3D model - control drawings

Hi group,

I have a question for the plastics oriented people in the group.

For years, we've been doing business with a select few local mold houses. We
know these vendors real well, and they know what we expect from them. What
we usually do is supply them with a 3D model and a control drawing that
shows critical dimensions and tolerances. This arrangement has worked out
pretty well, in most cases.

We now find ourselves in a client driven situation where we need to specify
an overall tolerance, relative to the model, for those features that aren't
specified in the control document. The parts may be freeform shapes and
would require a 3 axis CMM to measure.

Have any of you had to deal with a similar problem ?? If so, how did you
solve it ?

Regards

Mark

 

It sounds like the customer is asking you to tolerance their part/drawing.
Can you put that responsibility back on them?

Ken B.

 

If the design concern is that parts must fit together, namely your plastics
along with their freeform shapes, you may be able to use a go/nogo
inspection procedure. Your plastic parts would be checked as fitting a
sample supplied by your client. This could be a "dumbed down" piece that
concentrates on the shapes involved rather that color, etc. The molder
would check his parts against these "gauges" to within an acceptable level
of deviation... such as holes must line up within ".xxx" or visible seam in
this area not to exceed ".xxx" etc.

I've done this many times to overcome issues of having manufactured parts
fitting sculpted or "freeform" parts as you stated.

- Eddy