Using Induction Heating for Shrink Fitting

Shrink fitting is a process where a size change after assembly, which can be achieved with induction heating, 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. In fact, after the assembly cools, it generally cannot be separated without reheating the assembly to reverse the process. 

Typically, with shrink fitting you heat a part to roughly 300 to 500 ˚F (150 to 300 ˚C), which is enough to allow the part to expand enough to enable insertion without changing the metallurgical structure. There are a number of advantages to shrink fitting with induction heating including:

• Precise heating: Localized heating means heat is directed only where it is needed, not to the whole part, minimizing distortion.
• Rapid heating: This makes induction a great fit in a high-volume shrink fitting production process. 
• Repeatability: With induction, you can expect the same result every time. So once the process is determined, it is set and can be repeated over and over. This also makes it highly conducive to automated manufacturing processes. 
• Flameless heating: Which offers safety advantages and introduces less heat into the work environment. 

THE LAB at Ambrell has worked on numerous induction shrink fitting applications. Additionally, they offer complimentary applications testing. Check out our shrink fitting applications page to read dozens of shrink fitting application notes.