Shrink-fitting

Shrink-fitting is a technique in which pieces of a structure are heated or cooled, employing the phenomenon of thermal expansion, to make a joint. For example, the thermal expansion of a piece of a metallic drainpipe allows a builder to fit the cooler piece to it. As the adjoined pieces reach the same temperature, the joint becomes strained and stronger.

Another example is fitting the iron strip around the edge of a cartwheel. The strip will be heated and expands to the wheel's diameter, and is fitted around it. After cooling, the iron rim contracts, binding tightly in place. A common method used in industry is the use of induction shrink fitting which refers to the use of induction heating technology to pre-heat metal components between 150˚C and 300˚C thereby causing them to expand and allow for the insertion or removal of another component. Other methods of shrink-fitting include compression shrink fitting which uses a cryogen such as liquid nitrogen to cool the insert, while heating the housing.

This technique falls under the broader category of interference fits.

See also

• Interference fit

External references

• Guideline calculations for metal shrink-fitting
• Information about compression shrink-fitting