How to Choose a Magnetic Yoke for an Induction Furnace
A yoke is not selected from capacity alone. Two 20 ton furnaces can need different cooling: copper tubes on one, stainless tubes on another, oriented sheet on a third.
Ask for six numbers before a price: capacity, frequency, power, coil diameter, coil height, and the number of yokes around the coil. Add the cooling the furnace water system can supply, and a photograph of the yoke that is in the furnace now.
Oriented silicon steel is the right core when the coil is curved and leakage at the joint has been a problem. A water channel or tank is the usual cooling on 12 to 70 ton shells. Copper tubes pull heat directly from the laminations. Stainless tubes are used where a welded water pocket has cracked or the cover plate has pitted.
Vacuum furnaces from 2 to 5 tons use their own yokes, often with 316L or a non-magnetic cover, because the shell and the bolts must not add stray flux.