Joining gearwheels

Induction heating: temperature is critical for shrink fitting

A German OEM relies on EMAG eldec technology for shrink fitting gearwheels: Inductors made with high precision ensure that the required joining temperature is reached in the part before shrinking.

Shrink fitting: induction ensures process reliability

Precise, reliable, and fast – the enormous advantages of shrink-fitting when installing complex components are utilized in many industries. Such as the automotive industry: One German OEM uses the process to reliably shrink-fit gearwheels onto a transmission shaft. Shrink fitting takes place as part of an automated production process: Initially, the gearwheel is heated by induction to about 155 degrees Celsius, expanding the inside diameter. Next, a gripper quickly and precisely positions the heated gearwheel on the transmission shaft. The gearwheel shrinks as it cools down, creating a firm bond with the transmission shaft.

The team from EMAG eldec is responsible for the induction heating of the gearwheel, which is done in as little as 15 seconds. Designing the inductor for the gearwheel did admittedly present challenges for the EMAG eldec experts. They carried out simulation and testing to define the final shape. Now the inductor not only satisfies the geometric requirements exactly, it also reaches into the center bore of the gearwheel. This means the heat flows through the gearwheel in an ideal manner.    

The heat spreads evenly throughout the gearwheel, even in the inside bore. In addition, the tests showed that no structural changes occur in the component. This is also thanks to the MF generator from EMAG eldec. It controls the flow of energy precisely and efficiently. Moreover, a robust rectifier, inverter modules, and resonant-circuit components ensure reliability – which is an important prerequisite for quality in the automated joining of high-volume transmission components, because the stability of the entire production process is also critically dependent on the stability of the generator.

Joining gearwheels


  • Temperature reached in just 15 seconds
  • High repeatability for shrink fitting
  • Even heat build-up in the gearwheel
  • Precisely controlled application of energy
  • Minimal energy consumption


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