What are machining tolerances?

In machining, the tolerance is the deviation from the value of the cut. As such, it is related to accuracy, but it is a value specified by the customer, not a property of the machine itself.

If the customer requires a feature of the part to be very consistent from cell to cell, they will set tight tolerances on that feature to allow for minimal deviation. In practice, this means that the machine must be operated more slowly and carefully.

If more lenient tolerances are specified - for example on non-machined features - the machining can be done faster.

Although the tolerances are defined by the customer, the machine usually specifies its standard tolerances and minimum possible tolerances.