Most of the gears are made of steel. This article summarizes some information about the cast gear and relevant heat treatment.
The weight of the cast gear usually ranges from a few kilograms to several tons. The material of the cast gear usually is high carbon cast steel. Some also use of chromium, nickel, molybdenum alloy steel, in order to achieve high tensile strength. Generally, the physical demand of large gear is lower than small gear.
Because most parts of the gear need to be processed, higher casting process is not required. Usually the floor forming process is applicable and can meet the normal demand. As for cast steel gear, such as driven gear and idler gear, molding process of Quartz sand floor is a good choice. In addition, molding process of quartz sand floor is almost the only choice on the medium and large steel casting .
All steel castings must be standardized to eliminate internal pressure. Some parts of the cast gear can be welded. If the casting parts are welded, the welding position must be annealed. If the gear hardness is still very high after hobbing , you can anneal again to reduce the hardness and eliminate the internal hard spots. Quenching after machining and hobbing can improve the surface hardness of gear teeth. Small gear can be carburized. Large driven gear can be treated with surface quenching. The service life of gear that has not been hardened is only a few weeks to a few months.
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