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To shrink or not to shrink... (was to draft or not to draft..)

MarkRafn
1-Newbie

To shrink or not to shrink... (was to draft or not to draft..)

ok, we've answered the draft or not to draft question... what about
adding the shrinkage?
tia
-mark
3 REPLIES 3

NEVER !

Let the tool maker take that into account in their CAM software. That's their area of expertise.
They can control the X,Y,Z shrinkage properly as long as they know that material being molded.

Bob

No. You give them the exact data you want. They are responsible fro
the shrink factor based on the material chosen.

Doug Schaefer
--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn

Go wild, as long as you are ready to take responsibility for the end
result.

The master is not black magic, it's simply shrinkage factors.

I have done it and it has worked out great, but make sure you understand
the whole process and have folks you can work with.



We have saved a decent amount on tooling by using Pro to make the
complete drafted solid model, a CAM package to mill the master, a local
shop to make the pattern, the foundry concentrated on the mold -
everybody working within their areas of knowledge.

You have to account for all the shrinkages involved in the process -
work closely with a good foundry and a good pattern maker, let them tell
you the shrinkages to apply.



I modeled the part to finished dimensions, then added a Warp feature
(easy and powerful) driven by a relation to account for the shrinkage.

Then I made it a family table so I could have both states with minimal
pain.



Bear in mind the design of the part, inconsistent wall thicknesses, poor
symmetries around the CG all have an adverse effect the end result.

If you deal with a metal that needs tempering, have fun!

For really complex or tight tolerance stuff, you may need more than Warp
to account for local distortions, etc.



The mold would be another thing entirely, and that I would not recommend
if you wanted to get it right your first time out.



Regards,

Walt Weiss




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