Dimensional changes after Heat treat

[brudje]

I am curious how you guys handle the dimensional differences before and after heat treating on your drawings. Do you build in the shrink factor,do you inspect the components before heat treat ,or do you call out a before and after heat treat dimensional specification?????

Thanks in advance...

 

[swall]

The given dimensions on an engineering drawing are for the finished part after heat treating (and all other manufacturing operations). How you get there is described in the manufacturing routing sheet/process sheet. The manufacturing experience learned from trial and error tells you what those processing steps have to be, whether they imvolve rough machine, heat treat, finish machine, etc. If you are working with a forging or casting, then you will also have drawings for the semi-finished part.

 

[brudje]

Thanks for the input. That is the exact issue...
I am of the same mind set, the finished print should be to finished dimensions.
We have a couple of inspection steps in the route and do produce semi-finished parts, so where you choose to inspect in the process can effect the pass/fail criteria for a part, but not necessarily the assembly.
The "shrink" does not effect Form, fit, or function, and we haven't had any issues over the last few years, but as we try to limit inspection steps and simplify the inspection criteria, this issue came to light.