Common types of materials for gears

Gears are important mechanical components in transmitting motion and power, and gear materials have a great influence on the load-bearing capacity and structural dimensions of gears. Reasonable selection of gear materials is one of the important contents of gear design. It can be seen from the failure mode of gear teeth that when designing gear transmission, the tooth surface should have sufficient hardness to ensure the tooth surface's ability to resist wear, pitting, gluing, and plastic deformation; the core of the gear tooth should have sufficient strength. and toughness to ensure the tooth root's ability to resist bending and fracture.

Therefore, the basic requirements for gear material properties are: the tooth surface must be hard and the tooth core must be tough. At the same time, gear materials should also have good mechanical processing and heat treatment processability, economic requirements, etc.

The following are commonly used types of gear materials:

1.Steel

Steel has good toughness and impact resistance. Its mechanical properties and tooth surface hardness can be improved through heat treatment or chemical heat treatment, so it is most suitable for manufacturing gears.

(1) Cast steel

Except for those that are too large in size or have complex structural shapes that can only be cast, forged steel is generally used to make gears. Carbon steel or alloy steel with a carbon content of 0.15%-0.6% is commonly used.

(2) Cast steel 

Cast steel has good wear resistance and strength, but it should be annealed and normalized, and can also be quenched and tempered if necessary. Cast steel is often used for larger gears.

2.Cast iron

Gray cast iron is brittle in nature, has poor impact resistance and wear resistance, but has better resistance to gluing and pitting corrosion. Gray cast iron gears are often used in situations where the work is smooth, the speed is low, and the power is not high.

3.Non-metallic materials

For high-speed, light-load and low-precision gear transmissions, in order to reduce noise, non-metallic materials (such as cloth-covered plastic, nylon, etc.) are often used as small gears, and large gears are still made of steel or cast iron. In order for the large gear to have sufficient resistance to wear and pitting corrosion, the hardness of the tooth surface should be 250-350HBS.

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Common types of materials for gears