Shrink Fitting: Best When Interference Fit is Needed

There could be numerous applications that involve fitting of one component into another. One such case exists when a close interference fit is required. The conventional way of achieving is either the force fit method or to expand the outer component with heat. Although these methods are in use since long but there are many disadvantages of it. The former method can lead to mechanical damage between the two faces while the latter can cause local damage or stress due to irregular or bad heating procedures along with the utilities of heating large frames or housings.

What is Shrink Fitting?

Shrink Fitting is typically a technique in which pieces of a structure are heated or cooled, thus making the use of thermal expansion in order to make a joint. For example, the thermal expansion of a piece of a metallic drainpipe enables a builder to fit the cooler piece to it. As the joined to pieces reach the same temperature, the joint becomes strained and stronger.

A very good example of shrink fitting is the fitment of an iron strip around the edge of a cartwheel. The strip is heated to expand to the wheel's diameter. After getting it fitted, it is then cooled to make the perfect fit around the wheel. 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 150ÚC and 300ÚC 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.

Among various methods of shrink fitting, liquid nitrogen fitting is found to be the safest method as it is inert and therefore reasonably safe to use in a workshop if proper ventilation is provided. By using this method, you can ensure minimum damage because liquid nitrogen tends to cause no permanent effect on ferrous or non-ferrous metals. The major reason behind the employment of shrink fitting is that it results into minimum damage which is far better than conventional methods.  Moreover, this method is best when interference fit is required. The advantages include little or no distortions on effected parts, efficient method, convenience of on-site or off-site service, and lower costs. However, before choosing the service, do consult with an experts about a reliable and trusted service provider.

Want to know more about Shrink fitting? With over 20 years experience, Allied Pipefreezing can provide a cost effective solution to fit large or small components by interference.

Visit our website for more information on Shrink Fitting and Hot Tapping.