Induction Heating Depth Of Penetration

Depending on the task a detailed analysis must therefore be performed in order to select the optimal generator for the induction heating task. Higher operating frequencies have a shallow skin depth while lower operating frequencies have a thicker skin depth and greater depth of penetration.

Induction Heating Principles

Skin Effect Wikipedia

Numerical Simulation Of Graphite Crucible At Different Frequency

Coupling efficiency the relationship of the current flow in the work piece and the distance between the work piece and the induction coil is key.

Induction heating depth of penetration. At two standard depths of penetration 2d eddy current density has decreased to 1e squared or 135 of the surface density. Reference or penetration depth. At a frequency of 50 hz is the effective depth of penetration from about 1 cm at 10 khz is the effective depth of penetration already less than 1 mm and at 10 mhz is the effective penetration depth only 20um steel which means that in this last frequency power actually only runs on the surface.

When deep penetration of heat is required extensive cycles of heating at low frequency are essential frequency range being 5 30 khz. Next to the inductor the frequency is one of the key criteria for the success of induction heating process. Because of this induction has a number of intrinsic trumps such as a very quick response and a good efficiency.

Induction heating formula the depth penetrated by eddy current into the material is determined by the frequency of the inductive current. Lower frequencies are suitable for a higher depth of penetration. Passing high current density big i through that shallow depth big r results in high ri2.

The closer the coil the more current in the work piece. Although eddy currents penetrate deeper than one standard depth of penetration they decrease rapidly with depth. At a frequency of 50 hz is the effective depth of penetration from about 1 cm at 10 khz is the effective depth of penetration already less than 1 mm and at 10 mhz is the effective penetration depth only 20um steel which means that in this last frequency power actually only runs on the surface.

The skin effect of heating refers to the natural tendency of the eddy currents to flow on the surface of a material thus producing heat there. Induction heating has the important characteristic that the heat is generated in the material to be heated itself. The thickness of the material measured from the surface in which 80 to 90 percent of the total heat is concentrated is called the penetration depth or the reference depth.

For current carrying layers the effective depth can be calculated as d5000 ruf. The most transfer of energy during the process of induction heating is at high frequency when the depth of current penetration is low. Induction heating also allows heating very locally.

Using high frequencies in induction heating industry mainly 10khz to 700khz implies very thin penetration depths in metals typically less than 1mm.