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Inductors from eldec: custom manufacturing for perfect induction heating

Induction heating is a growth sector, and for good reasons. The technique is energy efficient, reliable, reproducible, very fast and its range of possible applications is almost unlimited. For example, induction can be used on parts to heat, join, braze, harden, or even melt them. A critical component in these processes is the inductor. Its design is crucial in determining how precisely a part is heated. Complex manufacturing processes are therefore used to produce this central tool with precision to a tenth of a millimeter—a task perfectly suited to the experts at eldec, with facilities in Auburn Hills, MI USA and in Dornstetten, Germany. The technicians at these EMAG subsidiary have a thorough understanding of the different applications of induction heating. For more than 30 years, they have been developing inductors to match, which are adapted to the geometry of the workpiece with painstaking dimensional accuracy.

The crucial quality in induction heating is best summarized by the word “precision.” The technology is used anywhere where a lot of energy or heat needs to be applied to a workpiece in a very short time. Temperature accuracy plays an important role here and is often process critical – and precise heating is only possible with the right mix of inductor geometry, frequency, power, and magnetic field characteristics. Furthermore, the application of energy through induction ensures fast production processes, minimal workpiece distortion, and economical energy consumption.

The process relies both on the generator used (as the power source) and, above all, on the inductor, since the form of this tool is crucial in determining which areas of the workpiece are heated. Consequently, it should not be surprising that the inductors used are as many and varied as the corresponding parts or components. For example, eldec produces ring inductors and shaped inductors that enclose the part being heated with millimeter precision. Rod inductors sit inside the part during the process, heating the metal from the inside out. Flat inductors are also frequently used, for example, in induction brazing. They heat large areas of the part surface evenly and simultaneously.

Experience is key

“In total, we produce up to 1,000 inductors every year – and the numbers are rising,” said Stefan Tzschupke, Head of Business Development Generators at eldec. “The crucial quality that many customers put their trust in is the experience of our fitters and engineers. Inductor manufacture is a demanding process that can't be automated because it depends on so many highly precise details. When you're brazing or assembling the inductor, every move has to be right.”

eldec's customers benefit right from the start, when they present a part drawing or blank, for instance. Application engineers at eldec then propose a production process by asking and answering the following questions:

  • How is the induction process carried out in detail?
  • What sort of temperatures need to be reached and what is the power capacity of the generator?
  • And what is the shape and size of the inductor?

“Once these questions are answered, we begin designing the inductor with the aid of the latest 3D CAD software and CNC machine tools,” Tzschupke explained. “We test the end result on the real part. If the quality of the manufactured part doesn't satisfy us 100 percent, we make changes and rework the inductor, on a milling center for example. In the case of highly complex inductors, like those used for induction hardening for instance, this can be a matter of a few tenths of a millimeter.”

Currently the eldec specialists are testing new simulation software that they use to check the working of a virtual inductor model on a computer. This application will be put into practical use soon.

“That will take us to the next level,” Tzschupke said. “The users will ultimately benefit from even faster processes in development and even more precise induction processes.”

Another innovation at eldec is the use of sintering to manufacture the coils. This allows exceptionally complex inductor geometry to be produced.

A growth area for the company

Another important aspect of eldec's services is the high degree of flexibility offered in inductor design and production. Customers requiring a certain number of tools each year can enter into an agreement with eldec to produce new inductors on a just-in-time basis. Users also have the option of producing additional inductors themselves. All in all, inductor manufacture is a very important growth area for eldec. The reasons why are obvious: First, more and more companies in industries such as automobile production or aerospace are discovering the vast potential of induction heating. Increasingly complex parts are being heated, hardened, or annealed. Second, these developments call for specialized expertise in inductor manufacturing.

“eldec is ideally positioned for these developments,” Tzschupke said in conclusion. “We apply the knowledge gained from our experience to all aspects of the process, ensuring highly efficient and reliable production processes as a result.”