Heat Treatment of Gears
Gears are an integral component in many mechanical systems, including gear boxes, engines and other drive-train components. As such, it is important to ensure that the gear material is appropriately heat-treated for optimal performance. Heat treating is a process used to alter the physical and chemical properties of a gear in order to improve its strength, hardness, toughness, and wear resistance. In this article, the specifics of the applicable heat-treating processes, as well as their effects, are discussed.
Heat treatment begins with an initial hardening stage, where the gear is heated to an elevated temperature and then quickly cooled with either a liquid, gas or through quenching with oil. Quenching involves immersing the gear in a high temperature medium and agitating it to ensure that the entire part cools uniformly. Hardening increases the hardness and strength of the gear material by increasing the number of particle bonds in the material structure.
Following the hardening stage, the gears are subjected to the tempering process. Here, they are re-heated to a lower temperature than the original hardening stage and then slowly cooled. This helps to relieve residual stresses in the material, as well as improve its ductility. The end result is a gear with improved toughness and impact resistance but reduced hardness and strength.
Finally, the gears may be carburized or nitrided, depending on the application. Carburizing involves heating the material to a high temperature and then introducing a compound containing carbon. This process diffuses the carbon into the gear material, which increases its hardness, Wear and Corrosion resistance. Nitriding is similar in that it also involves introducing an element, in this case nitrogen, to the material surface. Nitriding increases fatigue strength and wear and corrosion resistance, making it ideal for high stress and/or contact applications.
Overall, heat treating is an important step in the gear manufacturing process, particularly for applications where superior strength, wear resistance, and toughness are of utmost importance. By understanding the types of processes available and their effects, manufacturers are able to create gears with the necessary characteristics to meet the goals of any application.
