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Thread: Maximum Material Boundary Condition Interpretation

  1. #1
    Associate Engineer
    Join Date
    May 2022

    Maximum Material Boundary Condition Interpretation

    Can someone explain the implication of the MMB modifier on datum C for the hole position? I'm trying to understand what is restricted or gained by using the MMB vs not. I've seen examples with holes/pins, but not with a center plane setup. Size tolerance: +/- .005.

    Maximum Material Boundary.pdf

  2. #2
    Technical Fellow Kelly_Bramble's Avatar
    Join Date
    Feb 2011
    Bold Springs, GA
    In this example as datum C diverges from MMB size (largest to smallest) the referenced part feature (2X holes) are allowed to shift more left or right.

    Alternatively, the hole feature position is allowed more left and right tolerance variability as the datum feature C decreases in size from MMB toward LMB.

    Think of the datum simulator "C" as a fixed boundary of that being two vertical planes at a separation of nominal size + tolerance + geometric tolerance and the as-built part can shift within (left and right with respect the the drawing view given) depending of datum "C" divergence from MMB size.


    ( 2.000 + unstated tolerance for MMC) + .010 = separation = virtual condition of datum feature "C".
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