Proceedings of the 1996 Winte'" Sirnv,lation Conferenceed. J. M. Charnes, D. J. Morrice, D. T. Brunner, and J. J. Swain

SIMULATION-BASED LEARNING TOOL FOR FACILITIES DESIGN

BalaRam

Department of Industrial EngineeringNorth Carolina A&T State University

Greensboro, NC 27411

ABSTRACT

This paper describes a tool, LAYSIM, toemphasize to the students the important role ofmaterial handling cost in choosing the type oflayout; i.e., Product, Jobshop or GroupTechnology-based layout for a certain set ofproducts. It addresses how throughexperimentation with LAYSIM studentsunderstand and appreciate the manufacturingcosts associated with each type of layout. Thepaper describes the underlying learning model,development of the LAYSIM, the features ofLAYSIM and the proposed disseminationtechnique.

1 INTRODUCTION

Allowing students to experience the practicaland realistic situations of their profession has tobe the thrust of the curriculum in engineering.The design process is iterative, the analyzer hasto go back and forth between the different stepsof defining, developing, analyzing, testing, andevaluation until a satisfactory design is obtained.Design is also a creative process of devising aproduct or a system to meet the ultimate goal ofsatisfying the customer needs (Steudel 1993). Toaid the process of designing, the student has tobe provided with enough tools in the form offundamental concepts, which can be embeddedinto their minds by using the experientiallearning approach. Experiential learning is apedagogical approach that offers students anopportunity to link classroom theory withpractical applications. People learn by manydifferent means, but prefer to gain knowledgeand skills through experiential opportunities(Richardson 1994).

1413

Rajiv Girdhar

General Electric CorporationPO Box 414

Milwaukee, WI 53201

Learning tools that are interactive are a cost­effective way of giving several differentexperiences to a student. Simulation is the artand science of creating a representation of aprocess or system for the purpose ofexperimentation and evaluation (Gogg and Mott1993). It is a powerful analytical tool that cansignificantly facilitate the problem solvingprocess. The capability of the simulationenvironment to allow the user to experiment bychanging the different parameters is unique, andin the process helps the user discover whatadditional infonnation is needed to solve theproblem. With the increased power of thepersonal computers and software, simulation ­the interactive teaching tool - has a much widerscope in the engineering curriculum.

This paper describes a tool, LAYSIM, toimpart to the students the impact of choosing atype of layout: i.e., Product, Jobshop or GroupTechnology-based layout for a certain set ofproducts on manufacturing costs includingmaterial handling cost. The simulation tooldeveloped is meant to be used in introducing thetopic of Facilities Design in an engineering ormanagement curriculum. The module is intendedto give the students a frrst-hand experience inunderstanding the relationship between the typeof layout, number of components beingmanufactured in the factory and the resultingmanufacturing costs.

2 LEARNING MODEL

LAYSIM has been developed as a means ofproviding the students an environment forexperimentation with different plant layoutoptions. It presents the students with threedifferent types of plant layouts: 1) ProductLayout, 2) Group Technology-based Layout,

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Jobshop Layout

2 components

6 components

12 components

Ram and Girdhar

Table 1 Layouts used in LAYSIM

Group Technology-Based Layout

6 components

12 components

6Number Of Products

Figure 1 P - QChart

Product Layout

2 components

.6 components

12 components

Product

Layout

GroupTechnologyBased

o LayoutJobshop

Layout

3) Jobshop Layout and a common set of products.LAYSIM incorporates eight layouts as shown in theTable 1. The students have an opportunity to computethe material handling costs with each type of layout fordifferent levels of production volume and differentnumbe~ of products. (This is explained in more detail inthe next section.)

LAYSIM will enable students to perfonn thefollowing experiential exercise. They would be able tochange certain parameters and perfonn a number ofsimulation runs to collect enough data based on whichthey would be able to construct the P - Q Chart, whereP represents the number of products beingmanufactured in the factory and Q represents thevolume of production. For example, one simulation runwill be perfonned for each of the layout types for 2components with "large" production volumes. Thesimulation runs would provide the manufacturing costsin each case; the layout type with the leastmanufacturing costs will be the "preferred layout". Atypical P - QChart is shown in Figure 1.

The above exercise will enable the students tounderstand and appreciate the manufacturing costsassociated with each type of layout. The layouts and thenumber of components chosen has been designed insuch a way that after going through the exercise thestudent is able to come up with results which supportsome of the theory behind the P - Q Chart (Tompkins etal. 1996).

3 DEVELOPMENT OF THE LEARNINGTOOL

3.1 Development of Software

ProModel 3.0 was chosen as the simulation softwarefor LAYSIM. ProModeI 3.0 is a PC-based softwarewhich runs under the Windows environment. Thissoftware was chosen because of the followingcapabilities:

• a run-time model can be made for distributing themodule for feedback and dissemination;

Simulation-Based Learning Tool for Facilities Design 1415

•

•

•

•

•

•

animation of the material handling equipment,material and personnel is possible;appropriate icons for production environment suchas machines, material handling equipment; etc. arebuilt into the software;importing of AutoCAD drawings into the layoutbackground is possible;shifts can be defmed and assigned, and down-timefor machines can be specified;global variables can be defmed: this is used tocompute the manufacturing costs duringsimulation;subroutines can be built: this has been used tomake the models interactive; and

• a number of views of different parts of the plantcan be defmed for the factory layout and can bepresented to the user in a defmed sequence duringthe simulation run, or can be used by the user in arandom manner;Multimedia ToolBook 3.0 was chosen as a driver

software for LAYSIM. It is possible to run anyWindows-based software, such as ProMoqel,from within Multimedia ToolBook 3.0 and ToolBookcan help in building aesthetic screens with buttons fornavigating through the module. A sample of the driverscreens used in the module are shown in Figures 2 and3 as seen by the user of the module.

Figure 2 LAYSIM Main Screen

Figure 3 LAYSIM Simulation Environment

1416 Ram and Girdhar

The floorplan of the factories used for the simulationmodel have been built using FactoryCAD which runson a AutoCAD software platform and providesadditional features for developing floorplans. Thefloorplan includes the boundary walls for the factory,office, break rooms and also the workcenter/machineboundaries as laid out on the floor of the factory. Theseboundaries are then used as a reference to place the

icons of the various machines in ProModel. The layoutdrawing developed using FactoryCAD is saved as aWindows metafile and then imported into ProModel. Asample of the layout imported into ProModel is shownin Figure 4, and in Figures 5a and 5b is shown theinterrelationship of all the software which has beenused in developing the learning tool.

TWO-COMPONENT JOBSHOP LAYOUT

9 130RE

r--l r---------I I II I II I II I II I II I I

I II II II I 6 PRESSI I'I II II II II II I

I J I~. DRIL~II I II I II I IL __ J L _

'---II II II II II II II II I

PGRINDER:

I II II II IL ...J

3 LATHE

----------------,IIIII_______________ ...J

IIIIIIIII

2 MILLING III,II

, ......,J

---~ ~-~~-------------~~~~p~m~-

~===~==:::::::::!::::=

Figure 4 An Example Floorplan in FactoryCAD

Mult media

ToolBook 3.0

Layout

LAYSIM

Simulation

I FactoryCAD ~ Layout ,... ProModel

(Simulation)

Figure 5a Components of LAYSIM Figure 5b Relationship between FactoryCAD, Multimedia ToolBook

and ProModel

Simulation-Based Learning Tool for Facilities Design

Table 2 - Components to be Manufactured

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Part No.

2

3

4

5

6

7

8

9

10

11

12

Part Name

Crank Case

Cylinder

Cylinder Head

Crankshaft

Connecting Rod

Outside Bearing

Inside Bearing

Breather

Cover plate

Suction Fitting

Discharge Fitting

Breather Plate

Wt/Pc in Ibs.

1.1000

0.5000

0.3000

0.1500

0.0750

0.0125

0.0150

0.0500

0.0125

0.0125

0.0125

0.0125

Production Routing(process times in minutes)

1- 2 - 3 - 6 - 4 - 10(5) (3) (2) (2)

1 - 3 - 4 - 7 - 10(2) (1) (0.5)

1 - 3 - 4 - 10(3) (2)

1 - 8 - 3 - 2 - 4 - 10(0.8) (3) (3) (1)

1 - 5 - 4 - 9 - 4 - 2 - 6 - 4 - 6 - 10(2) (1) (3) (1) (1) (1) (0.5) (0.5)

- 3 - 10(0.5)

- 3 - 10(0.5)

- 2 - 4 - 10(1) (0.5)

- 6 - 10(0.1 )

1 - 3 - 10(0.3)

- 3 - :2 - 10(0.3) (0.5)

- 6 - 10(0.1 )

3.2 Example Table 3 - Machines and their area requirements

Table 4 Material Handling Alternatives

Wt. Of Unit MethodLoad Handling(Lbs.)

A set of compressor components have been chosen formanufacturing in the example factory. Thesecomponents are listed in Table 2. The table has detailson the Weight of the components in pounds and theprocessing sequence along with the process times. Theprocessing sequence is shown by numbers whichrepresent the machines, the reference for the numberrepresenting the machine is found in Table 3.

The machines required for manufacturing thecomponents and the areas per machine are shown inTable 3. Three different choices are possible formoving material. Table 4 provides data for selection of

appropriate material handling method.Table 5 presents the calculation for the calculation

for the number of machines and floor space for one ofthe eight layouts used in LAYSIM. Table 5 is for the 2

component Job Shop case.

MachineNumber

12345678

MachineName

MillLatheDrillGrinderPressHoneSawBore

Reqd. Area(Sq.Ft.)10090501002004550100

Of CostIMove1Ft.Traveled

o To 2526 To 500501 And Up

Manual Handling $0.010Walkie Pallet Lift $0.015Fork Lift Truck $0.025

1418 Ram and Girdhar

The fITst step in developing the simulation modelswas to import the FactoryCAD layout into theProModel model; the procedure for doing this hasalready been described earlier. The layout forms a staticbackground for the simulation. The next step is tointroduce machine icons in the space allocated in thelayout, this is specifying of the locations, beyond thatentities, resources, path networks, and processingsequence are specified for running the model. Salientfeatures of the module are described below.

It is possible to defme regular shift hours and shiftbreaks for the full week and save it as a separate file. Anumber of such shift times can be defmed and stored inseparate files. These files can then be assigned to thevarious locations and resources in the simulationmodel. For the models developed for LAYSIM threedifferent shift files have been created and assigned todifferent locations and resources.

By defming the distance traveled by the materialhandling resources and the material handling cost as"global variables" and incrementing their value thematerial handling cost is dynamically presented on thesimulation screen. A few parameters such as the batchsize of the components being processed are variableand the user will have an opportunity to specify thevalue before the simulation run.

The run time model has been made for distributingthe tool to get feedback about its effectiveness. The runtime model can be used on any personal computerwithout having the need to buy the simulation software.ProModel 3 has a provision to create a model packagewhich can then be distributed to the users'; the modelpackage consists of the models and ProModel whichhas to be installed at the users' site before the packagedmodel can be run. The user, however, cannot modifythe model or develop other models.

Figure 6 Simulated Environment in ProModel

Table 5 - Calculations For Machine Detennination And Space Allocation For Two Component Jobshop Layout

Part # & Name No. of Rough Milling Lathe Drill Grinder Press Hone Saw Bore Final Total

Comp. Stores Insp. Area

per shift 1 2 3 4 5 6 7 8 9 10

1 Crank Case 2500 12500 7500 5000 5000

2 Connecting Rod 2500 2500 1250 6250 5000 3750 7500 ~S

Total Minutes Needed 0 15000 8750 11250 5000 8750 0 0 7500 0 ~t--

~

Total No. of Components 5000~o·

Machines Needed0

I

to(Total mins./480 mins.) 0 31.25 18.23 23.44 10.41 18.23 0 0 15.63 0 ~

(b

Efficiency Rate 80%* 39.06 22.79 29.3 13.02 22.79 0 0 19.53 0 Q..

Machines Needed 0 40 23 30 14 23 0 0 20 0~(b

~..,~.

Area (Sq. Ft.)* 800 5000 2588 1875 1750 5750 0 0 2500 500 20763 0O'q

~2-<Y

* Assumptions:..,

1. An additional 25% was added to sq. footage required for machines for: ~

- Maneuverability (i.e. work-in-process, aisleways, etc.) ~N-

- Storage of parts, tools, misc.(t,.rJ"J

t::1(bCJ:l

2. 80% Efficiency Rate assumed for all machines §.

~

~~

CD

1420 Ram and Girdhar

The user is able to see the movement of the materialthrough the various stages of production in thesimulated factory. The material is moved from thestores to the fITst stage of production and from there tothe various departments/machines before it is fmallyrouted to the fmal inspection and then dispatched. Anumber of different icons are used to identify thecomponents in various stages of production, materialhandling icons are used to simulate the movement ofmaterial between the departments. There is also anindicator for machines in use. All this gives thestudents a better understanding of the material handlingoccurring with each type of layout. A sample screen fora model in ProModel shown in Figure 6.

On the simulation screen several different viewshave been defined. A few of these get activated fromwithin the model during the simulation run to highlightthe various regions of the factory and present a betterview to the user, a list of these views also appears onthe simulation screen with information on accessingthese via the keyboard during the simulation.

4 DISSEMINATION

The learning tool discussed here has been developedfor the Product Realization Consortium. Thisconsortium is funded by the Technology ReinvestmentProgram and involves Cornell University,Massachusetts Institute of Technology, TuskegeeUniversity, Worcester Polytechnic Institute, Society ofManufacturing Engineers, and North Carolina A&TState University as partners. The objective of theconsortium is to revitalize manufacturing engineeringeducation. One significant task identified by theconsortium is the development of appropriatecourseware. The courseware developed will be tried atmultiple campuses to establish its usefulness.

ACKNOWLEDGMENTS

The work reported here was partially supported by theNational Science Foundation Cooperative Agreement

DMI-9413089 under the interagency TechnologyReinvestment Project (TRP).

REFERENCES

Steudel, H. J., "Integrating Simulation into Team-BasedClass Projects", Proceedings of the 1993 WinterSimulation Conference, eds. G. W. Evans, M.Mollaghasemi, E. C. Russell, W. E. Biles.

Richardson, 1. G., "Learning Best ThroughExperience", Journal of Extension, vo1.32, No.2,Aug.1994.

Gogg, T. 1., Mott, 1. R. A., "Introduction toSimulation", Proceedings of the 1993 WinterSimulation Conference, eds. G. W. Evans, M.Mollaghasemi, E. C. Russell, W. E. Biles.

Tompkins,1. A., White, 1. A., Bozer, Y. A., Frazelle, E.H., Tanchoco, J. M. A., Trevino, J., "FacilitiesPlanning", 2nd Edition, John Wiley, NY, pp. 54-55,1996.

AUTHOR BIOGRAPHIES

BALA RAM is a Professor in the Department ofIndustrial Engineering at North Carolina A&TState University in Greensboro. He received his BSin Mechanical Engineering and MS in IndustrialEngineering from Indian Institute of Technology,Madras in 1975 and 1977 respectively, and hereceived his PhD in Industrial Engineering fromthe State University of New York at Buffalo in1983. His research interests are in MaterialHandling and Simulation. He is a member ofASEE, lIE and SME.

RAJIV GIRDHAR is a Manufacturing Engineer withGeneral Electric Corp. in Milwaukee, WI. Hereceived his BS in Mechanical Engineering fromthe University of Bombay in 1992. He received hisMS in Industrial Engineering from North CarolinaA&T State University in Greensboro in July 1996.He is a member of SME.