Flame Hardening Gears

Gear Flame Hardening for Various Steel Grades

The flame hardening process produces a hardened case layer on the gear in the heat affected zone. The core of the gear remains relatively unheated and ductile.

This process will provide a strong wear surface on the flame hardened area and may allow for gears to be made from less expensive alloys in cases where through hardening is not required.


All flame hardening of gears is performed on ThermTech’s fully automated flame table equipped with infrared temperature control, ensuring that the gear is fully & uniformly heated prior to quenching.

This also allows for more precise control of the hardened case depth from part to part.

ThermTech also has the ability to custom-design tooling for any flame-hardening job, especially in cases with unique part geometry. Please be aware that if this is necessary it will add 2-4 weeks depending on the exact design needed.


ThermTech offers flame hardening of gears for components up to 45” in diameter & a max weight of 2,500 lbs.

ThermTech’s flame hardening processes span a wide range of gear alloys, including the following:

  • Flame Hardening 1045 Gears
  • Flame Hardening 1060 Gears
  • Flame Hardening 4140 Gears
  • Flame Hardening 4340 Gears

Flame hardening is a good processing option for:

  • Very large gears that may be impractical to perform a whole-part quench & temper or carburizing process on.
  • Cases of very tight dimensional tolerances, as the smaller heated area may result in less distortion.
  • Cases when hardness is only required on a small segment or particular surface of the gear.

It is strongly suggested that all flame hardening jobs go through the formal quoting process to ensure all aspects of the job can be performed to customer satisfaction.

Contact ThermTech today to learn more about how our flame hardening process can benefit your gear products!