How to design the diameter of the inductor coil of the forno di riscaldamento a induzione?

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.