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3. GROUP TECHNOLOGYGroup technology is a manufacturing philosopwhich similar parts are identified and groupedtogether to take advantage of their similaritiesdesign, production planning and manufacturin

3.1 Core of Group Technologya) Coding and Classification of "Mechanical" Com

Code representationObjective: to form a compact and descriptiveformat that can effectively separate parts intodifferent families. The code needs to be shoease of use, and contains enough detailedinformation of a part.Grouping and Classification of PartsA separation process in which parts are sepainto groups based upon the existence or absof characteristic attributes.Objective: to determine the number of total pfamilies, and to define the members of eachfamily.


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Planning:The GT approach arranges production equiinto machine groups, or cells, to facilitate woflow. Higher efficiencies of material flow, invcontrol, production planning, etc. can be ach

shorter material flow pathsa simpler control problems (divide & con10,000 parts, 50 families)

ManufacturingGT allows efficient manufacturing equipment developed. Special purpose tools and fixturesgroup (family) of parts have greater productivi

reduce set-up timeincrease productivity

Assignment 1:Read Chapters 1 and (3) of Chang et al BookRead Chapters 1 and 2 of Bedworth's Book.Problem 3.3 and 3.5 of Chang's Book.


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3.3 Part-Family FormationPart families are loosely defined, no rigid rube applied to the formation of the GT familiA General Rule - all parts in a family must brelated.- For Design: parts sharing primary shape functions, and only being different at deta- For production-flow: parts requiring similamanufacturing processes.

3.3.1 "Coding" of Production ProcessOP code- a series of operations on one maand/or workstation.It is used to represent a logical group of opeon a machine, not necessarily include alloperations required on the machine for acomponent.Operation Plan- operations represented byOP code.

Representation of components and their requoperations


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M E C H 411 Organization of Production ProcessZ. Dong

4. Introduction to Process Planning4.1. A General Definition:

Process planning is the function that determines which manufactuparameters are to be used to convert p part from its initial raw materiaspecified in the design drawing.

4.2. Types of Process Planning MethodManual Process Plan Generation - process plan generation

experienced process planner, based upon his knowledge processes, machinability data handbooks, and existing similar

Computer-Aided Process Planning Systems- Variant Type - etrieving existing process plans based on the sim

part to be planned and the stored part with a known process pThe stored standard process plans were manually generatmechanical components,and were stored with their part famil

- Generative Ty pe - a computer system that synthesizes process into create a process plan for a new design automaticallintervention. The process planner's decision making procecapturing and encoding manufacturing knowledge, and by knusing decision logic tools (decision tree, decision table).

4.3 Outcome of Process Planninga list of manufacturing operations (machining, heat treatment, surface tretc.) and a route of the partmachine and tool selection for each operation


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4.4 Knowledge Required for Process Plan Generationability to interpret an engineering drawingfamiliarity with manufacturing processes and practicefamiliarity with tooling and fixturesknow what resources are available in the shopknow how to use reference books, such as machinability data handbooksability to do computations on machining time and costfamiliarity with the raw materialsknow the relative costs of processes, toolings, and raw materials

4.5 Procedure for Process Plan GenerationStudy the overall shape of the part. Use this information to classify the partand determine the type of workstation needed.Thoroughly study the drawing. Try to identify all manufacturing featuresand notes.Determine the best raw material shape to use if raw stock is not given.Identify datum surfaces. Use information on datum surfaces to determimethe setups.--Select machines for each setup.Determine the rough sequence of operations necessary to create all thefeatures for each setup.Sequence the operations determined in the previous step. Check whetherthere is any interference or dependency between operations. Use this infor-mation to modify the sequence or operations.Selecta or each operation. Try to use the same tool for several opera-tions if possible. Keep in mind the trade-off on tool-change time and esti-mated machining time.Select or design fixtures for each setup.Evaluate the plan generated thus far and make necessary modifications.Select cutting parameters for each operation.Prepare the final process-plan document.

4.6 An Example Process PlanOPERATIONSHEET (ProcessPlan)

pan N ~ .55 76 - 6 ~ ~ ~ ~ ~ ia s t I t a n 9 1 b / ~ ~part N~~~ Ecccn t oG StCOlP- HalfOrig. ChangesChecked Approved


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