Article | June 7th, 2019
Dr. Valery Rudnev – Inductoheat Inc.; Madison Heights, Mich.
Whenever someone is discussing induction heating, reference is often made to the skin-effect phenomenon, which is a fundamental property of induction heating. It can be clearly observed during billet heating (Fig. 1). Skin effect represents a nonuniform distribution of an alternating current within the workpiece cross section.
According to the skin-effect phenomenon in induction heating, eddy currents induced within the workpiece will primarily ﬂow in the surface layer (the “skin”), where a majority of all induced power will be concentrated. This layer is called the reference depth or current penetration depth, δ. The value of penetration depth varies with the square root of electrical resistivity and inversely with the square root of frequency and relative magnetic permeability.