Carburizing and Hardening Gear Deformation Control
Covers steel hardenability, carburizing temperature uniformity at 920-940°C, and quenching medium selection for controlling gear deformation.
Main Factors Affecting Deformation#
1. Hardenability of Steel The higher the hardenability of steel, the greater the deformation. 20CrMnTi is a commonly used carburizing steel with moderate hardenability and controllable deformation. For gears with higher precision requirements, materials with more stable hardenability such as 20CrNiMo or 20CrMo can be selected.
2. Carburizing Temperature Uniformity The carburizing temperature is usually 920~940°C, and the temperature uniformity in the furnace should be controlled within ±5°C. Uneven temperature will cause inconsistent case depths in different parts of the gear, resulting in uneven deformation.
3. Selection of Quenching Medium
- Hot oil quenching (80~120°C): minimal deformation, suitable for gears with module M≤6
- High-speed quenching oil (40~60°C): moderate cooling rate, suitable for gears with module M6~M12
- Salt bath quenching (160~220°C): low deformation, but high equipment investment, suitable for precision gears
4. Furnace Loading Method
- Gears should be hung vertically or placed flat, avoiding stacking
- Long shaft-type gears should be hung vertically to prevent bending deformation
- Thin-walled gears should be fixed with dedicated fixtures
Deformation Control Measures#
| Measure | Effect | Application Scenario |
|---|---|---|
| Reserved gear grinding allowance | 0.15~0.30mm per side | Ground gears |
| Press quenching | Deformation can be reduced by 50% | Thin-walled gears |
| Cryogenic treatment (-80°C) | Stabilizes dimensional accuracy | High-precision gears |
| Secondary tempering | Stress relief | All carburized and quenched gears |
Geyang Transmission adopts mature carburizing and quenching processes, with mature deformation control solutions for gears with module M1~M16, and batch machining accuracy is consistently stable at GB grade 4~5.