Worm gear heat treatment
Classification： Blog
Release time：2025-06-30
In worm gear transmission, heat treatment is the core process for improving its load-carrying capacity, wear resistance, anti-galling ability, and fatigue life. The core objective is to strengthen the worm gear surface while ensuring the comprehensive performance of the worm wheel teeth 。
1. Worm gear heat treatment (core: high hardness and wear resistance of the tooth surface)
Process: Surface hardening
Induction hardening/flame hardening of the tooth surface: Most commonly used. Only the tooth surface and a certain depth of the tooth root are rapidly heated and quenched + low-temperature tempering to obtain a high-hardness (58-62 HRC) martensite layer, while the core maintains toughness. High efficiency and relatively controllable deformation.
Carburizing and quenching: Suitable for heavy-duty, high-precision worm gears (such as automotive steering gears). After carburizing, quenching + low-temperature tempering of low-carbon alloy steel (such as 20CrMnTi), the tooth surface obtains extremely high hardness (58-63 HRC) and wear resistance, deep hardening, and a strong and tough core.
Nitriding (gas/ion): Low processing temperature (~500°C), minimal deformation, extremely high surface hardness (above 1000-1200 HV), good wear resistance and anti-galling properties, but the hardened layer is relatively shallow. Suitable for precision, light to medium load worm gears.
Key requirements: Uniform hardened layer depth, reasonable profile (covering the tooth surface and tooth root transition area); strict control of deformation; avoidance of quenching cracks; high surface hardness, sufficient strength and toughness in the core.
2. Worm wheel heat treatment (core: wear resistance, anti-galling, overall strength of the tooth surface)
Material determines the process:
Cast tin bronze (ZCuSn10P1, etc.): Generally, no quenching and strengthening is performed . Stress relief annealing Eliminates casting/processing stress to prevent deformation and cracking.
High-strength brass/aluminum bronze/cast iron: Can be Overall quenching + tempering (tempering) to improve the base material strength and hardness. Sometimes supplemented by Surface treatment (such as phosphating, plating) to improve anti-galling ability.
Steel worm wheels (rare): Requires Tempering treatment (quenching + high-temperature tempering) to ensure the comprehensive mechanical properties of the core. The tooth surface can be Surface quenching (such as induction hardening) or Nitriding to improve wear resistance.
Key requirements: Ensure the strength and toughness of the core of the gear teeth; the tooth surface has good running-in and anti-galling properties (especially matching with the worm); control overall deformation.
3. Core focus points of heat treatment quality
Hardness: The hardness of the worm gear tooth surface and the hardness of the worm wheel (steel) tooth surface and core must meet the design requirements.
Hardened layer depth and distribution: The surface hardened layer of the worm gear needs to be deep enough and uniformly cover the meshing area.
Microstructure: No overheating, burning, abnormal microstructure (such as quenching soft spots, excessive residual austenite), etc.
Deformation: Strictly control the changes in size and form and position tolerance caused by heat treatment to ensure assembly accuracy and meshing quality.
Stress state: Eliminate harmful residual stress (especially worm wheels).
Summary: The core of worm gear heat treatment lies in Targeted strengthening of the worm gear tooth surface (high hardness and wear resistance), and ensuring that the worm wheel tooth surface has good anti-galling properties and sufficient base material strength . The choice of process needs to be closely combined with material characteristics, working conditions, and performance requirements, and quality must be strictly controlled to achieve efficient, reliable, and long-life operation of the transmission pair.
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