Forged gears are manufactured by first producing a gear blank via a forging process and then subjecting it to precision machining to achieve the final product. Compared to gears formed directly through casting or machining, forged gears offer superior strength and durability, making them ideal for heavy-load, high-precision mechanical transmission systems. The primary manufacturing workflow includes raw material preparation, heating and forging, rough machining, heat treatment, and finish machining.
Raw Materials
Forged gears typically utilize alloy steel or carbon steel billets (such as 20CrMo or 42CrMo); the chosen material must possess good toughness and forgeability. Prior to production, the billets undergo inspections for chemical composition, mechanical properties, and surface defects to ensure the absence of cracks, inclusions, or porosity.
Heating and Forging
The steel billet is heated to an appropriate forging temperature (generally 1100–1250°C) to enhance plasticity for forming. Forged gears can be produced using die forging or hot extrusion processes. In die forging, the billet is gradually shaped into the gear blank profile through repeated stamping within a die, ensuring a dense and continuous grain structure at the tooth root, tip, and flank. Die forging ensures dimensional consistency and high mechanical performance for the gear blank.
Rough Machining
Following forging, the gear blank undergoes turning, milling, or boring to remove excess material and establish a precise profile prior to heat treatment. Subsequent heat treatment-which may include quenching and tempering, or carburizing-is performed to enhance the gear's hardness, strength, wear resistance, and fatigue resistance, enabling it to withstand high-load and high-speed operating conditions.
Finish Machining
After heat treatment, the gear undergoes finishing processes such as gear grinding, hobbing, or shaving to ensure that the tooth profile, pitch, coaxiality, and surface roughness meet design specifications. Finished forged gears outperform gears produced via direct machining or casting in terms of transmission efficiency, load-bearing capacity, and service life.