What does the term "tolerances" refer to in machining?

The term "tolerances" in machining refers to the acceptable limits of variation in a physical dimension. This concept is critical in precision manufacturing, as it defines the range within which a part's dimensions can vary while still being considered acceptable for its intended function.

Tolerances are usually specified in terms of both upper and lower limits, ensuring that parts fit together correctly and function properly in assembly. For example, if a shaft is supposed to have a diameter of 1 inch with a tolerance of ±0.005 inches, the acceptable diameter ranges from 0.995 inches to 1.005 inches. This precision is vital, as too much variation could lead to a malfunctioning assembly or product.

Understanding tolerances helps machinists and engineers to ensure that the parts they produce or work with meet the necessary specifications for quality and functionality, thus allowing for mass production without compromising on performance or safety.