Induction Sealing Principles
At the heart of this process lies the technology of induction heating. Induction heating is a long established non-contact means of heating up a metal component (the workpiece) which uses electromagnetism to generate the heat from within the workpiece itself. By introducing a metal object into the electromagnetic field it is possible to raise its temperature by several hundred degrees Celsius in less than a second without any direct contact. The electromagnetic field induces eddy currents to form in the workpiece which having no means of being earthed or otherwise transferred, rapidly generate heat due to the resistance of the material.
This is a very similar principle to that upon which an electrical transformer works, except that where the secondary winding is normally connected to a load, in the case of induction heating the workpiece takes the place of the secondary winding and is in fact a dead-short. In addition, frequencies for induction sealing are typically higher, normally being in the range of 40kHz to 120kHz.