Magnetic Flux Concentrators

Magnetic flux concentrators (also called flux intensifiers, diverters, or controllers) are made from high- permeability, low-power-loss materials.
They are routinely used in induction heat treating applications (Fig. 1) in a manner similar to that of mag- netic cores in power transformers.
There are three traditional functions of flux concentrators in induction hardening: (a) providing a selective heating of certain areas of the work- piece; (b) improving the electrical ef- ficiency of the induction coil; and (c) acting as an electromagnetic shield to prevent the undesirable heating of ad- jacent regions.1 In some cases, mag- netic flux concentrators are credited with turning a seemingly impossible development task into a fairly rea- sonable one. This article presents basic informa- tion about magnetic flux concentra- tors and concentrator materials, and provides design and selection guide- lines for their use in induction heat treating.