Press-fits are a simple and cost effective means to connect two parts. A
press-fit is usually applied to connect a hub to a solid or hollow shaft, or
to fix a bush in its housing. Interference between the two parts supplies the
required pre-stress to enable the connection to transmit an axial force or a
torque. The hub and the shaft may both be of plastic, but a combination of
plastic and metal is also possible. If different materials are used, attention
must be paid to differences in thermal expansion, which may cause loosening of
the connection or too high stresses.