Classification, Selection, and Material Properties of Rack Gears-Renqiu Shouyue Transmission Machinery Co., Ltd.

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Classification, Selection, and Material Properties of Rack Gears

2026-03-20

Spur racks are relatively easy to manufacture and find widespread application; helical racks, with their inclined tooth lines, offer higher contact ratio, smoother operation, and lower noise, making them well suited for high-speed or heavy-load applications. In addition, there are circular racks for specialized applications and flexible racks that can be bent.

Classification, Selection, and Material Properties of Rack Gears

Based on the tooth orientation, rack gears are primarily classified into straight racks and helical racks. Straight racks are relatively simple to manufacture and find widespread application; helical racks, with their inclined tooth lines, offer higher contact ratio, smoother transmission, and lower noise, making them well suited for high-speed or heavy-load applications. In addition, there are circular racks for specialized applications and flexible racks that can be bent.

The selection of a rack must comprehensively consider the load, operating environment, and required precision. Common materials include:

Carbon steel (e.g., S45C) : Exhibits excellent overall mechanical properties and can achieve enhanced tooth-surface wear resistance through high-frequency quenching.
Alloy steels (such as SCM440, SCM415) : High strength; commonly used for ground rack gears that require quenching and tempering or carburizing and quenching, capable of withstanding substantial loads.
Stainless steel (e.g., SUS304, SUS303) : Possesses rust- and corrosion-resistant properties, making it suitable for humid or clean environments such as food and medical settings.
Engineering plastics (such as polyoxymethylene and MC901 nylon) : Lightweight and capable of operating without lubrication, making it suitable for light-load office equipment or clean environments.