Figure 1. Typical flame-hardening arrangement (Photograph courtesy of Metals Engineering)

We have a possible interest in doing flame hardening on the end of a 52100 shaft. Who does this type of work?

Flame hardening (Fig. 1) can be used for both small and large parts by either spinning or by a progressive heating technique. In the progressive heating method, the flames gradually heat the part in front of the flame head, and sometimes this effect must be compensated for by gradually increasing the speed of travel or by pre-cooling. A wide range of materials can be hardened by this technique, including plain-carbon steels, carburizing grades, cast irons and certain stainless grades.

The principle operating variables are: rate of travel of the flame head or work; flame velocity and oxygen-fuel ratios; distance from the inner flame cone or gas burner to the work surface; and the type, volume and angle of quench. The success of many flame-hardening operations for small production runs is dependent on the skill of the operators. For high-volume work, modern controls simplify the task.

Here are some commercial heat-treating companies who do flame hardening (in alphabetical order). They will have the "hands-on" practical experience to help you further.

1. Chicago Flame Hardening, East Chicago, Ind. Contact: John Farnsworth (tel: 219-397-6475, e-mail:

2. Metals Engineering, Green Bay, Wis. Contact: Ted Kemen (tel: 920-437-7686, e-mail:

3. PennaFlame, Zelienople, Pa. Contact: James Orr (tel: 724-452-8750, e-mail:

4. Precision Flame Hardening, Cleveland, Tenn. Contact: Jim Hughes (tel: 423-479-1608, e-mail: