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ComputerAided_Design_Engineering_amp_Manufactur.pdf

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FIGURE 5.19 Graphical model of the part shown in GIFTS.<br />

in Data-GIFTS, it is possible to reference the MRIR based on the machine code/number to get these<br />

details.<br />

Setup<br />

Description of a setup will be with respect to the part geometry at a given machining stage. The complexity<br />

involved in representing a setup is a factor of part type. For ex<strong>amp</strong>le, the majority of rotational parts<br />

can be machined by the between centers method (BC), chuck and center method (CC) and the chuck<br />

only method (CO). These setups can be easily represented in PPIR by referencing through codes such<br />

as BC, CC and CO.<br />

Pockets<br />

Since the actual machining starts only after the entire planning is done, it can be surmised that the<br />

material being removed in each operation (or pockets) must be known in advance. The pockets described<br />

here should be understood in the context of the machining. The role of pockets can be appreciated when<br />

machining processes are viewed as elements responsible for cutting out the volumes of material from<br />

initial stock (or semi-finished part) to produce the final shape of the product.<br />

The definition of a pocket depends upon the machining domain. Three cases of interest are shown in<br />

Figure 5.20. The pocket can be defined as the material being removed in a single operation (grooving)<br />

involving a single tool (grooving tool). However, this definition might not be convenient in other cases.<br />

For ex<strong>amp</strong>le, consider a hole-making operation that involves drilling, boring and reaming operations.<br />

Instead of representing the material being removed to produce the hole as three distinct pockets associated<br />

with three different cutting tools, it is convenient to represent it as a single pocket. Similarly, in CNC<br />

turning operation, defining the pocket as the material being removed in a single setup will facilitate easy<br />

representation of a pocket.

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