force is transferred on the brake shoes (5)
and onto the wheels of the wagon. The slack ad-
juster (2) has a function to compensate for the wear
of the brake shoes (5) and wheels. When the brake
shoes or wheels are wearing, the brake cylinder has
larger stroke than nominal and it is activating the
trigger (6) of the slack adjuster which decreases the
lenght of the slack adjuster and compensates the
wearing. The gap between the shoes and wheels can
be adjusted by changing the length of the trigger (6).
The simple design of the conventional brake
system is the reason why this system is dominant in
the rail freight market worldwide until the introduc-
tion of integrated bogie brake systems.
Fig. 2. Shematic view of conventional brake system [6]
2.3. Model of innovative brake system
As railway operators focus on the need for
greater improvements in efficiency and safety, there
is a significant need for improvements of the brake
systems [2, 6]. Advanced brake systems lead to
many benefits like improvements in the load
capacity, increasing the safety and optimized life
cycle costs.
The proposed model of the innovative brake
system IBB10 is intended for use in freight wagons
and has the lowest weight on the market. It consists
of a brake cylinder which through a system of levers
and slack adjusters, transfers the force on the brake
shoe holders and onto the brake shoes that come in
frictional contact with the wheels of the wagon. The
brake force is achieved through the brake cylinder
and multiplied through the levers. Two slack adjust-
ers serve to compensate the wear of the brake shoes
and wheels. This brake system design allows easy
assembly and disassembly on each subassembly
separately, which is a great advantage in mainte-
nance and repair of the system. The innovative
IBB10 brake system can be fitted between the
wheels of a bogie type Y25 or similar and it fits the
standard built-in measures as the conventional
brake system. The function of the innovative brake
system is to provide approximately equal brake
force on all four wheels at the same time. The design
is characterized by the use of a brake cylinder with
(or without) a hand brake and two slack adjusters
for automatical adjustment of the gap between the
wheels and brake shoes.
In Figure 3 is shown the innovative system
IBB10 without hand brake. This model of the
innovative IBB10 system is the base for all other
variants.
20 T. Smileski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 17–27 (2019)
Fig. 3. Model of innovative brake system IBB10 without hand brake [6]
The service brake force is calculated according
to the following equation (1):
F = (p·S·10 – FB)·i·η – FS (N) (1)
where:
– brake cylinder pressure (bar);
– effective piston area (cm2);
– return spring force (N);
– lever ratio;
– efficiency;
– slack adjuster counterforce (N).
From all the listed factors that influence the
service brake force, only the brake cylinder pressure
is a variable, while all other factors are constant.
Taking into account the fact that for different types
of freight wagons a different brake force is needed
and the pressure is defined according to the UIC
standard, from design point of view the ratio of the
levers can be changed.
The innovative brake system IBB10 is in-
stalled on one bogie, and since one freight wagon
usually has two bogies, in most cases, two IBB10
systems will be installed per wagon as a set. Be-
cause each freight wagon should have parking op-
tion when is removed from the train composition (or
because some other reasons), at least one IBB10
unit must have a parking hand brake. In Figure 4 is
shown a variant of the innovative brake system
IBB10 with a platform hand brake. This brake
system with platform hand brake has the same
function as IBB10 without hand brake, but with
added function of the hand application of a parking
brake. The application of the platform hand brake is
done from the platform of the wagon.
Fig. 4. Model of innovative brake system IBB10 with platform hand brake [6]
p
S
BF
i
SF
p
i
Development of innovative brake system for rolling stock 21
Маш. инж. науч. спис., 37 (1–2), 17–27 (2019)
The activation of the platform hand brake
should be performed from the platform of the freight
wagon by turning the hand wheel through a box
with conical gears and a telescope cardan shaft,
which is connected with the spindle of the platform
hand brake mechanism. In Figure 5 is shown a
model of Y25 bogie with installed brake system
IBB10 with platform hand brake and connecting
components for activation with segment of the
wagon platform. By turning the hand wheel, the
torque is transmitted through the gears and the
cardan shaft to the spindle of the platform hand
brake mechanism activates (extends) the brake
cylinder. This mechanism is connected to the piston
rod and during service brake it moves together with
the piston rod. The connection of the hand brake to
the platform is necessary to be performed with a
telescope cardan shaft in order not to decrease the
degrees of freedom of the brake system during
braking and releasing.
Fig. 5. Model of Y25 bogie with installed brake system IBB10 with platform hand brake and connection components
for activation with segment of the wagon platform
3. MULTI-BODY SIMULATION OF THE
INNOVATIVE BRAKE SYSTEM
In the multi-body simulation is used finite ele-
ment method, which is a key method for design, ho-
mologation and research in the field of railways and
railway vehicles [7]. This type of simulation is one
of the most advanced methods for developing and
optimizing a designed mechanism. Because the
brake system is a subject of large static and dynamic
loads during the braking process, it is necessary that
the brake system has undergone multi-body simula-
tion before the prototype is produced. Figure 6
shows a 3D model of the innovative brake system
IBB10 with platform hand brake for multi-body
simulation.
The main components of the innovative brake
system IBB10 with platform hand brake, which are
shown in Figure 6 and are evaluated in the simula-
tion are the following:
1. Four hangers on which the brake system are
supported.
2. Special rubber bushings mounted on the han-
gers to provide freedom of movement and
reduce vibration.
3. Brake shoes that in the 3D model are shown
with an approximate geometry.
4. Primary beam which is one of the most loaded
elements in the system.
5. Secondary beam which due to the slack adjust-
ers location is not subject to high loads.
6. Two slack adjusters that in the 3D model are
presented as rigid bodies with a weight corres-
ponding to the real one. Given the complexity
of the slack adjusters that would greatly comp-
22 T. Smileski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 17–27 (2019)
licate the simulation, the internal components
will not be analyzed.
7. Brake cylinder which is connected with four
levers to the primary beam.
8. Four levers which perform multiplication of the
force from the brake cylinder to the slack ad-
justters. In addition to the loads in the horizon-
tal direction, under the action of vertical vibra-
tions, they are heavily loaded in the vertical
direction.
9. Platform hand brake which due to the large
number of levers and connection elements will
be represented as a rigid body with a weight
equal to the real one.
Fig. 6. 3D model of IBB10 with platform hand brake for simulation [10]
Considering that the brake system is in direct
relation with the bogie of the wagon, it is necessary
to include in the simulation all main elements that
are in direct relation to the brake system and the rail.
The accelerations to be included in the simula-
tion are according to BS EN 13749 [9]. This stand-
ard defines the accelerations in each direction which
are used in the calculation and are divided into two
classes. For components related to the bogie are
considered the acceleration values in Table 1, while
the components related to the wheelset are the ac-
celeration values listed in Table 2. It is obvious that
the accelerations of the wheelset related compo-
nents are greater (especially in the vertical direc-
tion) because the wheels are the most exposed com-
ponents of the entire wagon and are directly affected
by all irregularities of the rail. All components con-
nected to the bogie are subject to minor accelera-
tions because there are suspension springs between
the body of the bogie and the axles of the wheels.
As the brake system is connected to the bogie,
the accelerations shown in Table 1 are most com-
monly used (when the system is released). In case
of braking, due to the frictional contact between the
wheels and the brake shoes, the acceleration of the
wheels is transmitted to the brake system. In this
case there will be combined acceleration values
from Table 1 and Table 2. Also, becuse of the dy-
namic nature of the braking process caused by the
contact of the brake system and the rotating wheels,
there are additional loads which need to be consid-
ered.
Development of innovative brake system for rolling stock 23
Маш. инж. науч. спис., 37 (1–2), 17–27 (2019)
T a b l e 1
Accelerations according to EN 13749 – Table D.1
(bogie mounted parts) [9]
Direction Extreme
acceleration (g)
Continual acting
acceleration (g)
Vertical ±20 ±6
Transversal ±10 ±5
Longitudinal ±5 ±2.5
T a b l e 2
Accelerations according to EN 13749 – Table D.2
(wheelset mounted parts) [9]
Direction Extreme
acceleration (g)
Continual acting
acceleration (g)
Vertical ±70 ±25
Transversal ±10 ±5
Longitudinal ±10 ±5
Figure 7 shows 3D model of Y25 bogie, which
includes the innovative brake system IBB10 with
platform hand brake. This 3D model does not show
the springs between the wheel axles and the body of
the bogie to reduce the complexity of the entire sys-
tem, but during the simulation itself, the functio-
nality of the springs is taken into account.
The dynamic simulation model has a role to
simulate the analyzed system as realistically as
possible. In this case, during the simulation, it is
assumed that the wheels are in contact with the rail
and rotate in the direction shown in Figure 8. In the
middle area where the spherical joint of the bogie is
positioned is added a load in the form of a mass
dummy. This mass dummy simulates the load,
expressed as half of the mass of the entire wagon
(Figure 9).
For a clearer view of the analyzed model, in
Figure 9 is shown in several views, where the main
components of the 3D model are described.
Fig. 7. 3D model of Y25 bogie and IBB10 with platform hand brake for simulation [10]
Fig. 8. Supports and constraints on the 3D model of the bogie and IBB10 for simulation [10]
24 T. Smileski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 17–27 (2019)
Fig. 9. Description of the 3D model for multi-body simulation [10]
Given that the mass of the wagon is variable,
depending on whether it is empty or loaded, know-
ing the stiffness characteristics of the springs on the
bogie, the position of the entire analyzed system can
be simulated. Figure 10 shows the height of the
IBB10 in relation to the wheel axis in the case of
empty wagon (m = 26 t) and in fully loaded wagon
(m = 90 t). In fully loaded static position the height
of the bogie is 30 mm lower compared to the empty
wagon. Because in the analysis is included only one
bogie, while the wagon has two, the weights that
will act on one bogie will be two times smaller than
the indicated ones.
Fig. 10. Height of the bogie relative to the wheel axis on empty wagon (left) and fully loaded wagon (right) [10]
Taking the above parameters, in order to verify
the connection of the elements in the 3D model, it is
necessary to make an initial simulation. Figure 11
shows the force on the hangers (position 1 in Figure
6) due to gravity load. The results of this initial
simulation show a good correspondence with the
analytical calculation.
It should be noted that there is a different load
force on the hangers because there is unequal
distribution of the masses due to the location of the
Development of innovative brake system for rolling stock 25
Маш. инж. науч. спис., 37 (1–2), 17–27 (2019)
brake cylinder (and the hand brake). The H1 and H2
hangers which are located near the primary beam
are more loaded (in a static position with force F ≈
750 N), while the hangers located near the second-
ary beam H3 and H4 are less loaded (in a static
position F ≈ 250 N). The goal of correctly setting
the initial conditions is to get as much accurate
results as possible. The results of such analysis are
obtaining the stresses and deformations in the
analyzed cases. More important is the get the maxi-
mum stresses in the analyzed cases, but in some
cases when the system needs to have a smaller or
larger elasticity, deformations play more important
role.
Fig. 11. Hanger force due to gravity load [10]
Figure 12 shows deformations of the levers
which are connecting the brake cylinder to the
primary beam and the slack adjusters. As can be
seen, the maximum deformation is ≈ 3.7 mm and
it occurs in the case of extreme vertical vibrations.
The design of this brake system limits these
deformations due to cylinder holder which is in a
sliding connection with an U-profile which is
mounted on the primary beam. This holder limits
the movement and deformation of the levers in a
vertical direction. This is shown in Figure 13.
Obtaining the maximum stresses from the load
cases is of great importance in order to create
optimized design and to make maximum utilization
of the material. In this way lighter and cheaper
products can be designed, which is a very noticeable
trend nowadays. Figure 14 shows the stresses of the
levers in extreme load case
Fig. 12. Lever - deformation in extreme load case [10]
26 T. Smileski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 17–27 (2019)
Fig. 13. Brake cylinder holder limits the deformation of the levers [10]
Fig. 14. Lever – stresses during extreme load case [10]
CONCLUSION
This paper shows one part of the development
of a complex mechanical system – an innovative
brake system for rolling stock. Considering that the
brake systems are of great importance for the safety
of rail traffic and are exposed to large static and
dynamic loads under external conditions, the
development of such system is a long and complex
process.
In the process of developing a brake system,
the most important asset is to use the most advanced
softwares, methods and techniques. Multi-body
simulation together with finite element analysis is
one of the key methods for design, homologation
and research in the field of railways and railway
vehicles. Multi-body simulation can replace very
expensive tests and measurements of the railway
vehicle. Nowadays almost every newly developed
product for the railway industry goes through multi-
Development of innovative brake system for rolling stock 27
Маш. инж. науч. спис., 37 (1–2), 17–27 (2019)
body simulation. The results of the simulation
indicate that the brake system satisfies the UIC
standard criteria and meets the requirements of the
customers. By successfully passing the simulation,
there is a significant increase of the chances for
successfully completing the validation tests and
successfully palcing this innovative brake system
on the market.
REFERENCES
[1] Chary, R., Khan, E.: Design and Analysis of Train Brake
System, International Journal of Advanced Research and
Innovation, Vol. 7, Issue 3, pp. 27–33 (October 2014).
[2] Wynd, D., Connelly, M.: Advanced Bogie Brakes, Proce-
edings, Conference on Railway Engineering, Wellington,
September 12–15, 2010.
[3] Sharma, R. C., Dhingra, M., Pathak, R. K.: Braking Sys-
tems in Railway Vehicles, International Journal of Engi-
neering Research & Technology, Vol. 4, Issue 1, pp. 204–
211 (January 2015).
[4] Дуковски, В.: Менаџмент на развојот на нови произ-
води, Универзитет „Св. Кирил и Методиј“, Скопје,
2001.
[5] Smileski, S., Smileski, T.: Integrated bogie brake and
slack adjuster for the use with said integrated bogie brake,
Patent WO 2013098350 A2, December 27, 2011.
[6] Smileski, T., Rakipovski, R., Mičić, M.: Comparison of
Classical Brake for Freight Wagons with New Integrated
Bogie Brake IBB10 for Freight Wagons, RAILKON `16,
Niš, October 13–14, 2016.
[7] Weidemann, C.: State of the Art Railway Vehicle Design
with Multi-Body Simulation, Journal of Mechanical
Systems for Transportation and Logistics, Vol. 3, No 1, pp.
12–26 (2010).
[8] Bhuiyan, N.: A framework for successful new product de-
velopment, Journal of Industrial Engineering and Mana-
gement (JIEM), Volume 4, Issue 4, pp. 746–770 (2011).
[9] BS EN 13749:2011, Railway Applications – Wheelsets and
Bogies. Method of specifying the structural requirements
of bogie frames, 2011.
[10] Artner, W.: MBD/FEA-Analysis IBB10 Brake System New
Design, Report a 13010 RV0, November 2013.
[11] Вртаноски, Г.: Иновациите и инвенцијата – vслов за
излез од економската криза, предавања на постдип-
ломски студии (ПЛМ), Развој и менаџмент на произ-
водите, Универзитет „Св. Кирил и Методиј“, Машин-
ски факултет, Скопје, 2012.
[12] Kim, L.: Imitation to Innovation – The Dynamics of Ko-
rea's Technological Learning, Harvard Business School
Press, 1997.
[13] Lunden, R., Vernersson, T.: Mechanical braking systems –
development and challenges, Presentation at 19th Nordic
Seminar on Railway Technology, Chalmers University of
Technology, Lulea, September 14–15, 2016.
[14] Pugi, L., Palazzolo, A., Presciani, P., Fioravanti, D.: Simu-
lation and optimization of railway pneumatic braking sys-
tem, World Congress for Railway Research WCRR2006,
Montreal, June 2006.
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 29–40 (2019)
Number of article: 615 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: May 21, 2019 UDC: 005.61-049.3:621.98-034.1
Accepted: August 21, 2019
Original scientific paper
TOTAL PRODUCTIVE MAINTENANCE – TOOL TO IMPROVE
THE COMPANIES PERFORMANCE
Andon Naskovski1, Gligorče Vrtanoski2
1MSc Student at the Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia 2Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: The research of the paper shows the implementation of TPМ methodology on total maintenance
and its main tool, Autonomous Maintenance (AM). The goal is to increase the productivity and efficiency of an existing
production line for pickling metal sheet. Total analysis of the production line is done by identifying weak points, i.e.
assemblies using the Overall Equipment Effectiveness (OЕE) indicator. With applying the main tool, autonomous
maintenance from TPM methodology, an attempt has been made to identify the anomalies, a system for reporting errors
has been created, the number of standards and education of the operators has increased, and in order to reduce the
number of delays in the production line. This will improve the efficiency of the employees and the productivity of the
company as a whole.
Key words: maintenance; total productive maintenance – TPM; preventive maintenance; autonomous maintenance;
overall equipment effectiveness
ЦЕЛОСНО ПРОДУКТИВНО ОДРЖУВАЊЕ – АЛАТКА ЗА ПОДОБРУВАЊЕ
НА ПЕРФОРМАНСИТЕ НА КОМПАНИИТЕ
А п с т р а к т: Истражувањето претставено во трудот ја прикажува имплементацијата на методологијата
на целосно продуктивно одржување (ТРМ), како и нејзината главна алатка – автономно одржување (АM).
Целта е зголемување на продуктивноста и ефикасноста на постојна производствена линија за лужење на чели-
чен лим. Целосното анализирање на производствената линија е направено преку утврдување на слабите точки,
т.е. склопови со помош на индикаторот за севкупна ефективност (ОЕЕ).. Со имплементацијата на главната
алатка – автономно одржување (АM) на методологијата ТРМ, направен е обид да се идентифкуваат аномалии-
те, креиран е систем за информирање за грешки, зголемен е бројот на стандарди и едукации на операторите, а
со цел да се намали бројот на застои на производствената линија. Со тоа ќе се подобри ефикасноста на врабо-
тените и продуктивноста на компанијата во целост.
Клучни зборови: oдржување; целосно продуктивно одржување – ТРМ; превентивно одржување;
автономно одржување; севкупна ефективност на опремата
1. INTRODUCTION
In today’s dynamic environment, the reliabil-
ity of the systems is crucial to creativity. The poor
organizational competence in the management of
the maintenance functions may have a serious im-
pact on the competitiveness by reducing the pro-
gress, increasing the supply and not meeting the
deadlines. The equipment, technology and develop-
ment of its features become a substantial factor that
demonstrates the power of the organization and in
that manner separates it from the other companies.
The maintenance is becoming a strategic tool, un-
like before, when the only objective of surveillance
was the maintenance cost decrease. The investment
in the maintenance is one of the basic functions of
the company. It reflects in the quality improvement,
the safety, the flexibility and production time. Over
30 A. Naskovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 29–40 (2019)
the last decade, the opinion that the maintenance is
not a separate, isolated function and it needs to be
treated as all the other company activities have be-
come predominant. Maintenance is a full partner of
the rest of the organizational functions and should
strive to realize the company’s strategic goals. The-
refore, maintenance is becoming a strategic neces-
sity for the manufacturers worldwide. Increase of
business pressure put the maintenance as a key role
in the company’s functions. The modern manufac-
turing requires that the organization, if it wants to
achieve have a World Class Manufacturing – WCM,
has both features – effective and efficient mainte-
nance.
As part of the benchmark ideas for organiza-
tional performances and processes improvement,
regarding the competition, the TPM has been identi-
fied as the best solution to increase the company
productivity.
2. OVERVIEW OF THE LITERATURE
RESEARCH
The researcher R. Kennedy [5] actualizes total
productive maintenance (TPM) in the manufactur-
ing as a revolutionary approach in the maintenance.
The main point of the TPM is that it develops out-
side the lean approach. Its significance goes far bey-
ond the limited view of maintenance because it is a
part of a total approach to more productive manu-
facturing. The TPM concept addresses the maxi-
mization of overall plant and equipment effecttive-
ness through the elimination or minimization of the
six machine losses, creating a sense of ownership
for plant and equipment operators through a process
consisting of training, involvement and promoting
continuous improvement through small group acti-
vities involving production, engineering and mate-
rial personnel.
There are several researches carried out by dif-
ferent researchers that review and determine the sig-
nificance of the development and application of the
TPM in the production [3, 7, 8]. It is well known
that TPM is introduced in the company, if the appli-
cation is done when many employees participate.
All involved participants need to be focused and
need to cooperate at all levels. Team work is the
most important factor. There are many approaches
in the application of the TPM, but there is no evi-
dence for non-application due to a certain problem.
The total productive maintenance (TPM) is an
improvement in the manufacturing, i.e. it is a practi-
cal analogy to the total quality maintenance (TQM),
while the Japanese researchers explain it as concept
for management with the equipment in order to
achieve increased productivity by involving all em-
ployees. According the researcher S. Nakajima [3],
TPM’s objective is to continuously improve the
equipment and prevent equipment deterioration, in
order to achieve maximum efficiency. These ob-
jectives require strong management and great sup-
port from all involved employees.
TPM may be analyzed in three words [3]:
• Total: Meaning involvement from workers to
top management employees.
• Productive: Meaning no more unnecessary ac-
tivities or manufacturing delay and focusing
on services that satisfy the consumers’ needs.
• Maintenance: Keeping the equipment and
company clean and in an operating condition
that is good or even better than the original.
The success of every business improvement is
a strategy that rests on a strong and dynamic leader-
ship that has to be presented by winners. The author
J. Levitt [6] in his work points out that the key play-
ers for the TPM are the machine operators. In this
case the maintenance staff has an advisory role.
Also, he states that the winning factor of the TPM is
to train the operators to an extent that would be suf-
ficient to achieve full AM.
The earliest application of the TPM is in Japan,
especially in the fast-growing automobile industry,
i.e. in the Toyota Company and its branches. As a
result, many Japanese companies, encouraged by
the Toyota’s success, started to apply the TPM, but
at the early beginning there was no noticeable suc-
cess [9]. All of this changed in 1970 when Japan
faced economy decrease. From that moment it star-
ted to rapidly adapt TPM in order to improve the
manufacturing productivity [10]. The TPM applica-
tion process has been developed by the researcher
S. Nakajima [3]. He developed the process in sev-
eral stages in order to provide standardized and re-
peatable methodology.
For comparison, there are two different ap-
proaches to define the TPM: the Japanese approach
presented by the authors S. Nakajima [3], F. Gotoh
[9] and K. Shirose [11], and the Western approach
by the authors P. Willmott [12] and T. Wireman
[13]. These two approaches are also supplemented
by the approach of the author C. Bamber [14]. The
differences between the Japanese and the Western
approaches defining the TPM are small compared to
the similarities that are much more significant. The
Japanese value the team work in small groups and
participation of all company employees in the TPM
Total productive maintenance – tool to improve the companies performance 31
Маш. инж. науч. спис., 37 (1–2). 29–40 (2019)
process application, in order to meet the improve-
ments intended for the equipment used. The West-
ern approach is more focused on the equipment,
while the employees’ involvement in the goal achie-
vement is not crucial. Although it can be noticed
that both approaches are very similar, the Japanese
approach focuses on the people and the process,
while the Western approach starts from the im-
provement of the equipment efficiency, which does
not separate it from the team work, but also does not
lead to correct equipment management and equip-
ment use [14].
3. TOTAL PRODUCTIVE MAINTENANCE
(TPM)
TPM is an innovative Japanese concept. The
origin of TPM can be traced back to 1951 when pre-
ventive maintenance was introduced in Japan. How-
ever, the concept of preventive maintenance was
taken from USA. Nippondenso was the first com-
pany to introduce plant wide preventive mainte-
nance in 1960. Preventive maintenance is the con-
cept wherein operators produced goods using ma-
chines and the maintenance group was dedicated
with work of maintaining those machines, however
with the automation of Nippondenso, maintenance
became a problem, as more maintenance personnels
were required. So the management decided that the
operators would carry out the routine maintenance
of equipment [1].
TPM is a complex and long process that shows
the employees that it is a legitimate methodology
which would improve the processes. If the TPM is
to be successful in any industry, both teams – the
management and workers, must operate in an at-
mosphere that would be beneficial to the company.
The company employees need to truly take action if
this methodology is to succeed.
TPM is consisted of eight pillars. Its method-
ology has a manner of excellent planning, organiza-
tion, monitoring and practical control applied
through the eight pillars. The TPM initiative, as pro-
moted by the Japanese Institute for Plant Mainte-
nance, includes a plan for application of all eight
pillars that need to make gradual improvement of
the productivity through controlled maintenance,
reduction of costs and decreased delays. The meth-
odology core (Figure1) is classified in eight pillars
and activities:
• 5S
• Autonomous maintenance (AM).
• Focused maintenance.
• Planned maintenance.
• Quality maintenance.
• Education and training.
• Office TPM.
• Safety, health and environment protection.
Fig. 1. The pillars of TPM [10]
The mission of each pillar is to reduce losses
in order to eliminate all losses in the process.
Prior to the initiation of the TPM application it
is necessary for the management to compose a pro-
gram and inform all employees so that they could
understand that it is a matter of long-term program
that change the company culture, and not just an in-
itiative intended for the maintenance services.
TPM structure supports the culture changes
where the responsibilities and ownership of the pro-
cesses are clearly defined and supported.
We may also mention that the pillars within
themselves change the direction, develop the sys-
tem, process and standards along with the employ-
ees. It enables and motivates the leaders to operate
with their employees and teams to decrease the bar-
riers between them in order to create a single and
cohesive system where all employees from all levels
would work to achieve the same goal. This is a man-
ner of change management and observance of a
strict methodology which would provide consistent
future results. The manner of establishing of this
methodology is the application of all eight pillars.
By applying TPM many companies mark productiv-
ity increase as well as increase of the reliability of
the machines, the malfunction frequency is de-
creased and the effectiveness of the quality is in-
creased. However, it mostly affects the increase of
the productivity. This proactive strategy may con-
tribute to the improvement of the performances
stressed in many researches.
32 A. Naskovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 29–40 (2019)
4. TECHNICAL DESCRIPTION
OF PRODUCTION EQUIPMENT
The application of one of the TPM tools, i.e.
the AM, and the need of its application will be
displayed in this chapter. The production line for
pickling metal sheet is integral part of the company
Arcelor Mittal – Skopje. The equipment is com-
posed of several assembly parts and it works as one
entirety. During its operation there are often delays
that are predictable due to certain events, but some
of them cannot be predicted as they occur suddenly.
The production pickling metal sheet line is shown
on Figure 2 and is made by the British company
WEAN LIMITED INC. The production line is for
producing the pickled metal sheets in a form of
strips, made from the hot rolled materials according
to the standards used for cold forming of sheet.
Fig. 2. Production process of pickled metal sheet [2]
4.1. Overview of delays and problems within
the period 2014–2017
The use of all tools offered by the AM defines
the critical equipment of the pickling metal sheet
line. The annual reports on the delays, as well as the
total line effectiveness are the biggest indication on
the major problems. The five most critical pickling
metal sheet assemblies are determined through
these reports for the period from 2014 to 2017, as
well as the analysis of the total effectiveness, but
they also determine the year of worst delays. The
chart shown on Figure 3 displays the delays in a
time interval on the pickling metal sheet assemblies
for the period from 2014 to 2017.
Fig. 3. Duration of delays of the assembly from 2014 to 2017 [2]
Total productive maintenance – tool to improve the companies performance 33
Маш. инж. науч. спис., 37 (1–2). 29–40 (2019)
The Figure 4 is a graphical display of the total
delay period of the pickling metal sheet line assem-
blies, for each year separately for the period from
2014 to 2017. Based on that, it has been determined
that the worst year with the biggest number of de-
lays on the pickling metal sheet line is 2014. This
year is taken as a reference for the determination of
the overall equipment effectiveness (ОЕЕ).
Fig. 4. Total pickling metal sheet delay period by years
5. DEFINITION OF OVERALL EQUIPMENT
EFFECTIVENESS INDICATOR
The overall equipment effectiveness (OEE) is
a key indicator for the performances of a process or
equipment. It may be set as a benchmark for the
measuring or analysis of a process and its effective-
ness. In other words, the OEE is the full use of time,
materials and facilities during the production pro-
cess [4]. The ОЕЕ is calculated based on the follow-
ing three indicators:
1. Availability (R) – is the ratio of actual produc-
tion time that a machine is working divided by
the time the machine is available.
2. Performances (P) – is the percentage of total
number of parts on that machine to its produc-
tion rate. In simple words, performance mea-
sures the ratio of actual operating speed of the
equipment and the ideal speed.
3. Quality (Q) – is an indicator calculated as the
proportion of the total number of functional
products manufactured with the machine and
the total number of products manufactured
within a period of one year production.
After the three indicators are defined, the OEE
can be calculated with the equation (1):
OEE = R·P·Q (1)
The calculated values of the OEE with the
equation (1) are values between 0 and 1 or expres-
sed in percentage it would be between 0% and
100%. The Table 1 displays the ideal values of the
three indicators, as well as the value of the ОЕЕ
after the application of the recommendations for
World Class Manufacturing [3, 4]. It is recommen-
ded and acceptable for the OEE to be 60% in which
case the companies achieve satisfactory results [4].
The Table 1 displays the calculated indicators
and the ОЕЕ for each individual year within the re-
viewed period. According to the data in the Table 1,
it is visible that 2014 has the worst effectiveness.
The reason due to which 2014 has this result is the
system of operation that existed that year, i.e. the
small-scale production planned. The occurrence of
a large number of delays of the pickling metal sheet
line contributed to this outcome. This shows that the
pickling metal sheet line in 2014 was at a delay for
one fifth of the available time and did not manu-
facture.
T a b l e 1
Ideal and calculated indicators
of the overall equipment effectiveness [3] (%)
Year R
Availability
P
Performances
Q
Quality
ОЕЕ – total
efectiveness
2014 82 64 92 48
2015 86 63 91 49
2016 80 71 94 53
2017 84 72 95 57
Ideal
values 90 95 99 84,645
5.1. Determine of critical equipment
Following the instructions from the research
[2], the most critical year within the period from
2014 to 2017 needs to be determined and then also
the five most critical assemblies for that year. Figure
3 displays the duration of the delays of the pickling
metal sheet line for the period from 2014 to 2017,
with 2014 being the most critical one. It also dis-
plays the ОЕЕ of the equipment for the period from
2014 to 2017 with the results given in Table 1, con-
firming that 2014 is a critical year when the equip-
ment is less effective. Analyzing the aforementi-
oned, it shall be considered that 2014 defines the
five critical pickling metal sheet line most critical
assemblies.
The critical assemblies of the pickling metal
sheet line are determined using the recommenda-
tions [2]. The Table 2 displays the ranked critical
assemblies based on special marks indicators for
34 A. Naskovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 29–40 (2019)
several parameters such as: delays, quality, manu-
facturing, safety, maintenance costs, average time
for repair etc. By expressing the real evaluation of
the assemblies in Table 2, the classification of the
assemblies can be made. In this manner the assemb-
ly with over 15 points are set in the “AA” class, of
the most critical assemblies, the assemblies with 10
to 15 points are set in the “A” class, or critical as-
semblies, the assemblies with 1 to 9 points are set in
the “B” class, or problematic assemblies, and with 0
points are set in the “C” class, or defect free assem-
blies. The evaluation of the steel sheet metal pick-
ling line assemblies is made in the presence of ex-
perts from the maintenance and production sectors.
T a b l e 2
Pickling metal sheet line equipment ranking
Assembly MTTR
(min)
Number
of delay
Quality
impact
Production
impact
Safety
impact
Maintenance
costs
Total
points Class
1 Entry conveior 0 0 0 5 5 5 15 AA
Entry coil opener 0 0 0 2 1 1 4 B
2 Uncoiler 84 5 5 5 5 5 20 AA
3 Entry transfer car 300 6 5 5 5 5 20 AA
Entry hydraulic 250 4 3 5 1 5 14 A
4 Processor 112 7 5 5 1 5 16 AA
6 Mechanical shear 0 0 5 0 0 1 6 B
5 Welding machine 40 3 5 5 5 5 20 AA
7 Entry bridle rolls 360 2 5 5 0 3 18 AA
8 Entry Looper 0 0 1 1 1 2 5 B
Baths 0 0 1 1 1 1 4 B
12 Exit roll after baths 30 1 4 3 1 5 13 A
14 Side trimming machine 45 2 5 5 5 5 20 AA
Crop shear 0 0 1 1 1 1 4 B
Rubber conveior for mettal waste 0 0 1 1 1 1 4 B
15 Exit bridle rolls 540 1 5 5 1 2 13 A
System for oiling of strip 0 0 0 0 0 0 0 C
Coiler 0 0 5 5 1 3 14 A
Exit hydraulic 0 0 5 5 1 5 16 AA
16 Coil oppener 0 0 0 0 0 0 0 C
18 Fan 0 0 0 5 5 5 15 AA
Other 60 2 3 3 2 3 11 A
6. IMPLEMENTATION OF TPM TOOL:
AUTONOMOUS MAINTENANCE
The calculations that were done show the pro-
duction pickling metal sheet line has to be modified
regarding the manner of operation. By applying the
TPM tool: autonomous maintenance (AM), the de-
crease of the number of delays will be affected, as
well as the productivity increase. The application of
the AM will be based on the five critical points.
Also, the application of the AM is intended to elim-
inate the several adverse aspects occurring in the
course of operation such as:
• High costs due to excessive number of delays.
• Contaminated and damaged equipment.
• Important quality losses.
Total productive maintenance – tool to improve the companies performance 35
Маш. инж. науч. спис., 37 (1–2). 29–40 (2019)
• Limited knowledge of the equipment by the
operators.
• Very small number of improvement proposi-
tions.
By applying the AM, which is a part of the
TPM methodology, many good results may be achi-
eved regarding the improvement of the productivity
and decrease of the number of delays. This is confir-
med by using a line of indicators appearing during
the application of the seven steps of the AM. While
applying the first step, cleaning, an equipment ano-
maly notification system has been introduced. The
system is composed of two notification manners
with blue labels intended for the solution of the
problems by the AM-teams and red labels intended
for more serious problems solved by the maintenan-
ce teams.
Fig. 5. Expected blue label results
Figure 5 displays the expected results of the
blue labels after the application of the first step of
the AM. The blue labels mark which of the AM-
team members can solve the problems without
company maintenance assistance. By analyzing the
receive results displayed on Figure 5 it can be
expected that the number of found anomalies and
solved anomalies will grow each year. The solved
blue labels intended for the AM-teams shall mark
the defects solved by the AM-teams.
Fig. 6. Expected red label results
The Figure 6 displays the red label results after
the application of the first step of the AM. The ano-
malies marked with red labels are intended for the
company maintenance members, i.e. those are ano-
malies which the AM-teams cannot solve them-
selves. Analyzing the results displayed on Figure 6,
it can be expected that an increase will take place
regarding the solved and detected anomalies mar-
ked with red labels each year. After the application
of the first step of the AM, it is expected that the
AM-teams’ members will be trained for correct use
of the notification system.
While applying the second step of the AM an
inspection has been made of the most critical points
of the steel sheet metal pickling line, whereby the
anomalies detected are divided in several categories
and are displayed on Figure 7. After the application
of this step, the operators will be one level higher in
732
1427
2163 2167
701
1427
2099 2112
0
500
1000
1500
2000
2500
2018 2019 2020 2021
Nu
mb
er
of
an
om
ali
es
Time (years)
found anomalies marked withblue labels
solved anomalies marked withblue labels
274
559
886 881
235
444
786 790
0
200
400
600
800
1000
2018 2019 2020 2021
Nu
mb
er
of
an
om
ali
es
Time (years)
found anomalies markedwith red labelssolved anomalies markedwith red labels
36 A. Naskovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 29–40 (2019)
the familiarization with the equipment and its func-
tioning. In that manner, they are no longer passive
observers, but become active participants in the
problem prevention.
The Figure 7 displays the critical equipment
anomalies prior to the application of the AM. Ana-
lyzing the results, it can be noticed that there are too
many anomalies of the critical equipment. The ano-
malies detected refer to all critical points. The
Figure 7 also displays that the category of unneces-
sary openings and damaged protective parts is the
most critical.
After the application of the second step, it may
be expected that all anomaly categories decrease.
This fact is displayed on the Figure 8.
With the application of the third step from the
AM, standardization, intended to create standards
for the critical points, it can be expected that the
number of small delays will decrease. It is due to the
insufficient knowledge of the equipment the opera-
tors have. The development of the standards for the
critical points of the equipment is necessary, as well
as the mutual cooperation with the operators,
includeing the company maintenance.
Fig. 7. Critical equipment anomalies prior to the application of the autonomous maintenance (AM)
Fig. 8. Critical equipment anomalies after to the application of the autonomous maintenance (AM)
Total productive maintenance – tool to improve the companies performance 37
Маш. инж. науч. спис., 37 (1–2). 29–40 (2019)
The Figure 9 displays the number of expected
developed standards after the first year of applica-
tion of the AM. Analyzing the obtained results, it
can be observed that rapid progress is expected
within a year from the application of the AM. This
progress is necessary because there are no standards
developed for the pickling metal sheet line up until
the AM commencement, and with that the entire
system is based on the operators’ experience.
The Figure 10 displays the number of devel-
oped standards after the first year of application of
the AM, for each individual critical point of the
equipment.
Fig. 9. Number of standards developed after the first year of the AM application
Fig.10. Number of standards developed after the first year of the AM application
The Figure 10 displays the results from which,
it can be observed that the most of the developed
standards are envisaged for the critical equipment –
welding machine. No standards exist for this equip-
ment and therefore the operators face problems such
as machine settings that sometimes can take up to
two or three hours. After the application of the third
step these problems are expected to be eliminated
and in the same time the operators’ knowledge of
the equipment is expected to increase.
The achieving of the objective to decrease the
number of delays and increase productivity may be
0
15
20
23
2526
2829
3130
35
38
0
5
10
15
20
25
30
35
40
jan feb mar apr may jun jul aug sep oct nov dec
Nu
mb
er
of
sta
nd
ard
s
Time (months)
89
10
56
0
2
4
6
8
10
2.Uncoiler 3.Entry transfercar
5.Weldingmachine
7.Entry bridlerolls
14.Sidetrimmingmachine
Nu
mb
er
of
sta
nd
ard
s
Critical equipment
38 A. Naskovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 29–40 (2019)
expected to be reached after the application of all
seven steps of the AM. The Figure 11 displays the
increase of the overall epquipment effectiveness
(ОЕЕ) of the equipment after the application of the
AM of an identical production line in the Arce-
lorMittal Company, Gent, Belgium. The displayed
results on the Figure 11 show the OEE increase
trend from the beginning of the application of the
seven steps of AM in 2005, until the final applica-
tion of the AM in 2008.
Analyzing the Figure 11, it can be noticed that
the ОЕЕ of the equipment is satisfactory, staring
from 2005 and finishing in 2008. The achieved
results fully justify the correct decision of the
ArcelorMittal Company, Gent, to apply AM.
The Figure 12 displays the expected results for
the ОЕЕ of the pickling metal sheet line in the
ArcelorMittal – Skopje company. The columns
marked with blue and red color, i.e. the time period
by years from 2014 to 2017, give the actual data
used in the calculation to prove the need of
modification of the AM in the operation manner of
the production line. The columns marked with green
color, i.e. the time period by years from 2018 to
2021, represent the time during which the AM is to
be applied. That is the time period for which there
is no particular data, but due to comparison, the data
given on the Figure 11 for the period from 2005 to
2008 are used, as comparison values in the
application of the AM.
Fig. 11. Overall equipment effectiveness (ОЕЕ) after the application of the autonomous maintenance (AM) [9]
Fig. 12. Envisaging of the overall equipment effectiveness (OEE) for the period from 2014 to 2021
74,83
75,59
70,11
66,42
69,964,74
72,4372,52
58,94
63,61
69,5670,59
75,15
71,4571
77,21
68,96
64,94
79,02
0
10
20
30
40
50
60
70
80
90
Ove
rall
Eq
uip
me
nt
Eff
ec
tive
ne
ss
-ОЕ
Е (
%)
Time (years, months)
48 4953
57
75,59 76 77,5 79,02
0
10
20
30
40
50
60
70
80
90
Basis 2014 2015 2016 2017 2018 2019 2020 2021
Ove
rall
Eq
uip
me
nt
Eff
ec
tive
ne
ss
-ОЕ
E (
%)
Time (years)
Total productive maintenance – tool to improve the companies performance 39
Маш. инж. науч. спис., 37 (1–2). 29–40 (2019)
The predictions given in the Figure 12 repre-
sent the results from the ОЕЕ by years during the
application of the AM of the equipment and if in any
part of the four year application the results obtained
differ from the expected, immediate reaction is
needed to detect and solve the problem and correct
the course of events in the application.
The Figure 13 displays the comparative analy-
sis of the application of the AM between the expec-
ted results from ArcelorMittal – Skopje and the
achieved results in ArcelorMittal – Gent. The co-
lumns marked with blue color on Figure 13 are the
delays from 2014 to 2017 in ArcelorMittal – Skopje.
The columns marked with green color are the
expected results after the application of the AM in
ArcelorMittal – Skopje. The columns marked with
orange colour are the results obtained after the
application of the AM in ArcelorMittal – Gent. The
comparative overview shows that during all years of
application of the AM the same results as in Arce-
lorMittal – Gent are expected. The second and third
application years are considered to be exceptions,
and in that period the OEE of the production line in
ArcelorMittal – Skopje is expected to increase.
Fig. 13. Comparative overview after the АО application
7. CONCLUSION
The main benefits from the TPM methodology
application are the decrease of the number of delays
of the equipment, decrease of the clients’ com-
plaints, dedicated and educated workers, as well as
improvement of the quality of the product. The suc-
cessful TPM methodology application depends on
all involved participants in the company. Mainly,
the TPM methodology is helpful in the determina-
tion and decrease of the unnecessary costs. Accord-
ing to the obtained results from this research it can
be concluded that by applying the TPM methodol-
ogy the goal is achieved, i.e. the productivity is in-
creased and the number of steel sheet metal pickling
line delays are decreased.
REFERENCES
[1] Venkatesh, J.: An Introduction to Total Productive Mainte-
nance (TPM), The Plant Maintenance Resource Center,
2007.
[2] TPM Activity report – ArcelorMittal – Gent, Transformati-
on Program ArcelorMittal-Gent, Gent, 2008.
[3] Nakajima, S.: Introduction to Total Productive Mainte-
nance (TPM) (Preventative Maintenance Series), Cam-
bridge, MA, Productivity Press, 1988.
[4] Moradizadeh, H.: Overall Equipment Effectiveness and
Overall Line Efficiency Measurement Using Intelligent
Systems Techniques, University of Regina, April 2014.
[5] Kennedy, R.: Plant and Equipment Effectiveness, Mainte-
nance Journal, 1995.
[6] Levitt, J.: Handbook of Maintenance Management, Indus-
trial Press, 2009.
48 4953
57
75,59
70,1166,42
79,0276 77,5
0
10
20
30
40
50
60
70
80
90
Ove
rall
Eq
uip
me
nt
Eff
ec
tive
ne
ss
-ОЕ
Е (
%)
Time (years)
for period 2014-2014 AM-Skopje
results after implementation of AO in AM-Gent
expected results after implementation of AO in AM-Skopje
40 A. Naskovski, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 29–40 (2019)
[7] Maggard, B.: OTPM That Works: The Theory and Design
of Total Productive Maintenance: A Guide for Imple-
menting TPM, Tpm Pr, 1992.
[8] Karlsson, U., Ljungberg, O.: Ways to Implement Total
Productive Maintenance in Europe, Proceedings of the
Second International TPM Conference, Birmingham,
1993.
[9] Gotoh, F., Tajiri, M.: Autonomous Maintenance in Seven
Steps: Implementing TPM on the Shop Floor, Productivity
Press, 1999.
[10] Ireland, F., Dale, B. G.: A Study of total productive ma-
intenance implementation, Journal of Quality in Main-
tenance Engineering, Vol. 7, Issue 3, pp. 183–192 (2001).
[11] Shirose, K.: TPM – Total Productive Maintenance: New
Implementation Program in Fabrication and Assembly
Industries in Tokyo, Japan Institute of Plant Maintenance,
1996.
[12] Willmott, P.: Total Productive Maintenance: The Western
Way, Butterworth Heinemann, Oxford, England, 1994.
[13] Wireman, T.: Total Productive Maintenance – An Ameri-
can Approach, Industrial Press, New York, 1991.
[14] Bamber, C., Sharp, J., Hides M.: Factors affecting success-
ful implementation of total productive maintenance: A UK
Manufacturing Case Study Perspective, Journal of Quality
in Maintenance Engineering, Vol. 5, No. 3, pp. 162–181
(1999), https://doi.org/10.1108/13552519910282601
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 41–54 (2019)
Number of article: 616 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: May 28, 2019 UDC: 658.5:621.382.049.76]:519.86
Accepted: June 25, 2019
Original scientific paper
SIX SIGMA METHODOLOGY – TOOL FOR IMPROVING THE CAPABILITY
OF THE PRODUCTION PROCESS
Elena Papazoska1, Gligorče Vrtanoski2
1 MSc Student at the Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia 2Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: Modern industrial production companies on a global scale over the past decade have been facing
sectoral challenges in terms of competitiveness, reducing production costs and increasing the quality of products and
services. This challenge is especially focused on investing in scientific, systematic models for development, monitoring
and maintenance of production facilities, but always the main emphasis is on the sustainability of quality in the condi-
tions of rapid expansion of the global market and automation of the industry. Topic in this paper is Six Sigma Method-
ology. Six Sigma is statistical methodology for normalizing process and a methodology that is data-driven and customer
focused, highly disciplined process that help develop and deliver near perfect product and services. Results of research
in this paper, the practical example, clearly show the importance of the sistematic analysis and usage of the Six Sigma
methodology in the productive processes with DMAIC method for stabilization, improvement and reduction of standard
deviation.
Key words: 6 sigma; black belt; depanelization; printed circued board (PCB); DMAIC
МЕТОДОЛОГИЈАТА ШЕСТ СИГМА – АЛАТКА ЗА ПОДОБРУВАЊЕ НА СПОСОБНОСТА
НА ПРОЦЕСОТ НА ПРОИЗВОДСТВОТО
А п с т р а к т: Современите компании за индустриско производство на глобално ниво во последната
деценија се соочуваат сo сериозни предизвици од аспект на конкурентност, редуцирање на трошоците за
производството и зголемување на квалитетот на производите и услугите. Овој предизвик е посебно насочен
кон инвестирање во научни, систематски модели за развој, следење и одржување на производните капацитети,
а секогаш главен акцент е ставен на одржливоста на квалитетот во условите на брзата експанзија на глобалниот
пазар и автоматизацијата на индустријата. Во трудот е претставена методологијата шест сигма. Шест сигма е
статистичка методологија за нормализирање на процесот, а наедно и методологија ориентирана кон податоци
и клиенти за високо дисциплинирани процеси кои овозможуваат постигнување услуги и производи кои се
стремат кон совршенство. Резултатите од истражувањата во овој труд, поточно квантитативното подобрување
добиено со практичниот пример, ја посочуваат важноста на систематското анализирање и на примената на
методологијата 6 сигма во производствените процеси преку методот DMAIC за стабилизирање, подобрување
и намалување на стандардната девијација.
Клучни зборови: 6 сигма; црн појас; депанелизирање; печатено електронско коло (ПЕК); методологија DMAIC
1. INTRODUCTION
The research carried out in this paper relates to
the 6 Sigma methodology and its practical applica-
tion in the production process. The main goal is to
demonstrate the importance and the benefit of im-
proving production processes through the applica-
tion of the 6 Sigma methodology.
The implementation of the 6 Sigma methodol-
ogy will be explained by the five phases of a real
42 E. Papazoska, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 41–54 (2019)
practical example, and in order to achieve a reduc-
tion in the number of defective outputs from it.
In the first phase, define phase, explains the
importance of setting a measurable target for the
project. Proportionately predicts improvement and
a clear direction for the movement of the team that
will prepare the project, its selection and the special
role of all the members. It is also analyzed according
to which parameters it is chosen whether the project
should be developed using the 6 Sigma methodol-
ogy.
In the second phase, measure phase, the dia-
grams WPI-input-process-output and the basic pro-
cess flow diagram are presented [5].
Initially, the validation of the measuring tool
that the team selected for use in measuring the exit
from the process, as well as all the conditions that
need to be fulfilled, is presented. Their quantitative
values are displayed and analyzed in the Minitab
software package [2] which gives the acceptance of
the measurement system. The parameters that
should be measured as a way out of the process are
also defined. At this stage, tests for stability, nor-
mality and ability of the process are shown.
In the third phase, the analyze phase provides
an overview of the cause-effect diagram used to
identify the potential causes of the defect to be elim-
inated. In particular, the way in which the causes,
i.e. the reasons that can be controlled and the rea-
sons that can not be controlled, are shared. To elim-
inate potential causes, the "5 Why" tool (the tool
that continuously asks "Why" until the problem is
reached) and by analyzing the other reasons with the
tests of the 6 Sigma methodology and the Design of
Experiment (DE), and hypothesis testing [5].
The next phase of the 6 Sigma methodology is
the improve phase shown through the performed
setting of the improvement parameters and the way
how to validate the selected solution.
Control is the last phase that represents the
way how to control the improved process and how
to set up solid controls for the solution to stay set for
the process for which it has been defined.
2. THEORETICAL CONCEPT OF 6 SIGMA
METHODOLOGY
Interesting fact is that despite the great interest,
available literature, research, international confe-
rences, workshops and seminars, each company has
its own specific method and method of applying the
6 Sigma methodology.
Six Sigma methodology refers to the orienta-
tion towards finding and eliminating the causes of
variation in the processes. Also 6 Sigma develops
an alternative that will lead to a reduction in varia-
tion. Six Sigma seen from an organizational level is
a quality management structure that focuses on con-
tinual improvement of four key areas [7, 8]:
➢ understanding and managing the require-
ments of customers,
➢ streamlining the key processes to the desired
results,
➢ using a large amount of data to analyze in
order to minimize variation in key
processes,
➢ fast and constant improvements in business
process.
Six Sigma as a quality management tool also
includes metrics and methodology. That largely
contributed to a marked success is the fact that the
result of the improvement can be quantitatively ex-
pressed in number of defects and savings in money
[7, 8].
When implementing the 6 Sigma model there
are certain conditions that need attention and
fulfillment increases the chances for success of the
6 Sigma initiative, which are [10, 11]:
➢ support from top management.
➢ organizational structure.
➢ application of advanced statistical tech-
niques,
➢ developing ways to reward 6 Sigma team.
The goal of 6 Sigma is to generate an improve-
ment in the performance of an organization that
aims to determine based on the requirements of its
customers at which level of Sigma is appropriate the
operation of the process. Sometimes a 6 Sigma level
with 3.4 DPMOs is not a target for all processes due
to the financial aspect of the bet [12, 13].
Six Sigma methodology uses two different
models [3]:
➢ basic model for project – based projects in
the functioning processes (DMAIC), shown
in Figure 1, and
➢ basic model used to design new processes
and create new products or services
(DMADV), shown in Figure 2.
Six Sigma methodology – tool for improving the capability of the production process 43
Маш. инж. науч. спис., 37 (1–2) 41–54 (2019)
Fig. 1. DMAIC basic model
Fig. 2. DMADV basic model
3. APPLYING 6 SIGMA METHODOLOGY
IN REAL PRODUCTION CASE
The selected practical project using the 6
Sigma methodology shows the main benefit of ap-
plying the 6 Sigma through the results obtained
from the real case. Using the Minitab software pack-
age allows you to analyze and display the results ob-
tained from the practical example.
3.1. Define phase
The 6 Sigma project that has been developed
refers to improving the process of depanelization.
The process of depaneling of the printed circuit
board is one of the main reasons for the quality
problems and returned products by the client. De-
panelization is a production process that is placed in
the central position during production, more pre-
cisely, any defect in this process means spent time
and money from all preceding processes.
Printed circuit board (PCB) arrives in panel
and is depanelized on the milling machine.
Depaneling operation is done of combination
of manual and machine work in the next steps:
➢ Operator place PCB in the machine (Figure
3).
➢ Machine using rotation movement of the
blades perform the depanelization process.
➢ Operator take the PCBs out and throw not
needed borders as a waste material.
➢ Operator visualy checks depanelization
quality.
Fig. 3. Printed circuit board (PCB) in panel
Milling machine produces defective products
(Figure 4) which can not be completely detected in
the production scope and as such are sent to the cli-
ent.
3.1.1. Problem statement
Inside process of depanelization we can notice
several risks:
➢ Improper depanelization (demaged PCB) of
the printed circuit boards.
➢ The cutting quality is checked visually after
the depanelization is performed, which does
not guarantee the assurance that only "good"
pieces will be sent to the client.
3.1.2. Project objective
The goal of the project is measurable of the
quality of the process expressed through the benefit
of the business YB and product quality expressed
through customer satisfaction from the product Yc.
This can be explained as: eliminating the defects for
the production unit and eliminating products that are
returned from the client.
44 E. Papazoska, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 41–54 (2019)
Fig. 4. Defects of depanelization process
3.1.3. Selection and problem elimination
When selecting is a priority for improvement,
Pareto diagrams are used that show the need to pri-
oritize the elimination of an appropriate problem.
Data for returned products from customers, de-
fects in the production process, utilization / inexpe-
rience of production facilities, delays and others are
used as input data for analysis. However, the most
important data in the analysis are the products re-
turned by customers.
The Pareto diagram given in Figure 5 shows
the total number of monthly returned products from
customers, of which 50% belong to one product
from the entire range of products (Figure 6).
Fig. 5. Number of returned printed circuit boards from customeres
Six Sigma methodology – tool for improving the capability of the production process 45
Маш. инж. науч. спис., 37 (1–2) 41–54 (2019)
Fig. 6. Number of returned printed circuit boards of the analyzed product
With deeper analysis we can see which internal
process is giving most defective non-wanted type of
products which are main reason for customer
returns. This is shown on the Pareto diagram on Fig-
ure 7, where we can observe number of montly cus-
tomer returns due to depanelization process of the
selected product.
Fig. 7. Number of returned PCB of the analyzed product per months
46 E. Papazoska, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 41–54 (2019)
It is obvious that by eliminating deviation in
the process of depanelization, improvement is
made. This will reduce the number of returned prod-
ucts by the client by 60%, which would increase cli-
ent satisfaction, confidence and the success for fur-
ther cooperation.
3.2. Measure phase
3.2.1. Diagrams for clarifying the process
Measure phase is closely connected with ana-
lyze phase. This phase contains several crucial ele-
ments, such as selecting a proper correct measure-
ment system (MS, gage), a method of measurement,
trained personnel to perform the measurement, and
selecting an appropriate measurable product that
will clearly reflect the problem. Later this measura-
ble will be used through the phase analysis and
phase control. That's why the team's versatility and
their specific knowledge of production play a key
role here.
In the measure phase, it is decided what will be
measured and the validation of the measuring sys-
tem is carried out.
At this stage, the goal to be achieved by the
client YC1 and the business YВ1 is set.
The improvement expected to be achieved by
the team is the reduction of the products returned by
the client and the reduction of the production de-
fects. They are:
➢ YC1 = reduce customer return for the milling
defects due to not proper cutting (x-axis and
y-axis dimensions) for 100%. ➢ YВ1 = reduce internal scrap for the milling de-
fects due to not proper cutting (x-axis and y-
axis dimensions) for 90%.
In addition to defining the goal of the business
and the client, the goal to be achieved from the
corresponding process is also defined YP1:
➢ YP1 = distance between two dots of the
printed circuit board (dimensions of x-axis
and y-axis).
The Input-Process-Output diagram shown in
Figure 8 provides the input attributes, the main
process and the output attributes of the system being
analyzed.
The 6 Sigma methodology always provides
more reliable results if the variables of the automatic
processes are analyzed, rather than from the manual
ones. This is because automated processes are sub-
ject to greater variation.
Fig. 8. Input-Process-Output diagram
The initial flow of the process is presented in
the diagram shown in Figure 9 which purpose is to
have a visual display of the process.
In this process there is only one automatic op-
eration to which the improvement is expected later.
3.2.2. Determinating and validation
of the measure system
The next step is to determine the measurement
system that will be used in the phase of measuring,
improving and validating the solution.
First, Gage R&R is being developed to imple-
ment validation of the measurement system. In this
case, ten printed electronic circuits (PCBs) and two
operators (employees who have previous experi-
ence with manipulating the measuring machine).
The graphical display for validating the mea-
surement system given in Figure 10 clearly shows
that there is an insignificant variation between the
operator one (1) and the operator two (2) in the
execution of the measurement process, but also that
there is an insignificant variation between the
printed circuit boards (PCB) in all four measure-
ments performed.
In the part of the numerical display of the val-
idation of the measurement system, the number of
categories is 30 which is greater than 5 (30 > 5).
This proves that the selected measurement system is
suitable for measurement.
The most complicated point of the printed cir-
cuit board (PCB) or precisely the distance between
the two closest points and the same is used to meas-
ure it.
Input
PCB in panel
Milling force(electric power)
Process
Depanelizing PCB
Output
PCB depanelized
Borders waste
Six Sigma methodology – tool for improving the capability of the production process 47
Маш. инж. науч. спис., 37 (1–2) 41–54 (2019)
Fig. 9. Process flow diagram
Fig. 10. Grafical table for validation of the measurement system
48 E. Papazoska, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 41–54 (2019)
For the appropriate data obtained in the meas-
urements, it can be decided that the measurement of
the PCU samples used in the process can be
performed by x-axis and y-axis measurements to
cover all directions of depanelization. This is shown
in Figure 11.
Fig. 11. Technical drawing of PCB with x and y dimensions with tolerances
3.2.3. Normality tests, control diagram and
capability tests for the process by x-axis and y-axis
By measuring the dimensions of 30 printed
electronic circuits along the x-axis and the y-axis,
the normality test, the control diagram and the capa-
bility test were made. All tests are made at panel
level.
The normality test given in Figure 12 shows
that the process is not normal, p < 0.005, for the x-
axis, and the process is normal, p = 0.184, for the y-
axis.
The control diagram given in figure 13 shows
that the process is stable, in fact, none of the groups
of printed electronic circuits (with a group of two
circuits) does not go beyond the x-axis and y-axis
control limits. In particular, only one group is at the
x-axis limit value.
Capability test of the process given in Figure
14 shows that the process is not capable, Cpk = Ppk
(because the process is not normal) = 1 for the x-
axis and the process is not capable, i.e. Cpk = 0.97
for the y-axis .
Fig. 12. Normality test for x-axis and y-axis
Six Sigma methodology – tool for improving the capability of the production process 49
Маш. инж. науч. спис., 37 (1–2) 41–54 (2019)
Fig. 13. Control diagram for x-axis and y-axis
Fig. 14. Capability test for the process for x-axis and y-axis
With analyzing panel level information
received does not provide a complete picture of the
process, so 6 Sigma team concludes that it is
necessary to analyze the printed circuit board level
with the possibility to get more detailed information
about the process of depaneling.
After the conducted analysis it was concluded
that the measurements will have to be divided indi-
vidually for each printed circuit board.
On the basis of the obtained observations, con-
trol diagrams for all printed electronic circuits are
made, starting from the first to the sixth printed cir-
cuit board respectively, according to the x-axis and
the y-axis.
With the detailed control diagrams made in x-
axis and y-axis, each printed circuit board individu-
ally shows that the process is not stable in x-axis for
the printed circuit boards PCB 3, PCB 5 and PCB 6,
while along the y-axis for all six printed circuit
boards on the panel (Figure 15).
With this kind of analysis and result 6 Sigma
project can not continue, until the variation in the
depanelization is eliminated.
3.2.4. Stabilizing the process and repeated tests
for the normality of the process
The nature of the 6 Sigma methodology re-
quires a stable process before starting the analysis
50 E. Papazoska, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 41–54 (2019)
and the process of improvement. The process should
produce stable-predictable, more precisely defec-
tive products to appear consistently.
The 6 Sigma team is focused on analyzing the
process and finding the cause of instability and var-
iation in the process. After the analysis of the pro-
cess, it was concluded that there was too much vi-
bration of the panel on the support, which is placed
along the y-axis of the milling machine. A solution
is proposed that could reduce vibration by increas-
ing the diameter of the supporting pins of the sup-
port on the dimensions Φ3.9 mm and Φ2.85 mm.
With this change in the support, it is expected that
the panel will occupy a more secure position, with
less vibrations during depanelization, and thus re-
duce the variation between the cuts. New pins were
made and placed on the support for the panel of the
machine for depanelizing. This is shown in Figure
16.
Fig. 15. Control diagrams for x-axis and y-axis (PCB1)
Fig. 16. Machine support for depanelization with marked changed pins
Six Sigma methodology – tool for improving the capability of the production process 51
Маш. инж. науч. спис., 37 (1–2) 41–54 (2019)
After the change made to the pins, it is neces-
sary to depanelized the new panels in a total of 30
printed circuit boards. For them, control diagrams
are made to confirm whether there is a reduction in
the variation in the process. In doing so, a re-analy-
sis of the control diagrams is performed for all
printed circuit boards respectively in the x-axis and
in the y-axis.
With the detailed control diagrams made in the
x-axis and in the y-axis for each printed circuit board
respectively, it is shown that the process is stable in
x-axis and in the y-axis for all the printed electronic
circuits on the panel.
With this obtained result, the 6 Sigma project
can proceed further in implementing the steps of the
6 Sigma methodology.
3.2.5. Capability tests for the process
for x-axis and y-axis
Next is the elaboration of the tests for the abil-
ity of the x-axis and y-axis depanelization process
for all six panel positions individually for the
printed circuitry from PCB 1 to PCB 6. The capa-
bility of the process and the corresponding coeffi-
cients are given summarized in Table 1, whereby it
can be verified that the process is not capable of
proper depanelization of any position from the ex-
isting six on the panel, both in the x-axis and the y-
axis.
T a b l e 1
Cpk results for capability for PCB 1 to PCB 6
for x-axis and y-axis
Cpk x y
1 1.21 1.89
2 0.22 2.02
3 1.70 2.10
4 0.09 1.86
5 1.40 –0.77
6 0.23 –0.16
Accordingly, it can be concluded that the
process of depaneling is an appropriate candidate
for further analysis and improvement in order to
enable it to produce the consistently required
standards.
3.3. Analyze phase
Analyze phase is the most comprehensive
phase that requires critical thinking and great dedi-
cation. At this stage 6 Sigma team must work as an
individual with a common goal and devote suffi-
cient time to the 6 Sigma project whenever neces-
sary.
In the analyze phase, in the implementation of
the appropriate required experiments, such as the
DOE, there may be defective products, so in no case
6 Sigma team should not start the 6 Sigma project
without the presence of a process expert. Also, it is
necessary that all affected competent individuals are
informed that on the process there is ongoing 6
Sigma project for smooth analysis and improve-
ment.
The first step that 6 Sigma team does at this
stage is analyzing with the brainstorming and using
the diagram fish bone. Figure 17 shows the fish
bone diagram for the depanelization process, ana-
lyzing the four elements of the process: people, ma-
chine, materials and methods.
For each of these elements the 6 Sigma team
sets out the reasons that are probable possibilities to
be the reason for the variation and malfunctioning
of the panel.
By using the analysis WHY-WHY part of the
possible reasons for variation divided by categories
is rejected.
By eliminating some of the potential causes of
malfunctioning and producing defective printed
electronic circuits, there are still three potential
causes (X1, X2 and X3) that need to be further ana-
lyzed.
3.4. Improve phase
From the analyze phase using DOE and hy-
pothesis tests it has been determined that all three
analyzed factors have an impact on the process of
depanelization, and that factor B: speed of depanel-
ization on the very process of depanelization in the
x-axis and along the y-axis; and the factors A: z-
axis; and C: fixation on the standard deviance.
All three factors need to be set at a minimum
level to obtain the most accurate and stable process
of depanelizing.
By setting the factors to a minimum level, sev-
enteen (17) panels were depanelized to confirm the
reduction in standard deviation. In this case, an anal-
ysis of all positions in the x-axis and along the y-
axis was performed on all six positions of the PCB
on the panel. With the results obtained, it can be
concluded that by adjusting all three factors to a
minimum level, a process of depanelization is ob-
tained with a significantly lower standard deviation
52 E. Papazoska, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 41–54 (2019)
for all 6 (six) PCP positions in the panel and it is
decided that this set of factors should be introduced
into the production control plan, in order to start
batch production with the changed factors.
Fig. 17. Fis-hbone diagram for depanelization process
3.5. Control phase
The control phase takes place in a test period
of one month, as follows: on a daily basis the quality
department notice a fall in the defectively depene-
trated PCU and on a weekly basis if the client does
not return the PCU with a defect of depanelization.
At this stage, it is crucial to monitor the process on
a daily basis in order to detect all the variations, and
with slightest problem occurs the factors and im-
provement will be compromised and the process
part will be restored to a dead end.
Internally by the team it is necessary to take 3
(three) randomly selected PCUs on a daily basis and
take measurements within a month.
With the daily results obtained during the con-
trol month, backward tests of capability and control
diagrams were performed. The results are shown in
Figure 18 in the x-axis and on the y-axis, corre-
sponding to all 6 (six) positions of the PCB on the
panel.
Fig. 18. Capability tests for all six positions for x-axis and y-axis for PCB1
Six Sigma methodology – tool for improving the capability of the production process 53
Маш. инж. науч. спис., 37 (1–2) 41–54 (2019)
An increased process capability for all 6 (six)
positions is seen, as shown in Table 2.
T a b l e 2
Срк capability results for PCB 1 to PCB 6
for x-axis and y-axis
Cpk x-axis y-axis
1 2.52 3.16
2 1.58 2.80
3 1.22 2.19
4 1.39 2.64
5 1.44 0.66
6 1.39 0.67
3.6. Analyze and improvement
By analyzing the control diagrams given in
Figure 19 and in Table 3, it is found that the process
is with narrower boundary values and with reduced
standard deviation.
In none of the positions there is no unit that
comes out of the control boundaries. With these an-
alyses 6 Sigma project is closed and is proclaimed
for successfully implemented 6 Sigma improvement
project.
Fig. 19. Control diagrams before-after for PCB1 to PCB6 for x-axis and y-axis
T a b l e 3
Standard deviation values before-after
for PCB1 to PCB6
The same variation is analyzed on all the same
machines that are installed in the production capac-
ity and the stabilization of them is applied subse-
quently.
Additionally, 6 Sigma team reviewed the key
parameters that affected the incorrect depaneliza-
tion and produced a matrix to monitor the change in
parameters in the current production, which is filled
in and updated by the responsible engineers.
4. CONCLUTION
By applying the 6 Sigma methodology, the
company has the opportunity by reducing defects
Standard deviation values before-afte
Before After Before After
X1 0.26 0.13 Y1 0.26 0.16
X2 0.53 0.21 Y2 0.25 0.14
X3 0.25 0.17 Y3 0.22 0.12
X4 0.37 0.17 Y4 0.31 0.13
X5 0.35 0.19 Y5 0.24 0.23
X6 0.32 0.22 Y6 0.27 0.24
54 E. Papazoska, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 41–54 (2019)
and variations to become more competitive on the
market and to establish a suitably acceptable relati-
onship with its customers by delivering products
and/or services that have the required quality and
timely delivered or performed.
The practical example demonstrates the ability
of the 6 Sigma methodology to stabilize and im-
prove the production process. It is delicate enough
to be enhanced during the day-to-day adjustment of
parameters or be enhanced with tools that contain a
lower level of statistical analysis.
Using the DMAIC model in the 6 Sigma meth-
odology helped the team in improvement of the
process of depanelization through stabilization of
the process was carried out, narrower limit values
were obtained at all PCB positions and a significant
decrease in the standard deviation by up to 50% for
part of the positions.
The very improvement of the product and the
machine for the depanelization in the production
capacity has been analyzed and replicated as a good
practice of all the same machines for the entire
range of products.
The fixing and placement of the z-axis of the
tool is implemented in the same way for all products
and machines while the speed of depaneling is ad-
justed depending on the material of the product, its
defective category and production capacity. This
shows that the 6 Sigma methodology is powerful
enough that results obtained from one improvement
can be replicated and standardized on processes that
are of the same nature as the one subjected to anal-
ysis.
REFERENCES
[1] McCarty, T., Daniels, L., Bremer, M., Gupta, P.: The Six
Sigma Black Belt Handbook, McGraw-Hill, 2004.
[2] Minitab софтверски пакет, верзија 17, Minitab Inc,
USA.
[3] Papazoska, E.: Application of the 6 Sigma Method to Im-
proving the Capability of the Production Process, Master
thesis, UKIM, Faculty of Mechanical Engineering,
Скопје, June 2019 (in Macedonian).
[4] Sheehy, P., Navarro, D., Silvers, R., Keyes, V., Dixon, D.,
Picard, D.: The Black Belt Memory Jogger: A Pocket
Guide for Six Sigma Success, Goal/QPC, January 2002.
[5] Wiklund, H., Edgeman, R.: Six sigma Seen as a Methodo-
logy for Total Quality Management, Measuring Bussiness
Excelence, March 2001.
[6] Henderson, R. G.: Šest Sigma Quality Improvement with
Minitab, A John Wiley & Sons, Ltd Publications, 2011.
[7] Lazibat, T., Baković, T.: Šest sigma sustav za upravljanje
kvalitetom, Znanstveni časopis za promicanje kulture
kvalitete i poslovne izvrsnosti, Vol. 1, No. 1, pp. 55–66
(2007).
[8] ISO 13053-1: Quantitative methods in process improve-
ment – Six Sigma, Part 1: DMAIC methodology, 2011.
[9] ISO 13053-2: Quantitative methods in process improve-
ment – Six Sigma, Part 2: Tools and techniques, 2011.
[10] ISO 18404: Quantitative methods in process improvement
– Six Sigma. Competencies for key personnel and their or-
ganizations in relation to Six Sigma and lean implementa-
tion, 2015.
[11] http://www.asq.org/topics/sixsigma.htm (accessed on 15.
01. 2019).
[12] Milosavljević, P.: Six Sigma Metoda, Mašinski fakultet u
Nišu, Srbija, Oktober 2016.
[13] Wilson, D., Wiltsie, P.: PMPA – Lean Six Sigma tools and
methods, 2005 (https://www.pmpa.org/docs/defaultsource
/technical-conference/09-today%27s-quality-lean. Pdf?sf
vrsn=0) (accessed on 15. 01. 2019).
[14] Lazić, M.: Six Sigma – Metodology for quality improve-
ment, Quality Festival, Kragujevac, Serbia, May 2011.
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 55–64 (2019)
Number of article: 617 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: July 9, 2019 UDC: 005.61:519.86]:368
Accepted: September 1, 2019
Original scientific paper
PROCESSES OPTIMIZATION AND REDUCTION OF OPERATIONAL COSTS
– CASE IN INSURANCE COMPANY –
Vesna Gjorčeva1, Gligoče Vrtanoski2
1MSc Student at the Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia 2Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: The insurance industry is mainly based on its primary activity which is exercising the right to claim
payment in case of insured case occurrence, arising unexpectedly as a sudden event, not in any way related to the will
of the insured. For this purpose, work organization in an insurance company implies application of a complex and well
designed system of activities and processes. Each separate process should be functional in both directions. The first
one should be directed towards itself, thus providing high quality performance of the planned process activities. The
second one is to be focused on its complementary functioning together with the remaining processes included within
the insurance business. Clearly defined processes, based on empirical techniques and methods contribute to greater
effectiveness and efficacy which result in greater profitability as a final objective in the work of one insurance company.
The research in this paper aims to ascertain the impact of improved processes of operational cost reduction and increase
of profitability as the ultimate goal.
Key words: insurance industry; business processes; sales; claims; organization; synergy; efficiency; effectiveness
ОПТИМИЗАЦИЈА НА ПРОЦЕСИТЕ И НАМАЛУВАЊЕ НА ОПЕРАТИВНИТЕ ТРОШОЦИ
– СЛУЧАЈ ВО ОСИГУРИТЕЛНА КОМПАНИЈА –
А п с т р а к т: Осигурителната индустрија начелно се базира на својата примарна активност: остварување
на правото на осигурениците за надомест на штета која настанала како резултат на ненадеен, од волјата на
осигуреникот независен осигурен случај. За таа цел, организацијата на работењето на една осигурителна ком-
панија подразбира комплексен и пред сè добро осмислен систем на активности и процеси. Секој одделен процес
треба двонасочно да биде функционален. Еднаш во насока на функционирање сам за себе, со што би се обез-
бедило квалитетно извршување на планираните процесни активности, и еднаш во насока на негово комплемен-
тарно функционирање со другите процеси од дејноста. Добро дефинираните процеси, димензионирани врз
основа на емпириски техники и методи, придонесуваат за поголема ефикасност и ефективност, а со тоа и за
поголема профитабилност како крајна цел на дејствувањето на осигурителното друштво. Истражувањата од
овој труд имаат за цел да го констатираат влијанието на подобрените процеси врз оперативното намалување
на трошоците и зголемување на профитабилноста како крајна цел.
Клучни зборови: осигурителна индустрија; деловни процеси; продажба; штети; организација; синергија;
ефикасност; ефективност
1. INTRODUCTION
The subject of this research are the analyses of
a part of the sales processes, specifically those re-
ferring to their administration and management, as
well as their improvement, whose ultimate goal is to
increase profitability.
The insurance industry is basically based on its
primary activity which is exercising the right of the
insureds to be compensated for the damage occur-
ring as a result of a sudden, unexpected insured
event as opposed to their will or intention. For that
purpose, the organization of the work operations in
56 V. Gjorčeva, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 55–64 (2019)
one insurance company includes a complex and
primarily well-designed system of activities and
processes. Each separate process should function in
both directions. Namely, its first instance would be
functioning for itself, which would ensure the qual-
ity execution of the planned process activities; sec-
ondly in the direction of its complementary opera-
tion together with the other business processes.
Processes can be divided into core business
processes and auxilliary processes.
Essential processes include [1, 11]:
• Sales processes.
• Underwriting processes.
• Processes for assessment and claim settlement.
• Processes for claims in court proceedings.
Auxiliary processes are [1, 11]:
• Financial processes.
• Legal processes.
• Employee management processes.
• IT processes.
• Control processes.
Among the sales processes and those for un-
derwriting are the processes for administering the
sales, which at the same time cover the adminis-
trative procedures for making the policies and the
policy documentation and the part of the underwrit-
ing referring to data control before the actual
issuance of the policies and their distribution.
Depending on the structure of the sales net-
work in an insurance company (size and organiza-
tion, the manner of managing the activities referring
to sales and related to data entry, their processing in
the system, and the creation of policies and policy
documentation submitted to the insured) the admi-
nistration process may be an integral part of the acti-
vities of the sales network or separate work unit
(section or a department) may be designated to
make sure it functions smoothly.
2. INSURANCE MARKET
The definition of the term market is different.
Basically, it refers to a place where the processes of
buying and selling occur. However, it also can be
defined as a ratio of supply and demand for certain
products and services. It is this kind of supply and
demand relationship that functions on the insurance
market [7].
Four main factors for the functioning of the
insurance market are [8]:
1. Need,
2. Payment ability,
3. Desire,
4. Authorization.
That is the market functions as a link between
the need of the individual or legal entity for pur-
chase of a particular insurance service (that need
may be self-initiated or prompted by a legal pro-
vision for mandatory procurement of the service),
the solvency of the individual / legal entity for the
procurement of that service, the desire to complete
the transaction and the authorization to negotiate,
purchase or sell an insurance service. The lack of
any of the listed factors prevents the functioning of
the insurance market as a whole [8]. In any case, the
existence of the insurance market is determined by
the existence and active participation of two inter-
ested parties, insurance buyers, i.e. potential in-
sureds, on the one hand, and insurance vendors, or
insurers, on the other.
2.1. Market potentials and targeted
insurance sales
The potential of the insurance market are all
existing insureds who have purchased an insurance
policy of a different type or a class of insurance and
which they intend to renew, as well as those who
have all the prerequisites to become insured, and
have still not bought an insurance policy. In order to
acquire approximate data on the potential of the
insurance market, market research has to be carried
out in order to provide answers to several key issues,
as shown in Figure 1 [7].
The answers to these questions have a major
impact on the structure of the portfolio of one insur-
ance company and the organization of sales chan-
nels.
Defining the most appropriate offer for a target
group of people or individuals that are deployed in
different territorial units is the basis for the targeted
sale of insurance products. With the registration of
the insurance company itself, the market potential
or the target group of that company has been already
determined. Thus, the insurance company that sells
life insurances has a different target group from the
company that is registered for the sale of non-life
insurance.
Companies registered for reinsurance aim at
insurance companies on the market which can trans-
fer the surplus risks to a reinsurance company thus
protecting their solvency.
Processes optimization and reduction of operational costs – Case in insurance company 57
Маш. инж. науч. спис., 37 (1–2), 55–64 (2019)
Fig. 1. Insurance market potential [7]
In each of these cases, market potential lies in
the same groups of people or individuals who buy
different insurance products, only in different roles.
Namely, one can potentially insure his/her property,
professional liability, health and life. However, this
is not entirely finalized, that is, the buyer can once
appear as an insured who insured the home, in an-
other case the car, next time the same insured can
buy an accident or health insurance policy, etc. So,
the diversity of supply and the multiplied role of the
potential insured makes the diversification of the
market potential towards a particular target group a
complex and a dynamic process that often changes,
and therefore requires the insurance companies to
constantly monitor those changes and offer an ap-
propriate and timely response.
The insurance market allows mass access only
to certain types of insurance. These are, as a rule,
obligatory types of insurance or insurance that is
traditionally accepted on a particular market (some-
where it is household and family insurance, some-
where group personal accident insurance [10]. The
sale of this type of insurance is carried out through
standardized forms and ways enabling coverage of
the overall insurance market [7].
All other types of insurance require a diffe-
rential approach on the market. The practice shows
that when it comes to voluntary insurance of pro-
perty, liability or life insurance, insured persons
have different needs, desires and interests. In order
to respond adequately to such requirements, the ins-
urance companies constantly upgrade their product
portfolio and promote the level of the services they
offer. In order to achieve a better access on the insu-
rance market, it is inevitable to make market seg-
mentation on different grounds (territorial, demo-
graphic, etc.) in order to meet the requirements of
the clients (insureds), which will ultimately contri-
bute to the increase in sales. A typical example of
this is the territorial segmentation based on a preli-
minary analysis of the results of sales of a particular
product to a particular territorial unit.
3. PROCESSES IN INSURANCE SALES
It is extremely important that the process of
selling insurance policies, burdened with all the
complexity previously elaborated, is thoroughly
planned because it is most closely related to the
success of the insurance company. Even if all other
aspects of management, planning, communication,
marketing, claims, finances etc., are organized im-
peccably, yet the sales process does not function
properly, the company will not show satisfactory re-
sults.
This is the most important reason to create a
detailed sales process that provides all the necessary
steps, tasks and levels of responsibility that will lead
to maximum efficiency and effectiveness.
The sales process should be simple and well
defined. This is the key to a successfully executed
selling process, which will eventually turn the op-
portunity into a factual client. For this purpose, the
first step in defining the process, the mapping,
Market potential
Who are the participant on the Market?
What do clients mostly
puchase?
Why do clients buy certain products?
Who most frequently
buys a certain product?
How does the sales take
place??
When do the clients buy?
Where does the sales mostly
happen?
58 V. Gjorčeva, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 55–64 (2019)
should be performed by analyzing the basics of the
process through 5 key words: Who (Which), Where,
When, How and Why [9]. Mapping, in fact, should
answer questions that begin with the stated words
and through those responses, it will determine the
efficiency of the process and its further steps.
When the mapping is completed and answers
to all questions are evident encompassing the entire
process cycle from start to finish, including all the
auxiliary processes, the methods for successful
planning of the sales process needs to be defined. It
should be noted that whenever sales are discussed,
due to its natural connection with marketing, these
two processes are considered simultaneously and
when planning the same, this mutual relation must
be taken into consideration [9].
The methodology of the sales planning process
is based on several postulates. Below is the list of
the most important ones in order to obtain a well-
planned process [9, 11]:
▪ Repetition of steps – In the world practice, only
2% of sales are successfully completed after the
first contact. This means that more contacts are
required, more sales interviews and, finally,
more steps in the sales process are needed to
conclude the sale. For even 80% of sales, it
takes five to eight contacts to conclude the deal.
This means that if you contact a potential buyer
or customer less than five times or more than
eight times there is a high probability that there
is a problem with repeating the steps. Therefore,
it is necessary for a specific sales process to ac-
curately define the optimal number of steps that
are repeated until the conclusion of the sale.
• Efficiency of the sales process – Time kills
purchase deals. The speed at which the potential
buyer turns into a customer and the number of
potential customers that need to make that
change determines the efficiency of the sales
cycle. In order to achieve greater efficiency, the
right steps need to be taken to measure this pe-
riod of time required for such change from a po-
tential buyer to a client. This results in loss re-
duction since the number of those potential buy-
ers who became clients becomes bigger which
has positive effects on the profit.
• New versus existing customers – Profitability
of a client who has concluded an insurance con-
tract over a certain period of time determines the
time cycle for successful sales. Insurance com-
panies spend much more time getting new cus-
tomers than keeping the existing ones. In fact, it
is very likely that existing customers will re-buy
a policy, that is, to renew their existing one, to
buy an additional product and spend more
money. In that way they have bigger potential to
become even more profitable. Hence, knowing
the time cycle for successful sales, you can de-
termine the amount of funds that should be spent
on a particular segment of potential buyers.
▪ Predictability of requirements – Every sale
takes place in cycles, so the sale of policies is no
exception to this rule. This means that when
planning the process, the time of the sales cycle
and the variations of that same cycle should be
monitored in order to predict the loyalty of the
buyer as accurately as possible. Knowing the
time of the policy renewal of already existing
buyers, it becomes certain and provides an
opportunity for a quantitative and qualitatively
improved offer.
• Brand awareness – In order to preserve the
structure of the sales portfolio in a good condi-
tion, a high level of brand recognition and the
solutions that it provides should be constantly
maintained. In that direction, much more attenti-
on should be paid to constantly improve and
maintain a certain level in reference to public
relations since they are much more important
and should be treated with greater care as com-
pared to the classical marketing approach in
advertising certain products. Especially in in-
surance, where the recognizable quality of a par-
ticular brand, whether it's a company, a brand
product, or a brand service, brings a lot more
clients than advertising that is just spending
money. When it comes to insurance marketing,
it's more important to increase the positive
brand recognition and the good reputation of the
insurance company than to increase the funds in
the advertising budget.
• Reduction on discounts – Although the most
commonly used tool in selling insurance on our
market, discounts are disadvantages in sales and
advertisements of the insurance products and
services. It would be best if they are used occa-
sionally, only when other sales methods fail. In-
stead of using discounts, the reason that creates
the need for it needs to be discovered as well as
to make an effort to locate and remove such
reason from the selling process. If that is ren-
dered impossible, then it needs to be replaced it
with an improved offer. A potential buyer or an
existing one who wants to renew the policy sho-
uld be offered added value and this should lead
Processes optimization and reduction of operational costs – Case in insurance company 59
Маш. инж. науч. спис., 37 (1–2), 55–64 (2019)
him to focus on the improved offer rather than
the discount.
• Trained sales agents – Nothing sells better than
a well-trained seller. The constant training of
insurance sales agents is imperative. They must
at any time improve their knowledge about
products, the way they are presented, improve
their negotiating and sales skills. In this way
they will be able to improve their effectiveness.
That will increase their morale at the same time
improving the profitability of the company. This
would be a winning combination for everyone
included in the insurance business.
To sum up, well defined sales processes can
increase the effectiveness through reduction of non-
efficient selling programs.
3.1. Division of sales processes
The division of the selling process may be
based on [3, 11]:
• the type of distribution channel through which
the sale is made,
• defined separate operating units for execution of
sales.
The type of distribution channel defines the
steps in the process, their interdependence and the
duration of their execution. Depending on the struc-
ture of the distribution channel, the process can be
simple, with a small number of involved stakehold-
ers and with a small number of steps, as in the case
of direct sales. This process is shown in Figure 2.
Fig. 2. Process of direct sales in insurance
4. ADMINISTRATION PROCESS
OF INSURANCE POLICIES
AND POLICY DOCUMENTATION
Sales processes and underwriting processes are
essential processes for the functioning of one insu-
rance company. The part of the underwriting pro-
cess, which is actually a continuation of the sales
process, is the process of administering policies and
policy documents. This process at the same time
covers administrative procedures for the preparation
of policies and policy documents and the underwrit-
ing section relates to data control before issuance of
policies and their distribution. Furthermore, it tracks
the policy and ultimately finalizes with the return of
the verified policy documentation in the insurance
60 V. Gjorčeva, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 55–64 (2019)
company where it is recorded and kept in the com-
pany's archive.
Depending on the structure of the sales net-
work in an insurance company, its size and orga-
nization, the manner in which sales activities are
managed pertaining to the data entry, their proces-
sing in the system and the production of the policy
documentation, the administration process can be an
integral part of the sales network activities. Additi-
onally, the administration process may be delegated
to a separate working unit (service or sector) in the
insurance company.
Below is a presentation of data and findings
from the analysis of a typical example of policy
administration and policy documentation of are
insurance company, where a separate work unit has
the responsibility to run this process.
The reviewed period covers a time span of 10
consecutive years, in which two working units
merged into one, rationalization of the work
activities and jobs was done, the parts of the process
related to the use of application software were
improved, all these leading to reduction of total
costs.
4.1. Structure of the process
The administration process in the two re-
viewed years is with a different structure. In the in-
itial year it is more complex due to the greater
number of employees, lower utilization of applica-
tion software and other IT solutions as well as
greater volume of manual work. The latter it was
characterized with several steps in the process and
poor effectiveness, because the weight of the
process lay in manual administration and data entry
(number of employees, placement in the process), at
the expense of data control which should ensure the
process quality.
The most simplified version of this process is
shown in Figure 3 which shows the main stages of
the process that function as separate entities and
which have different dynamics in the execution of
the activities that comprise each individual unit.
The second comparative year, 2016, has a
smaller number of steps due to the introduction of
smart solutions through application software for this
kind of activities, which automatically reduces the
phases of the process, the steps of the individual
phases in the process and consequently the changed
processes, the number of employees .
Fig. 3. Structure of the process of policy administration for 2006 [11]
Legend (Explanation of the process):
• Administration – in the part of the administration, the following activities are included: reception of documentation, printing of policies
and archiving of the returned documentation from the client.
• Data entry – refers to the input of data required for creation of the computer system policy through appropriate application software.
The operator should be trained in recognizing the elements of the policy and the police documentation.
• Data control – means control of the entered data in the system, whereby, as a rule, these officers have a higher level of authorization,
which allows them to intervene in the process of making the policy.
• Archiving of documentation – the insurance company must keep a proper record of all issued policies and policy documents, because they are contracts signed by the company and by the client, and as such they are referred to as documents for an obligatory relation.
The collection of all documentation related to the policy and its archiving in accordance with the legal regulations is the task of this
unit.
Processes optimization and reduction of operational costs – Case in insurance company 61
Маш. инж. науч. спис., 37 (1–2), 55–64 (2019)
Fig. 4. Structure of the process of policy administration for 2016 [11]
Legend (Explanation of the process):
• Sales network – in 2016, the insurance market recognizes broad diversification in the direction of sales channels. Direct sales,
insurance brokers, agents, insurance agents, travel agencies, banks. Regardless of the source of all information from the domain of sales, they are processed in one place. This ensures the consistency of the administration process.
• Data entry – refers to the input of the data required for the development of the computer system policy through appropriate application
software. The operator should be trained in recognizing the elements of the policy and the police documentation.
• Data control – means control of the entered data in the system, whereby these officers, as a rule, have a higher level of authorization,
which allows them to intervene in the process of making the policy.
• Archiving documentation – collecting all documentation related to the policy and its archiving in accordance with legal regulations is
the task of this unit.
By comparing the two processes, it is evident
the existence of rationalization both in the process
phases and in the number of officers. The process
in 2006 is composed of four working units, while
the latter from 2016, comprises of three. The
number of officers is doubled. This is achieved with
the help of automation.
Automation in administrative processes is a
key to increased efficiency. In these processes, since
activities are largely dependent on strict monitoring
of administrative procedures, it is very simple to
replace the manual work with a systemic routine us-
ing a computer application. Also, the control mech-
anisms of the process are mostly left to the computer
system serving process. Thus, through savings in
human resources, office supplies and operating
costs, the process is streamlined.
4.2. Description of separate phases in the process
Both processes from the previous item, the one
that shows the state in the policy administration
department in 2006, and the one from 2016, have
several stages. In order to understand the impor-
tance of certain parts of the process and their impact
on rationalization, we will present them in detail as
follows.
It is evident that the 2006 process (in short
process 2006) has several stages and the activities
are performed by two units within the department.
Figure 5 shows all the elements of the process and
their connection. Such organization determines the
activities of the departments and their interdepen-
dence.
In addition to being a process with fewer sta-
ges, in the process in 2016 (in short process 2016)
changes in the steps and in the descriptions of indi-
vidual activities can be noted. The elements of the
process and their connection are shown in Figure 6.
It is evident that the department for policy
administration and policy documentation is absent.
The activities of this department are fully trans-
ferred to the data entry department and the control
department, which in the process of 2016 counts 10
officers. The archive of the documentation is a
responsibility of one operator, the team being an
accoutability of a department manager.
62 V. Gjorčeva, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 55–64 (2019)
Fig. 5. Placement of officers in separate phases of the administration process 2006 [11]
Fig. 6. Placement of officers in separate phases of the administration process 2016 [11]
Processes optimization and reduction of operational costs – Case in insurance company 63
Маш. инж. науч. спис., 37 (1–2), 55–64 (2019)
4.3. Statistical indicators and analysis
The analysis of statistical indicators, as well as
the description of the individual phases of the
process, should provide a detailed picture of the
process optimization.
The following is an overview of the analysis of
the three selected parameters: reduction of the
number of employees, reduction of the salary costs
and overhead costs, consequently the automation of
the parts of the process related to renewal of policies
and policy documentation.
Table 1 shows the reduction in the number of
employees in the department, with the comparative
percentage of the two reviewed periods being 47%.
On the basis of these data, a comparison of the
salaries in both reviewed periods was made, taking
into account the average gross salary of the jobs in
the financial department with similar complexity,
and a comparative value of –27% was obtained,
which means that the reduction in the number of
employees brought savings in payroll costs of 27%
An analysis was made of overheads by policy
and salaries of the employees of the sector by
policy, and in both items significant decrease was
determined. The obtained results are shown in
Figures 7 and 8..
T a b l e 1
Comparison – number of employees and salaries
in the reviewed time spans
Number of:
Employees Salaries
2006 2016 2006 2016
Manager 1 1 – –
Administrators 6 – –
Data entry officers 8 6 – –
Control officers 4 4 – –
Archive records officers 2 1 – –
Total: 21 12 – –
–43% –27%
Fig. 7. Graph on the total number of cases per different products [11]
Fig. 8. Graph on the rationalization of overheads and cost for salaries per policy [11]
0
10000
20000
30000
40000
50000
60000
2006
2016
0
10
20
30
40
50
60
Overheadexpences/per policy
Salary/per policy Total Expences/perpolicy
2006
2016
64 V. Gjorčeva, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 55–64 (2019)
5. CONCLUSION
Based on the conducted research it can be con-
cluded that the sales network is the driving force of
an insurance company. The better its organization
and the more educated and motivated employees
work in it, the greater and more reliable the growth
of the insurance company becomes. This logically
leads to a conclusion that in order to accomplish
planned sales, it is just as important to work on its
backup, that is, the administrative support needs to
function according to a well-designed process, with
an optimal number of officers and impeccable IT
support. It enables a high quality execution of the
activities in all stages of this two-way process, once
in the direction of efficient functioning for itself and
once in the direction of its complementary operation
with the other processes related to sales.
The presented data and results from the analy-
sis of one typical example of how policy administra-
tion and administration of policy documents is or-
ganized, are taken from an insurance company
where a separate work unit is responsible for per-
forming such operations.
They show that in the reviewed period of 10
consecutive years within which there was a merger
of two work units into one, rationalization of the
working activities and jobs was made with the
improvement of those parts of the process related to
the use of application software. The number of
process phases in general, as well as certain
individual phases is reduced. In this way, many ben-
efits have been achieved such as savings in human
resources, overheads and operating costs (salaries
and allowances). The results are as follows:
• reduction of the number of employees by 43%
and salaries by 27%,
• reduction of overheads by 54%,
• reduction of total costs by 47%.
Reduction of costs and simultaneous increase
in the volume of sales result in great effects in the
risk management process as a part of the underwrit-
ing business. Because sales and insurance processes
are half of the core processes in an insurance
company, their optimization is the key to profitable
operation of the company and the achievement of a
positive financial result.
REFERENCES
[1] Nanda, V.: Quality Management System for Product De-
velopment Companies, CRC Press, Boca Raton – London
New York Washington, DC, 2005.
[2] De Bettignies, H.-C., Lépineux, F., Tan, C. K.: The insu-
rance business and its image in society: Traditional issues
and new challenges, ABCM, 2006.
[3] Vaughan, E. J., Vaughan, T. M.: Fundamentals of Risk
and Insurance, Wiley, 2013.
[4] Miller, D.: Breaking with tradition in the insurance indus-
try: Strategies to insure operational efficiency and future
growth, Business Process Solutions, Executive perspec-
tive, OpenTex, 2011.
[5] Rejda, G. E., McNamara, M. J.: Principles of Risk Mana-
gement and Insurance, Pearson Series in Finance, Twelfth
edition, 2013.
[6] Barbir, V.: Čimbenici uspješnosti prodaje usluge osigu-
ranja, Ekonomski pregled, 55 (9–10), pp. 815–839 (2004).
[7] Njegomir, V.: Uloga finansijskih derivata u upravljanju
rizikom osiguranja, Računovodstvo, vol. 55 (2011).
[8] Nakić, S.: Menadžment prodaje usluga osiguranja, Puto-
kazi – Interdisciplinarni znanstveno-stručni časopis Sve-
učilišta Hercegovine, Vol. 1. No. 2., pp. 185–197 (2013).
[9] Anderson, C.: 8 Procedures to Take Control of Sales and
Marketing, Research paper, https://www.themanager.org/
Strategy/Procedures_3_Sales.htm.
[10] Law on compulsory traffic insurance, Official Gazette of
the Republic of Macedonia no.88/05, 70/06, 81/08, 47/11,
135/11, 112/14 and 145/15.
[11] Gjorčeva, V.: Optimization of Processes in Insurance
Company in Order of Operational Costs Reduction,
Master Theisis (in Macedonian language), Faculty of
Mechanical Engineering, UKIM, Skopje, July 2019.
,
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 65–70 (2019)
Number of article: 618 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: May 21, 2019 UDC: 334.724:005.334]:001.891.7(497.7)
Accepted: August 21, 2019
Original scientific paper
MANAGING ORGANIZATIONAL CHANGE IN COMMUNAL PUBLIC ENTERPRISES:
A LITERATURE REVIEW
Georgi Hristov1, Gligorče Vrtanoski2
1MSc Student at the Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia 2Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: This work presents a literature review regarding the organizational change. The resistance to change
– a “natural associate” on change – was not considered as a separate topic under the scope of this work. More than
thirty academic articles were reviewed and analyzed. An effort was done to link, to confront and, whenever possible,
to compare the different findings about the organizational change as found by the academic research. In general, the
review focuses on the organizational change literature and, in particular, the available peer reviewed academic articles
that focus on the organizational change in public sector. The influence of different factors and behaviours (employees’
participation and commitment, the change context, the management and leadership support, timing, communication
and strategic change process) over the change process was examined. Some models for implementation the change
process and the revolutionary change are mentioned. The concept of changing “whole system” is also mentioned as an
important one when speaking about the change in public sector. The lack of research regarding the organizational
change in communal public enterprises is noted and suggestions for further research are given.
Key words: change process; organizational change; communal public enterprise
УПРАВУВАЊЕ СО ОРГАНИЗАЦИСКИТЕ ПРОМЕНИ ВО КОМУНАЛНИТЕ
ПРЕТПРИЈАТИЈА: ПРЕГЛЕД НА ЛИТЕРАТУРАТА
А п с т р а к т: Трудот дава преглед на литературата во врска со организациските промени. Oтпор кон
промените, што природно го следи нивното воведување, не беше посебно анализиран. Анализирајќи над 30-
ина академски и научни трудови, беше направен обид да се поврзат, спротистават и, секогаш кога е можно, да
се споредат различните научни сознанија за организациските промени. Општо земено, прегледот се фокусира
на литературата за организациските промени со посебен акцент на научните трудови кои се однесуваат на
јавниот сектор. Трудот го проучува влијанието на различните фактори (учеството на вработените и нивната
посветеност, контекстот на промените, управувањето и поддршката од раководството, времето, комуникација-
та и процесот на стратешки промени) во текот на процесот на промена. Споменати се некои модели за импле-
ментација на процесот на промени и радикални промени се споменати. Концептот за промена на „целиот сис-
тем“ е спомнат како клучен во случај на промени во јавниот сектор. Нотиран е недоволниот број истражувања
на организациските промени во комуналните јавни претпријатија се нотирани и се дадени предлози за поната-
мошни истражувања.
Клучни зборови: процес на промена; организациски промени; комунално јавно претпријатие
1. INTRODUCTION
Provision of potable water in the Republic of N.
Macedonia is responsibility of municipalities which
establish utility companies named as Communal
Public Enterprises (CPEs). The term “public” refers
that the government (local or central) owns the util-
ity and that the goods or services are provided in a
66 G. Hristov, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 65–70 (2019)
monopolistic market. Since the collapse of com-
munism in late 80’s, the planned economy has been
replaced by market economy and most of state-
owned companies have been privatized. However,
the water utility companies are still operating, or
better to say “surviving” as public enterprises. De-
centralization process transferred many responsibil-
ities for delivery of public services from central
governmental level to municipalities, but it has not
been followed with suficient funds to develop the
sector adequately. Thus, the current situation at
CPEs can be characterized as a critical one due to:
poor operational and financial performance, long
debt collection period, over employment, outdated
IT and other equipment [1, 2]. Additionally, even
day-to-day operations seem to be highly influenced
by political interests. In short, the current operations
of the CPEs, still carrying much legacy of the for-
mer system, are not sustainable anymore and could
harm and potentially destroy the water supply sys-
tems in operation. An intensive debate about differ-
ent possible forms of CPEs’ transformation, like
privatization, concession, build-operate-transfer
(BOT), public-private partnership (PPP), outsourc-
ing, contracting etc., which might replace the exist-
ing (unsustainable) way of service delivery is ongo-
ing. Whatever form is decided, and eventually ap-
plied, the changes are inevitable in the CPEs.
The publication “Introduction to Outsourcing
and EU Water Sector Review” authored by the Asso-
ciation of Communal Service Providers (ADKOM)
urged for an immediate action to improve (1) finan-
cial liquidity, (2) maintenance of the water supply
networks and (3) capital investments [3]. Addition-
ally, it showed that both, the politically appointed
managers and employees agreed that “something”
must be changed. Therefore, the municipalities face
the challenges to find solutions for immediate im-
provement in the sector. Some have called for “rad-
ical” changes, too. In such a case, the universally
accepted maxim that “people resist change” might
not be true, at least verbally. This supportive envi-
ronment toward change is in line with findings that
individual resistance is quite rare [4]. Instead, it is
suggested that obstacles to change more often reside
in the organization's structure or in its performance
appraisal or compensation system. This observation
shifts the attention from individuals to the greater
organizational system within which the change is
occurring [5]. Also, the change outcomes are
stronger when perceived need for change is high
than when it is low [6], thus one can assume that
current environment is supportive to introducing
change process in communal public enterprisies.
Therefore, this article aims to provide literature re-
view about the organizational change in the public
utility sector. Eventually, it can serve the managers
as a guide to the available academic findings on this
topic to better prepare themselves, the enterprises
and employees for a coming change process, but
also to the asset owners as well as to customers.
Literature review of some academic research
regarding the organizational change as found in
the public enterprises is given in Section 2. It be-
gins with some pioneering “classics” articles re-
garding the change and continues with the particular
research and findings that address public enter-
prises. Section 3 gives short overview of Macedo-
nian communal sector and assess possibilities for
practical utilization of organizational change. Fi-
nally, the conclusion and recommendations for fu-
ture research are given in Section 4.
2. LITERATURE REVIEW
a) Organizational change
Change is a part of life. In business context,
particularly in recent years, as companies face in-
creased competition, globalization, increased use of
information and communication technologies, re-
cession and at the same time search for excellence
(or survival), changes are inevitably tied with the or-
ganizations [7]. Thus, managing change has at-
tracted many researchers becoming a popular topic
in the wider framework of social change [8] as well
as in the organizational and management literature.
Kurt Lewin – the “father” of the term resistance to
change [9], – suggests a change-implementation
process of unfreezing, moving (change) and refreez-
ing. Relaying on Lewin’s theory, Coch and Franch
published the first known reference [10] on re-
sistance to change concluding that groups which
participate in the design and development of the
changes have much lower resistance than those that
do not. Furthermore, they advise managers to hold
meetings, communicate the need for change and en-
courage employees’ participation in change plan-
ning. Later, it has been noted that the Coch and
Franch’s research is actually about the participation,
not about the resistance [9, 11].
Recently, many authors [12, 6] recommend
employees’ participation as a strong tool for suc-
cessful change process. But, others have challenged
this finding as well. For instance, even long ago
[11], additional criticism of the Coch and French’s
Managing organizational change in communal public enterprises: A literature review 67
Маш. инж.науч. спис., 37 (1–2), 65–70 (2019)
study regarding the concept of participation has
been expressed. In this sense, the Lawrence’s study
symbolizes a first effort to escape from dominant
thinking that participation as a magic panacea for
every change misfortune. Kotter and Schlensiger
were among the first who claimed that organizations
and individuals need to change continually [4]. Uti-
lizing the contingency approach, they suggested that
one must consider the context in which the changes
occur as well. This is in line with findings suggest-
ing that organizational change is difficult to separate
from the context of the business it is in [13]. There-
fore, it is essential to have a thorough understanding
of the organization and its people, as well as of the
change and its consequences. Refference [12]
agrees that the analysis of the context with the
choice of a contingent strategy, question the idea
that participation and involvement are the recipe for
any change process.
Similarly to Lewin, but for the level of an or-
ganization, [14] distinguishes three stages in the or-
ganizational change process – idea generation,
adoption and implementation. It distinguished be-
tween organizations that promote and those that
resist change. In addition, [15] indicated that or-
ganizational change usually engages changes at
three levels: individual, structures and systems, and
climate (interpersonal style). Therefore, an individ-
ual’s response to change depends not only on her/his
personal characteristics, but also on the type of or-
ganization, the existing climate and culture. In this
line, the mechanistic organizations (strong hierar-
chical structure, well defined job descriptions, au-
thority and power based on seniority and experi-
ence) are far worse at managing and coping with
change than organic organizations (flat structure,
flexible job descriptions, weaker authority and pro-
cedures) [12]. Other contribution how organization
can support employees in case of revolutionary
change and to assess whether actions taken depend
on various contextual criteria, is presented in [7].
The authors found that when “behaviours that are
supportive of revolutionary change are undertaken
… there can be a positive impact on critical out-
come variables. Conversely, when behaviours per-
ceived as non-supportive are undertaken … there
can be a decidedly negative impact on both the or-
ganization and the employee” (p.197).
Other important determinant which influences
change is time. Many behavioural scholars, busi-
ness executives and management gurus agree that
timing is one of the most important elements in
planning, delivering, implementing and managing
change [12]. Intentionally or not, most of the
changes are planned and implemented during crisis.
Some authors [16] consider it to be THE crucial var-
iable. Even more, others claim that individual reac-
tions are subject to modifications over time [12].
Communication is other important determi-
nant influencing the implementation of change. The
research literature points that communication is
positively related with an effective change process
[17]. Reference [6] contributed to change theory by
addressing the knowledge gap related to participa-
tion in strategic change. The findings suggest that,
generally, the use of participation seems to be
strongly related to successful implementation of
strategic change, particularly in case when a com-
pany faces the “survival threat”. Also, it was con-
firmed again that “employees' perceptions of the or-
ganization's need for change interact with the use of
participation, making the participation-outcome
links stronger when perceived need for change is
high than when it is low” (p.210).
Refference [6] proposes a 12-step model for
change implementation. The model is based on
three previous well-known change models, i.e.
Kotter’s 8-step model [18], Jick’s 10-step model
[19] and 7-step change acceleration process used at
General Electric which follows notion of unfreez-
ing, moving and refreezing [9]. While Kotter points
out that “skipping any step creates only an illusion
of speed with the consequence of no satisfying re-
sults” [18], in addition, it has been suggested that
all 12 steps are not to be regarded only sequentially,
but also as an integrated, iterative process to enable
change [20]. But, do these criteria of strictly follow-
ing the steps in a change process allow for flexibility
regarding the organizational context? No, they do
not. The reference [21] advises that any organiza-
tional context requires different change strategies
and tools. Even more, they argue that if various
change initiatives are not priority on top manage-
ment agenda, if leadership is not seen as a vital com-
ponent to successful implementation of change ini-
tiatives, then it is hard to accept that such an organ-
ization has committed itself to organizational
change regardless of the model it has chosen.
Although it is generally accepted that em-
ployee commitment plays prominent role in the im-
plementation change models, only recently a model
on commitment to organizational change initiatives
that could serve as guide towards systematic future
investigation has been developed [22]. The model
suggests that commitment could take different
forms and have different implications on the nature
68 G. Hristov, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 65–70 (2019)
and level of employees’ behavioural support for a
change. The further research [23] replicates and ex-
tends this model using samples from different
change contexts. The fact that the obtained results
are similar, provides for a proven evidence about
generalization of the model proposed at [22]. In ad-
dition, refference [23] extended the previous find-
ings by examining relations between commitment
and behavioural support for change (1) over time
and (2) in a non-western societal culture. Actually,
the findings obtained with a sample of Indian man-
agers were very similar to those obtained in [22]
with Canadian nurses. Finally, the findings regard-
ing the relations between commitment and support
for organizational change are consistent with the
claim that employee commitment is a key to the suc-
cessful implementation of organizational change,
but even more, they conclude that commitment to
change is more important than commitment to the
organization.
b) Organizational change in public utilities
The changes in public sector in most Western
economies have been mainly inspired by increased
demand for greater financial accountability, effi-
ciency and effectiveness [24]. Others have found
different reasons for initiating changes. For exam-
ple, the reasons for initiating changes in public sec-
tor is to exhibit many features of the private sector,
including some scope for entrepreneurial behaviour
[25]. Reffernce [26] connects it with the need to deal
with turbulent environments and shifting public sec-
tor towards greater competition by applying private-
sector management style in public domain. Some
public organizations used the Lewin’s three-step
model while others have adopted business process
re-engineering [27]. Some authors argue that what-
ever model is implemented, the progress can be
achieved only if a transformation team is appointed
which has been given authority for change and in-
ternal power [28].
Many authors (e.g. [26 – 28]) agree about deep
differences between public sector organizations and
private companies when it comes to implementation
of the organizational change. Some argue that gov-
ernments have no alternative, but to utilize different
market-based business-oriented reform in the public
sector [29]. Contrary, others [30] argue that trans-
ferring change concepts and approaches from pri-
vate to public sector can lead to contradictory re-
sults. From current perspective, the later findings
seem to be the correct ones. This means that the con-
cepts and approaches to organizational change in
public sector should be accommodated to public
context, which not necessarily has the same motive
to introduce and implement change as private sec-
tor. This is supported by other authors [31] about
what a “changed” public organization is expected to
perform: enact new relationships and partnerships;
think and act strategically; network with other agen-
cies; manage resources effectively; redefine bound-
aries of systems and govern for accountability and
transparency. In short, this type of change is differ-
ent from other forms of organizational change as it
involves the “whole system” approach – getting the
widest representation in the room and that all stake-
holders would try to improve the “whole system” at
the same time [31].
3. ORGANIZATIONAL CHANGE
IN MACEDONIAN’S CPEs
Public enterprise is a form of government in
business. It is expected to achieve economic and op-
erational efficiency, and at the same time serve so-
cial or policy objectives and be accountable to the
public. The reality in Republic of North Macedonia
is that CPEs’ assets are significantly depreciated
and, in general, employees are old, poorly educated
and not-motivated. Although over employment is
evident, there are still pressures for additional new
politically motivated employments. In addition, be-
sides the awareness of need for change (and sur-
vive), there is an emphasized resistance to change
due to fear of losing jobs, IT frustration, loosing po-
litical influence etc. As previously mentioned, there
is on-going debate in the country about the urgent
necessity of transforming (changing) the CPEs. The
debate is mainly focused about what changes are to
be implemented which will provide for companies’
sustainability, improved service level delivery and
increased customer satisfaction leading to increased
performance and cheaper services eventually. The
proposals fall in a continuum from full privatization,
at one side, to keeping the public form, at the other
side.
Practical examples of different management
forms already exist over the world. For example, in
Canada, water and sewage utilities are publicly
owned and operated. In France, many municipali-
ties contract out water and sewage operations to pri-
vate companies. England and Wales have fully pri-
vatized their water and sewage services. Anyway,
the main goal to be achieved is affording an efficient
company that will provide quality service delivery
at reasonable prices. Regarding the efficiency, some
Managing organizational change in communal public enterprises: A literature review 69
Маш. инж.науч. спис., 37 (1–2), 65–70 (2019)
authors claim that there are several reasons to be-
lieve that public enterprises will be less efficient that
private enterprises producing the same product [32].
They mainly relay on the studies reviewed [33]
which offer quite convincing evidence that private
firms are more efficient than public enterprises,
even in different country settings and industries. For
example, for water utilities, it was found that private
firms are more efficient than public firms by
amounts ranging from 15% to 40%. Very contrary
to these findings, others argue against privatization
of CPEs as a possible change model for increasing
efficiency [34]. They claim that CPEs appear no less
efficient than privatized ones. Some of their argu-
ments against are “that privatization carries signif-
icant risks in water and sanitation, given the nature
of the service as a natural monopoly, the de facto
lack of competition on an international scale, the
difficulty of regulating multinational companies, es-
pecially in transition and developing countries, the
potentially high economic and social costs of mo-
nopolistic behaviour by commercial operators” [34,
p. 52]. Even more, they provide evidence that public
water supply sector in transition and developing
countries is as affordable as the developed coun-
tries.
A snapshot on the current efficiency of the al-
ready privatized Macedonian companies in other
sectors is in line with above Lobina and Hall’s find-
ings. Namely, the evidence showed that the effi-
ciency of the privatized companies has not in-
creased as expected, although, the profitability does.
The increased profitability satisfies an owner’s in-
terest only, however, on the costs of lower invest-
ments and capacity development. Very probably,
weak regulatory and institutional mechanisms to
control financial operations of private companies
and lacking expertise in regulating public (particu-
larly water supply services), might be enough argu-
ments towards keeping public form of communal
services delivery. However, this shall not prevent
introducing change processes in the public enter-
prises’ operations. It is only suggested that privati-
zation might not be the magic panacea for solving
the operation and financial inefficiency of public
communal enterprises in Republic of North Mace-
donia.
Clearly, changes are necessary and urgent. The
employees and management of Macedonian public
companies are convinced in the need of change and,
at least, verbally are supportive. However, the ru-
mours against the change are already spread around.
The issue of rumours is not a new one and it is al-
ready well addressed by organizational change and
resistance to change literature. Three main reasons
[35] are revealed for organizational resistance to
change: technical barriers (habit and inertia), politi-
cal reasons (threats to coalitions may signal leader-
ship problems), and cultural reasons (lack of a cli-
mate’s support of change, regressing to “old days”
of operations). All three reasons perfectly fit in the
current real situation with the political and cultural
ones having probably the biggest influence in the
Republic of North Macedonia. It is also important
to note that the CPEs carry a huge legacy system and
company’s history of “status quo” and such enter-
prises which have not practiced changes before can-
not carry out the change successfully [12].
4. CONCLUSION
The paper provided some insights of the basic
organizational change factors with focus on public
sector. Based on the literature reviewed it is obvious
that public sector faces more challenges than private
with managing the organizational change process.
Many water supply utilities from Central and East-
ern Europe experience the process of transformation
in the last twenty years, however, on the other side,
there is still lack of research regarding the change in
public enterprises (e.g. [34 – 21]). Therefore, it is
suggested for more research on the topic in the sec-
tor in order to fill-in the existing gap between the
accumulated knowledge and theory about organiza-
tional change, in general, and the CPE’s change, in
particular. It is also advised to test the existing find-
ings regarding the participation, communication,
commitment, management and leadership support,
etc. in public utility sector in Central and Eastern
Europe.
Such future research should focus on contex-
tual factors within the public enterprises bearing on
mind the legacy they carry as well as political influ-
ence. In this regard, attention must be paid on dif-
ferent cultural settings, company’s history and the
customers. This “whole system” approach should be
verified under such settings, as customers are an im-
portant stakeholder in public sector operations. This
will enable to reveal the reasons and factors prevent-
ing public companies to achieve the required im-
provements when introducing change process,
something what is well noted in [21].
REFERENCES
[1] Ristovski, B.: Benchmarking Project in 28 Utilities in the
Republic of Macedonia, Country Report, Ministry of Fi-
nance of RM, 2014.
70 G. Hristov, G. Vrtanoski
Mech. Eng. Sci. J., 37 (1–2), 65–70 (2019)
[2] Hristov, G.: Do service quality and efficiency of water /
wastewater enterprises urge reforms? Case of Macedo-
nian Communal Public Enterprises (CPEs), Master The-
sis, University of Sheffield, UK, 2009.
[3] Vrteski, J.: Introduction to Outsourcing and EU water sec-
tor review, ADKOM publication, 2008.
[4] Kotter, J. P., Schlesinger, L. A.: Choosing Strategies for
Change. Harvard Business Review, Vol. 57, Issue 2, pp.
106–114 (1979).
[5] Jansen, K. J.: The Emerging Dynamics of Change: Re-
sistance, Readiness, and Momentum, Human Resource
Planning, Vol. 23, Issue 2 (2000).
[6] Lines, R.: Influence of participation in strategic change: re-
sistance, organizational commitment and change goal
achievement, Journal of Change Management, Vol. 4, Is-
sue 3, pp. 193–215 (2004).
[7] Szamozi, L., Duxbury, L.: Development of a measure to
assess organizational change, Journal of Organizational
Change Management, Vol. 15, No. 2, pp. 184–201 (2001).
[8] Lewin, K.: Frontiers in group dynamics, I: Concept,
method and reality in social sciences; social equilibria and
social change, Human Relations, Vol. 1, pp. 5–41 (1947).
[9] Dent, E., Goldberg, S.: Challenging Resistance to Change,
Journal of Applied Behavioral Science, Vol. 35, No. 1, pp.
25–41 (1999).
[10] Coch, L., French, J. R. P. Jr.: Overcoming resistance to
change, Human Relations, Vol. 1, No. 4, pp. 512–532
(1948).
[11] Lawrence, P. R.: How to deal with resistance to change,
Harvard Business Review, Vol. 32, No. 3, pp. 49–57
(1954).
[12] Giangreco, A.: A review of the literature and the discus-
sion of the six issues in the analysis of resistance to change,
Luic Papers, No. 79, Seria Economia Aziendale, 2000.
[13] Stace, D. A.: Dominant ideologies, strategic change, and
sustained performance, Human Relations, Vol. 49, No. 5,
pp. 553–70 (1996).
[14] Shepard, H. A.: Innovation Resisting and Innovation Pro-
ducing Organizations, Journal of Business, Vol. 40, Issue
4, pp. 470–477 (1967).
[15] Goodstein, L. D., Burke, D.: Creating Successful Organi-
zational Change, Organizational Dynamics, Vol. 19, Issue
4, pp. 4–17 (1991).
[16] Brief, A. P.: Attitudes In and Around Organizations, New
York, Sage Publications, 1998.
[17] Hall, G., Rosenthal, J., Wade, J.: How to make reengineer-
ing really work, Harvard Business Review, Vol. 71, No.
12, pp. 119–31 (1993).
[18] Kotter, J. P.: Leading Change: Why Transformation Ef-
forts Fail, Harvard Business Review, Vol. 73, No. 2, pp.
59–67 (1995).
[19] Jick, T.: Implementing Change, Harvard Business School
Press, 1991.
[20] Mento, A., Jones, R., Dirndorfer, W.: A change manage-
ment process: Grounded in both theory and practice, Jour-
nal of Change Management, Vol. 3, No. 1, pp. 45–59
(2002).
[21] Soltani, E., Lai, P-C., Shams, N.: Learning about the Prac-
tice of Change Management: The Case of Non-for-Profit
Organisations, Kent Business School, 122, 2006.
[22] Herscovitch, L., Meyer, J. P.: Commitment to organiza-
tional change: Extension of a three-component model,
Journal of Applied Psychology, Vol. 87, Issue 3, pp. 474–
487 (2002).
[23] Meyer, J. P., Allen, N. J.: A three-component concepttual-
ization of organizational commitment, Human Resource
Management Review, No. 1, pp. 61–89 (1991).
[24] Hopwood, A.: Accounting and the pursuit of efficiency,
Governance and the Public Sector, Vol. 2005, pp. 278–298
(2005).
[25] Leadbetter, C.: The Rise of the Social Entrepreneur, De-
mos, London, 1997.
[26] Hood, C.: A public management for all seasons? Public
Administration, Vol. 69, Issue 1, pp. 3–19 (1991).
[27] Harrington, B., McLoughlin, K., Riddell, D.: Business pro-
cess reengineering in the public sector: A case study of the
Contributions Agency, New Technology, Work and Em-
ployment, Vol. 13, No. 1, pp. 43–50 (1998).
[28] Schein, A.: How Can Organizations Learn Faster? The
Challenge of Entering the Green Room, Sloan Manage-
ment Review, pp. 85–92 (1993).
[29] Williams, I.: Competing for quality: competition in the
supply of central government services, in: R. Lovell (Ed.)
Managing Change in the Public Sector, pp. 216–227,
1994.
[30] Sminia, H., Van Nistelrooij, A.: Strategic management and
organization development: Planned change in a public sec-
tor organization. Journal of Change Management, Vol. 6,
Issue 1, pp. 99–113 (2006).
[31] Lowdnes, V., Skelcher, C.: The Dynamics of Multi-Organ-
isational Partnership: An Analysis of Changing Mode of
Governance. Public Administration, Vol. 76, Issue 2, pp.
313–333 (1998).
[32] Bradburd, R.: Privatization of Natural Monopoly Public
Enterprises: The Regulation Issue, Review of Industrial
Organization, Vol. 10, Issue 3, pp. 247–267 (1995).
[33] Borcherding, T. E., Ponunerehne, W. W., Schneider, F.:
Comparing the Efficiency of Private and Public Produc-
tion: The Evidence from Five Countries, Public Produc-
tion, pp. 127–156, 1982.
[34] Lobina, E., Hall, D.: Public Sector Alternatives to Water
Supply and Sewerage Privatization: Case Studies. Interna-
tional Journal of Water Resources Development, Vol. 16,
Issue 1, pp. 35–55 (2000).
[35] Tichy, N., Devanna, M.A.: The Transformational Leader,
John Wiley & Sons, Inc., New York, 1986, p. 306.
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1, pp. 71–77 (2019)
Number of article: 619 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: May 18, 2019 UDC: 004.896:531.17]:007.52-025.42
Accepted: May 25, 2019
Original scientific paper
KINEMATIC MODELLING AND ANALYSIS OF SERIAL MANIPULATOR
Simona Domazetovska, Hristijan Mickoski, Marjan Djidrov
Faculty of Mechanical Engineering, "Ss. Cyril and Methodius" University in Skopje,
Karpoš II bb, P.O. box 464, 1001 Skopje, Republic of North Macedonia
A b s t r a c t: The purpose of this paper is modelling and simulation of serial manipulator type with four rotating
joints (RRRR). CAD model was developed by using the software SolidWorks for modelling the serial manipulator.
Simulation model of serial robot is made by conversion from SolidWorks to Matlab/Simulink. The serial robot can be
shown schematic as a kinematic connection of rigid bodies that are interconnected using rotary kinematic pairs. The
manipulator movement is defined so the movement of each member is related to the previous one. The position and
orientation of the gripper must be defined to ensure safe handling. In this paper, the steps needed to model the serial
manipulator together with all its components, its transfer into Simulink and its Proportional Integral Derivative (PID)
controlling and simulation is described. The obtained results for velocity and acceleration in kinematic pairs contribute
in detailed analysis of kinematics and control design.
Key words: serial robots; serial robot kinematics; manipulator; PID control
КИНЕМАТСКО МОДЕЛИРАЊЕ И АНАЛИЗА НА СЕРИСКИ МАНИПУЛАТОР
А п с т р а к т: Целта на овој труд е моделирање и симулација на сериски робот со четири ротирачки
зглобови (РРРР). Моделот CAD е изработен во програмскиот пакет SolidWorks со цел моделирање сериски
робот. Извршена е симулација во програмскиот пакет Matlab/Simulink. Имитационен модел на сериски робот е
добиен со префрлање на моделот од SolidWorks во програмскиот пакет Matlab/Simulink. Серискиот робот може
да биде анализиран како кинематска врска на крути тела кои меѓусебно се поврзани со ротирни или кинематски
парови. Движењето на роботот се дефинира така што се дефинираат движењата на секој член во однос на
претходниот. За да се обезбеди сигурна манипулација во просторот, потребно е да се дефинира положбата и
ориентацијата на фаќачот. Во овој труд целосно се дефинирани и опишани сите чекори потребни за моделира-
ње на овој робот заедно со сите негови составни делови, негово префрлање во програмскиот пакет Мatlab/
Simulink и управување преку пропорционална потполнo деривирана (изведена) контрола (PID-контрола) и
симулација. Добиените резултати за брзините и забрзувањата во неговите кинематски врски служат за детална
анализа на кинематиката и контрола на движењето.
Клучни зборови: сериски робот; кинематика на сериски робот; манипулатор; PID-контрола
1. INTRODUCTION
Computer modelling, simulation and imple-
mentation tools have been widely used to support
and develop nonlinear control, robotics, and MAT-
LAB/SIMULINK courses. MATLAB with its tool-
boxes such as SIMULINK [1] is one of the most
accepted software packages used by researchers to
enhance teaching the transient and steady-state
characteristics of control and robotic courses [2].
The international organization defines the
robot as an automatically controlled, reprogram-
mable, multipurpose manipulator with three or more
axes. Robot manipulator is a collection of links that
connect to each other by joints, these joints can be
revolute and prismatic that revolute joint has rotary
motion around an axis and prismatic joint has linear
motion around an axis [3]. Each joint provides one
or more degrees of freedom (DOF). From the
mechanical point of view, robot manipulator is
72 S.. Domazetovska, H. Mickoski, M. Djidrov
Mech. Eng. Sci. J., 37 (1–2), 71–77 (2019)
divided into two main groups, which called; serial
robot links and parallel robot links. In serial robot
manipulator, links and joints is serially connected
between base and final frame (end-effector).
Most of industrial robots are serial links and
can be used as surgical robot and space robot mani-
pulator.
Kinematics is an important subject to find the
relationship between rigid bodies and end-effector
in robot manipulator. Kinematic modelling of ro-
bots benefits the industrial automation processes by
making them semi-autonomous or even fully auto-
nomous. Because of the task nature and operational
environment, the industrial robots are usually com-
posed up of series of rigid links mounted on a base.
A 6-Degree оf Freedom (DOF) robotic arm mani-
pulator is widely used in the industry. The most
common applications of industrial robots include
Spot welding, Spraying, Assembling and Manufac-
turing. Many of these applications actually require
accomplishment of pick and place task. Implemen-
tation of this task fundamentally requires having the
kinematic model of the robotic arm being active.
The forward kinematic model predicated on
Denavit Hartenberg (DH) parametric scheme of
serial robot arm position placement using Robotics
toolbox is analyzed by the researchers in [4]. Given
the desired position and orientation of the robot end-
effector, the realized kinematics model provides the
required corresponding joint angles. In the area of
robot modelling and simulation, kinematics is a
widely researched topic. The robot modelling and
analysis techniques are typically based on line trans-
formation or on point transformation. Clothier et al.
[5] proposed a geometric model to solve the un-
known joint angles required for autonomous positi-
oning of a robotic system. In [6] is presented a
method for forces and moments determination in
kinematic joints of a three-member manipulator
analytically by using the Lagrangian second-order
equation and the principle of virtual work. Sahu et
al. [7] derived a new method, quaternion algebra,
for solution of forward kinematic problem. Popovic
et al. [8] developed a strategy to analyze the upper
extremity movement of the arm, while complete
Wang et al. [9] presented body kinematics of a
radial symmetrical six legged robot. Kinematic ana-
lysis of a new type of hybrid (parallel–serial) robot
manipulator, consisting of two serially connected
parallel mechanisms were analyzed in [10].
A method for solving the complete dynamic
problem in serial robots with rigid links and ideal
joints using the Gibbs-Appell equations as starting
point is presented in [11].
The researchers in [12] present a new formu-
lation method to solve kinematic problem of serial
robot manipulators, aiming to formulize inverse
kinematic problem in a compact closed form to
avoid singularity problem. The main targets in de-
signing control systems are stability, good distur-
bance rejection, and small tracking error [13]. Seve-
ral industrial robot manipulators are controlled by
linear methodologies [e.g. Proportional Derivative
(PD) controller, Proportional Integral (PI) controller
or Proportional Integral Derivative (PID) control-
ler].
Modelling and simulation of serial manipu-
lator, type RRRR (rotation, rotation, rotation, rota-
tion) will be analyzed in this work. For this purpose,
CAD modelling in Solid Works and modelling and
simulation of the behaviour of the serial manipu-
lator in Matlab/Simulink will be analyzed. PID
control will be applied to the manipulator in order
to control the robot.
2. MODELLING OF THE SERIAL ROBOT
IN SOLID WORKS
Modelling of different systems is a process of
creating appropriate model of the analyzed system
thus, all the necessary research and teaching of the
system can be performed on the model, rather than
on a real system. The process of modelling systems
is important stage while researching in terms of
reducing the time and resources. The simulation is
not a method to make an optimal solution, but pro-
vides an opportunity to evaluate the quality of the
system relative to another.
Modelling of the parts and their kinematic
pairs was analyzed in SolidWorks. In order to
understand and develop the properties of serial
robots, a model of a serial manipulator (Figure 1)
was developed and based on this model direct
kinematics is presented.
As it can be seen from Figure 1, the serial robot
has a functional and a simple structure. The model
is consisted of six individual parts that are con-
nected through kinematic pairs, creating a compact
structure of serial manipulator. The components of
which the robot is consisted are:
– base, which is attached to the work surface,
– rotational joints which allows one degree rota-
tion of the robot,
– connection part, that enables the second rota-
tion of the robot and has a larger dimension,
so it can allow larger working space,
Kinematic modelling and analysis of serial manipulator 73
Маш. инж. науч. спис., 37 (1–2). 71–77 (2019)
– cylindrical part that allows the third rotation
of the manipulator. It has a cylindrical recess
which enables translation of the connected
kinematic pair,
– piston section, which enables increasing of the
working space,
– gripper, the executive member, located at the
end of the robot’s structure in order to perform
the certain mission.
Fig. 1. Structure of the serial robot modelled in Solid Works
Due to the greater stability required to ensure
high accuracy of the gripper, four support parts are
placed at an angle of 90° to eachother. The robots
control interface is attached on the base consisted of
electronics. The material and dimension of the base
are chosen according to the required performance.
The rotary part is composed of a cylinder that
has the same dimensions as the cylindrical opening
of the base. Using the mate tool, the rotary part is
connected with the base. The robustness and relia-
bility of the serial manipulator while increasing the
working space are one of the things that have to be
considered while modelling.
The cylindrical part is consisted of two mutu-
ally normal cylindrical openings. The opening of the
cylinder part is intended to form a piston mecha-
nism, whose main achievement is to increase the
robot’s working space. The piston part is composed
of a cylinder, a circular heat for limitation of the
movement and holder for the gripper. The gripper is
the last link from the serial robot, which structure is
shown on Figure 2.
All of the previous parts actually serve to posi-
tion the gripper to the required location of perfor-
mance. The gripper is the most complex part of the
serial manipulator, composed of many parts that
form one functional structure. The structure allows
performing movements of the gripper through
cylindrical axis located in the middle, hydraulic
driven. The movement of the gripper is transferred
through the mechanisms.
Fig. 2. CAD model of the gripper
Figure 3 shows a schematic representation of
the serial robot, showing all of its parts along with
the provided manoeuvres. The workspace is rela-
tively high, allowing the gripper manipulating away
from the base with great accuracy.
Fig. 3. Schematic representation of the serial manipulator
2.1. Direct kinematics modelling
Denavit-Hartenberg’s method is an efficient
procedure for the determination of direct kine-
matics, widely used in robotic applications. In order
to calculate the direct kinematic equations for an
open chain manipulator, it is necessary to derive and
define a relative position and orientation of two
consecutive links. While solving the kinematics of
the links, relationship between the two parts has to
be defined.
74 S.. Domazetovska, H. Mickoski, M. Djidrov
Mech. Eng. Sci. J., 37 (1–2), 71–77 (2019)
The axis 𝑖 is defined for the connections of the
parts 𝑖 − 1 and 𝑖 .The axis of the joint 𝑖 + 1 is
chosen, and the point Oi is located between the inter-
section of the zi axis with the normal segment to the
zi–1 and zi axes. Axis xi is defined which has the same
direction as the drawn segment and at the same time
is normal on the z-axis. In order to complete the
coordinate systems, axis yi is selected.
Once the kinematic parameters are defined, the
transformation between the 𝑖 − 1 and 𝑖 coordinate
systems can be expressed.
The homogeneous transformation matrix for
the chosen system in the selected coordinate system
will be:
𝐴𝑖𝑖−1 (
cos(𝜃𝑖) −sin(𝜃𝑖) 0 0sin(𝜃𝑖) cos(𝜃𝑖) 0 0
0 0 1 𝑑𝑖
0 0 0 1
) (1)
If the selected system is moved from its
position along the x-axis, the position is rotated for
angle αi along the x-axis. The new position will
match with the new position of the coordinate
system i. Its homogeneous transformation matrix
will be:
𝐴𝑖𝑖′
(
1 0 0 𝛼𝑖
0 cos(𝛼𝑖) −sin(𝛼𝑖) 00 sin(𝛼𝑖) cos(𝛼𝑖) 00 0 0 1
) (2)
The resulting transformation of the coordinate system is obtained by multiplying the individual
homogeneous transformations:
𝐴𝑖𝑖−1(𝑞𝑖) = 𝐴𝑖
𝑖−1𝐴𝑖𝑖′
(
cos(𝛳𝑖) −sin(𝛳𝑖)cos(𝛼𝑖) sin(𝛳𝑖)sin(𝛼𝑖) 𝛼𝑖cos(𝛳𝑖)sin(𝛳𝑖) cos(𝛳𝑖)cos(𝛼𝑖) −cos(𝛳𝑖)sin(𝛼𝑖) 𝛼𝑖sin(𝛳𝑖)
0 sin(𝛼𝑖) cos(𝛼𝑖) 𝑑𝑖
0 0 0 1
) (3)
The Denavit-Hartenberg method allows the
definition of kinematic functions by combining
individual homogeneous transformations into a
resultant transformational matrix. This procedure
can be applied to any open kinematic chain.
3. ANALYTICAL MODELLING OF SERIAL
ROBOT
The behaviour of physical systems in many
situations may better be expressed with an analy-
tical model. Modelling a robot involves study of its
kinematic behaviour. A kinematic model is con-
cerned with the robot’s motion without considering
forces producing the motions. The Simulink pro-
gramming package is part of Matlab and has a great
application in the technique and serves for mode-
lling, simulation and analysis of dynamic systems in
multiple areas. It can work with non-linear and
linear systems in discrete and continuous time and
explore the impact in the real models, which are real
phenomena and affect the real model. Simulink uses
a block library that, with a simple drag-and-drop
procedure, ships into a separate window for a model
and with appropriate blocking of the blocks, a
model is created that can be easily repaired and
updated later on. It is connected to the Matlab tools
and has instant access to them, so Simulink models
can be easily analyzed and visualized. Once the
Solid Works model is developed, in order to
perform a simulation, it should be transferred to
Matlab/Simulink which is enabled automatically by
the Multibody tool provided by MathWorks. The
basic criteria needed to be established are: the prog-
ram compatibility, installation files, connectivity,
solid model support and model export. The Matlab/
Simulink model of the serial robot is shown on
Figure 4.
The simulation of the gripper is created as an
imitation model independent of the previous one,
modelled due to its functionality in Matlab. The
controlling of the gripper is performed due to the
geometry of the two parts of the gripper, rotated for
450, in order to achieve closing of the gripper.
Figure 5 shows the visual look and the Simulink
model of the gripper.
Kinematic modelling and analysis of serial manipulator 75
Маш. инж. науч. спис., 37 (1–2). 71–77 (2019)
Fig. 4. Matlab/Simulink model of the serial robot
Fig. 5. Matlab/Simulink model of the gripper
4. PID CONTROL
PID (Proportional Integral Derivative) con-
trollers use a control loop feedback mechanism to
control process variables and are the most accurate
and stable controller. PID integral differential meth-
od is the expansion of simpler PD management.
Enlargement is done by adding an integral compo-
nent. Adding this component substantially reduces
the positional error in the joints of and it is approxi-
mate to zero.The PID law is represented by the
following equation:
u(t) = 𝐾𝑝𝑒(𝑡) + 𝐾𝑖 ∫ 𝑒(𝑡)𝑡
0𝑑𝑡 + 𝐾𝑑
𝑑𝑒(𝑡)
𝑑𝑡 (4)
where 𝐾𝑝 is a proportional amplifier, Kd is a differ-
rential amplifier and Ki is a integration amplifier.
The connection of the PID controller to Simul-
ink simulated models is very useful and effective.
Since the wanted motion is initiated in kinematic
pairs, the actuator block is linked to the kinematic
link between two rigid bodies. In order to have
control accuracy data, a kinematic relationship
sensor is set which measures displacements, velo-
city and acceleration. To assign a value to the mana-
gement, a step function is used which is passed thro-
ugh one slider and will have values from −100° ÷ 130 °, and it can be real-time during the simulation
to change and in that way to perform planned cont-
rol in real time.The sum of the two values is dedu-
cted by the return function representing the error
and thus controlling the accuracy of the entire sys-
tem. The controlling of the system in Matlab/Simu-
link is shown on Figure 6.
Individual PID controllers can operate inde-
pendently in relation to each other and this is their
great advantage. It is possible to generate a force in
a kinematic pair and thus move one part of the robot,
while the previous parts remain stationary.
76 S.. Domazetovska, H. Mickoski, M. Djidrov
Mech. Eng. Sci. J., 37 (1–2), 71–77 (2019)
Fig. 6. PID control of the serial manipulator
5. RESULTS
The velocity and acceleration of each of the
kinematic pairs are analyzed. The results of the
measured data are shown on a graph for each
kinematic pair separately. The serial robot requires
fivesuch structures that are placed in the model and
tested. The results for the five parts are shown on
Figure 7.
After applying control on the manipulator’s
gripper, the results for the velocity and acceleration
are analyzed, shown on Figure 8.
Fig. 7. Velocity and acceleration results for each of the kinematic pairs
Fig. 8. Velocity and acceleration – results for the gripper
6. CONCLUSION
Modelling and simulation of robotic systems
using various software reflects the process of de-
signing, constructing and controlling robots in the
real world. Simulating the dynamic processes pro-
vides an overview of the behaviour of the existing
dynamic system with proper management. Simula-
tion is of great importance because with it the cons-
tructors can presume and evaluate the behaviour of
the robot, as well as to confirm and optimize the
robot movement plan for the given problem. The
simulation significantly reduces the time and costs
Kinematic modelling and analysis of serial manipulator 77
Маш. инж. науч. спис., 37 (1–2). 71–77 (2019)
that are unavoidable in experimental research of
dynamic systems, and plays an important role in the
evaluation of production.
The presented serial robot manipulator has
been kinematically modelled followed by the ana-
lysis of its workspace and for the modelling of the
robot SolidWorks and Matlab softwares were used.
Forward kinematic model has been validated by
using Matlab and PID controlling was used to con-
trol the serial robot manipulator.
The possibility of simulation opens up a wide
range of opportunities for creative solving of many
problems. Serial manipulators are more and more
used in industry, and in environments that are inac-
cessible or risky for humans. Their simple structure
made up of rotary and translator kinematic pairs
allows the executive member to easily position and
orient in the workspace. They work with great accu-
racy and speed, in places that require great precision
and responsiveness.
REFERENCES
[1] Kurfess, T. R.: Robotics and Automation Handbook. CRC
Press, 2004.
[2] Ogata, K.: Modern Control Engineering (pp. 6142–6143).
Upper Saddle River, NJ, Prentice Hall, 2009.
[3] Piltan, F., Emamzadeh, S., Hivand, Z., Shahriyari, F.,
Mirazaei, M.: PUMA-560 robot manipulator position
sliding mode control methods using MATLAB/SIMU-
LINK and their integration into graduate/undergraduate
nonlinear control, robotics and MATLAB courses. Inter-
national Journal of Robotics and Automation, 3 (3), 106–
150 (2012).
[4] Iqbal, J., Islam, R. U., Khan, H.: Modelling and analysis of
a 6 DOF robotic arm manipulator. Canadian Journal on
Electrical and Electronics Engineering, 3 (6), 300–306
(2012).
[5] Clothier, K. E., Shang, Y.: A geometric approach for
robotic arm kinematics with hardware design, electrical
design, and implementation. Journal of Robotics, Volume
2010, Article ID 984823, 10 pages,
http://dx.doi.org/10.1155/2010/984823
. [6] Mickoski, H., Mickoski, I., Djidrov, M.: Dynamic
modelling and simulation of three-member robot mani-
pulator. Mathematical Models in Engineering, Vol. 4,
Issue 4, pp. 183–190 (2018).
[7] Sahu, S., Biswal, B. B., Subudhi, B.: A novel method for
representing robot kinematics using quaternion theory,
2008.
[8] Popovic, N., Williams, S., Schmitz-Rode, T., Rau, G.,
Disselhorst-Klug, C.: Robot-based methodology for a
kinematic and kinetic analysis of unconstrained, but
reproducible upper extremity movement. Journal of
Biomechanics, 42 (10), 1570–1573 (2009).
[9] Wang, Z., Ding, X., Rovetta, A., Giusti, A.: Mobility
analysis of the typical gait of a radial symmetrical six-
legged robot. Mechatronics, 21 (7), 1133–1146 (2011).
[10] Tanev, T. K.: Kinematics of a hybrid (parallel–serial) robot
manipulator. Mechanism and Machine Theory, 35 (9),
1183–1196 (2000).
[11] Mata, V., Provenzano, S., Valero, F., Cuadrado, J. I.:
Serial-robot dynamics algorithms for moderately large
numbers of joints. Mechanism and Machine Theory, 37
(8), 739–755 (2002).
[12] Sariyildiz, E., Temeltas, H.. Solution of inverse kinematic
problem for serial robot using dual quaterninons and
Plücker coordinates. In 2009 IEEE/ASME International
Conference on Advanced Intelligent Mechatronics, IEEE,
2009, July, pp. 338–343.
[13] Kieffer, J.: A path following algorithm for manipulator
inverse kinematics. In: Proceedings. IEEE International
Conference on Robotics and Automation, IEEE, 1990,
May, pp. 475–480.
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 79–86 (2019)
Number of article: 620 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: November 4, 2018 UDC: 004.896:531.17]:007.52-025.41
Accepted: February 20, 2019
Original scientific paper
CAD MODELLING OF PARALLEL ROBOT (TRIPOD) IN MATLAB/SIMULINK
Maja Anačkova, Hristijan Mickoski
Faculty of Mechanical Engineering, "Ss. Cyril and Methodius" University in Skopje,
Karpoš II bb, P.O. box 464, 1001 Skopje, Republic of North Macedonia
A b s t r a c t: The purpose of this paper is to create a model simulation of a parallel robot with PID controller
using the programming package Matlab/ Simulink. In this paper, forward and inverse kinematics of parallel robot tripod
is presented; model of the parallel robot in the programming package Solid Works is constructed; simulation model of
the parallel robot tripod is made by conversion from Solid Works to Matlab/Simulink and results for velocities and
accelerations in its kinematic joints are obtained that serve to the management and control of the mobile platform as a
major problem in the construction of a parallel robot. Model simulation of parallel robot will be the basis for creating
models of parallel robots with more complex structure, detailed understanding of their kinematics and control design
as an inevitable part of the future of robotics and mechatronic.
Key words: parallel robots; tripod; parallel robot kinematics; model simulation
CАD-МОДЕЛИРАЊЕ НА ПАРАЛЕЛЕН РОБОТ (ТРИПОД) ВО MATLAB/SIMULINK
А п с т р а к т: Целта на овој труд е креирање на имитационен модел на паралелен робот со пропорцио-
нално целосно деривирано (PID) управување во програмскиот пакет Matlab/ Simulink. Во овој труд е разрабо-
тена директна и инверзна кинемaтика на паралелен робот со три нозе; модел на паралелниот робот е изработен
во софтверскиот пакет Solid Works; имитационен модел на паралелен робот со три нозе е добиен со префрлање
на моделот од Solid Works во програмскиот пакет Матлаб/Симулинк и се добиени резултати за брзините и
забрзувањата во неговите кинематски врски кои служат за управување и контрола на движењето на подвижната
платформа, што е главна задача при конструкција на еден паралелен робот. Симулацијата на модел na парале-
лен робот со три нозе ќе биде основа за креирање на модели на паралелни роботи со многу посложена струк-
тура, детално разбирање на нивната кинематика и управување како неизбежен дел од иднината на роботиката
и мехатрониката.
Клучни зборови: паралелен робот; кинематика на паралелен робот; симулација на модел
1. INTRODUCTION
In the last decades, parallel robots have moti-
vated a great interest because of their characteristics
of small moving masses, preciseness and high-
speed controllability compared to the serial robots.
They have been widely used for the reconfigurable
structure due to their inherent modularity. Such de-
sign and analysis for a reconfigurable parallel robot
is given in [1] and [2]. Generally, parallel robots are
constructed from a fixed, called stationary platform,
a mobile or moving platform and legs which con-
nect these two platforms. This parallel kinematics
have significant advantages over the serial robots
because of their accuracy, rigidness and higher load
capacity. These parallel kinematics machines
(PKMs) have many applications such as from air-
crafts simulators, machining tools, micro-motion
machines [3]. In industrial applications, most
widely used are the parallel robots that generate
spherical rotation around a certain point as shown in
[4].
The problem of kinematics of these parallel
structures means determination of their direct and
inverse kinematics equations. The direct kinematics
explains the motion in terms of a base fixed
80 M. Anačkova, H. Mickoski
Mech. Eng. Sci. J., 37 (1–2), 79–86 (2019)
Cartesian coordinate systems according to which
the position and orientation of the end effector (in
this case the moving platform) are determined. The
inverse kinematics is more complex, it includes
calculation of the possible values for the angular and
linear displacements of the joints in order for the
mobile platform to achieve a certain trajectory or a
desired position [5]. A comparative analysis of these
two methods is presented in [6].
The kinematics and dynamics problems of the
robots in general are solved by using the modelling
and simulation methods in a certain software that
supports this analysis. Most commonly used soft-
ware is Matlab software package, more concisely
Matlab/Simulink which allows this kind of identi-
fication and analysis of the robot parameters in a
virtual environment. It allows real-time simulations
of the motion of the robot showing the changes in
the position, velocity and acceleration of a desired
joint or body [7]. From the simulated model of
parallel manipulator in [8] it can be concluded that
the choice of the generalized coordinate does not
provide a unique determined position on the mobile
platform without taking into account the conditions
of the kinematic joints, linear and the angular velo-
cities. Matlab/Simlunk also allows integrating a
control algorithm and the response of the robot
under the given control. A model of 3-RRR planar
parallel robot controlled by a PID controller in
Matlab/Simulink is explained in [9].
In this paper, a three-legged RRR parallel
robot model in the Solid Works program package-
was developed as given in Section 2. Based on this
model, a simulation of the movement of the mov-
able platform (its trajectory) was later conducted
considering the direct and inverse kinematics ex-
plained in Section 3. Further, PID control was
implemented and graphs of the dynamic parameters
were exported and shown in Section 4 in order to
understand the motion of the movable platform.
2. MODELLING OF THE TRIPOD IN SOLID
WORKS
The kinematic and dynamic analytical study of
different systems (mechanical, electrical, etc.) is
usually done by their modelling and simulation. The
goal of the modelling process of a single system is
to create an adequate, verifying model of the sys-
tem. Thus, all the necessary research and system
studies can be performed on the model instead of a
real system, which saves time and resources.
Modelling is the most important stage in the rese-
arch of a single system. It should lead to a model
that will contain the basic properties of the system
necessary to solve the tasks of the research. The
model should be fully available for the means of
appropriate science and mathematics and to store all
the characteristic elements of the systems output.
Closely related to the modelling process is the
process of simulation. The term simulation refers to
an experimental approach for analyzing and obser-
ving the functional properties of a system using its
simplified model. The simulation of mechanical
systems gives us visualization of the dynamic beha-
viour of the mechanical system. At the core of the
simulation is the verifying model of the system as a
real object for testing. Simulation is not a method to
make an optimal solution, but provides an opportu-
nity to evaluate the quality of the system relative to
another. It represents an experiment performed on
the model. In order to understand and analyze the
properties of parallel robots, a three-legged parallel
robot model was designed in the Solid Works prog-
ram package.
The model of parallel robot consists of a sta-
tionary (bottom) platform, three legs representing
clips that can perform a translatory movement and a
movable (upper) platform (Figure 1). The bottom
platform fixed to the base through the three pairs of
screws and nuts. The joints of the platform's legs are
made by means of rotational connections (Figure 2).
Fig. 1. Model of tripod in “Solid Works”
Fig. 2. Rotational joints between the legs
and the stationary platform
CAD modelling of parallel robot (tripod) in Matlab/Simulink 81
Маш. инж. науч. спис., 37 (1–2), 79–86 (2019)
The lower and upper platforms are flat triang-
les that are identical by their dimensions (Figure 3).
Fig. 3. Platform geometry
Tripod motion is allowed in three degrees of
freedom: translation along the y-axis (top-down)
(Figure 4a), rotation around the y-axis (Figure 4b)
and translation by z-axis (Figure 4c).
Fig. 4. Degrees of freedom of the tripod
Since we have already defined the geometry
and degrees of freedom of this robot, we can easily
obtain the equations for its direct and inverse kine-
matics.
2.1 Direct kinematics
The rotational connections attached to the fix-
ed platform are 𝐴𝑖, while those on the mobile plat-
form are 𝐵𝑖 , where 𝑖 = 1, 2, 3 . Accordingly, the
three feet of the robot will be 𝐴𝑖𝐵𝑖 . The points
𝐴𝑖 and 𝐵𝑖 form a flat triangle with sides 𝑎 and 𝑏
respectively. We specify the lengths of the sides
with 𝑖 = 1, 2, 3 and their slope to the fixed base is
0, i.e. they are placed at right angles to the base
(Figure 5).
Fig. 5. Coordinate systems of the platforms
On the stationary platform, we join the coordi-
nate system Axyz, such that point A is at the center of
the symmetry of the base, the axes x and z lie on the
base, and the y-axis is normal to the stationary
platform. Analogously, the Bxyz coordinate system is
attached on the mobile platform.The positions of the
rotational pairs 𝐴1, 𝐴2, 𝐴3 in the Axyz coordinate
system are:
𝐴1 = (𝑎
2, 0,𝑎
2)𝑇
= (𝐴11,𝐴12,𝐴13,)𝑇,
𝐴2 = (𝑎
2, 0, −
𝑎
2)𝑇= (𝐴21,𝐴22,𝐴23,)
𝑇, (1)
𝐴3 = (−𝑅, 0,0)𝑇 = (𝐴31,𝐴32,𝐴33,)
𝑇.
Similarly, the positions of the rotational pairs
with respect to the Bxyz coordinate system are:
𝐵1 = (𝑏
2, 0,𝑏
2)𝑇
= (𝐵11,𝐵12,𝐵13,)𝑇,
𝐵2 = (𝑏
2, 0, −
𝑏
2)𝑇= (𝐵21,𝐵22,𝐵23,)
𝑇, (2)
𝐵3 = (−𝑟, 0,0)𝑇 = (𝐵31,𝐵32,𝐵33,)
𝑇.
The position of the mobile platform relative to
the stationary platform is determined by the Euler
angles 𝜑1and 𝜑2 and the vector 𝐵 = (0, 𝐵𝑇). The
geometric relationship of the coordinate systems,
that is, the position of the movable coordinate
system relative to the stationary of the lower
platform is described using a 4×4 matrix with
homogeneous transformations:
𝑇 = 𝑇(0, 𝜑1, 𝜑2) =
= [
cos𝜑1 −sin 𝜑1𝑠𝑖��𝜑1cos𝜑2 −cos𝜑1cos𝜑2
0 0𝑠𝑖��𝜑2 0
sin𝜑1 sin𝜑2 −cos𝜑1sin𝜑20 0
cos𝜑2 00 1
] (3)
From the previous equation follows that the
position of the rotational pairs Bi in relation to the
coordinate system Axyz are determined by the vector:
[𝐵𝑖] =
(
[𝐵𝑖,1]
[𝐵𝑖,2]
[𝐵𝑖,3]
1 )
= 𝑇(0, 𝜑1, 𝜑2)
(
[𝐵𝑖,1]
[𝐵𝑖,2]
[𝐵𝑖,3]
1 )
=
= 𝑇(0,𝜑1, 𝜑2)𝐵𝑖 = 𝑇𝐵,
82 M. Anačkova, H. Mickoski
Mech. Eng. Sci. J., 37 (1–2), 79–86 (2019)
[𝐵1] =
(
𝑏
2cos𝜑1
𝑏
2sin𝜑1 cos𝜑2 +
𝑏
2
sin𝜑2
𝑏
2sin𝜑1 sin𝜑2 +
𝑏
2
cos𝜑2
1 )
,
[𝐵2] =
(
𝑏
2cos𝜑1
𝑏
2sin𝜑1 cos𝜑2 −
𝑏
2
sin𝜑2
𝑏
2sin𝜑1 sin𝜑2 +
𝑏
2
cos𝜑2
1 )
, (4)
[𝐵3] = (
−𝑟cos𝜑1−𝑟sin𝜑1 cos𝜑2−𝑟sin𝜑1sin𝜑2
1
).
Consequently, the generalized coordinate 𝑙𝑖 is
calculated according to the following equation:
𝑙𝑖 = 𝑙𝑖(0, 𝜑1, 𝜑2) = √∑(𝐴𝑖,𝑗 − [𝐵𝑖,𝑗])2,
𝑗 = 1, 2, 3 and 𝑖 = 1, 2, 3. (5)
2.2. Inverse kinematics
The rotational pairs are designed on the base
(stationary platform) with A, B and C while they are
on the movable platform with a, b, and c. We repre-
sent the lengths of the legs with the generalized
𝑙1, 𝑙2 and 𝑙3 coordinates:
𝒍𝟏 = (𝑿𝑨𝟏 − 𝑿𝑩𝟏)𝟐+ (𝒀𝑨𝟏 − 𝒀𝑩𝟏)
𝟐+
+ (𝒁𝑨𝟏 − 𝒁𝑩𝟏)𝟐,
𝒍𝟐 = (𝑿𝑨𝟐 − 𝑿𝑩𝟐)𝟐+ (𝒀𝑨𝟐 − 𝒀𝑩𝟐)
𝟐+ (6)
+ (𝒁𝑨𝟐 − 𝒁𝑩𝟐)𝟐,
𝒍𝟑 = (𝑿𝑨𝟑 − 𝑿𝑩𝟑)𝟐+ (𝒀𝑨𝟑 − 𝒀𝑩𝟑)
𝟐+
+ (𝒁𝑨𝟑 − 𝒁𝑩𝟑)𝟐.
3. MODEL SIMULATION IN
MATLAB/SIMULINK
For faster and more efficient problem solving
in the modern practice, advanced software and soft-
ware packages are required. Such program package
is Matlab created from MathWorks and it is a pro-
gramming language for technical calculations
which can also perform visualization and program-
ming. The Simulink programming package is a part
of Matlab software and has a great application in the
modelling, simulation and analysis of dynamic sys-
tems in multiple areas. It is practical, because it can
work with non-linear and linear systems, and can
work in discrete and continuous time. It also can
explore real models, their impact from friction, air
resistance, etc., which are real phenomena and af-
fect the real model. Simulink uses a block library
that, with a simple drag-and-drop procedure, ships
into a separate window for a model and with appro-
priate arranging of the blocks, a model that can be
easily repaired and updated is created. It is connec-
ted to the Matlab tools and has instant access to
them, therefore Simulink models can be easily ana-
lyzed and visualized (Figure 6).
Fig. 6. Block scheme of the tripod in Simulink
CAD modelling of parallel robot (tripod) in Matlab/Simulink 83
Маш. инж. науч. спис., 37 (1–2), 79–86 (2019)
Once the Solid Works model is developed, in
order to perform a simulation it should be
transferred to Matlab/Simulink which is enabled
automatically by the Multibody tool provided by
MathWorks.
The first generation of SimMechanics under
Matlab/Simulink includes a library of blocks and
visualization tools that have been released in Sim-
Mechanics versions before Matlab R2012a. The
latest generation is simpler modelling with a new
library of blocks, with a much more powerful com-
puting machine, more advanced visualization based
on OpenGL® computer graphics, and more detailed
integration between SimscapeTM products. Sim-
Mechanics first and last generation technologies
have different sets of capabilities. Furthermore,
Matlab automatically builds the imitation model of
the parallel robot and the simulation of its motion
(Figure7).
Fig. 7. Model simulation built in Matlab/Simulink
4. PID CONTROL OF THE TRIPOD
The Proportional Integral Derivative (PID)
controlled law of motion management introduces a
new, time-dependent variable, which is denoted by
𝜉 and whose time differential is:
�� = 𝑞. (7)
The previously defined law now receives the
form:
𝜏 = 𝑘𝑝�� + 𝑘𝑣 �� + 𝑘𝑖𝜉. (8)
By combining the previous equations, we
define the behaviour of a manipulative robot with n-
degrees of freedom during its management of the
PID controller:
𝐵(𝑞)�� + 𝐶(𝑞, ��)�� + 𝑔(𝑞) = 𝑘𝑝�� + 𝑘𝑣 �� + 𝑘𝑖𝜉 (9)
or the solution for the equivalent in relation to the
vector of the position is:
[𝜉𝑇0𝑇0𝑇]𝑇. (10)
To achieve the desired position 𝑞𝑑for which 𝜉∗ is a constant, one way is to solve a differential
equation where 𝜏0 is a constant vector and the
solution is given with:
𝜉∗ = 𝑘𝑖−1𝜏0. (11)
If we assign a constant moment to the mani-
pulation robot 𝜏 = 𝜏0, the solution to the previous
equation is simply the position vector 𝑞 and the
velocity ��. In case when the desired position 𝑞𝑑 is a
function of the time, the equation has no solution,
i.e. it can not be expected that the error of position
q is tending to 0. In the best case also assuming that
the initial error of the positions 𝑞(0) and ��(0) the
velocity are small, so the error of positions 𝑞 over
time remains limited. In this case, the PID controller
is connected to the mobile platform, as shown in
Figure 8.
The P, I, and D amplifiers can be modified by
clicking in the according blocks. The PID controller
manages the trajectory that describes the mobile
platform, which is actually the ultimate goal of the
parallel robot controllability. By changing the valu-
es of the proportional, differential and integral amp-
lifier, its position, velocity and acceleration are
changing. Namely, with the aid of a sensor, we can
explicitly obtain the schedules of displacement, spe-
ed and acceleration corresponding to the given
ratios for the amplifiers. To calculate these three
sizes, we create subsystems with mathematical ope-
rations as shown in Figure 9
The subsystems contain blocks with which the
displacement, velocity and acceleration vectors
along the three axes are depicted in one graph as
total displacement, total speed and total accelerati-
on, using the well-known equation:
𝑝 = √𝑝12 + 𝑝2
2 + 𝑝32,
𝑣 = √𝑣12 + 𝑣2
2 + 𝑣32, (12)
𝑎 = √𝑎12 + 𝑎2
2 + 𝑎32
84 M. Anačkova, H. Mickoski
Mech. Eng. Sci. J., 37 (1–2), 79–86 (2019)
Fig. 8. Block diagram in Matlab/Simulink with PID control
Fig. 9. Calculation of the position, velocity and acceleration
5. RESULTS
To show and verify the function of the sub-
systems, the values for the position, speed, and shift
in the values of the amplifiers of the controller P =
0.8, I = 0.2 and D = 0.2 are selected arbitrarily. The
mobility examination of the mobile platform is
proceeded during a period of 3 seconds (T = 3). The
graphs for the position, velocity and acceleration
accordingly are given in Figure 10. These graphs
were obtained for the chosen arbitrary values of the
PID controllers amplifiers that we have set in advan-
ce.
CAD modelling of parallel robot (tripod) in Matlab/Simulink 85
Маш. инж. науч. спис., 37 (1–2), 79–86 (2019)
The graphs will be different for different
amplifier values. This means that with the PID con-
troller we directly influence on the movement of the
centre of gravity of the mobile platform, that is, its
trajectory, which was actually the purpose of its
installation. We also control its speed and accelera-
tion, thus affecting the dynamics of the manipulator.
a)
b)
c)
Fig. 10. Graphs for the a) position, b) velocity and c) acceleration
86 M. Anačkova, H. Mickoski
Mech. Eng. Sci. J., 37 (1–2), 79–86 (2019)
6. CONCLUSION
With the help of the software package "Solid
Works", a new parallel manipulator with three de-
grees of freedom was modelled. The structure of the
manipulator consisted of three legs, each connected
with a rotary pair to the movable and stationary
platform of the manipulator. Direct and inverse
kinematics was considered for this manipulator,
following with simulation of the motion. Finally,
the movement of the mobile platform was control-
led by a PID controller, with reference to the relia-
bility of the trajectory of the mobile platform from
the values of the PID controllers.
Primarily, the purpose of this paper work was
to look at parallel manipulators, whose applications
today are innumerable and spread new horizons in
the robotics industry. Furthermore, the possibilities
of direct communication between the Solid Works
and Matlab/Simulink software packages for model-
ling a parallel manipulator through the Multibody
tool were presented. So far, the application of these
two software packages as independent has perhaps
been more complicated, but through the Multibody
tool, it has become unlimited. The PID controller
was considered as the most used in today's applica-
tions in the technology processes and was used as
an ideal option for managing the parallel manipu-
lator in order achieving complex trajectories which
is widely used and extremely important.
REFERENCES
[1] Xi, F., Li, Y. and Wang, H.: Module-based method for
design and analysis of reconfigurable parallel robots.
Frontiers of Mechanical Engineering, 6 (2), pp. 151–159
(2011).
[2] Xi, F., Xu, Y., Xiong, G.: Design and analysis of a re-
configurable parallel robot. Mechanism and Machine
Theory, 41 (2), pp. 191–211 (2006).
[3] Bi, Z. M., Lang, S. Y.: Kinematic and dynamic models of
a tripod system with a passive leg. IEEE / ASME Trans-
actions on Mechatronics, 11 (1), pp. 108–111 (2006).
[4] Karouia, M., Hervé, J. M.: A three-DOF tripod for genera-
ting spherical rotation. In: Advances in Robot Kinematics,
Springer, Dordrecht, 2000 (pp. 395–402).
[5] Laski, P. A., Takosoglu, J. E., Blasiak, S.: Design of a 3-
DOF tripod electro-pneumatic parallel manipulator. Robo-
tics and Autonomous Systems, 72, pp. 59–70 (2015).
[6] Staicu, S.: Recursive modelling in dynamics of Delta
parallel robot. Robotica, 27 (2), pp. 199–207 (2009).
[7] Lapusan, C., Matis, V., Balan, R., Hancu, O., Stan, S. and
Lates, R.: Rapid control prototyping using Matlab and
dSpace. Application for a planar parallel robot. IEEE
International Conference on Automation, Quality and
Testing, Robotics,Vol. 2, pp. 361–364). IEEE, May 2008.
[8] Jovčevski, D., Djidrov, Marjan, Mickoski, H.: Kinematic
model analysis of a parallel manipulator with six and three
degrees of freedom, Mechanical Engineerring – Scientific
Journal, Vol. 36, No. 2, pp. 137–144 (2018). ISSN 1857–
5293.
[9] Stan, S. D., Manic, M., Maties, V., Balan, R.: Kinematics
analysis, design, and control of an Isoglide3 Parallel Robot
(IG3PR). In: 34th Annual Conference of IEEE Industrial
Electronics, IEEE, November 2008 (pp. 2636–2641),
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 87–91 (2019)
Number of article: 621 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: May 21, 2019 UDC: 697.34:697.2]:696.2-047.44
Accepted: August 21, 2019
Original scientific paper
LIFECYCLE COSTS COMPARATION BETWEEN DISTRICT HEATING
AND INDIVIDUAL GAS HEATING
Dame Dimitrovski, Dalibor Stojevski
Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: The purpose of this work is to define the economically more feasible solution to the air pollution
problem in Skopje through use of district heating (DH) or individual gas heating. Suburb model is Lisiče in Skopje.
Analyzed are the total lifecycle costs of entire city quarter through use of the mentioned heating types. The energy
consumption and CO2 emissions from different lifecycle phases depend on the properties of pipe material, type of
technologies used (during manufacturing the pipe, installing equipment and pumping technologies) and the type of
fluid. Four phases are considered in this lifecycle assessment, which are production and fabrication, transportation to
job site, pipe installation and operation or service phase. As can be concluded, total lifecycle costs in DH system are
lower than the costs for individual gas heating. The slightly higher operating costs are annulled by the costs for
maintenance and CO2, which are significantly larger by use of individual gas heating system. By use of DH system in
the suburb of Lisiče, the emission of PM10/2,5 will be practically extinguished as the DH system uses natural gas as only
source. This will lead to improved air quality in this part of Skopje.
Key words: district heating, gas heating, air pollution, heating costs
СПОРЕДБА НА ТРОШОЦИТЕ ВО ТЕКОТ НА РАБОТНИОТ ВЕК НА СИСТЕМOT
ЗА ЦЕНТРАЛНО ГРЕЕЊЕ И ИНДИВИДУАЛНОТО ГРЕЕЊЕ СО ГАС
А п с т р а к т: Целта на овој труд е да се дефинираат економски исплатливи решенија на проблемот на
загадувањето на воздухот во Скопје преку анализа на системи за централно греење со гас и индивидуално
загревање на објектите со гас. Како модел е земена населбата Лисиче. Во трудот се анализирани параметрите
од целиот работен век на производот (услугата) за двата вида греење. Анализирани се процесите: проектирање,
производство и транспорт на материјалите, вградување и работа на системот. Поради долготрајноста на
системот, управувањето со отпад по завршувањето на работниот век на услугата не е земено предвид. Како
што може да се заклучи, трошоците за централното греење се пониски во споредба со индивидуалното
загревање со гас. Повисоките трошоци кај централниот дистрибутивен систем за топла вода се компензираат
со трошоците за одржување на индивидуалните системи. Со користење централен систем за снабдување со
топла вода, погонуван со природен гас, во населбата Лисиче, емисиите од системите за загревање во овој дел
на градот ќе бидат нула. Па така, за очекување е дека со тоа ќе се подобри квалитетот на амбиенталниот воздух
во овој дел од Скопје.
Клучни зборови: централно греење; греење на гас; загадување на воздух; трошоци за греење
BACKGROUND
Skopje is at the top of most polluted cities in
the world. The situation repeats every heating sea-
son [1]. Figure 1 shows the monthly distribution of
PM10 and PM2,5 in Skopje in 2017.
All relevant studies get to the conclusion that
the air pollution is caused by burning wood which
is most common heating by the individual house-
holds [2, 3].
The city quarter JI03 (Lisiče suburb) is charac-
terized with dense structure of individual houses,
88 D. Dimitrovski, D. Stojevski
Mech. Eng. Sci. J., 37 (1–2), 87–91 (2019)
which the highest percentage use wood in old stoves
as heating source. Figure 2 shows the disposition of
the Lisiče suburb. Figure 3 shows the fuels used for
household heating in Skopje.
Fig. 1. Monthly distribution of PM10/2,5 in Skopje in 2017
Fig. 2. Disposition of Lisiče suburb
Fig. 3. Used type of heating in Skopje area
Detail analysis was made for the entire life-
cycle costs of district heating and individual gas
heating.
The following costs groups were taken into
calculation:
• material costs,
• installation costs,
• exploitation and maintenance costs.
All costs were summarized as a whole for the
entire quarter, in order to find solution which can be
promptly initiated and can lead to the fastest solving
of the air pollution problem.
EXPERIMENTAL
The Lisiče suburb is located in the eastern part
of Skopje. Even though it’s relative close to the city
urban part, its conjuncture can be considered as
rural. For getting info regarding number of objects
and their heat consume, poll through the cadastre
Lifecycle costs comparation between district heating and individual gas heating 89
Маш. инж.науч. спис., 37 (1–2), 87–91 (2019)
was made and the following type of objects were
counted:
As can be viewed from the satellite view,
predominantly the suburb is consisted of individual
houses. According several polls, most widely used
type of heating in areas with dominant individual
houses is the wood heating in stoves [3]. Table 1
shows the number of objects considered in the study
and the heat consume.
T a b l e 1
Objects and heat consume
1 story 2 story 3 story
Number of objects 321 93 2
Heat consume (kW) 3624 2789 76
The relative age of the houses in Lisiče suburb
is > 40 years, with poor thermal insulation. In the
recent years, the trend of improving the energy
efficiency of the houses is obvious. Therefore, we
take average thermal insulation in the calculation.
Taking into consideration the above menti-
oned, the following input parameters were taken
into account for the heat type economic feasibility:
• Equipment is designed for heating of the
whole house;
• Specific heat consume of the houses is taken
as 115 W/m2;
• Design room temperature is 20 ˚C;
• Design ambient temperature is –15 ˚C;
• Heating hours per year is 2745.
RESULTS AND DISCUSSION
Design of district heating system
This part of Skopje does not have district
heating (DH) network. The main DH network under
control of BEG AD is approximately 1000 m from
the potential connection point with the conceptual
secondary and connection line network in Lisiče.
According design parameters (flow velocity, heat
consume…), the main pipeline should be DN150.
The secondary DH network should be 3 km′ DN80.
Connection lines are 15 m′ at DN25. In Table 2, the
prices of components used in central district heating
system are shown.
T a b l e 2
Prices of components used in DH system
Pipes
(EUR/m')
Control valves
(EUR/piece)
Heat meter
EUR/piece)
Inner
installation
(EUR/kW)
DN25 63 590 301 133
DN32 74 826 413
DN40 86 1.062 578
DN50 98 2.360 826
DN65 113 3.340 826
DN80 134 5.310 1.333
DN100 181 / /
DN150 262 / /
DN200 378 / /
The heat station is designed as indirect, with
installation of heat exchanger which separates the
network medium from the indoor installation
medium. Other necessary components and their
costs (installation and VAT included) are:
Design of individual gas system
This part of Skopje does not have gas infra-
structure. The main gas network is approximately
3000 m from the potential connection point with the
conceptual secondary and connection line network
in Lisiče.
According design parameters (flow velocity,
heat consume, etc.), the main pipeline should be
DN100. The secondary gas network should be
HDPE DN65, while the gas connections should be
G3-G10, depending of heat consume. Table 3 shows
the prices of components used in individual gas
system for heating.
T a b l e 3
Prices of components used in gas system
Capacity
(kW)
Boiler
(€)
Connecting line with GMS
(€)
24 770 1.036
28 803 1.036
33 1.306 1.036
55 2.033 1.569
85 3.084 2.369
90 D. Dimitrovski, D. Stojevski
Mech. Eng. Sci. J., 37 (1–2), 87–91 (2019)
Other necessary components and their costs
(installation and VAT included) are:
– Exploitation and maintenance costs of DH
system.
Final yearly heat need of the Lisiče suburb at
6.5 MW heat consume are 7.137 MWh. The costs
towards the DH operator are as follows [5]:
• engaged heat consume – 17.863 EUR/MW/year;
• heat energy price – 35 EUR/MWh.
There is no maintenance costs in this system.
– Exploitation and maintenance costs of indi-
vidual gas system.
Gas boiler efficiency is taken at 92% according
low heating value [4]. This requires 814.216
Nm3/year gas consumption.
The costs for the gas consumption are as fol-
lows:
• gas border price – 354 USD/1000 Nm3;
• import costs – 2% of border price;
• trading margin – 47 EUR/1000 Nm3;
• gas transmission tariff [6] – 27 EUR/1000 Nm3;
• gas distribution tariff [7] – 52 EUR/1000 Nm3.
Maintenance costs are costs for inspection of
the gas boiler and inner installation and cleaning of
chimneys, total 60 EUR/house.
– CO2 footprint in production and installation
phase of DH system [8].
The energy consumption and CO2 emissions
from different lifecycle phases depend on the pro-
perties of pipe material, type of technologies used
(during manufacturing the pipe, installing equip-
ment and pumping technologies) and the type of
fluid. Four phases are considered in this lifecycle
assessment, which are production and fabrication,
transportation to job site, pipe installation and
operation or service phase. The working period of
this heating is 40 years.
– CO2 footprint in production and installati-
on phase of individual gas system.
The working period of specific components of
this heating varies between 10 (boilers) and 40
(pipes) years. CO2 emissions from the DH and gas
system in the early phase are given in Table 4 and
Table 5.
T a b l e 4
Emission of CO2 in early phase of DH system
DN25 DN150
Pipes production
Weight (kg/m') 7,06 12.480
Total length (m) 40,66 6.000
CO2 in production (t) 585 1620
Pipes transport
Distance between site and plant (km) 4000 4000
Max pipe sections per truck 165 29
Total truck sessions 6 17
Total fuel consumption (l) 10.070 27.881
CO2 per fuel (CO2/l) 3 3
Total CO2 for transport (t) 27 74
Pipes installation
Necessary excavation/fill hours (h) 5.200 5.000
Fuel consumption (l/h) 10 10
Total fuel consumption (l) 52.000 50.000
CO2 per fuel (CO2/l) 3 3
Total CO2 for installation (t) 154 148
Total CO2 emission of DH system in early
phase is 2608 t.
T a b l e 5
Emission of CO2 in early phase of gas system
DN20 DN65 DN100
Pipes production
Weight (kg/m') 0,12 1,05 3,13
Total length (m) 6240 3000 3000
CO2 in production (t) 11 45 134
Pipes transport
Distance between site and plant (km) 360 360 360
Max pipe sections per truck 4.000 378 176
Total truck sessions 1 1 2
Total fuel consumption (l) 144 144 288
CO2 per fuel (CO2/l) 3 3 3
Total CO2 for transport (t) 0,4 0,4 1
Pipes installation
Necessary excavation/fill hours (h) 1.560 1.000 1.250
Fuel consumption (l/h) 10 10 10
Total fuel consumption (l) 15.600 10.000 12.500
CO2 per fuel (CO2/l) 3 3 3
Total CO2 for installation (t) 46 30 37
Total CO2 emission of individual gas system in
early phase is 303 t.
Lifecycle costs comparation between district heating and individual gas heating 91
Маш. инж.науч. спис., 37 (1–2), 87–91 (2019)
CONCLUSION
Comparation of costs of different heating types
and CO2 emissions is given in Table 6.
T a b l e 6
Lifecycle CO2 emission and cost comparison
DH Gas
Total CO2 emission in early
phase (tCO2) 2608 303
Total CO2 emission in
exploitation (tCO2) 16.869 48.623
Total CO2 emission (tCO2) 19.477 48.926
CO2 price (EUR/t) 22 22
Total CO2 costs (EUR) 428.500 1.076.362
Total investment costs (EUR) 2.743.463 3.664.730
Total operating costs (EUR) 18.399.652 18.151.475
Total maintenance costs (EUR) – 1.250.000
Total costs (EUR) 21.571.615 24.142.567
As can be concluded, total lifecycle costs in
DH system are lower than the costs for individual
gas heating. The slightly higher operating costs are
annulled by the costs for maintenance and CO2,
which are significantly larger by use of individual
gas heating system.
By use of DH system in the suburb of Lisiče,
the emission of PM10/2,5 will be practically extin-
guished as the DH system uses natural gas as only
source. This will lead to improved air quality in this
part of Skopje.
Acknowledgements. This work was supported by
the colleagues from Balkan Energy Group. The authors
would like to thank all of them for providing the data.
REFERENCES
[1] European Environment Agency: Air Quality in Europe, 23
(2015).
[2] Tashevski, D., Filkovski, R., Armenski, S., Dimitrovski,
D., Shesho, I.: Defining techno-economic optimal and
ecologic sustainable heat structure of Skopje, 59 (2017).
[3] Dimitrovski, D.: UNDP Support: Analysis of household
heating practices in Skopje Valley, 2017.
[4] Or, G., Lelyveld, T., Burton, S.: Final Report: In-situ mo-
nitoring of efficiencies of condensing boilers and use of
secondary heating, Prepared by: GASTEC at CRE
LtdAECOM EA Technology, Prepared for: The Energy
Saving Trust, Contract Number: GaC3563, June 2009.
[5] Energy Regulatory Agency of Macedonia: Decision for
heat price for supply Heat Balkan Energy, 2018.
[6] Energy Regulatory Agency of Macedonia: Decision for
gas transmission tariff for GA-MA, 2019.
[7] Energy Regulatory Agency of Macedonia: Decision for
gas distribution tariff for Kumanovo Gas, 2019.
[8] Khan, L. R., Tee, K. F.: Quantification and comparison of
carbon emissions for flexible underground pipelines,
Canadian Journal of Civil Engineering, 42 (10), pp. 728–
736 (2015).
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1, pp. 93–98 (2019)
Number of article: 622 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: January 20, 2018 UDC: 633.18:664.782.4-97
Accepted: February 20, 2018
Original scientific paper
DRYING CONDITIONS FOR PADDY PROCESSING
IN MIXED-FLOW HIGH-CAPACITY PLANT
Filip Mojsovski
Faculty of Mechanical Engineering, "Ss. Cyril and Methodius" University in Skopje,
Karpoš II bb, P.O. box 464, 1001 Skopje, Republic of North Macedonia
A b s t r a c t: A research was conducted to obtain information on needed procedures for transforming one uni-
versal cereal dryer in special equipment for paddy. Harvested paddy was dried under controlled air conditions in con-
tinuous-flow high-capacity grain dryer. The realization of the planned study was carried out in three steps: 1) cor-
rection of dryer construction, 2) insertion of intermittent drying process, and 3) selection of correct drying conditions.
Intermittent drying process was studied by tempering paddy during its processing. In a drying section two zones sys-
tem was exploited, zone 1 with air temperatures up to 45oC, and zone 2 with air temperatures up to 40 oC. In a cool-
ing section air temperatures up to 26 oC were used. Variations in moisture content, between the grains from two suc-
cessive horizontal elements of the dryer, were in the range of near one percentage points. In the first horizontal ele-
ments of heating section, the variation of moisture content wet basis was two times higher than in the rest horizontal
elements of drying section. Correct drying conditions, for local paddy varieties, were selected and are reported.
Key words: food drying; paddy; drying conditions
УСЛОВИ НА СУШЕЊЕ ЗА ТРЕТМАН НА ОРИЗОВА АРПА
ВО ИНДУСТРИСКА СУШИЛНИЦА СО КОМБИНИРАНО СТРУЕЊЕ
А п с т р а к т: Спроведено е истражување со цел да се добијат информации за потребните постапки при
трансформирањето на една универзална житна сушилница во специјална опрема за оризова арпа. Ожнеаната
оризова арпа е сушена, при контролирани состојби на воздухот, во индустриска сушилница со континуиран
протек на воздух. Реализацијата на планираната студија беше спроведена во три етапи: 1) приспособување на
конструкцијата на сушилницата, 2) воведување сушење со прекини и 3) избирање правилни услови на суше-
ње. Процесот на сушење со прекини е проучуван со менување на температурата на оризовата арпа во текот на
нејзиниот третман. Во делот за сушење беше користен систем со две зони, зона 1 со температури на воздухот
до 45oC, и зона 2 со температури на воздухот до 40 oC. Во делот за ладење беа користени температури на воз-
духот до 26 oC. Промените на содржаната влага во зрната од два сукцесивни хоризонтални елементи на
сушилницата беа во опсег од близу еден процент. Во првите хоризонтални елементи од делот за греење про-
мената на содржаната влага по влажна основа беше два пати поголема од онаа во другите хоризонтални еле-
менти од делот за греење. Избрани се оптимални услови за сушење на локалните сорти оризова арпа и се
објавуваат.
Клучни зборови: сушење на храна; оризова арпа; услови на сушење
INTRODUCTION
It is certain that rice is among the world basic
foods and feeds. The annual world production of
paddy was 650 million tonnes in 2007 and 770
million tonnes in 2017 [1].
Paddy hull is removed during the milling pro-
cess in order to produce white rice. In the milling
process approximately 70 % white rice is produc-
ed, because the loss for dehulling is up to 30 % [2].
94 F.Mojsovski
Mech. Eng. Sci. J., 37 (1–2), 93–98 (2019)
Paddy is harvested at high moisture content
and must be dried. Drying of grain, in forced con-
vection system, is the most practiced preservation
method. Estimation of the quantity of air required
to remove the moisture from the dried rice is based
on psychrometric [3, 4]. Of all cereals, rice is
probably most difficult to process without quality
loss.
Immediate drying of the harvested paddy is
essential to prevent quality deterioration. The qual-
ity characteristics of paddy can be seriously dam-
aged by early harvesting (immature and high-
moisture content grain), incorrect combine settings
(broken kernels) and rapid drying (stress-cracked
kernels). To obtain the desired product quality, the
pre and post treatment of dried product is also im-
portant. Radical cleaning and correct storage are
necessary.
In the five steps grain processing, harvesting-
drying-storage-handling-transportation, drying is
the duty of a thermal engineer.
Paddy drying is thermal process of simultane-
ous heat and mass transfer. The kernel is capillary-
porous body. The pore, tiny opening trough which
fluids may pass, are partially filled with liquid wa-
ter and partially filed by mixture of air and water-
vapor. In the thermal drying process, the moisture
evaporates and leaves the kernel. The movement of
evaporated moisture inside the grain is influenced
by capillary forces, but at the kernel surface, partial
vapor pressure difference between the water-vapor
in the kernel and surrounding air, is driving force.
The moisture movement in capillary-porous body
due to the diffusion and Еarth gravitation is also
present, what additionally complicates the under-
standing of the matter. Existing food drying theory
cannot be sufficient to evaluate the drying rate un-
der different drying conditions. It remains to be
seen if the solution can be find using laboratory
and field tests.
Throughout the harvest season, huge quanti-
ties of paddy are available daily and the need for
reduction of drying time, favors the use of high-
capacity dryers.
In the actual research, tower-type mixed-flow
dryer is exploited (Figure 1).
Composed of 17 horizontal elements, with di-
mension 3 × 3 × 1 m, the dryer reaches 26 m
height. The inner construction of the horizontal
element provides mixed-flow in the dryer. The rel-
ative direction of the air and the grain in this
mixed-flow system is a combination of crossflow,
concurrent and countercurrent flow. Therefore, the
variation in the kernel moisture content is small.
This is the major advantage of mixed-flow dryer
application.
Fig. 1. Tower-type cereal dryer
1 – filling module, 2 – horizontal element,
3 – lower horizontal element, 4 – hot air duct,
5 – cold air duct, 6 – unloading auger
The moist grain kernels, after cleaning, are in-
troduced at the upper side of the dryer, into the
drying section and then into the cooling section.
In a drying section heated air carries heat into
the paddy mass, to evaporate its moisture and then
removes the evaporated water out of the system.
The amount of moisture removed from paddy, per
horizontal element of drying section, should be
controlled and limited.
In a cooling section the ambient air removes
heat from the paddy mass and then discharges it,
into the environment.
Drying section consists of 13 horizontal ele-
ments, each 1 m high, built-up in six groups, 3 + 2
Drying conditions for paddy processing in mixed-flow high-capacity plant 95
Маш. инж. науч. спис., 37 (1–2). 93–98 (2019)
+ 2 + 2 + 2 + 2. Every group is separated by 0.5 m
high horizontal element. These five lowers hori-
zontal elements provide the intermittent regime of
drying.
Intermittent cereal drying process uses dis-
continuous heat input. During the pause in the heat
supply, the moisture has enough time to be dislo-
cated within the material. This kind of drying pro-
cess can improve the quality of dried product [5].
Intermittent cereal drying has already wide
application in practice.
High-capacity cereal-drying systems improve
grain quality as a result of the intermittent drying.
A tempering section or tempering period separates
two adjoining drying stages. This results in a reten-
tion time, adequate to sufficiently reduce the tem-
perature and moisture content gradients in the ker-
nels, before subsequent further drying.
Cooling section consists of 4 horizontal ele-
ments, in which the hot, dried grain is cooled with
the ambient air, to within 5oC of its dry-bulb tem-
perature. During the cooling process, some mois-
ture is also removed.
According to the manufacturer documenta-
tion, the actual dryer is designed as universal, for
all cereals drying.
OBJECTIVE AND PROCEDURES
The purpose of this paper is to summarize the
results of the efforts to make this type of dryer pri-
marily convenient for paddy drying.
The realization of the planned study was car-
ried out in three steps: 1) correction of dryer con-
struction, 2) insertion of intermittent system of dry-
ing, and 3) selection of correct drying conditions.
In the phase of preparation for planned tests,
air distribution was modified to enable zonal air-
flow and uniform air velocities at the entrance of
drying room. To satisfy the exact needs of drying
process, the drying space was organized as multi-
thermal zone system [6].
Grain cleaner was introduced, as auxiliary but
important equipment, one that can enhance the dry-
er performance. In the case when cleaning is not
enough effective, accumulated impurities obstruct
the correct grain flow in the horizontal elements of
the mixed-flow dryer.
Rice is highly sensitive to amount and intensi-
ty of received heat during the drying. The experi-
ence, from industrial drying practice, shows that
drying rice slowly, with intermittent tempering, is
a suitable drying method.
The level of drying air temperature has basic
influence on grain drying. Temperature gradients
in a kernel, cause expansion in the nonhomogene-
ous grain material. Drying process in which paddy
temperature reaches 38 oC, provoke cracks in the
interior of the kernel. Then, in the milling process,
the percentage of whole kernels will be not toler-
antly low.
Only during the pass-through in the first hori-
zontal elements of drying section, since paddy is
still cool and relatively high in moisture, the tem-
perature can be slightly higher.
The resistance to the airflow into drying room
is a result of energy lost through friction and turbu-
lence. It depends on three factors: the rate of air-
flow, the surface and shape characteristics of pad-
dy, and the realized voids in the horizontal ele-
ments during the mutual movement of air and pad-
dy. Paddy has the roughest hull surface of all cere-
als. Higher rate of airflow was provided by pres-
sure build-up on the air-entrance side.
The airflow rates necessary to dry and cool
the grain mass are provided by centrifugal fans.
Tests were carried out in order to find the correct
fan regime. The airflow, at the entrance of heating
and cooling section, was controlled by measure-
ments. At the same measuring points, temperature
and relative humidity of air were registered.
The intermittent drying is realized with con-
structive and functional interventions. All five
lower horizontal elements are built as vertical
ducts and have not direct drying-air supply. The
grain moves within the lower horizontal element
but is not heated. The second kind of pause in heat-
ing is controlled by unloading auger and heating
process. Simultaneously grain movement and heat
supply are stopped. Duration of tempering period
was evaluated by tests.
Drying conditions (“the combination of dryer
construction, dried product state during the process
and drying medium state during the process”),
were selected as correct, in the case when the dried
product was of first-rate quality. Drying conditions
were investigated by computer simulation and
fieldwork activities [7].
The paddy state in drying process was con-
trolled continuously. The tests procedure contained
measurements, visual evaluation and test judging.
Dried material state (initial, zonal and final
moisture content and temperature), drying medium
96 F.Mojsovski
Mech. Eng. Sci. J., 37 (1–2), 93–98 (2019)
state (temperature, relative humidity, flow) and
dryer function (zonal drying time, energy con-
sumption) were controlled by measurements. The
field tests were necessary to verify the expected
dried rice quality, reached under specified drying
conditions.
Dried paddy state control was realized by
sampling in time and space. Measuring platforms
were built at the base level of every horizontal el-
ement. Sampling tube enables to take specimen
from all horizontal elements during the drying pro-
cess. It is constructed as tube-in-tube device, which
collects grains from measuring points for laborato-
ry analysis. The movement of sampling tube into
the paddy mass was obstructed because of the
tough and abrasive nature of husks. Direct meas-
urement, moisture content determination method,
with apparatus based on infra-red radiation, was
used in laboratory conditions. Drying medium state
was controlled by digital psychrometers and ane-
mometers. Attention was concentrated on regime
parameters, operation problems, diagnostics and
plant efficiency.
RESULTS AND DISCUSSION
In the period of September to November,
when local paddy varieties, Monticelli, Saint An-
drew and RS76 are dried, the atmospheric air tem-
perature range, at the location of drying plant, is
between 30 and 2 oC. For these temperatures, from
the climatic curve, the level of relative humidity is
graphically evaluated from 35 to 80 %, and en-
thalpies from 54 to 10 kJ/kg [8].
Psychrometric chart, with coordinates of tem-
perature and humidity ratio, was used for conven-
ient graphical illustration of drying air states
changes during its heating and humidifying (Figure
2).
Fig. 2. Psychrometric diagram
The comparison of data, obtained from the
psychrometric diagram for the two extreme atmo-
spheric states (2oC, 80 % and 30 oC, 35 %), shows
great difference in needed amount of heating en-
ergy, for more than three times, ∆i for (1L, 2L) = 49
– 10 = 39 kJ/kg, and ∆i for (1H, 2H) = 65 – 54 = 11
kJ/kg.
By examination, it was found that the heat de-
mand of the dryer, can be provided by applying
paddy husk as fuel. Heating values of up to 15 000
kJ/kg were obtained, by measuring the heat gener-
ated during combustion of local paddy husk in cal-
orimeter. Such an approach was considered as
most desirable from an ecological standpoint [9].
Drying conditions for paddy processing in mixed-flow high-capacity plant 97
Маш. инж. науч. спис., 37 (1–2). 93–98 (2019)
The option for recirculation, of part of the
dryer exhaust air, was examined and abandoned as
not attractive. The grain was cleaned before it was
dried. The used grain cleaner removed up to 1 kg
weed seed and trash from 100 kg of processed
paddy. The level of examined parameters, relevant
for the selection of drying conditions, is presented
in Table 1.
T a b l e 1
The relevant data from field and laboratory tests
Parameter Value
1. Air
1.1. Atmosphere,
– Temperature, oC 2 – 30
1.2. Drying room
1.2.1. First two horizontal elements,
– Temperature, oC 32 – 45
1.2.2. Third to thirteenth horizontal element,
– Temperature, oC 32 – 40
1.2.3. Fourth to seventeenth horizontal element,
– Temperature, oC 2 – 30
2. Paddy
2.1. Filling auger:
– Moisture content, wet basis, % 16 – 28
– Temperature, oC 12 – 22
2.2. First two horizontal elements:
– Moisture content, wet basis, % 14 – 23
– Temperature, oC 15 – 28
2.3. Third to thirteenth horizontal element:
– Moisture content, wet basis, % 11 – 15
– Temperature, oC 24 – 36
2.4. Fourteenth to seventeenth horizontal element:
– Moisture content, wet basis, % 10 – 14
– Temperature, oC 16 – 35
2.5. Unloading auger:
– Moisture content, wet basis, % 10 – 14
– Temperature, oC 16 – 35
Paddy was harvested at an average moisture
content, wet basis, between 18 and 30 %, during
the wet harvest season, and between 16 and 26 %,
during the dry harvest season. Up to 8 % difference
in initial moisture content was registered, between
the most mature and least mature kernels.
Variations in moisture content, between the
grains from two successive horizontal elements of
the dryer, were in the range of one percentage
points. In the first horizontal elements of heating
section, the variation of moisture content wet basis
was two times higher than in the rest horizontal
elements of drying section.
Regarding to the temperature regime, at the
entrance of drying room, three zones system was
selected as a correct one. In the zone 1, the first
98 F.Mojsovski
Mech. Eng. Sci. J., 37 (1–2), 93–98 (2019)
two horizontal elements of drying section, air tem-
peratures up to 45oC were used, in the zone 2, the
rest of horizontal elements of heating section, air
temperatures up to 40oC were used, and in the zone
3, four horizontal elements of cooling section,
temperatures up to 26 oC were used.
The exit kernel temperature of 35 oC was not
surpassed.
CONCLUSIONS
Dryer construction was adjusted for zonal
paddy drying and requirements of measuring equi-
pment.
True drying intensity was reached with in-
volving intermittent paddy tempering of up to 2
hours.
Correct drying conditions, for local rice varie-
ties, were obtained.
REFERENCES
[1]FAO (Food and Agricultural Organization of the United
Nations), Faostat, Data, 2019.
[2] Brouker, D. B., Bakker-Arkema, F. W., Hall, C. W.:
Drying and Storage of Grain and Oilseeds, Van Nostrand
Reinhold, New York, USA, 1992.
[3] Gatley, D. P.: Understanding Psychrometrics, American
Society of Heating, Refrigerating and Air-Conditioning
Engineers, Atlanta, USA, 2013.
[4] ASHRAE (American Society of Heating, Refrigerating
and Air-Conditioning Engineers), Handbook Fundamen-
tals, Chapter 1: Psychrometrics, Atlanta, USA, 2013.
[5] Aquerreta, J., Iguaz, A., Arroqui, C., Virseda, P.: Effect
of high temperature intermittent drying and tempering on
rough rice quality, Journal of Food Engineering, Vol. 80,
No. 2, pp. 611–618 (2007).
[6] ASHRAE (American Society of Heating, Refrigerating
and Air-Conditioning Engineers), Handbook HVAC Ap-
plications, Atlanta, USA, 2011.
[7] Mojsovski, F.: Drying conditions for rice and tomato, In-
ternational Journal of Mechanical Engineering and Tech-
nology, Vol. 5, No. 10, pp. 78–85 (2014).
[8] Mojsovski, F.: Analysis of humidity level in psychromet-
ric thermal processes, PhD Thesis, Faculty of Mechanical
Engineering, Skopje, Macedonia, 2007 (in Macedonian).
[9] Mojsovski, F., Dimitrovski, D.: Thermal conditions for
rice parboiling process realised with the use of renewable
energy resource, Journal of Environmental Protection
and Ecology, Vol. 16, No. 2, pp. 699–704 (2015).
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 99–105 (2019)
Number of article: 623 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: June 6, 2019 UDC: 725.21.05:624.012.6]:[519.612:531.2
Accepted: July 8, 2019
Original scientific paper
CONCEPT FOR STUDENT GLASS PAVILION
Bojana Trajanoska, Elisaveta Dončeva, Daniela Pana, Hristijan Gjorgievski
Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: Contemporary architecture and engineering are based on combining structural glass and steel,
where glass is used for its transparency and steel for its strength. The intention behind this pavilion concept is decreasing
the lack of modern glass structures in our surrounding. This article describes the FE modelling and analysis of а glass
structure planned tо be located in the technical campus of the Faculty of Mechanical Engineering in Skopje. The final
exterior of the structure is consisted of five glass frames adhesively bonded and mechanically connected with bolts
which give the support of the structure and hold the façade and roof panels. Different scenarios were presented regard-
ing the stability and safety of the glass structure. The carried out FEM simulations are presented, based on predicted
static loads, according to the pavilion's location and the climatic parameters. At the end of this article, visual represen-
tation of the CAD model within the campus space is given.
Key words: glass pavilion; steel connection; structural glass; state of the art; finite element analysis
КОНЦЕПТ ЗА СТУДЕНТСКИ СТАКЛЕН ПАВИЛЈОН
А п с т р а к т: Модерната архитектура и инженерство се темелат на комбинирањето на конструктивно
стакло и челик, при што стаклото се користи поради провидноста, а челикот поради својата јакост. Овој кон-
цепт за студентски павилјон произлегува од недостигот на модерни стаклени конструкции во нашата околина.
Трудот го опишува моделирањето и анализата со метод на конечни елементи на конструкција од стакло пла-
нирана да се постави во техничкиот кампус на Машинскиот факултет во Скопје. Крајниот надворешен изглед
на конструкцијата се состои од пет стаклени рамки атхезивно споени и механички зајакнати со завртки, кои го
даваат скелетот на конструкцијата на која се поставуваат стаклените фасадни и покривни панели. Во поглед на
стабилноста и безбедноста на стаклената конструкција, прикажани се различни конструктивни случаи. Презен-
тирани се извршените симулации со примена на методот на конечни елементи, при што статичките оптова-
рувања се пресметани врз основа на локацијата и климатските услови. Визуелната репрезентација на моделот
CAD е прикажана на крајот од трудот каде што се забележува хармоничното совпаѓање на конструкцијата со
околината на техничкиот кампус.
Клучни зборови: стаклен павилјон; челични врски; конструктивно стакло; преглед на постојните трендови;
метод на конечни елементи
1. INTRODUCTION
In the modern architecture and engineering,
structural glass elements tend to replace the tradi-
tional structural materials, like steel or concrete.
This dramatic change brought a new trend in glass
roofs and external glass frames in home living. The
two primary factors for using structural glass over
any other building materials are innovative day-
lighting and transparency, which empower a sense
of unlimited space [2, 5]. Aditionally these reasons
are basic requirements when designingл a student
friendly environment for continuous learning or group
working.
Although structural glass cannot be compared
with steel in terms of durability and toughness, it is
the only transparent material with high strength that
can be used in many contemporary load-bearing
structures. Strength values for structural glass de-
sign and its application are summarized in Table 1.
100 B. Trajanoska, E. Dončeva, D. Pana, H. Gjorgievski
Mech. Eng. Sci. J., 37 (1–2), 99–105 (2019)
T a b l e 1
Strength values of structural glass [4]
(MPa)
Compressive strength 880 – 930
Tensile strength 30 – 90
Bending strength 30 – 100
The high brittleness of the structural glass
makes it risky to use in crowded locations because
under tensile loads, any surface crack might cause
failure of the glass element.
One of the common solutions regarding this
problem is using treatment such as annealing, tem-
pering and heat strengthening, as well as laminating
in order to improve the mechanical properties and
structural characteristics. Laminated glass has be-
come extensively used as a safety glass in modern
hybrid structures due to the polymeric interlayer
that holds together the elements pieces when shat-
tered. The interlayer, typically PVB or EVA, keeps
the glass plies together even broken, constraining
from breaking into large sharp pieces. Different
types of glass breaking are shown in Figure 1.
tempered laminated annealed
Fig. 1. Breaking of common glass types
The low ductility and the high compressive
strength of the glass allows connections with greater
strength and hardness, like the ones with stainless
steel. Bolted connections (Figure 2) are used for
connecting glass elements where stress concentra-
tions may occur. Regarding the performance of the
bolt, forces up to 30 kN can be transmitted per bolt
[6]. In addition to prevent restraint forces, the num-
ber of bolts should be as minimal as possible in fa-
vor of greater bolt diameters.
Based on the above mentioned structural char-
acteristic, the mechanical behavior the transparency
and the inovative daylighting prospects of the struc-
tural safety glass as a laminated glass, it is chosen
as the most adequate material for designing the stu-
dent pavilion accommodating new modern concepts
with psychological benefits.
Fig. 2. Bolt connection [6]
Concept for student glass pavilion 101
Маш. инж.науч. спис., 37 (1–2), 99–105 (2019)
2. CONCEPT
The student glass pavilion idea arouse from the
need of creative and inovative working space which
students can use in their spare time at the technical
campus of the Faculty of Mechanical Engineering
in Skopje, and later the concept was introduced ac-
cordingly.
The glass pavilion is 5 × 5 × 2.5 m, supported
on a concrete fundament where steel groundwork is
placed. The contact glass-steel is prevented with
rubber installed inside the groundwork. The glass
columns and beams are formed of tempered glass,
joint with PVB, giving a high strength laminated
panel (Figure 3).
Fig. 3. Structural members
The lateral and horizontal glass panels that
confine the structure consists of one fully tempered
glass ply and heat-strengthened ply with inner PVB
layer. Dimensions of the structural members are
given in Table 2.
When designing, a previously detailed plan is
required. Furthermore, a comprehensive research
and calculations were carried out in order to realize
the concept of glass pavilion. Finally, a flow dia-
gram with various steps of work is presented (Fig-
ure 4).
Fig. 4. Concept realization steps
A state of the art research has been done in the field
of glass building construction. Wilson reviews the Glass
Reading Room of the Arab Urban Development Institute
in Riyadh, Saudi Arabia (Figure 5) [2]. The glass cube is
formed of laminated glass panels, connected with friction
grip connections in order to provide stability through the
frame that carries the applied loads.
T a b l e 2
Dimensions of designed structural members
Structural
member
Glass type, layer of
glass (mm)
Dimensions
L × W × H (mm)
Column 1 fully tempered,
2 × 10 200 × 20 × 2500
Inner column 1 fully tempered,
4 × 10 200 × 40 × 2300
Beam 1 fully tempered,
4 × 10 5000 × 40 × 200
Column 2 fully tempered,
2 × 10 200 × 20 × 2500
Inner column 2 fully tempered,
4 × 10 200 x 40 x 2300
Beam 2 fully tempered,
4 × 10 920 × 40 × 200
Roof pane
fully tempered
1 × 5 + heat
strengthened
1 × 5
2500 × 1000 × 10
Façade pane
fully tempered
1 × 10 + heat
strengthened 1 × 5
2500 × 2500 × 15
Fig. 5. Glass Reading Room in AUDI in Riyadh, Saudi Arabia
[2]
In [10] the new pavilion located in Zurich,
Switzerland (Figure 6) is analyzed). Matt-finished
stainless-steel frame and colored but transparent
glass, are the primary exterior details that give this
polygonal-plan structure compliance with the envi-
ronment and fulfill the illumination requirements.
102 B. Trajanoska, E. Dončeva, D. Pana, H. Gjorgievski
Mech. Eng. Sci. J., 37 (1–2), 99–105 (2019)
Fig. 6. The color glass pavilion in Zurich, Switzerland [10]
All glass enclosure is discussed in [3, 7], built
at the Leibniz Institute for Solid State and Material
Research in Dresden, Germany (Figure 7). Their
main goal is to describe the arrangement of the stru-
ctural members, frame assembly and final installla-
tion. The fully glazed enclosure is made from lami-
nated safety glass, bonded to the frame with a struc-
tural silicon adhesive as a joining technique. Hence,
the glass corners are joint with acrylate adhesives,
which give an exclusively transparent outlook.
Fig. 7. All glass enclosure at Leibniz Institute in Dresden,
Germany [3]
Breakthrough in the application of structural
glass was building the Apple Inc glass cube, the
Fifth Avenue, store located in New York City,
which was the first of a kind [1]. The structure itself
shows functionality and simplicity. First glass cube
(Figure 8) connected the engineering with the art;
the second cube (Figure 9), further enhanced that
connection. The limiting factors of the production
technologies of glass resulted in a glass cube with
164 units joined, forming a standing art piece [1].
Fig. 8. Original glass cube – Apple store
Fig. 9. New glass cube- Apple store
The advancement in the production technology
of structural glass was validated with constructing
the second glass cube. Thirty-five units joined to-
gether proved that glass production has moved for-
ward. Comparing the two of them (Table 3), it is in-
evitable not to see the difference in the roof design.
Two spanning beams with secondary roof beams
from sides and between the spanning beams holed
with roof fins. The façade panes were able to be as
large as 15 m × 3.6 m, which gave the final look of
the second glass cube.
The reduction of the number of the glass struc-
tural members in the new Apple store, led to fewer
glass-steel connections. One of the few reasons for
rebuilding this glass cube was to establish the new
developed connection that holds the glass panes to-
gether (Figure 10). Before it was completed, a nu-
merical analysis was run with particular attention to
the interaction between the glass, interlayers and fit-
tings. The connection model (Figure 11) confirmed
the expected behavior of the joined materials [1] and
let to a unique challenge- rebuilding the glass cube.
Concept for student glass pavilion 103
Маш. инж.науч. спис., 37 (1–2), 99–105 (2019)
T a b l e 3
Comparison of the structural members
of the two Apple glass cubes [1]
Building part Cube 1 Cube 2
Columns 5 per elevation
× 4 = 20
2 per elevation
× 4 = 8
Façade panles
(incl. doors)
72 12 + 2 doors + 2
side lights = 16
Roof beams 25 at 3.3 mm + 10
at 1.6 m = 35
2 at 10 mm + 7
at 3.3 m = 9
Roof panles 36 3
Entrance canopy 1 1
Subtotals 109 panels
20 fin columns
35 beams
20 panels
8 fin columns
7 beams
Total 164 glass units 35 glass units
Fig. 10. New developed fitting [1]
Fig. 11. Local connection model [1]
3. STRUCTURAL ANALYSIS
This paragraph shows the results of different
analysis performed on these article subject con-
cepts. Using laminated safety glass, all bearing ele-
ments were tested using FEM analysis, including
the enclosed structure itself. The frame members,
stated as glass beams and columns, are made of fully
tempered glass layers, each with thickness 10 mm.
The glass frame ware tested separately, as a primary
bearing column-beam assembly. Mainly, it was ex-
pected a local stress to occur between the glass and
the stainless-steel connection, because of the differ-
ent behavior of the materials under loading condi-
tions (Figure12).
Fig. 12. Stress distribution of the structural frame
However, significant displacement was evalu-
ated centrally on the glass beam, with maximum
displacement of 0.182 mm (Figure 13).
Fig. 13. Maximum displacement of the structural frame:
column-beam
Regarding the above-analyzed factors, three
different scenarios were examined under the same
load conditions (Table 4).
T a b l e 4
Scenarios for FEM analysis
Scenario No. Description
Scenario 1 Structured without support beam and column 2,
roof panel thickness 10 mm
Scenario 2 Structured with support beam and column 2,
roof panel thickness 15 mm
Scenario 3 Structured with support beams and five cross
beams with adhesive fittings, roof panel
thickness 10 mm
A brief comparison of the FEM results is given
in Table 5 and a significant explanation is summa-
rized.
104 B. Trajanoska, E. Dončeva, D. Pana, H. Gjorgievski
Mech. Eng. Sci. J., 37 (1–2), 99–105 (2019)
T a b l e 5
Comparison of FEM results
Scenario Max. stress
(MPa)
Max. displacement
(mm)
Scenario 1 13.80 26.39
Scenario 2 7.39 6.23
Scenario 3 7.96 7.57
The stress distribution is present for each sce-
nario and remarkably lower stresses were observed
on the front and back façade panes of Scenarios 2
and 3 (Figures 16 and 18, respectively), when com-
pared to stress result from the Scenario 1, shown in
Figure 14
The displacement analysis of Scenario 1 pre-
sented in Figure 15 shows considerably larger dis-
placement of the front and back façade panes under
buckling behavior, while the rest members of the
structure are sufficiently substantial for the sugges-
ted scenario. On the other hand, the results obtained
from both, Scenarios 2 and 3, illustrate smaller dis-
placement gradient (Figures 17 and 19, respective-
ly).
Fig. 14. Scenario 1 – Von Mises stress
Fig. 15. Scenario 1 – Displacement
Fig. 16. Scenario 2 – Von Mises stress
Fig. 17. Scenario 2 – Displacement
Fig. 18. Scenario 3 – Von Mises stress
Fig. 19. Scenario 3 – Displacement
Concept for student glass pavilion 105
Маш. инж.науч. спис., 37 (1–2), 99–105 (2019)
The exemplify results are due to the additional
central support frame (Scenario 1 is modeled with-
out the support beams and columns).
Another conclusion can be outlined from the
simulation analysis. As mentioned before, glass has
high compressive strength, but it depends on the
size of the glass panel [9]. The larger the size is the
more chance of finding critical imperfections and
defects in the glass element. The buckling phenom-
ena in glass panels under compression is frequent
problem in all glass structures [11]. Based on this
knowledge, laminated glass columns are arranged
on both, left and right side of the façade for support
and preventing sudden failure. Considering these
side columns arrangement, no significant stresses
nor displacement were determined in none of the
scenarios.
4. CONCLUSIONS
This comprehensive study on structural glass
student pavilion opens the possibility for conversion
of creative and innovative project. The mechanics
and safety for this structure was proven by using
FEM analysis on each scenario under static loads.
Scenario 3 was chosen as an eventual structural so-
lution for further detailed and accurate technical de-
velopment (Figure 20).
Fig. 20. Visual representation of the student glass pavilion
located in the technical campus in Skopje
Furthermore, the preceding results of the stress
and deformation that occurred in Scenario 3 were
dependable and rational when choosing the final
concept as well as the total weight of the glass struc-
ture.
The vast field of application of the glass struc-
tures is evaluated by the state of the art, which are
serving different functions. While being the driving
factor, safety is the main concern when designing
and constructing glass structure. Simplicity and the
ability to comply with the environment is one of the
benefits of an all-glass structure, which implies on
the physiological state of the users.
REFERENCES
[1] Bostick, C., O'Callaghan, J.: The Apple glass cube: Ver-
sion 2.0, In book: Challenging Glass 3 & Conference on
Architectural and Structural Applications of Glass, Tech-
nical University (TU) Delft, The Netherlands, 2012.
[2] Wilson, P.: All-glass enclosures – Spaces for working and
living, In book: Challenging Glass 4 & COST Action
TU0905 Final Conference, pp. 641–647, 2014.
[3] Weller, B, Nicklisch, F., Prautzsch, V. Döbbel, F.,
Rücker, S.: All glass enclosure with transparently bonded
glass frames. In: Challenging Glass 2 – Conference on Ar-
chitectural and Structural Applications of Glass, Bos,
Louter, Veer (Eds.), TU Delft, May 2010.
[4] Fröling, M.: Strength design methods for glass structures,
Doctoral thesis, Lund, Sweeden, Division of Structural
Mechanics, Lund University, 2003, pp. 9–15.
[5] Louter, C., Bos, F., Belis, J., & Lebet, J. P. (Eds.): Chal-
lenging Glass 4 & COST Action TU0905 Final Conferen-
ce. CRC Press, 2014.
[6] Wurm, J.: Glass Structures – Design and Construction of
Self-supporting Skins, Birkhäuser Verlag, 2007.
[7] Weller, F., Nicklisch F.: Bonding of glass – Latest trends
and research, In: Structures Congress, 2010 ASCE, Or-
lando, Florida, 2010.
[8] Trajanoska, B., Gavriloski, V., Bogatinoski, Z., Gavrilo-
ski. M.: State of the art in research of reinforced structural
glass elements, Mechanical Engineering – Scientific Jour-
nal, vol. 33, 1, pp. 27–32 (2015).
[9] Morgan, T.: Aspects of Structural Glass, Institute of Struc-
tural Engineers, SE Counties Branch, 2010.
[10] Helzel, M., Taylor, I.: Stainless Steel and Glass, Euro Inox,
The European Stainless Steel Development Association,
Brussels, Belgium, 2008.
[11] Bedon, C., Amadio, C.: Stability of flat glass panels under
combined in-plane compression and shear, In book: Chal-
lenging Glass 4 & COST Action TU0905 Final Confer-
ence, Lausanne, Switzerland, 2014.
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 107–115 (2019)
Number of article: 624 ISSN 1857–5293
CODEN: MINSC5 e-ISSN 1857–9191
Received: Jully 19, 2019 UDC: 72.05:57]:[005.961:005.336.1
Accepted: August 20, 2019
Original scientific paper
BIONIC PRINCIPLES OF SPACE OPTIMIZATION APPLIED
IN THE PRODUCT DESIGN PROCESS
Nikola Gerasimovski, Elena Angeleska, Sofija Sidorenko
Faculty of Mechanical Engineering, “Ss. Cyril and Methodius” University in Skopje,
P.O. box 464, MK-1001, Skopje, Republic of North Macedonia
A b s t r a c t: The main goal of the research presented in this paper is providing multi-functionality and space
optimization of products by exploring and applying modern bionic and design principles. The specific design issue that
needed to be addressed was – design of a multifunctional mountain hiking backpack that allows optimal use of space
and maximal comfort when being used. An ideal solution to this stated problem was accomplished by following several
phases in the process: study of available literature in the areas of multifunctionality, adaptability and product
optimization; analysis of bionic phenomena which were the basic inspiration for creating a modular and compact
design; detailed analysis of ergonomic aspects and anthropometric measurements; recognition of the target group and
market analysis; materials analysis; development of design solutions and selection of the most suitable concept
according to its strongest fulfillment of the given design requirements; elaboration of the final concept and its
evaluation.
Key words: bionics; biologically inspired design; ergonomics; multi-functionality; modularity; optimization of space
БИОНИЧКИ ПРИНЦИПИ ЗА ОПТИМИЗАЦИЈА НА ПРОСТОРОТ
ПРИМЕНЕТИ ВО ПРОЦЕСОТ НА ДИЗАЈНИРАЊЕ
А п с т р а к т: Главна цел на овој труд е преку истражување и примена на современите бионички методи
и принципи на дизајнирање да се изнајдат ефикасни начини за обезбедување мултифункционалност и опти-
мизација на просторот кај производите. Конкретниот дизајнерски проблем за кој беше потребна анализа на
споменатите принципи е креацијата на мултифункционален ранец за планинарење, кој овозможува оптимално
искористување на просторот и максимална удобност при негова употреба. Добивање идеално решение на овој
проблем беше постигнато низ неколку фази: проучување на расположлива литература од областите на мулти-
функционалност, адаптибилност и оптимизација на просторот кај производите; анализа на бионички феномени
кои беа основна инспирација за креирање модуларен и компактен дизајн; детална анализа на ергономските
аспекти и антропометриски мерки; анализа на целната група и пазарот; анализа на материјали; разработка на
идејни решенија и избор на најсоодветен концепт според најсилно задоволување на зададените дизајнерски
барања; разработка на финалниот концепт и негова евалуација.
Клучни зборови: бионика; биолошки инспириран дизајн; ергономија; мултифункционалност; модуларност;
оптимизација на простор
1. INTRODUCTION
Space optimization, modularity and multi-
functionality are complex design principles that al-
low creation of useful products that satisfy various
target group requirements and they could be adjust-
ed for optimal utilization by a wide range of users.
Therefore, these principles provide guidance in the
development of new products with an extended life
cycle in accordance of the fast growing “circular de-
sign model” trend.
Parkinson, Balling and Hedengren [1] define
optimization as the process of determining the best
design and explain the basics of the process. In order
108 N, Gerasimovski, E, Angeleska, S. Sidorenko
Mech. Eng. Sci. J., 37 (1–2), 107–115 (2019)
to optimize, the first step is to create a valid, accu-
rate model of the design problem. Besides a model,
variables which are free to be adjusted and criteria
(objectives and constraints) to be optimized are also
required. The objectives represent goals to be max-
imized or minimized and constraints are limitations.
The design variables of the model are adjusted in
order to achieve objectives and satisfy constraints.
Modularity is another crucial design principle
which aim is to assist creation of flexible products
with low sensitivity to change. These modular pro-
ducts have multiple benefits: reduced production
costs, simplified design updates and reparations, in-
creased product diversity, reduced transportation
time and costs, easier testing etc. Designers and en-
gineers have developed numerous methods for cre-
ating modular products. The Modular Function De-
ployment (MFD) [2] differs from other product
building methods by providing a comprehensive ap-
proach that takes into account the requirements of
all stakeholders in relation to the product develop-
ment. It suggests following 5 steps: defining user re-
quirements, choosing technical solutions, generat-
ing concepts, grading concepts and improvement of
the modules. Creating a modular design helps main-
taining the complexity of the product at a low level,
good deployment of the functions and structure of
the interface.
In the last decade, there is a drastic increase in
the demand for products with added value, that need
to be easy to use, comfortable, flexible to changes
and with modern aesthetics – or in one word, multi-
functional. Multi-functionality can be achieved by
combining many aspects in the design process such
as: following the latest technologies of materials
and production, in-depth analysis of the target
group, creating models of the products, testing their
performance and evaluating results. A well-desig-
ned multifunctional product will increase the feel-
ings of satisfaction and comfort when being used.
The overall comfort is defined as ‘a pleasant state,
physiological, psychological and physical harmony
between a human being and the environment’ [3]
and plays a great role in product design.
All mentioned design principles were recog-
nized as crucial for a successful design of a hiking
backpack and were therefore followed as a guide in
the process of concept generation. They were appli-
ed by using bionic design strategies, detailed study
of the market, ergonomic analysis, study of the lat-
est technologies for backpack production and study
of the user needs.
2. PRINCIPLES OF SPACE OPTIMIZATION
DISCOVERED IN NATURE
Bionic design is a tool that provides functional
principles and forms of nature as an inspiration for
generating concepts and product development.
Bionic methods in the process of product de-
sign are applied by two common approaches:
➢ Process guided by a bionic solution that ins-
pires how to solve an existing design problem.
➢ Process guided by a given design problem for
which a solution is searched in biological sys-
tems.
Versos and Coelho propose the bi-directional
bionic design method [4] and Helms [5] suggests
that in order to find solutions designers must rede-
fine and restructure the problem and functions to
bring them closer to similar problems in nature and
see how they are solved by natural organisms. Al-
ways ask the question ‘how does nature do or
doesn’t do it’.
The bionic method of Versos and Coelho [4]
was adopted for further application in order to study
bionic examples and receive knowledge that can
provide answers that will help achieve the set desig-
ner goals. This was done by the following steps:
1) Defining the designer problem – ‘How to en-
sure maximum utilization of space?’
2) Restructuring the problem in several functi-
ons (Table 1).
3) Asking questions about how those restruc-
tured functions might be solved in nature
(Table 1).
4) Analyzing natural examples (Table 2).
5) Defining solutions and drawing conclusions
(Table 3).
6) Application of the nature inspired solutions
in design concepts.
T a b l e 1
Redefining the design problem (steps 2 and 3)
Decomposition of the
design problem How does nature do it?
Shape and size
transformation
How do living organisms change
their size and shape to adjust to
change of events?
Modular composition
and compact structure
How does nature provide com-
pact structures? What kinds of
elements are natural organisms
composed of?
Multi-functionality How do living organisms achi-
eve multi-functionality?
Bionic principles of space optimization applied in the product design process 109
Маш. инж.науч. спис., 37 (1–2), 107–115 (2019)
T a b l e 2
Finding solutions in nature (step 4)
Shape and size transformation
Pangolins change their shape when they feel threatened
by curling up into a tight, impenetrable ball to protect
their tender undersides.
Armadillos have a similar strategy like pangolins – curling in
a sphere is their defence tactic.
Puffer fish use a reversed method. They maintain a compact
shape and when threatened ‘inflate’ into a virtually inedible
ball several times their normal size.
Modular composition and compact structure
Spirals
Arrangement of sunflower seed
Spiral structure of pineapples
Spiral structure of aloe
Spiral snail shell
Symmetry
Bilateral symmetry of insects
Radial symmetry of flowers
Fractals
Romanesco broccoli – fractals
Fern - fractal pattern
Tessellations
Honeycombs tessellation
of hexagons
Tessellation pattern
of snake and lizard skin
Natural organisms show us how compact complex shapes can
be achieved by a regular repetition of geometric elements.
Natural patterns are formed spontaneously from the forces that
act in the physical world, and at the most basic level these
patterns can often be described using the same mathematical
and physical principles [6].
Multi-functionality
Multi-functionality provides saving resources, material and
space and it is a common principle in nature. For example,
cockroaches and crabs use exoskeletons as a support – it is an
attachment framework for their musculature and at the same
time it has a role in defence from pests and predators.
T a b l e 3
Conclusions from the bionic research (step 5)
Shape and size
transformation
The main volume of the backpack needs to
have elements contained within itself to
enable compact design and small size.
Size enlargement can be achieved by
opening the contained elements one by
one to gradually increase the volume.
Modular
composition and
compact structure
A modular backpack can be created by
simplifying the design to basic geometric
shapes and then attaching them together.
By doing so, the use would be simplified
and the design multifunctional.
Multi-
functionality
Thinking of ways in which the basic mo-
dular and constructive elements of the
backpack can serve more than one func-
tion will help in maximum use of the space
and adding product value.
110 N, Gerasimovski, E, Angeleska, S. Sidorenko
Mech. Eng. Sci. J., 37 (1–2), 107–115 (2019)
The drawn conclusions from the bionic rese-
arch helped for better understanding of the princi-
ples of space optimization and they were used as de-
sign guides later on in the process.
3. ERGONOMIC ASPECTS OF BACKPACK
DESIGN
A) Ergonomic criteria for designing backpacks
Even though studies of ergonomics of school
backpacks are most common, all of them provide
valuable information about the crucial aspects that
need to be considered in order to design a comfort-
able backpack that won’t deform the users posture.
A study [7] of mountain backpacks was con-
ducted in order to analyze the impact of the back-
pack use on the muscles of the body and the tension
of the user's heart muscles. The study was perfor-
med with 10 male and 10 female subjects, three
most commonly used mountain hiking backpacks,
and modern laboratory techniques (EMG, EKG,
NBM). Results showed that users feel pain when us-
ing the backpacks – in the right shoulder (90%), in
the left shoulder (83.33%) and in the back (60%).
The study, as a conclusion, offers a useful list of rec-
ommendations for designers to follow in order to
create ergonomic backpacks. The backpacks should
be designed according to following:
1) possession of a head restraint for the condi-
tion when the body leans forward;
2) possession of a backrest adjustment system;
3) a sternum strap that serves as a balance bet-
ween the shoulder straps;
4) well-placed shoulder straps that correspond
to the curvature of the shoulder;
5) well-placed hip belt;
6) a design with an outer frame;
7) a back ventilation system;
8) size and shape that corresponds to the size
of the user's body (< 60 litres for small body
sizes and > 60 litres for large body size);
9) backpacks frame made of strong and light-
weight material:
10) strong and lightweight fabric for the back-
pack bag;
11) the backpack bag should be sealed neatly and
tightly to ensure waterproofness.
In addition, it is important to:
1) choose the right size of backpack according
to the body type (this is why backpacks need
to have adjustable straps and belts);
2) properly pack (a person shouldn’t carry
weight larger than 20–25% of his/her body
weight; light items should be packed at the
bottom and the heaviest equipment should be
placed close to the back, above shoulders);
3) choose a backpack with a high-quality back
pad (maximal freedom of movement, even
weight distribution, reduction of pressure on
shoulders).
B) Anthropometric measurements
In the design process, a more extensive anthro-
pometric analysis was necessary in order to provide
customization for users with different physical char-
acteristics.
The measurements were taken from the 95-th
percentile of males and 5-th percentile of females
(Figure 1, Table 4) in order to create a design suita-
ble for 95% of potential users.
Fig. 1. Anthropometric measurements
T a b l e 4
Anthropometric measurements,
95-th and 50-th PCTL male, 5-th PCTL female
(dimensions given in cm)
No. Description 95
male
50
male
5
female
1 Body height 181 171 160
11 Shoulder width 46.2 42 38
5 Hip width 38 32 27
12 Distance – knees to feet 57 53 49
8 Distance – hips to knees 61 56 46.6
3 Shoulder height 62 57 52
Bionic principles of space optimization applied in the product design process 111
Маш. инж.науч. спис., 37 (1–2), 107–115 (2019)
4. DEFINING USER NEEDS AND DESIGN
REQUIREMENTS
According to Cleverhiker [8], the most visited
mountain hiking web site, there is a list with basic
requirements of buyers of mountain backpacks:
1) Price – the backpack should be worth the in-
vestment and last for many years and miles.
2) Weight – a good balance between weight,
comfort and durability is needed (reducing its
weight reduces the overall load hikers carry).
3) Frame – the frame shouldn’t add weight, sim-
ple frames that are comfortable for carrying
up to 16 kg are a good choice.
4) Volume – 40–50 litres pack is sufficient for
fitting all gear, with a need for increasing the
volume for winter trekking due to bulky win-
ter gear.
5) Design – simple and rational design makes the
best backpacks.
6) Material – most backpacks are made from one
of two durable materials: Ripstop Nylon or
Dyneema Composite Fabric (DCF is lighter
and more water resistant, but also more expen-
sive).
7) Fit – comfort is one of the most important fac-
tors, therefore the right dimensions and ad-
justability of the backpack are crucial.
Taking this list into consideration, the designer
requirements are clearly defined. The designed
backpack should be:
• with a simple and practical design focused on
efficiency of the components;
• consisted of modular parts in order to enable
better functionality and easier use;
• multi-functional in order to meet as many user
requirements as possible;
• with an adjustable: back pad, hip belt, shoul-
der straps and sternum strap, in order to pro-
vide maximal ergonomics;
• with an appropriate frame that will distribute
the load forces and reduce the pressure on the
shoulders;
• with a volume of 40 – 50 litres with possibility
for increasing up to 70 litres;
• made out of durable materials.
5. DESIGN OF A COMPACT,
MULTI-FUNCTIONAL MOUNTAIN
HIKING BACKPACK
Taking into consideration all the gathered in-
formation and the defined designer requirements,
the next step was generating ideas and developing
the design of the backpack.
a) Generating concepts
Several concept designs were elaborated
through sketching (Figures 2 – 4) and then finally
compared and graded according to the most im-
portant criteria: comfort, ergonomics, compact de-
sign, multi-functionality, modularity, capacity, ma-
terials and design. The best concept was selected for
further development (Figure 5).
Fig. 2. Concept 1
Fig. 3. Concept 2
112 N, Gerasimovski, E, Angeleska, S. Sidorenko
Mech. Eng. Sci. J., 37 (1–2), 107–115 (2019)
Fig. 4. Concept 3
Fig. 5. Concept evaluation using the spider mesh diagram
b) Further development of the selected concept
The final design is a backpack built out of 5 independ-
ent modules which have individual functions (Figure 6;
Table 5). When joined together, the modules obtain the
final purpose of the product. As the examples found in
nature, the modular design enables simplified increasing
in size, form and function and easy adjustment to differ-
ent external conditions. Because the parts are independ-
ent they can be produced in different locations and there-
fore possibly reduce the overall production cost com-
pared to traditional production processes. In addition, any
issues with one component can be solved by its replace-
ment instead of replacing the whole product which pro-
longs the life expectancy of the product.
Fig. 6. Exploded view of the backpack modules
0
2
4Comfort
Ergonomics
Compact…
Multi-…
Modularity
Capacity
Materials
Design
Concept 1 Concept 2 Concept 3
Bionic principles of space optimization applied in the product design process 113
Маш. инж.науч. спис., 37 (1–2), 107–115 (2019)
T a b l e 5
Basic modules of the designed backpack explained
No. Description
1 External frame with ergonomic back plate
2 Shoulder straps
3 Backpack
4 Lumbar support belt
5 Exoskeleton
The 5 independent modules are:
1) External frame with ergonomic back plate
(Figure 7)
The outer frame is designed to detach the back-
pack from the body. It has an ergonomic design fol-
lowing the natural curvature of the spine. It is cov-
ered with a soft sponge and 3D air mesh fabric for
air circulation and comfort. Airflow and air contact
systems prevent the body from sweating. This frame
is a base, with guides on which different types of
backpacks (with their own external frames) can be
attached.
2) Shoulder straps (Figure 8)
The shoulder straps are also designed as a sep-
arate component that is attachable to the external
frame by straps and Velcro. There are 5 levels of
height adjustment for the shoulder straps so that
they can be used by different types of users without
ruining the ergonomic features. The shoulder straps
contain a sternum strap for additional fixation and
security, with incorporated plastic slider compo-
nents for obtaining of length adjustability.
3) Backpack
Inspired by the ways in which natural organ-
isms have perfected their adjustment to the external
factors by adapting their size and led by the user re-
quirements for maximum use of volume and multi-
functionality, the backpack was designed with an
adjustable volume. Like the pangolins or armadil-
los, this backpack unfolds to release additional vol-
ume. The basic part has a size of 40 liters, built with
a bottom plate made of cross-linked polyethylene
for maximum stiffness and damage protection (Fig-
ure 9). When a larger size is needed, the bottom zip-
per opens to release additional 15 liters (Figure 10).
In order to obtain extra 20 liters, there is an internal
mechanism for vertical extension which serves for
lifting the top and achieving the final volume of 75
liters (Figure 11). The backpack has an outer frame
for attaching to the basic frame with the back plate.
In addition, the design of the backpack frame allows
vertical sliding of 5–6 cm when the hiker is moving
and this sliding helps to reduce the load forces and
weight on the shoulders by 60%.
4) Lumbar support belt (Figure 12)
This belt is intended to be used when the back-
pack is heavily loaded. It can be attached to the ex-
ternal frame and when used it changes the gravity of
the whole backpack, and therefore, it also changes
the load forces on the body. It has been calculated
that when using a lumber support belt of over 80 cm,
the load on the body is reduced by 15%.
5) Exoskeleton
The exoskeleton is based on a bionic principle
and it has a purpose to transfer the entire weight
from the shoulders and hips to the shoes. It also sup-
ports the body and gives it extra strength. Natural
exoskeletons (like the ones found on insects and
crabs) are an external body cover for some inverte-
brates which provide support and protection. In this
case, the exoskeleton is used to increase the physical
capabilities of the backpack users and ergonomic
features of the backpack itself. The exoskeleton is
simple to mount on the external frame by screwing
it to the shaft (Figure 13). The mechanism is cus-
tomizable for each user. There is an option for hor-
izontal adjustment of the upper part and 2 points of
vertical adjustments among the legs.
The whole exoskeleton can be fastened to the
legs in 2 spots and fastened to the shoes in 1 spot. It
is meant to be attached on the outside of the legs and
it follows all the natural functions of the legs –
movement, kneeling, running etc. The exoskeleton
can be folded when not being used (Figure 14).
Figs. 7–8. Back view of the basic external frame
with shoulder straps and backpack attached
Fig. 9. Backpack 40 liters Fig. 10. Backpack 55 liters
114 N, Gerasimovski, E, Angeleska, S. Sidorenko
Mech. Eng. Sci. J., 37 (1–2), 107–115 (2019)
Fig. 11. Backpack 75 liters
Fig. 12. Lumbar support belt
Fig. 13. Exploded view of the exoskeleton components and
the way they are attached to the basic external frame
Fig. 14. Folded exoskeleton
Multi-functionality of the design is also achi-
eved by additional functions to some of the compo-
nents. There are solar panels installed on the front
side and batteries that provide energy for charging
electronic devices or LED lamps (Figure 15).
Another key feature is the special designed
structure of the exoskeleton, that could be easily
transformed to be used as a base construction for a
one person tent (Figures 16 and 17).
By thinking about additional features of the
components the value of the design is increased, the
backpack is brought closer to the needs of the target
users. This means they would be willing to invest in
it and used for many years.
Fig. 15. Solar panels installed at the front of the backpack
Fig.16. Use of the exoskeleton as a tent construction
Bionic principles of space optimization applied in the product design process 115
Маш. инж.науч. спис., 37 (1–2), 107–115 (2019)
Fig. 17. Use of the exoskeleton as a tent construction
6. CONCLUSIONS
The main goal of this research was to suggest
design methods for creating products that are com-
pact, modular, multi-functional and have adjustable
shape and size. Creating such products is in favor of
the circular design economy which challenges de-
signers to think about maintaining a loop life cycle
of items by: extending their utilization period, mak-
ing them multi-functional, easier for manufacturing,
suitable for reuse and repair etc.
For successful achievement of the main goal,
an in-depth analysis of bionic principles related with
the mentioned characteristics was done. Bionics as
an interdisciplinary field offers inexhaustible inspi-
ration for solving problems in many different indus-
try branches.
The design methods were used to propose a
concept for a mountain hiking backpack with maxi-
mum utilization of its volume in order to fit as much
equipment and tools as possible and enable carrying
larger weights without causing discomfort and pain
to the user. Seeking inspiration in nature, as well as
analyzing the ergonomic requirements, user prefer-
ences and latest technologies were important for of-
fering a backpack that has improved functional and
ergonomic features. The designed backpack takes
the users experience to the next level, offering: ad-
justable volume; independent modular components
that can be used and combined together according
to needs; system for reduction of the load forces on
the body, therefore reducing pain in the back and
shoulders; additional features including ecological
production of electric energy sufficient for charging
of electronic devices and using a part of the main
structure for building a tent.
The conclusions drawn from this research can
be used as an example or starting point for other de-
signers that seek a way to provide multi-functional-
ity and space optimization.
This paper also emphasises the importance of
conducting thorough researches on all aspects rele-
vant to the given problem and applying all available
technological and scientific achievements in order
to reach the best result.
REFERENCES
[1] Parkinson, A. R., Balling, R. J., Hedengren, J. D.: Optimi-
zation Methods for Engineering Design: Applications and
theory, Brigham Young University, 2013.
[2] Ericsson, A., Erixon, G.: Controlling Design Variations:
Modular Product Platforms, Modular management AB
and Society of Manufacturing Engineers, 1999.
[3] Fourt, Lyman; Hollies, Norman: Clothing: Comfort and
Function (Fiber Science), Dekker (Marcel), 1971.
[4] Coelho, D. A., Versos, C. A. M.: A comparative analysis
of six bionic design methods, International Journal of De-
sign Engineering, 4 (2), 114–131 (2011).
[5] Helms, M., Vattam, S. S., Goel, A.: Biologically inspired
design: process and products, Design Studies, Vol. 30, No.
5, pp. 606–622 (2009).
[6] Ball, P.: Patterns in Nature: Why the Natural World Looks
the Way It Does, University of Chicago Press, 2016.
https://www.amazon.com/Patterns-Nature-Natural-World
-Looks/dp/022633242X
[7] Retnari Dian, M., Velahyati, A., Hartati, H.: Desain Back-
pack Berdasarkan Analisis Biomekanika dengan Pendeka-
tan QFD dan TRIZ untuk Pendaki Wanita, Hasil Penelitian
Fakultas Teknik, Grup Teknik Mesin, Universitas Hasan-
uddin, Vol. 5, pp. 1–12 (2011),
[8] Cleverhiker: 10 Best Lightweight Backpacks of 2019,
(2019), www.https://cleverhiker.com/
Mechanical Engineering – Scientific Journal, Vol. 37, No. 1–2, pp. 117–120 (2018)
CODEN: MINSC5 ISSN 1857–5293
e: ISSN 1857–9191
INSTRUCTIONS FOR AUTHORS
The Mechanical Engineering – Scientific Journal is published twice yearly. The journal publishes origi-
nal scientific papers, short communications, reviews and professional papers from all fields of mechanical
engineering.
The journal also publishes (continuously or occasionally) the bibliographies of the members of the Fac-
ulty, book reviews, reports on meetings, informations of future meetings, important events and data, and vari-
ous rubrics which contribute to the development of the corresponding scientific field.
Original scientific papers should contain hitherto unpublished results of completed original scientific
research. The number of pages (including tables and figures) should not exceed 15 (28 000 characters).
Short communications should also contain completed but briefly presented results of original scientific
research. The number of pages should not exceed 5 (10 000 characters) including tables and figures.
Reviews are submitted at the invitation of the Editorial Board. They should be surveys of the investiga-
tions and knowledge of several authors in a given research area. The competency of the authors should be
assured by their own published results.
Professional papers report on useful practical results that are not original but help the results of the
original scientific research to be adopted into scientific and production use. The number of pages (including
tables and figures) should not exceed 10 (18 000 characters).
Acceptance for publication in the Journal obliges the authors not to publish the same results else-
where.
SUBMISSION
The article and annexes should be written on A4 paper with margins of 2.5 cm on each side with a standard
font Times New Roman 11 points, and should be named with the surname of the first author and then if more
and numbered. It is strongly recommended that on MS Word 2003 or MS Word 2007 and on PDF files of the
manuscript be sent by e-mail:
A letter must accompany all submissions, clearly indicating the following: title, author(s), correspond-
ing author’s name, address and e-mail addres(es), suggested category of the manuscript and a suggestion of
five referees (their names, e-mail and affiliation).
Articles received by the Editorial Board are sent to two referees (one in the case of professional papers).
The suggestions of the referees and Editorial Board are sent to the author(s) for further action. The corrected
text should be returned to the Editorial Board as soon as possible but in not more than 30 days.
PREPARATION OF MANUSCRIPT
The papers should be written in the shortest possible way and without unnecessary repetition.
The original scientific papers, short communications and reviews should be written in English, while the
professional papers may also be submitted in Macedonian.
Only SI (Système Internationale d'Unites) quantities and units are to be used.
118 Instructions for authors
Mech. Eng. Sci. Journal. 37 (1–2), 117–120 (2019)
Double subscripts and superscripts should be avoided whenever possible. Thus it is better to write 3(PO4)
than 4PO3 or exp(–E/RT) than e–E/RT. Strokes (/) should not be used instead of parentheses.
When a large number of compounds have been analyzed, the results should be given in tabular form.
Manuscript should contain: title, author(s) full-name(s), surname(s), address(es) and e-mail of the corre-
sponding author, short abstract, key words, introduction, experimental or theoretical background, results and
discussion, acknowledgment (if desired) and references.
The title should correspond to the contents of the manuscript. It should be brief and informative and
include the majority of the key words.
Each paper should contain an abstract that should not exceed 150 words, and 3–5 key words. The ab-
stract should include the purpose of the research, the most important results and conclusions.
The title, abstract and key words should be translated in Macedonian language. The ones written by
foreign authors will be translated by the Editorial Board.
In the introduction only the most important previous results related to the problem in hand should be
briefly reviewed and the aim and importance of the research should be stated.
The experimental section should be written as a separate section and should contain a description of the
materials used and methods employed – in form which makes the results reproducible, but without detailed
description of already known methods.
Manuscripts that are related to theoretical studies, instead of experimental material, should contain a
sub-heading and the theoretical background where the necessary details for verifying the results obtained
should be stated.
The results and discussion should be given in the same section. The discussion should contain an anal-
ysis of the results and the conclusions that can be drawn.
Figures (photographs, diagrams and sketches) and mathematical formulae should be inserted in the
correct place in the manuscript, being horizontally reduced to 8 or 16 cm. The size of the symbols for the
physical quantities and units as well as the size of the numbers and letters used in the reduced figures should
be comparable with the size of the letters in the main text of the paper. Diagrams and structural formulae should
be drawn in such a way (e.g. black Indian ink on white or tracing paper) as to permit high quality reproduction.
The use of photographs should be avoided. The tables and the figures should be numbered in Arabic numerals
(e.g. Table 1, Fig. 1). Tables and figures should be self-contained, i.e. should have captions making them
legible without resort to the main text. The presentation of the same results in the form of tables and figures
(diagrams) is not permitted. The use of equation editor (MS Word, Microsoft Equation, Math Type 6.0 Equation)
for typesetting the equations is recommended. Strokes (/) should not be used instead of parentheses.
Figures and tables must be centred in the column. Large figures and tables may span across both columns
(Figure 1).
Fig. 1. Example of a graph and a single-line caption
Graphics may be full colour. Please use only colours which contrast well both on screen and on a black-
and-white hardcopy because the Journal is published in black-and-white, as shown in Figure 2. The colour
version is only for the electronic version of the Journal.
Instruction for authors 119
Ma{. in`. nau~. spis., 37 (1–2), 117‡120 (2019)
Please check all figures in your paper both on screen and on a black-and-white hardcopy. When you
check your paper on a black-and-white hardcopy, please ensure that:
– the colours used in each figure contrast well,
– the image used in each figure is clear,
– all text labels in each figure are legible.
Please check all figures in your paper both on screen and on a black-and-white hardcopy. When you
check your paper on a black-and-white hardcopy, please ensure that the image used in each figure is clear and
all text labels in each figure are legible.
Fig. 2. Example of a graph and a single-line caption
Fig. 3. Example of an image as it will appear at the electronic version of the journal and a multi-line caption
Footnotes are also not permitted.
The reference should be given in a separate section in the order in which they appear in the text. The
surname of one or two authors may be given in the text, whereas in the case of more than two authors they
should be quoted as, for example:
120 Instructions for authors
Mech. Eng. Sci. Journal. 37 (1–2), 117–120 (2019)
Examples of reference items of different categories shown in the References section include:
• example of a book in [1]
• example of a book in a series in [2]
• example of a journal article in [3]
• example of a conference paper in [4]
• example of a patent in [5]
• example of a website in [6]
• example of a web page in [7]
• example of a databook as a manual in [8]
• example of a datasheet in [9]
• example of a master/Ph.D. thesis in [10]
• example of a technical report in [11]
• example of a standard in [12]
All reference items must be in 9 pt font. Please use Regular and Italic styles to distinguish different fields
as shown in the References section. Number the reference items consecutively in square brackets (e.g. [1]).
When referring to a reference item, please simply use the reference number, as in [2]. Do not use “Ref.
[3]” or “Reference [3]” except at the beginning of a sentence, e.g. “Reference [3] shows …”. Multiple refer-
ences are each numbered with separate brackets (e.g. [2], [3], [4]–[6]).
The category of the paper is proposed by the author(s), but the Editorial Board reserves for itself the
right, on the basis of the referees' opinion, to make the final choice.
Proofs are sent to the author(s) to correct printers' errors. Except for this, alterations to the text are not
permitted. The proofs should be returned to the Editorial Board in 2 days.
The author(s) will receive, free of charge, 1 reprints of every paper published in the Journal.
REFERENCES
[1] Surname, N(ame)., Surname, N(ame): Name of the Book, Publisher, Year.
[2] Surname, N(ame). Surname, N(ame).: Name of the Book, Name of the Series. Publisher, vol. XXX, Year.
[3] Surname, N(ame). Surname N(ame).: Title of the article, Name of the Journal, vol. XX, No. XX, pp. XXX–XXX (Year).
[4] Surname, N(ame). Surname N(ame).: Title of the article, Proceedings of the Name of the Conference, vol. XX, pp. XXX–
XXX.Year.
[5] Surname, N(ame). Surname N(ame).: Name of the Patent, Institution that issued the patent and Number of the patent (Date dd.
mm. yyyy).
[6] N.N.: The XXX web site, web address, Year.
[7] Surname, N.: XXX homepage on XXX, web address (Year)
[8] N.N.: Title of the Manual, Name of the Organization, Year.
[9] N.N.: XXX data sheet, Name of the Organization.
[10] Surname, N.: Title of the Thesis, Master/Ph.D. thesis (in Language), Institution. Year.
[11] Surname, N(ame), Surname, N(ame): Title of the Report, Organization that issued the report, Number of the report (Year).
[12] Institution that issued the standard, Name of the Standard & Number of the standard (Year):.