Gears perform the critical functions of transmitting power or carrying motion in mechanical assemblies. To perform these functions effectively, gears need to have certain properties that enable them to meet specified quality requirements.
Gear manufacturers and design engineers often designate “gear quality” based on the so-called AGMA gear-quality number. While this number provides an indication of the geometric accuracy of the gear teeth, it does not provide information on the metallurgical soundness of the gear. Therefore, the ANSI/AGMA 200 A88 Gear Classification and Inspection Handbook also provide specifications for the type of material and the heat-treatment process to be used in gear manufacture. The heat-treated gear in this study was evaluated based on its microstructure and its hardness values from the hardened surface to the softer core.