Effective Training Inc. Message Board

Profile question: If I had a block and the bottom suface was datum A. The dimension to the top of the block is 413.31 (mm) basic. The profile tolerence for the top surface is profile 2 mm to datum A.

The inspection readings for the 413.31 dimension range from 411.742 to 413.413. what is the out of tolerence condition?

I'm having a discusion with our inspection folks on this.

You don't state if it is Profile of a LINE or Profile of a SURFACE! If the only control applied to the top surface is the Profile of a Surface then the default distribution of the available 2mm of profile tolerance is bi-lateral, that is, 1mm above the true profile and 1mm below the true profile. The true profile is defined by the 413.31 basic Dim. All points on the surface must lie in the 2mm tolerance zone fixed by the basic dim and the Datum A surface. The part would have perfect form at MMC (Rule #1) at a MMC vaule of 414.31. The LMC value for the part size would be 412.31. Therefore, any Actual Local Size (when measured from a Datum A datum simulator, like a surface plate) below 412.31 or greater than 413.31 would be out of specification.