INTELLIGENT DECISION MAKING FOR REACTIVE SCHEDULING IN FMS

Product design print–defines all of the companies product characteristics
•Product design must support product manufacturability (the ease with
which a product can be made)
•Product design defines a product’s characteristics of:
•appearance,
•materials,
•dimensions,
•tolerances, and
•performance standards.
Service design print is unique in that the service and entire service
concept are being designed
must define both the service and concept
- Physical elements, aesthetic &
psychological benefits
e.g. promptness, friendliness, ambiance
Product and service design print must match the needs and
preferences of the targeted customer group

COMPUTER AIDED PROCESS PLANNING

Defining Process planning
• Process planning can be defined as the systematic determination of the
detailed methods by which work pieces or parts can be manufactured
economically and competitively from initial stages (raw material form)
to finished stages (desired form).
Initial FormFinal Form
• Geometrical features, dimensional sizes, tolerances, materials, and
surface finishes are analyzed and evaluated to determine an
appropriate sequence of processing operations.

• In general, the inputs to process planning are
 design data,
 raw material data,
 facilities data (machining data, tooling data, fixture data, etc.),
 quality requirements data, and
 production type data.
• The output of process planning is the process plan.
 The process plan is often documented into a specific format and
called
 process plan sheet,
 process sheet,
 operation sheet,
 planning sheet,
 route sheet,
 route plan, or
 part program.

• Recent research results have also demonstrated that process
planning plays an important role in Computer Integrated
Manufacturing – CIM
Process planning is the key link for integrating design and manufacturing
• the process plan provides necessary information
for technical and equipment preparation, such as:
 tools,
 jigs and fixtures,
 machines,
 inspection devices,
 raw material stocks,
 inventory plans,
 purchasing plans,
 personal requirements,
 etc.

Defining Computer Aided Process planning - CAPP
• Computer Aided Process Planning (CAPP) can be defined
as the functions which use computers to assist the work of
process planners.
• The levels of assistance depend on the different strategies
employed to implement the system.
 Lower level strategies only use computers for
storage and retrieval of the data for the process plans
which will be constructed manually by process
planners, as well as for supplying the data which will
be used in the planner's new work.
 Higher level strategies use computers to
automatically generate process plans for some
workpieces of simple geometrical shapes.

Defining Computer Aided Process planning - CAPP
CAPP a key factor in CAD/CAM integration because it is the
link between CAD and CAM.

Benefits of CAPP
1. Reduction in process planning time.
2. Reduction in the required skill of the process planner.
3. Reduction in costs due to efficient use of resources.
4. Increased productivity.
5. Production of accurate and consistent plans.

Approaches of CAPP
In general, two approaches to CAPP are traditionally
recognized:
• the variant approach or retrieval approach,
• the generative approach,

The Variant approach of CAPP
• The variant approach, which is also called retrieval approach,
uses a group technology (GT) code to select a generic process
plan from the existing master process plans developed for each
part family and then edits to suit the requirement of the part.
• Variant approach is commonly implemented with GT coding
system. Here, the parts are segmented into groups based on
similarity and each group has a master plan.

Advantages of Variant approach of CAPP
1. Once a standard plan has been written, a variety of components
can be planned.
2. Programming and installation are comparatively simple.
3. The system is understandable, and the planner has control of
the final plan.
4. It is easy to learn and easy to use.

1. The components to be planned are limited to previously planned
similar components.
2. Experienced process planners are still required to modify the
standard plan for the specific component.
3. Details of the plan cannot be generated.
4. Variant planning cannot be used in an entirely automated
manufacturing system, without additional process planning.
Disadvantages of Variant approach of CAPP

The Generative approach of CAPP
• In a generative approach, a process plan for each
component is created from scratch without human
intervention. These systems are designed to automatically
synthesize process information to develop a process plan
for a part

• Generative CAPP systems contain the logic to use manufacturing data
bases, knowledge bases and suitable part description schemes to generate
a process plan for a particular part.
The Generative approach of CAPP

Advantages of Generative approach of CAPP
1. Consistent process plans can be generated rapidly.
2. New components can be planned as easily as existing
components.
3. It has potential for integrating with an automated manufacturing
facility to provide detailed control information.

INTELLIGENT DECISION MAKING FOR REACTIVE SCHEDULING IN FMS

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INTELLIGENT DECISION MAKING FOR REACTIVE SCHEDULING IN FMS