The welding apparatus contains an induction coil that is energised with a radio-frequency electric current.
This generates a high-frequency electromagnetic field that acts on either an electrically conductive or a ferromagnetic workpiece.
Nonmagnetic materials and electrical insulators such as plastics can be induction-welded by implanting them with metallic or ferromagnetic compounds, called susceptors, that absorb the electromagnetic energy from the induction coil, become hot, and lose their heat to the surrounding material by thermal conduction.
Induction welding of carbon fiber reinforced plastics is commonly used in the aerospace industry.
It can be a very fast process, as a lot of power can be transferred to a localised area, so the faying surfaces melt very quickly and can be pressed together to form a continuous rolling weld.
The depth that the currents, and therefore heating, penetrates from the surface is inversely proportional to the square root of the frequency.
For example, a 120 Hz AC current will cause the field to change directions 120 times a second.
When induction welding takes place, the work pieces heat up to under the melting temperature and the edges of the pieces are placed together impurities get forced out to give a solid forge weld.
[2] Induction welding is used for joining a multitude of thermoplastics and thermosetting matrix composites.
The apparatus used for induction welding processes includes a radio frequency power generator, a heating station, the work piece material, and a cooling system.
The power generator comes in either the form of solid state or vacuum tube and is used to provide an alternating current of 230-340 V or a frequency of 50–60 Hz to the system.
The capacitor matches the power generators output and the induction coil transfers energy to the piece.
When welding the coil needs to be close to the work piece to maximize the energy transfer and the work piece used during induction welding is an important key component of optimal efficiency.