Gearmaterial

Gearmaterial refers to the material composition of gears, selected to withstand loads, speeds, temperatures, and environmental conditions encountered in mechanical systems. The choice influences strength, wear resistance, noise, weight, and manufacturability.

Metal gears are common, with steels offering high strength and toughness. Through-hardening bearing steels such as 8620 or 4140 are used for internal gears, while case-hardening steels provide a hard surface and tougher core. Cast irons, including gray and ductile grades, are economical options for low- to medium-load gears. Bronze and other copper alloys are favored for worm gears because of good embeddability and self-lubricating properties.

Engineering plastics like acetal (POM), nylon (PA), and PEEK are used for light- to medium-load gears, often in quiet-running or corrosion-sensitive applications. Polymers offer low weight and self-lubricating surfaces but lower strength and temperature limits than metals; thus they are typically not used for high-torque or high-temperature environments.

Ceramic gears made from silicon nitride or zirconia provide very high hardness and wear resistance at high speeds and temperatures, but are brittle and costly. Composite gears, such as fiber-reinforced polymers or metal-matrix composites, aim to combine low weight with improved stiffness and wear resistance.

Manufacturing and treatment methods include forging, casting, and powder metallurgy for metals; heat treatments such as carburizing, nitriding, and induction hardening to achieve surface hardness; and surface coatings (PVD, DLC) to reduce wear. Polymer gears rely on extrusion or molding and may require additives for thermal stability.

Material selection depends on load and torque, speed, lubrication regime, operating temperature, chemical exposure, and cost. Designers balance hardness, fracture toughness, fatigue resistance, and machinability, often using standards or manufacturer data to guide choices.