What does the term "tolerance" refer to in CNC machining?

The term "tolerance" in CNC machining specifically refers to the allowable deviation from a specified dimension. This concept is crucial because it defines the acceptable limits of variation in a part’s size or geometry, ensuring that even if a manufactured part isn’t made to an exact dimension, it remains functional and meets performance requirements. Tolerance is essential in engineering and manufacturing, as it accounts for the inherent variability in machining processes and material properties.

For instance, if a drawing specifies a hole diameter of 10 mm with a tolerance of ±0.1 mm, this means that the actual diameter can range from 9.9 mm to 10.1 mm and still be considered acceptable. Understanding and applying tolerances ensure that parts fit together correctly and function as intended in assemblies.

Other options discuss aspects such as exact measurements, processes for achieving perfection, and time taken for machining, but these do not accurately capture the definition of tolerance, which is specifically about the permissible limits of variation in size or geometry of machined parts.