Generally speaking, gear material design in gear motors often adopts carburizing steel, powder metallurgy, plastic, etc. The following details are the characteristics of various gear materials of gear motors:
1. The gear material design of gear motors is carburizing steel, whose performance requirements are as followed:
1.1 Strong ability to absorb carbon. The surface can absorb enough carbon; Faster permeability and flat carbon gradient are accessible; The retained austenite content is appropriate; The bulk, complete number, size and even distribution of carbides work together to ensure that the layer has enough hardness, strength and toughness.
1.2 Low overheating sensitivity. Austenite can still maintain fine-grain state when heated for a long time at the carburizing temperature, so as to achieve direct quenching, and prevent 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, mild cooling medium can be used to greatly reduce the possibility of deformation and cracking of carburized parts.
1.4 Inlow-alloy carbon steel, severe banded structure, coarse inclusions and cracks are not allowed. Especially, 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 parts via once-forming and finishing process without any other post-processing technology, which can fully meet the dimensional accuracy requirements, especially the tooth shape precision. Powder metallurgy gears are usually used in miniature low-power gear motors with the following main features:
2.1 Powder metallurgy tooth is a recrystallization process in which metal powder is formed at 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 proceeded by traditional machinery.
2.2 The precision of powder metallurgy gear is relatively low, because it is impossible to control the aspects in the process of high-temperature sintering and forming. The uncontrollable factors include burning bricks, what is the shape of the burnt brick, and its precise dimension. Thus, the transmission stability is poor.
2.3 The tooth contact strength of powder metallurgy gears is also relatively low, so large torque cannot be transferred.
2.4 The surface roughness of powder metallurgy gear tooth is also relatively large, which will produce noise in the transmission.
2.5 Although it can be made into an oil-bearing gear tooth, the effective duration of oil lubrication is relatively short. To ensure normal use,it is important to consider the external application of lubrication (bath lubrication is the best).
3. Plastic gears are mainly used in miniature precision gear motors. The common characteristics are as followed:
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, 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.