Induction heating – The Process
Induction heating is one of the unique methods of directly heating an electrical metal part by circulating electrical currents as opposed to a torch or open flame. Induction heating machine rely on the characteristics of radio frequency energy transferring heat to the part via electromagnetic waves. There are several benefits to this process. The part does not come into contact with any flame while there is no risk of contamination to the product. The inductor in the unit does not get hot. These machines work on the principle of Faraday’s Law. A solid state radio frequency power supply passes alternating current through a copper coil inductor containing the heated part. The inductor serves as the primary transformer while the heated metal part is a secondary short-circuit. The metal part that enters the magnetic field circulates eddy currents within the part. The flow of eddy currents generates localized heat without any contact made between the inductor and metal part.
Induction welding is used to soften, harden and bond metals and conductive materials. There is a variety of inducting heating machines that offer a combination of consistency, speed and control for manufacturing processes.
Factors to Consider
The efficiency of induction heating machines depends on several factors. Few factors includes the characteristics of the part, inductor design, capacity of the power supply, and precise temperature required for the application. One can use an electrically conducting object usually metals for induction welding. Plastics and other non-conductive materials requires indirect heating through a conductive metal susceptor. Magnetic materials are easier to heat through this process since they have high permeability as compared to non-magnetic materials.
Heat intensity, Power Supply and Inductor Design
Heating intensity is an important factor to consider because around 85 percent of the heating effect occurs on the surface of conductive materials.Heat intensity decreases with the increase of distance from the surface. Frequencies of 100 to 400 kHz are ideal for smaller parts, while longer heating cycles at lower frequencies are effective for deep, penetrating heat. The size of the induction power supply is often calculated by determining the amount of energy transfer needed for the work piece. This depends on specific heat of the material, its mass, and the required rise in temperature. The design of the inductor is an important aspect since the varying magnetic field required for induction develops within the inductor. The inductor provides the precise heating pattern and maximizes the efficiency of the induction heating power supply.