This hot forming steel cable application is a great fit for induction heat. For cables, there are additional factors to consider when heating with induction. If the cable was manufactured very tightly with large strands of wire, the cable may behave similar to a solid cylinder when heated; which is very efficient. However, a loosely assembled cable with small wires, will behave more like many small parts to heat. For smaller parts, higher frequency is more effective in induction heating.
In this case, the customer has a steel cable with a ferrule attached. After heating the end of the cable to approximately 2000°F (1093°C), they deform it with a hammer, which then keeps the ferrule in place. For this hot forming steel cable application, the customer wants to reduce the heating time for this process, which is currently heated with a torch. The goal of this test is to heat the end of the steel cable to 2000°F (1093°C) in a total cycle time of 90 seconds or less.
In this application we are heating above curie for the steel. Curie is the temperature where the metal’s properties change from magnetic to non-magnetic – in this case, 1390oF or 770oC. Since magnetic metals heat using induction more readily than non-magnetic metals, heating past the curie temperature affects how efficiently we can heat the metal. Post curie therefore requires more power to heat than pre curie.