The only time I modeled something that needed to be coated and paint would
be too thick, I plated the parts. So, to answer your question, I have never
modeled paint since I am generally not concerned with that thickness in
areas that I have to protect.
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I've never done that, but if it will effect assembly of the parts, its
not a bad idea.
If you need to be extremely anal about it, there are a few ways you
could actually do it:
- create a configuration that uses a different thickness (not a great idea)
- create offset surfaces around the mating faces. I would make these
faces a different color so you understand that they are due to a
finishing operation, not the real thickness of the metal itself
- just make distance mates in the assembly instead of coincident, and
check for clearance instead of interference.
On the part drawing, I would just call it out with a note.
It mainly depends on how critical your fits are. You may also be able to
specify some masked areas on the part which do not get painted for
assembly tolerance reasons.
Model the part to nominal and Dimension for Fit.
For example if you have a 4in part and it is going to have .01 paint on
it you may want your dimension to be 4 -.02/-.03 to make sure your part
As mentioned, dimension for fit, but also design for manufacturability.
Sheet metal form/fit tolerances (outside of stamping) are often +/-.03"
or greater, depending on metal thickness and machine capabilities. If
you design with this in mind paint can be a non-issue. Keep in mind
also the tolerances of structural and extruded parts the sheet metal is
fitting with too. Your sheet metal parts may also be flexible, which
can overcome some of the tolerance stack-up issues.
At our facility, we use an insert gauge of .0175 and with the paint it
brings the thickness to .019. We design everything at the .019 since
that is the finished size. We don't add a paint thickness to the model
as a seperate feature.
I handle that by specifying the following in the notes:
"All dimensions apply after the application of all finishes."
This seems to work well. The vendor knows how much thickness the paint
adds and they can compensate when they layout the part.
If you make your sheetmetal parts internally, then it puts the onus on
the shop foreman.
If you are the shop foreman, then my comments may not be much help.
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