In the case of large gear wheels, the optimum solution in terms of process time and heating power is to heat each tooth locally using a specially shaped inductor. The wheel in this solution is placed on a pitching machine which ensures the alignment of the teeth with respect to the inductor. This method is time consuming and problematic for small size wheels.

In order to optimise the hardening of small gears a heating process is used which consists of placing the whole gear inside the shaker. However, in this case, due to the skin effect, the high-frequency currents would only heat the outer part of the teeth, while the inner part closer to the center of the wheel would remain cooler. Conversely, if the heater were operated at a lower frequency, the entire wheel teeth would be heated, not just the edges. In order to eliminate this problem and optimize the heating process, dual-frequency heating is used, which is a process in which two frequencies take part in heating at the same time, in an optimally selected proportion.

The above solution allows to optimize gearwheel heating process, however it requires the use of technologically complicated induction heaters. EnergoEl has its own solution of this type, which can be manufactured to individual order.