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ComputerAided_Design_Engineering_amp_Manufactur.pdf

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5.1 Introduction<br />

Developments in the information age have caused the use of computers to spread rapidly throughout<br />

the manufacturing arena. With the cost of computing going to ever low levels and increases in its capability<br />

going by leaps and bounds, the use of computers has become increasingly important to the manufacturing<br />

industries. To this extent, great strides are taking place in the use of computers in design and manufacturing<br />

worldwide.<br />

A process planning function establishes the methods and means of converting raw material to a finished<br />

part. Thus process planning logically forms a link between the design and manufacturing functions.<br />

Computer-aided process planning (CAPP) is the application of computers to assist process planners in<br />

the planning function. In this chapter a brief presentation is made of the technologies involved in<br />

developing a CAPP system for rotational parts, along with a case study of GIFTS—a generative, interactive,<br />

feature-based, and technology-oriented system.<br />

5.2 Process Planning<br />

A process is a method by which products can be manufactured from raw materials. Process engineering<br />

takes place directly after product engineering has completed the design of a product. From the information<br />

received, it creates the plan of manufacture. Process planning is, then, the function of determining<br />

exactly how a product will be made to satisfy the requirements specified at the most economical<br />

cost.<br />

The importance of a good process plan cannot be over emphasized, particularly for mass production.<br />

A few minutes used to correct an error during process planning can save large costs that would be required<br />

to alter the tooling or build new tooling. The process plan created must permit the manufacture of a<br />

quality product at the lowest possible cost.<br />

The output from the process planning function can be itemized as follows:<br />

1. To determine and select the equipment needed to manufacture the part<br />

2. To determine the order or sequence of operations necessary to manufacture in terms of operation<br />

routing, process details and process pictures<br />

3. To specify production tolerances on blanks and on auxiliary surfaces<br />

4. To specify the process parameters for the various manufacturing operations selected<br />

5. Providing the necessary documentation to be used by the shop people.<br />

A typical process plan is shown below with the corresponding part shown in Figure 5.1.<br />

Op. No.<br />

Operation Tools Used<br />

10 Turning to length and facing the ends Facing tool, chuck<br />

20 Make the center hole Chuck, center drill<br />

30 Rough turning of �20<br />

diameter Rough turning tool<br />

40 Finish turning of �20<br />

diameter Finish turning tool<br />

50 Forming the radius at one end Form tool (radius turning)<br />

60 Diamond knurling of the handle Knurling tool<br />

70 Reverse the part in the chuck and rough turn to �10<br />

Rough turning tool<br />

80 Finish turning of �10<br />

size Finish turning tool<br />

90 Make the 3 mm radius groove Form tool<br />

100 Rough turning of �14<br />

diameter Rough turning tool<br />

110 Finish turning of �14<br />

diameter Finish turning tool<br />

120 Cutting the external threads M14 Thread cutting tool

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