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What heat treatment is required for CNC gear hobbing machining?


1. Normalizing treatment

Eliminating excessive stress inside the gear is the advantage of CNC gear hobbing machine normalizing treatment, increasing the toughness of the gear and improving the cutting performance of the material. The strength and hardness of normalized gears are lower than those of quenched or tempered gears. Therefore, normalizing is often used for large-diameter gears that do not require very high mechanical properties or are not suitable for quenching or tempering.

2. Conditioning and tempering treatment

Generally, after quenching and tempering treatment by CNC gear hobbing machine, the fine spherical pearlite-like structure can have a certain degree of dispersion and excellent comprehensive mechanical properties. The gear tooth hardness can reach HB220~285, and the hardness of smaller gears can be higher. During operation, the tempered gear tooth root has a large strength margin and strong impact resistance, and occupies a considerable proportion in heavy-duty gear transmission.

3. Surface quenching

After surface quenching, the gear needs to be tempered at low temperature to reduce internal stress and brittleness. Case-hardened gears have high load-carrying capacity and can withstand impact loads. Usually, the quenched gear blank that has been normalized or quenched and tempered can make the center of the gear teeth have a certain strength and toughness.

4. Carburizing and quenching

Carburized and quenched gears generally need to be ground or honed to eliminate the deformation caused by the heat treatment of the CNC gear hobbing machine. This type of gear has high contact strength and bending strength, and can withstand large impact loads.

5. Nitriding

  Improving the surface hardness, wear resistance, fatigue strength and corrosion resistance of gear teeth is the effect of nitriding on CNC gear hobbing machines. The low temperature of nitriding treatment makes the gear deformation very small, and no grinding or only fine grinding is required. Because the nitrided layer is thin, the hardened layer of nitrided gears is in danger of peeling off. Its load-bearing capacity is generally not as high as that of carburized gears, and it is not suitable for use in situations where it can withstand impact loads or has strong wear.

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