Passungsmaß

Passungsmaß, also known as allowance or interference, is a crucial concept in mechanical engineering and manufacturing that describes the intentional difference in size between two mating parts, typically a shaft and a hole. This difference determines how the two parts fit together. A positive passungsmaß, often referred to as clearance, means the hole is larger than the shaft, allowing for easy assembly and movement. The size of the clearance is important for applications requiring rotational or sliding motion, such as bearings or pistons.

Conversely, a negative passungsmaß, known as interference, indicates that the shaft is larger than the hole. This results in a press fit or shrink fit, where the parts are forced together, creating a strong and rigid connection. Interference fits are used when high strength and stability are required, such as in assembling gears onto shafts or fitting wheels onto axles. The magnitude of the interference dictates the force needed for assembly and the resulting strength of the joint.

The concept of passungsmaß is often expressed using a system of fits, which specifies a range of allowable sizes for both the hole and the shaft. This system ensures interchangeability of parts and predictable assembly outcomes. Accurate control of passungsmaß during manufacturing is essential to achieve the desired functional characteristics of the assembled components, preventing issues like excessive wear, loose connections, or difficulty in assembly.