Influence of the forming induced hardening on the wear behavior of aluminum gears within a metal-plastic material pairing and targeted adaption

The material pairing metal-plastic offers advantages such as a reduced weight and the ability to be operated in dry conditions, but the application is limited due to the occurring wear. The properties of the metallic gearing have a significant influence on the wear behavior. From previous investigations on the application of steel within the material pairing, the influence of the surface topography and the load case is known. With regard to further weight reduction, the application of light metals such as aluminum is promising. However, the low strength of aluminum poses a challenge due to the low wear resistance. The properties of the metallic gearing are not only determined by the choice of material but also by the manufacturing process. In this context, cold extrusion offers potential for the production of ready-to-use gears. Sufficient geometrical properties and a substantial increase in tooth flank hardness are achieved. In this contribution, the influence of the forming induced hardening on the wear behavior of aluminum gears was investigated. Wire eroded aluminum and steel gears were used for comparison. The low hardness of conventionally manufactured aluminum gears was identified as a major challenge. Subsequently, gears with significantly higher tooth flank hardness were manufactured in an adapted full-forward extrusion process and the improved wear behavior was verified. Finally, functional correlations regarding the hardness of the metal pinion and the resulting wear behavior were derived.