Maximum Material Condition (MMC) and Least Material Condition (LMC)
Maximum material condition (MMC) is used to indicate tolerance for mating parts such as a shaft and its housing. Least material condition (LMC) is used to indicate the strength of holes near edges as well as the thickness of pipes.
Indication
To apply the maximum material requirement to a certain dimension, you write after the geometric tolerance value, or, in some cases, after the datum symbol in the feature control frame. For the least material condition, you write .
- For maximum material condition
-
- a
- Tolerance allowed at maximum material size
- b
- Symbol that applies maximum material condition
- a
- Symbol that applies the maximum material condition to a datum
Advantages of Maximum Material Condition and Least Material Condition
Volume can be accurately specified with size deviation and geometric tolerance deviation, which caters to appropriate tolerance establishment. For example, using the maximum/least material condition for tolerancing shafts and bores can accurately indicate the volume of parts, which offers the benefits of reducing processing costs and improving quality.
