Positional Tolerances

This a fun exercise more than anything else. Do positional tolerances really allow more error than ±? This will give you a sense of perspective when calling up these tolerances.

PositionalTol.pdf (260.8 KB)


What is the meaning of MMC and MMB?

MMC is Maximum Material Condition. MMB is maximum material boundary. The term MMC is used systematically in ASME Y14.5M-1994. MMB is used systematically in ASME Y14.5-2009. Both terms are used in ASME Y14.5-2018. I am not absolutely sure, but I think MMB is used on FOS datums, and MMC is use on everything else.

Thank you RevDesigner. I would never have guessed in a million years.