20 Ton Induction Furnace Magnetic Yoke
The 20 ton size is a useful hub because one capacity covers four real shop builds.
The oriented-steel yoke uses Nippon Steel grain-oriented sheet, arc stacked, with copper tubes two in and two out, covering about 60 percent of the coil. The copper-tube yoke leaves the solid cover off, stacks the WISCO sheet on a hydraulic fixture, and cools with two shielded copper tubes plus a copper shield near the leads, clamped by six stainless through-bolts.
The stainless-tube yoke uses the same idea with stainless tubes, so a welded water pocket is not the cooling element. Step-lap joints are used. The 20 ton silicon steel column uses dual stainless water channels and four stainless bolts, covering about 65 percent of the coil.