When an interference fit is required, the traditional way of fitting a component into another is either the force fit method or to expand the outer component with heat. Both these methods have disadvantages in that the former can lead to mechanical damage between the two faces and the latter can cause local damage or stress due to uneven or poor heating procedures for each application using the traditional methods, liquid nitrogen shrink fitting can invariably be used as an alternative.
Shrink fitting is a technique in which an interference fit is achieved by a relative size change after assembly. This is usually achieved by heating or cooling one component before assembly and allowing it to return to the ambient temperature after assembly, employing the phenomenon of thermal expansion to make a joint.
Shrink Fitting Method?
The shrink fitting process is the method of employing a cryogenic agent to shrink a component so that it will fit into another component easily. When the nitrogen affect components returns to ambient temperature the component will expand to its resting dimension causing a friction (interference) fit with its mating component. This process is ideal for components such as shafts, tappets, sockets, roller bearings. Any component that may require a calculated interference fit.
Liquid nitrogen shrink fitting is one of the safest methods of assembly. The components will suffer no damage. Sometimes shrink fitting is the only possibility to connect different materials, which cannot be cemented, welded or soldered.