OND has added guidance on material and heat treatment options for industrial gear racks. The information is intended to help customers describe functional requirements rather than selecting a material only by name.

Material Selection Is Application-Dependent

Medium-carbon steel is widely used for general industrial gear racks because it offers a practical balance of strength, machinability, availability and heat treatment response.

Alloy and case-hardening steels may be considered when higher core strength, fatigue resistance or hardened surface performance is required. The final choice depends on load, size, duty cycle, manufacturing route and cost.

Hardened and Unhardened Options

A hardened tooth surface can improve wear resistance, especially under frequent operation or higher contact stress. However, hardness alone does not define overall performance.

The depth of the hardened layer, core properties, distortion control, finishing method, lubrication and mating pinion all influence service life.

Accuracy After Heat Treatment

Heat treatment can introduce distortion. When tighter pitch or tooth accuracy is required, the manufacturing process may include finishing after heat treatment, such as grinding.

Customers should state the required accuracy grade and functional positioning requirement rather than specifying an unnecessarily high grade without considering the complete system.

Information to Include on the Drawing

A gear rack drawing should identify material, heat treatment, tooth-surface hardness where required, module, pressure angle, tooth direction, accuracy, length, mounting holes and reference surfaces.

Where the rack is used in multiple sections, end conditions and joint requirements should also be defined.

Engineering Confirmation

The guidance provides a starting point. Material and heat treatment should be confirmed using the actual contact load, operating speed, lubrication, environment and expected service life.

Material Equivalence Requires Care

Material grades from different national standards may be similar without being identical. Chemical composition, mechanical properties, delivery condition and heat treatment response should be compared before one grade is substituted for another.

When a customer permits an equivalent material, the acceptance criteria should be defined. A material certificate can confirm the supplied grade, but it does not by itself confirm that the completed rack meets all functional requirements.

Cost and Performance Balance

A higher-alloy material and complex heat treatment are not always necessary. For moderate loads, a simpler material with correct lubrication and alignment may provide satisfactory life at lower cost.

Conversely, repeated wear on a high-duty axis may justify a hardened and finished rack. The most economical choice is the one that meets required life and accuracy with manageable maintenance and replacement cost.

Information Customers Can Prepare

Customers should avoid specifying only a hardness number without a process or depth requirement. The drawing should define whether the value applies to the tooth surface, core or complete section and whether finishing occurs before or after treatment.

Clear requirements allow the supplier to evaluate distortion risk, machining allowance, inspection method and cost before production.