Heat Treating Carbon & Alloy Steels

When considering a material for a gear design, the most significant decision is the ease of machinability vs. the durability of the material. Most designers only look at the maximum bending strength when choosing a material. However, this only addresses the shear failure of the gear. More important to the longevity of a gear system is the surface durability of the material. The surface durability of a gear should be viewed from the perspective of the life of the gear. Surface durability determines the number of cycles a gear, under a certain load, with proper lubrication and minimized vibrations, can remain operational. If the load is exceeded, then the life will be reduced. If the lubricant is not properly maintained, the life will be reduced. Surface durability typically affects the gear in the system with the fewest number of teeth as this gear is more frequently engaged than others. In order to increase the surface durability, an appropriate heat-treatment process should be applied in order to extend the life of this gear.