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Inspecting Draft

Inspecting Draft

Inspecting Draft

Hello Everyone,
Hoping someone can answer a question for me. I am a quality engineer at a plastic injection molding/manufacturing company. I am working on an inspection plan for a new part. There are several features that have draft amount specified on the drawing. Normally, if the amount of draft is not specified, the rule of thumb would be that the size must stay within the given tolerance throughout the length of the feature. With the draft specified for this feature, the size at the base of the cylinder is greater than the upper spec limit called out at the top of the cylinder. My question is, how do I properly tolerance the size at the base of the cylinder? Would I apply the same tolerance given for the feature of size? Thank you all for your help!

RE: Inspecting Draft

Seems like it should be 5.99 +/- 0.03

RE: Inspecting Draft

The diameter is checked at the top and the draft angle is inspected to be 0 degrees to 0.5 degrees.

One would not normally inspect the diameter at the base as it is affected by both the diameter at the top and the draft angle. You could calculate a do-not-exceed diameter based on how tall the feature is (you haven't shown that) but if the diameter at the top is at the small end, that do-not-exceed diameter could result from too much draft angle - which puts you back to measuring the draft angle anyway.

For example, it looks like the part was modeled with the 0.5 degrees of angle to produce a base diameter of 5.99 when the top diameter is 5.85; one could add the 0.03 to it to make a base diameter of 6.02 when the top diameter is 5.88, but if the top diameter is only 5.82 (from the -0.03 tolerance) then 6.02 would correspond to a draft that exceeds the draft tolerance.

RE: Inspecting Draft

Thank you both so much!

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