Gear castings are also called cast steel gears. This is because most gears are made of cast steel. Here, I would like to share some information about the production of gear castings and related heat treatment. The weight of gear castings usually ranges from a few kilograms to several tons.
The gear castings are usually made of high carbon cast steel, and some of them are made of alloy steel containing chromium, nickel and molybdenum to achieve high tensile strength. Generally, large gears have lower physical requirements than small gears.
As for the casting process, the floor molding process is usually applicable and can meet the normal requirements. As for cast steel gears, such as driven gears, gears and idlers, the floor molding process using quartz sand is a good choice. Why? Because most parts of gears need to be machined. Therefore, you do not need to use a higher casting process. In addition, for medium and large steel castings, the floor molding process using quartz sand is almost the only choice.
Regarding heat treatment, of course, all steel castings must be standardized to eliminate internal pressure. Some parts of the gear casting can be welded. If the casting is welded by the foundry, the welding position must be annealed. If the hardness is very high after hobbing, you can anneal again to reduce the hardness and eliminate the internal hard spots. After machining and hobbing, gear quenching or hardening treatment is used to improve the surface hardness of gear teeth. For the pinion, you can do carburizing treatment. For large driven gears, you can do surface hardening treatment. The service life of gears without hardening treatment is very short, only a few weeks to a few months.
Because gear castings have higher requirements for materials, defects, processing and heat treatment. Moreover, the order quantity of gear castings is relatively small. As a result, many steel foundries are reluctant to manufacture.
