After the high-frequency current is added to the induction coil (ie induction coil), it is converted into a high-frequency magnetic field by the principle of electromagnetic induction, and acts on the metal object in the magnetic field; the eddy current effect is used to generate the metal object in proportion to the intensity of the magnetic field Induced current, this eddy current is affected by the skin effect, the higher the frequency, the more concentrated on the surface of the metal object. When the eddy current flows in a metal object, it will use the inherent resistance value inside to generate heat using the principle of current thermal effect, and fuse the two plastic parts together to play a sealing role.