Induction Hardening
Induction hardening heats selected areas of a steel part with a high-frequency electromagnetic coil and quenches them immediately, producing a hard surface on journals, gear teeth, pins and shafts while the rest stays tough and machinable.
What it is
An induction coil shaped around the area generates heat within seconds; a water or polymer spray then quenches it. Coil design, frequency and power control the hardened depth and pattern.
It is fast, repeatable and easily automated, and suits medium-carbon and alloy steels.
Typical applications
- Shaft journals and bearing seats
- Gear teeth and splines
- Pins, axles and rollers
- Crankshafts and camshafts
- Machine guideways
Suitable materials
- Medium-carbon steels (EN8, EN9, C45)
- Alloy steels (EN19, 42CrMo4)
- Ductile iron (some grades)
Points to consider
- Use medium-carbon (≥0.4% C) or alloy steels for good results.
- Specify hardened zones and depth on the drawing.
- Coil tooling is part-specific; economical for repeat parts.
- Grind after hardening for precision fits.
Frequently asked questions
What steels are suitable for induction hardening?
Medium-carbon steels like EN8, EN9 and C45, and alloy steels like EN19 and 42CrMo4.
How deep is induction hardening?
Typically around 1–5 mm, controlled by frequency, power and time.
Can induction hardening harden just part of a shaft?
Yes. It hardens only the areas under the coil, such as journals, leaving the rest soft.