What is the permissible variation of manufactured or machined dimensions called?

The permissible variation of manufactured or machined dimensions is referred to as tolerance. Tolerance is a critical concept in engineering and manufacturing, as it defines the acceptable limits of variation in a dimension or measurement. This ensures that parts fit and function together correctly within specified limits, allowing for practical assembly and operational performance.

A tolerance specifies the range between the maximum and minimum acceptable dimensions of a part. For instance, if a hole is specified to be 10 mm in diameter with a tolerance of ±0.1 mm, this means the actual hole can be anywhere from 9.9 mm to 10.1 mm in diameter. Establishing tolerances is essential for ensuring that parts interchangeably fit together in assemblies, which is vital for maintaining quality and functionality in mechanical designs.

Understanding tolerances helps engineers and designers communicate how closely a manufactured part must adhere to the ideal dimensions. It plays a crucial role in the design process, affecting costs, manufacturability, and performance of the final product.