What does "tolerance" mean in machining?

Tolerance in machining refers to the permissible limit of variation in a manufactured dimension. It specifies how much a dimension can deviate from a desired value, ensuring that parts will fit together properly and function as intended. This concept is critical in manufacturing because precise specifications determine the quality and functionality of the finished product.

For example, if a shaft is intended to be 1 inch in diameter, a tolerance of ±0.01 inches means that the actual diameter can be between 0.99 and 1.01 inches. This minor variance still allows the components to fit together and work correctly, which is essential for the assembly and performance of mechanical systems.

Understanding tolerances is vital for machinists, as it directly impacts the manufacturing process, quality control, and the overall efficiency of production. This knowledge helps in selecting the right machining processes and ensuring that the finished parts meet both design specifications and functional requirements.