What is MMC LMC in gd t

Material condition modifier of tolerance zone (ASME)

For some geometric tolerances that are applied to a size feature, you must specify a material condition modifier (according to rule no. 2MMC, LMC or RFS) for the tolerance zone. Note that the MMC and LMC modifiers add a bonus tolerance to the specified tolerance zone.

The function of the part is the primary factor in selecting the material requirement. The following table provides tips on where to specify MMC, LMC, or RFS. One of the common functions for the workpiece is assembly (i.e. the size feature is built into another size feature); therefore MMC is the most common material requirement for the tolerance zone.

Requirement

general functions

Collective requirement applies

Relative cost of production or verification

• Assembly

• Position of the non-critical variable feature

Yes

Low

• Wall thickness

• Minimum distance

• Minimal machine blank

Yes

medium

<RFS>

• middle

• Alignment

No

High

Related topics

GD&T Advisor control panel - properties of geometric control

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