Case Study: Stepped Planetary Gear

Process: Conventional powder metallurgy

Density: 6.9 g/cm3

Material: FL-4405 prealloyed steel

Gear Quality: ANSI/AGMA 2000-A88 class 7

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End Use and Function

This component is a stepped planetary gear used in a ridged rear axle gear box for battery electric light commercial vehicles. To enable an 82:1 dual reduction planetary gear system, it was essential to be able to deliver tight dimensional control for this complex shaped part.


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The concept was brought to fruition using CNC powder compaction. To enable an 82:1 dual reduction planetary gear system, it was essential to be able to deliver tight dimensional control for this complex shaped part. The five-level pinion, that has different tooth gear geometries on both ends, a 15-tooth and 18-tooth separated by a thin guiding flange that is used for orientation during assembly, exceeds ANSI/AGMA 2000-A88 class 7 requirements. Validation testing is performed by the end customer for performance, durability, reliability, and NVH (noise, vibration, and harshness). The FL-4405 prealloyed steel pinion undergoes quench & temper heat treatment prior to oil impregnation. This provides a robust wear resistant part with internal lubrication, with lower torque loss at start up and in cold weather conditions than grease, under normal operating conditions.



No other metal forming technology could provide the part geometry at a commercially competitive price. The ability for PM to produce the stepped planetary configuration enabled the design to meet the overall required ration in a single planetary geartrain. This eliminated the complexity of the additional components to achieve the design goal. PM was the technology of choice.


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