Flame Hardening of Gears

Flame Hardening is another method for hardening the metal surface of gear parts. The process uses a an oxyacetylene flame. The method consists of rapid heating of a thin layer at the part's surface. This is done at the critical temperature. A quenching process follows this immediately. As a result of this a thin, hardened surface is produced. The internal parts does not get affected by this and retains their original properties. However a close watch is to be kept since the torch can heat the metal very quickly irrespective of the process being manual or mechanical. The following image shows Flame hardening process for gears.

Advantages of flame hardening
Generally there are following advantages of Flame hardening of gears:

• Minimal processing time for hardening
• Good hardness
• Minimal distortion to parts
• Efficiency in production
• Increased wearability because of higher surface
• Reduction in the steps of finishing operations
• Cutting down of maintenance expenses
• Selective hardness that saves costs

Disadvantages of flame hardening
Some of the limitations of flame hardening process includes

• Distortion
• Over heating
• Excessive depth of hardening
• Excessive scaling

Material for Flame hardening
A wide range of steels and cast irons can be used in Flame hardening process, ideally medium carbon steels that has 0.35-0.5% of carbon that can haver optional alloying additions are the best for a satisfactory hardening operation.