Effective Training Inc. Message Board

Regarding Tolerance Analysis on a thermally affected part.
Stacking between two holes in the part.
I would adjust for the thermal effects on the hole sizes and the Basic dimension between the holes.
Should the Tolerance of Position (i.e. cylindrical tolerance zone) values also be altered?

Bill, I haven't done thermal compensation in a stack before, but my vote would be "yes". To justify my thinking, I think of r*alpha*dT. Then I think of a limiting case because its hard for me to think in terms of .005 inch tolerances. Imagine the two hole centerlines being 3 inches apart. Then imagine an extreme case where the TOP tolerance was DIAM 1.0 inch. To me it then becomes obvious that the TOP tolerance must be thermally adjusted, otherwise, you are only adjusting the BASIC 3.0 inch, when in reality the hole centerlines could be 4 inches apart. I would use r*alpha*dT on the 4 inch value, not the 3.0 inch value. So, I would adjust the BASIC, hole SIZE, and TOP for thermal shift. Good question. Thanks, Matt