Timothy Miller of Spirit Ironworks shows how to use a induction heater to heat metal extremely quickly.
Here’s a great explainer on how these thingies work, but here are the basics:
Induction heating is a non-contact process which uses the principle of electromagnetic induction to produce heat in a workpiece. By placing a conductive material into a strong alternating magnetic field, electric current is made to flow in the material, thereby causing Joule heating. In magnetic materials, further heat is generated below the Curie point due to hysteresis losses. The generated current is predominantly in the surface layer, the depth of this layer being dictated by the frequency of the alternating field and the permeability of the material.
• Induction Heater and Power Hammer Action at Spirit Ironworks (YouTube / Timothy Miller)