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Heat Induction

Induction Heat Treating is the process in which a part is placed inside a copper coil and heated by a high-frequency alternating current to obtain beneficial metallurgical properties. Parts can be softened or hardened by this technique, depending on your requirements. Induction heat treating is also incredibly accurate, which is especially valuable in industries that have little room for error. 


  • Gears
  • Shafts
  • Pins
  • Sprockets
  • Hubs

Common Materials treated through Induction

  • Low-Alloy Carbon Steels, e.g., 1040, 1045, 1141, 1050
  • Medium-Carbon Alloy Steels, e.g., 4140, 4142, 4340, 8640
  • Tool Steels, e.g., O1, H13
  • Ductile Iron
  • Slow-Cooled Carburized Parts
Closeup Calcining Hot Metal Steel Gear Parts In A Factory

TMT’s Equipment and Variations of Induction

There are two main types of induction equipment: single-shot machines and scanning machines. A single-shot machine will have a stationary setup with a coil matched to the desired area of the part to harden. Once the part has been heated, it’s placed into a quench tank. Single-shot induction typically requires more power, but provides more optimal results for workpieces that have complicated geometries or large changes in their diameter across the piece.

A scanning induction machine moves the part relative to the coil to progressively heat and quench the part. This type of induction is best for long parts that have large diameters, and depending on the orientation of the machine, we can control the depth of hardening in different zones of the workpiece.

TMT maintains a complement of single-shot and scanning induction machines. Additionally, we have in-house coil manufacturing capabilities to tailor the induction process to your parts.

Applications of Induction

  • Induction Heat Treating is frequently used to harden select areas of a part, such as only the teeth on a sprocket or only a certain length of a shaft. This allows for higher hardness in select areas while retaining the original properties in the rest of the part. It can also be used to selectively soften components that were previously hardened through treatment.
  • Induction Heat Treating can be tailored to harden a certain depth of material. This is often used for pins and shafts to create a hard, wear-resistant outer layer while maintaining core toughness.
  • Induction Heat Treating is very similar to flame treating and can be used to achieve very similar results.

What To Consider When Specifying for Induction

  • ​Surface Hardness
  • Areas to be Hardened
  • Material

Still have questions?

Don’t hesitate to contact us today if you have more technical questions, or if you’d like to get started with us! Our engineers have years of heat-treating experience and would be happy to answer any questions you may have.