graphical method of job shop scheduling

JOB SHOP SYSTEM

GRAPH THEORETICAL APPROACH

C.S.Gowsick (16MI31)

ME-Computer integrated manufacturing

Department of mechanical engineering

PSG College of Technology

11 C.S.Gowsick(16MI31) PSG college of technology

Agenda :

• Introduction

• Job shop scheduling

• Objective of Job shop scheduling

• Characteristics of Job shop

• Graphical Method-(Gantt chart )

• Milestone-Charts

• Line of Balance

Case Study:De-manufacturing

4/12/2017C.S.Gowsick(16MI31) PSG college of

technology

Introduction

• Job shop productions are characterized by manufacturing of one or few

quantity of products designed and produced as per the specification of

customers within prefixed time and cost. (project centers, Engineering

works)

Fig:1.Job shop production (Merchant ricks)

4/12/2017 C.S.Gowsick(16MI31) PSG college of technology

Job shop scheduling

• An important function of job shop scheduling is the coordination and

control of complex activities, both optimum resource allocation and

sequence in the performance of the activities.

• Approaches are classified into two types:

1.Analytical techniques: Mathematical approaches of assigning jobs

to machines are derived to optimize certain criteria. This gives exact

solution or near optimal solution .

2.Graphical Methods: This method do not provide optimal or near

optimal solution directly. These method is used to find the error before

they are occurring and takes the alternative plans.


Objective of Job shop scheduling

1.The main objective is decrease the average in-process time of our work order

2.Also, we want to increase the degree of utilization of equipment.

• The first objective can be achieved by selecting the optimal processing

time, the transportation time, the waiting time, and the setup time.

• To achieve the second goal, we need to pick the schedule that maximizes

the utilization of existing capacity. this objective focuses on the machine

and sequence of jobs.


Characteristics of Job shop

• At any time there is a large number of orders at various stage of

completion.

• Every order differs to some extend. It is difficult to predict accurately the

time required to complete operation.

• It is difficult to determine which order in the queue should have a priority.

• There are many changes resulting from scrap , rework, machine

breakdown, material shortage, engineering changes and rush orders


Graphical Method-(Gantt chart )

Fig: 2.Gantt chart symbols (source:J.H.Greene,production control : system and decisions )


technology

Example of Gantt-chart

Fig: 3.Machine schedule chart (source:J.H.Greene,production control : system and decisions )

• The time scale is placed horizontally along the top of the chart.

• The row represents machines, departments, or whatever may be required to

accomplish a job.

• This time scale may be subdivided into calendar time or temporal units .


technology

Advantage and Disadvantage

• Advantage:

1. It is used as planning tool and as a control devices.

2.The progress of work is recorded and therefore the Gantt chart is instructive even

for the no specialist.

• Disadvantage:

1.There is no way of optimizing the operation or a sequence.

2.If the number of operation to be planned is high,it is impossible to maintain an

overview in a Gantt chart.

3.It does not give any information about the impacts of delay of single operation.


technology

Milestone-Charts

• The method of collecting and organizing data for milestone charts is similar

to the Gantt technique.

• The primary difference is the graphic display.

• The milestone system offers no basic improvement over the Gantt chart

expect to provide focus on the event to be achieved.

Fig: 4.Milestone chart(source:J.H.Greene,production control : system and decisions )


technology

Milestone-Charts

Fig: 5.Milestone summary(source:J.H.Greene,production control : system and decisions )


technology

Line of Balance

• Line of Balance is a method of showing the repetitive work that may exist

in a project as a single line on a graph.

Fig: 6.Line of Balance( source: www.mosaicprojects.com)


Modeling and analysis of Manufacturing system

De-Manufacturing Systems


technology

Abstract

• De-Manufacturing can be defined as the “break down of a product into its

individual parts with the goal of reusing and remanufacturing parts, or

recycling the remainder of the components”

• This paper formulates the concept of De-Manufacturing systems, provides

example of the potential impact of these solutions in a growing sector, the

mechatronic component industry, and sets the framework for future

research in this area.


technology

De-Manufacturing systems

• A De-Manufacturing System can be defined as the set of resources (human and technological), organization, IT infrastructure and associated business model to enable product De-Manufacturing.

Fig: 7.De-Manufacturing system( source: www.sciencedirect.com)


technology

De-Manufacturing systems

• De-manufacturing processes typically include Disassembly,

Remanufacturing, Recycling and Recovery processes.

• Disassembly:(I) hazardous components that cannot enter the recycling

flow(ii) re-usable parts with high residual value(iii) parts that need to go

through a dedicated recycling process chain.

• Remanufacturing: Dismantling the unit or a component, inspecting these components, repairing defective components or replacing them with new ones, reassembling the units, readjusting as specification and sent it to the inspection department.

• Recycling is mainly performed by mechanical processes or by thermal processes.

• Recovery processes make use of chemical reactions to separate the target materials at very high grade levels. They are typically performed in batches.


technology

Mechatronic Components

• Mechatronic products can be defined as systems combining mechanics,

electronics and information technology.

De-Manufacturing pilot plant:

• De-Manufacturing process chain is the pilot plant recently installed at

ITIA-CNR, the Institute of Industrial Technologies and Automation of the

National Council for Research, in Milan, Italy.


technology

Multi-level integrated De-Manufacturing research

approach.

Fig: 8.Multi-level integrated De-Manufacturing research approach. ( source: www.sciencedirect.com)


Layout of the De-manufacturing Pilot Plant

Fig: 9. Layout of the De-manufacturing Pilot Plant at ITIA CNR. ( source: www.sciencedirect.com)


technology

Layout of the De-manufacturing Pilot Plant

• The first cell is dedicated to the robotics disassembly of the mechatronic

components. Two cooperating robots and a lightweight robot assist the

operator in the disassembly operations.

• Second cell is dedicated to testing, repair and remanufacturing operations.

• Third cell is dedicated to assembly and final inspection to market.


technology

Research challenges

• Human-machine interaction:

All the industrial robots are designed to assemble the components not for

disassemble

• De-Manufacturing Process Models

• De-Manufacturing System Engineering: integrating all departments in a

demanufacturing company is so tough.

• Reconfigurability of De-Manufacturing Systems: De-Manufacturing

Systems should be reconfigurable to be able to process different types of

products over time

• Energy in De-Manufacturing systems :the energy consumption in De-

Manufacturing systems can be extremely high


technology

Conclusion

• De-Manufacturing Systems can constitute the driver for sustainable

economy and sustainable growth in high-wage countries.

• However, major technological, methodological and business oriented

innovations need to be developed as enabler for this new concept, which

directly affects both the energy footprint and the raw material consumption

in manufacturing operations.


technology

References

• www.merchant ricks.com

• J . H. Greene, production control : system and decisions

• www.sciencedirect.com

• www.mosaicprojects.com


technology