How Induction Shrink Fitting Works

Shrink fitting is a process where a size change after assembly creates an interference fit. By heating or cooling one component prior to assembly and allowing it to return to the ambient temperature after assembly, the thermal expansion creates a joint.

Shrink fitting with induction heating is ideal for your heating process, combining the precision, control, economics and safety inherent in the technology. Our Applications Laboratory, which offers free testing, has worked on this application numerous times, and you can read a number of application notes below. Check them out and be sure to contact us to discuss your shrink fitting application.

Fitting an aluminum tube; optical system

With an EASYHEAT 2 kW induction heating system, the aluminum tube heated to the required temperature within 30 seconds. Shrink fitting then took place

Shrink-fitting a gear securely on a shaft (automotive)

The customer was using a torch, which can lead to inconsistent part quality. Induction's precise heating means the client can count on consistent results in their process

Shrink-fitting an aluminum motor housing

The customer was using a cold press, but it was creating part defects. This was resolved with induction heating: the process took just two minutes compared to 40 minutes and they were able to achieve their targeted production rate. Induction's fast, precise heating means the client can count on consistent results once it is implemented into their process.

Heating a stainless steel sleeve for industrial washers

The customer currently uses electric ovens that run 24 hours a day, 5 days per week and their primary concern is to save on the energy cost of heating the parts in the ovens.

Shrinkfitting a steel mud pump liner

A twenty-turn helical coil is used to heat the chain. The chain is fed through the coil at a rate of 1 meter per minute to reach the desired 1760 °F (960 °C) for the tempering process...

Shrink fit a steel gear onto a steel gear motor shaft

A four-turn helical internal coil is used to heat the gear bore. The coil is inserted into the gear bore and power is applied for 90 seconds to reach the required 400 °F (204 °C) and expand the gear bore...

shrink-fitting a carbide ring into a valve seat

A three turn helical coil is used to heat the steel valve seat. The steel valve seat is placed in the coil and heated for 50 seconds to enlarge the center hole & drop the carbide ring in for the shrink-fitting process.

Shrink-fitting auto turbo charger impeller blades onto an aluminum shaft

Induction heating provides repeatable results, reduced cycle time, lower consumables cost and even distribution of heating

shrink-fitting aluminum pulley to insert inner bearing

A three turn helical coil is used to heat the aluminum pulley. The pulley is heated to 464 °F (240 °C) in 20 seconds to expand the inner diameter and then the inner bearing is inserted to form the completed part.

shrink-fitting an assembled wrist pin into a connecting rod

Induction heating provides more accurate control of heat vs a flame burner, it heats only the knuckle, not the whole part, it prevents discoloring due to lower temperature used and increases productivity due to repeatability & ease of operation. A foot pedal & timer is used.

shrink-fitting a cast iron rocker arm assemblies

A four-turn helical coil heats the ring at one end of the assembly. The coil is designed to concentrate the field towards the center of the assembly where the thermal mass is greatest.

Shrink fit a motor shaft and roller

Processing with induction heat saves power and time. The complete tube does not have to reach the desired temperature as it does when heating with an oven. Being able to selectively heat a zone allows for a much quicker transfer of heat.

Shrink-fitting a Camshaft Gear

Heating a camshaft gear with a bore size of 1.630 inch to shrink fit over a steel shaft that has a diameter of 1.632 inch. A temperature of 500F is required for the gear to expand 0.002 inch in order to slip over the shaft.

shrink-fitting a Fuel Pump Housing and Inserts

To heat an aluminum fuel pump housing measuring 8 x 45 x 3.5 inch to 375F, allowing steel parts to be inserted.

Shrink Fitting Cam Shaft Gears

To heat aluminum and steel camshaft gears to over 500°F within 4 minutes for a shrink fitting application.

Shrink fit a carbon graphite ring insert into an outer steel band

Induction heating provides a highly effective joint, accurate & repeatable heat, precise control of cycle times, uniform and repeatable results and hands-free heating that involves no operator skill for manufacturing