10.01.2013 Views

ComputerAided_Design_Engineering_amp_Manufactur.pdf

ComputerAided_Design_Engineering_amp_Manufactur.pdf

ComputerAided_Design_Engineering_amp_Manufactur.pdf

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

algorithms. (Some details of the product structures utilized for feature storage are given in Section 5.4:<br />

Decision Tables.)<br />

Planning for Cylindrical Surfaces<br />

Cylindrical surfaces are characterized by the operations that are carried out in lathes and turning centers.<br />

Some internal cylindrical operations can also be carried out in milling machines or machining centers.<br />

The achievable accuracies and surface finishes are given in Figures 5.22 and 5.23 for the external and<br />

internal cylindrical surfaces, respectively. While showing the lower limits of the process capability, these<br />

figures also show the possible sequence of operations to arrive at the required specifications. For ex<strong>amp</strong>le,<br />

to achieve an accuracy of IT grade 7 and surface finish of 0.63 �m, the possible sequences are<br />

Rough turning Rough turning<br />

Semifinish turning Semifinish turning<br />

Finish turning Rough grinding<br />

These could therefore act as a guide to selecting the operations. The given charts can be converted into<br />

the form of process capability tables and suitable algorithms could be developed for the process selection<br />

method.<br />

A major part of the reasoning that a planner does in the early stages of planning has to do with the<br />

selection of processes. The approach in GIFTS consists of three steps: (1) considering the finished part<br />

and the raw material, (2) constructing the material to be removed from the raw material to arrive at the<br />

FIGURE 5.22 Achievable lower limits of accuracies and surface finishes based on routing for external cylindrical<br />

surfaces.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!