The LMC of an external feature is which of the following?

• A. Upper limit of the dimension
• B. Mean value of the dimension
• C. Lower limit of the dimension
• D. Range of the dimension

Answer: (C)

The Least Material Condition (LMC) of an external feature refers to the condition in which an external feature contains the minimal amount of material while still being within specified limits. For external features, this means that the LMC is represented by the lower limit of the dimension.

In the context of the choices presented, the lower limit of the dimension indicates the smallest permissible size that ensures the feature can still function properly within the designed application. By adhering to this lower limit, the part is guaranteed to maintain adequate strength and fit when it is assembled with other components.

On the other hand, options such as the upper limit, mean value, or range do not correctly define the LMC for external features. The upper limit indicates the maximum allowable size, which is contrary to the concept of LMC. The mean value represents an average dimension, which does not specifically relate to material conditions, and range merely describes the difference between the upper and lower limits rather than defining the minimal material condition of the feature. Thus, LMC for external features is specifically tied to the lower limit of the dimension.