How to design the diameter of the inductor coil of the tungku pemanas induksi?

The shape of the inductor coil of the induction heating furnace is determined according to the surface contour of the heating part.

When heating the outer circle, the inner diameter D of the inductor = D0+2a; when heating the inner hole, the outer diameter D of the inductor = D0-2a. Where D0 is the diameter of the outer circle or inner hole of the workpiece, and a is the gap between the two. Take 1.5~3.5mm for shaft parts, 1.5~4.5mm for gear parts, and 1~2mm for inner hole parts. If medium frequency heating and quenching is carried out, the gap is slightly different. Generally, the shaft parts are 2.5~3mm, and the inner hole is 2~3mm.