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
4/12/2017
C.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 )
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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 .
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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.
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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 )
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Milestone-Charts
Fig: 5.Milestone summary(source:J.H.Greene,production control : system and decisions )
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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
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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.
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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)
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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.
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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.
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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)
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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.
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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
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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.
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References
• www.merchant ricks.com
• J . H. Greene, production control : system and decisions
• www.sciencedirect.com
• www.mosaicprojects.com
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Graphical method of job shop scheduling

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