Die hardening with induction
It’s a well-known fact that all dies used in the automotive industry have to be hardened. It’s also well known that traditional gas heating is slow, difficult and inefficient. But there is another way. Alessandro Mariani of EFD Induction Italy discusses the technology—and the benefits—of induction hardening. Surface hardening of dies is essential, not only when producing new dies, but also following repair welding. However, traditional hardening methods—which use gas flames as the heat source—are notoriously slow, costly and difficult.
The drawbacks of gas flames affect virtually every aspect of the hardening process. Controllability, for example, is limited. It is difficult to maintain the correct temperatures, and to deliver the heat to just those parts that require heating. And, of course, it is practically impossible to repeat the heating process accurately. With gas heating, the flames obscure the heating zones, making it impossible for operators to get a clear view. Also, gas flames produce toxic gases, and by raising the ambient temperature, make the working environment uncomfortable—and less productive.
So what can be done? One solution is to modify an EFD Induction Minac 18 converter, and harden the dies with induction heating. This method provides all the benefits associated with induction: quick heating, precise heat delivery, accurate repeatability, minimal deformation, comfortable working environment, visible heating zones, fast pre-heating for repair welding, etc. But using a Minac 18 brings other benefits. Mobility is one of them. Using a special carriage, the Minac, together with its chiller and external control unit (ECU), can be moved within, and between, workshops and factories. This allows in-situ repairs, and means an end to the costly and difficult problem of moving large dies. The Minac is easy to use, too. The operator need only glance at an LED display to ensure the heat in the workpiece is correct. To maximize efficiency, the coils—the component that actually delivers the heat to the workpiece—can be customized for specific dies. And since coils always remain cold, they can easily and quickly be changed, thus allowing the operator to treat different dies with minimal disruption.