What effect does the M modifier have on a position tolerance?

What effect does the M modifier have on a position tolerance?

• A. It ties the tolerance to the least material condition of the controlled feature.
• B. It increases the tolerance as material is added to the feature.
• C. It reduces the tolerance zone irrespective of material.
• D. It ties the tolerance to the maximum material condition of the controlled feature, modifying the tolerance zone accordingly.

Answer: (D)

The M modifier on a position tolerance ties the evaluation of true position to the feature’s Maximum Material Condition. In GD&T, MMC is the size condition where the feature contains the most material (for external features) or the least (for internal features). When a position tolerance is specified with M, the tolerance zone isn’t fixed in space; it changes in size relative to how the feature size approaches or moves away from MMC. This means the allowed positional variation adapts to the actual size of the feature, providing a compensating tolerance as material around the feature changes. That is why stating that the tolerance is tied to the maximum material condition and the tolerance zone is modified accordingly is correct. The other options describe either the least material condition or a fixed/inappropriate relationship with material, which isn’t how the M modifier works.

The M modifier on a position tolerance ties the evaluation of true position to the feature’s Maximum Material Condition. In GD&T, MMC is the size condition where the feature contains the most material (for external features) or the least (for internal features). When a position tolerance is specified with M, the tolerance zone isn’t fixed in space; it changes in size relative to how the feature size approaches or moves away from MMC. This means the allowed positional variation adapts to the actual size of the feature, providing a compensating tolerance as material around the feature changes. That is why stating that the tolerance is tied to the maximum material condition and the tolerance zone is modified accordingly is correct. The other options describe either the least material condition or a fixed/inappropriate relationship with material, which isn’t how the M modifier works.