Group Technology Applications

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Group Technology Applications

• Henry C. Co
• Technology and Operations Management,
• California Polytechnic and State University

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Group Technology Layout
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Traditional Layout Types
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GT Layout

• Layout the manufacturing facilities into
  manufacturing cells.
• Each cell is designed to produce a family of
  parts that require similar machinery, tooling,
  machine operations, and/or jigs and fixtures.
• The routing is greatly simplified by assigning
  each family of parts to a cell.

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GT Layout Benefits

• Implied reduction of necessary control.
• Reduced material handling.
• Reduced set-up time.
• Reduced tooling.
• Reduced in-process inventory.
• Reduced expediting.
• Increase operator expertise.
• Improved human relations.

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Limitations

• GT layout are not without limits. Since machines
  are not shared between cells, more units of
  machines are needed for the equivalent capacity
  in a functional layout.
• Also, not all machines can be grouped into cells.
  Typically, 30 to 40 of the total facility can
  not be included in any cell and are placed in a
  remainder cell. Parts produced in this remainder
  cell still have jumbled routings.

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Computer-aided Process Planning
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Process Planning

• A process plan establishes the machining process
  and parameters to be used (as well as those
  machines capable of performing these processes)
  in order to convert a work piece from its initial
  form to a pre-determined final form.

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Process Planning

• Computer-aided process planning (CAPP) increases
  the process planner's productivity and improves
  the accuracy of the resulting plan.
• Accuracy is increased because the new plan is
  assembled from pieces of information contained in
  already existing plans, which have been tested in
  actual production. Moreover, computerization
  allows the process planner to quickly evaluate
  alternative plans.

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Variant Process Planning

• Two approaches to computer-aided process
  planning.
• The variant approach and.
• The generative approach.

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Variant Process Planning

• The most common approach is variant process
  planning, which applies group technology.
• Parts requiring similar processes are grouped
  into families, and a standard plan is created for
  each family.
• The standard plan lists the processes common to
  all parts belonging to the same family.
• When planning for a new part, the standard
  process plan for the family to which the part
  belongs is retrieved.
• Then, using a "same as-except for" technique, the
  standard plan is made specific for the part in
  question.

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Classification Coding
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Generative Process Planning

• The generative approach uses decision rules for
  the selection of processes, tools, etc.
• Based on these decision rules, the system
  generates the sequence of operations, selects the
  most suitable machine tool for the process, and
  optimizes the machining parameters.

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Generative Process Planning

• Generative process planning is just beginning to
  be implemented in practice.
• The development of better 3-D representation of
  solid objects in CAD, and advancements in
  artificial intelligence will greatly encourage
  its more universal adoption, although much work
  remains to be done on the logic of process
  planning based on 3-D representation.