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Induction Coil Design & Frequency Selection for Heating Applications

Induction coil design

Induction coil design has a major impact on process efficiency and final part quality, and the best coil design for your product largely depends on your application. Certain coil designs tend to work best with specific applications, and a less than optimal coil-application pairing can result in slow or irregular heating, higher defect rates, and lower quality products.

Before designing your induction coil, consider these three factors along with your induction application:

  1. Part motion relative to coil - Several applications rely on part movement with the help of conveyors, turntables, or robots. A properly designed induction coil incorporates these individual handling requirements without the loss of heating efficiency.

  2. Frequency - Higher frequencies are used for applications like brazing, soldering, annealing or heat treating, where surface heating is desired. Lower frequencies are preferred for applications requiring through-heating of the parts to the core like forging and die heating.

  3. Powder-density requirements - Higher power densities are required for short cycle heating applications requiring high temperatures. Higher power densities may also be required to keep the hot zone confined to a small area, reducing the heat affected area.

coil shapes & frequencies used with different applications?

Application

Best Types of Induction Coils

Frequency

Annealing

  • Simple solenoid coils (single- & multi-turn)
  • Multiple position helical coils
  • Pancake coils, transverse flux coils
  • Channel coils

HIGH

Bonding

  • Simple solenoid coils (single- & multi-turn)
  • Multiple position helical coils
  • Pancake coils, transverse flux coils

HIGH

Brazing

  • Simple solenoid coils (single- & multi-turn)
  • Contoured coils to match the shape of the part being heated
  • Channel coils

HIGH

Curing

  • Simple solenoid coils (single- & multi-turn)
  • Multiple position helical coils
  • Pancake coils, transverse flux coils

MEDIUM

Forging

  • Simple solenoid coils (single- & multi-turn)
  • Multiple position helical coils

LOW

Hardening

  • Simple solenoid coils (single- & multi-turn)
  • Multiple position helical coils

LOW

Heat treating

  • Simple solenoid coils (single- & multi-turn)

HIGH

Melting

  • Multi turn helical coils, heaving parallel water and electric paths

LOW

Progressive hardening

  • Simple solenoid coils (single- & multi-turn)

LOW

Shrink-fitting

  • Pancake coils, transverse flux coils
  • Channel coils

MEDIUM

Soldering

  • Simple solenoid coils (single- & multi-turn)
  • Contoured coils to match the shape of the part being heated
  • Channel coils

HIGH

Tempering

  • Simple solenoid coils (single- & multi-turn)
  • Multiple position helical coils
  • Internal bore coils for internal diameter heating
  • Channel coils

LOW

Designing an induction coil for your application

Start with understanding where the heat needs to be generated in the part to perform the process, and then design the coil to achieve the heating effect. Similarly, frequency selection will depend on the induction heating application you’ll be using for your part.

Want to learn more? If you’d like to get an experienced set of eyes on your induction application, our team is available for consultation. Contact us here!

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