Taps - Tolerances

It is a reality of modern manufacturing processes that actual dimensions and target dimensions never match perfectly. Absolute manufacturing accuracy can hardly be achieved in practice and is not necessary in terms of time and cost-efficient production. However, to ensure that the fit of components is not compromised, tolerances must be adhered to. The tolerance specifies where and to what extent the workpiece may deviate from the specified drawing data.

Thread tolerance classes are identified by a number and a letter:

The degree of tolerance is indicated by a number, which in thread cutting is usually in the range between 4 and 7. This number indicates how much the actual value may deviate. In general, the smaller the number, the greater the accuracy.

The tolerance field is identified by a letter that describes where the tolerance is in relation to the nominal dimension or the zero line. For thread tolerances, a distinction is made between internal threads - designated with capital letters G or H - and external threads - designated with lower case letters e, f, g or h. The thread tolerance fields are designed so that external threads are above and internal threads are below the nominal dimension. This ensures that the screw and nut always fit correctly.