This is the condition when the actual mating size or envelope size is at the maximum material
condition which is maximum size for an external feature such as a cylinder and the minimum
size for an internal feature such as a hole. The symbol is m. The tolerance value specified for the
feature being controlled in the FCF applies only if the actual mating envelope is the MMC size.
If the actual mating envelope deviates from MMC an additional tolerance is allowed. The added
tolerance is the difference between the actual mating envelope size and the MMC size hence
the largest actual mating envelope named virtual condition is equal to the MMC size plus the
This is the opposite of MMC consequently this is the condition when the actual minimum mating
size or envelope is at the minimum material condition which is minimum size for an external
feature such as a cylinder and the maximum size for an internal feature such as a hole. The
symbol is l. Additional tolerance is allowed if the actual minimum envelope deviates from LMC
and is the difference between the actual mating size and the LMC size hence the smallest actual
mating size is equal to the LMC size minus the tolerance specified in the FCF for an external
feature and plus for an internal feature. The LMC symbol is used to assure a minimum amount of
machining stock for features that are to be machined and for assuring a minimum amount of wall
thickness between external and internal features. Hard gages cannot be used for inspection. An
example of position with LMS is shown in Fig. 5-10. It should be noted that the actual local size
has to meet the size tolerance however the local size does not affect the geometric characteristic
tolerance.