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Characteristics of Gear Material

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Generally speaking, gear material design in gear motors often involves carburizing steel, powder metallurgy units, plastic, etc. The following details are the characteristics of various gear materials of gear motors:  

1. Gear motors are designed with carburizing steel, which has the following performance requirements: 

1.1 Strong ability to absorb carbon. Faster permeability and flat carbon gradient are accessible. The retained austenite content is appropriate. The mass, amount, size, and even distribution of carbides work together to ensure that the layer is hard and tough enough.

1.2 Low overheating sensitivity. Austenite can still maintain a fine-grain state when heated for a long time at the carburizing temperature, achieving direct quenching, and preventing the mechanical properties from getting worse after quenching due to the large grain size of martensite.

1.3 Sufficient hardenability is required to ensure that the center has a higher yield strength and toughness after quenching. In addition, a mild cooling medium can be used to greatly reduce the possibility of deformation and cracking of carburized parts. 

1.4 With low-alloy carbon steel, severe banded structure, coarse inclusions, and cracks are not permitted. The surface of the carburized layer should focus more on these factors.   

2. Powder metallurgy gear (metal gear and powder gear) is a commonly used powder metallurgy part via once-forming and finishing process without any other post-processing technology, which can better meet the dimensional accuracy requirements, especially the tooth profile precision. Powder metallurgy gears are usually used in miniature low-power gear motors with the following main features:

2.1 The powder metallurgy tooth is made through a recrystallization process in which metal powder is formed at a high temperature. There is no rolling process and no metal fiber flow is formed, which is a non-oriented mechanical property. Therefore, the bending resistance and shear strength of the tooth is not as good as that of traditional machinery. 

2.2 The precision of powder metallurgy gear is relatively low because it is impossible to control this aspect in the process of high-temperature sintering and forming. The uncontrollable factors include burning bricks, shaping of the burnt brick, and its precise dimensions. For this reason, transmission stability is poor. 

2.3 The tooth contact strength of powder metallurgy gears is also relatively low, so high torque cannot be transferred.

2.4 The surface roughness of the powder metallurgy gear tooth is also relatively large, which produces noise during transmission. 

2.5 Although it can be made into an oil-bearing gear tooth, the effective duration of oil lubrication is relatively short. To expand normal use, it is important to consider the external application of lubrication (bath lubrication is most suitable).   

3. Plastic gears are mainly used in miniature precision gear motors. The common characteristics are as follows:

3.1 The precision of injecting plastic gears, to a large extent, depends on the precision of the mold and plastic performance.

3.2 Good chemical stability helps to resist acid, alkali, and organic solvent erosion.

3.3 Good wear resistance and self-lubrication allows for smooth transmission with no noise. 

3.4 Good electrical insulation and poor thermal diffusivity.

3.5 Due to small plastic density, plastic gears can reduce the weight of the product.

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