Passungsmaße

Passungsmaße, in German, translates to "fit dimensions" or "allowances" in English and refers to the controlled differences in dimensions between mating parts that determine the type of fit. These fits are crucial in mechanical engineering for ensuring proper function, interchangeability, and ease of assembly of components.

The system of fits is based on the concept of tolerance, which is the permissible variation in a dimension. Two types of tolerances are considered: the tolerance of the hole and the tolerance of the shaft. The relationship between these tolerances defines the nature of the fit.

There are three fundamental types of fits: clearance fits, transition fits, and interference fits. A clearance fit occurs when the hole is always larger than the shaft, allowing for free movement. A transition fit can result in either a slight clearance or a slight interference, depending on the actual dimensions within their respective tolerances. An interference fit occurs when the shaft is always larger than the hole, requiring force to assemble and creating a tight, permanent connection.

Passungsmaße are typically specified using standardized notation, such as ISO standards, which define specific tolerance zones for holes and shafts. This standardization ensures that parts manufactured by different entities can be reliably assembled. The selection of the appropriate Passungsmaß is critical for the performance and longevity of the assembled product.