Case Study: Gerotor Set

Process: Conventional Press & Sinter (PM)

Material: FN-0405-35 nickel steel

Density: 7.0 g/cm³

Hardness: 71 HRB

Torque: <1.5 N•m

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End Use and Function

The inner and outer gerotors pump automatic-transmission fluid in medium- and heavy-duty on-highway trucks, including construction, refuse, and emergency-service applications.

Fabrication

The rotors are compacted and sintered, then sized to calibrate their lobe profiles. Grinding establishes thickness, diameter, runout, perpendicularity, and cylindricity. Deburring, washing, and phosphate coating complete the components before mating and rotational-torque inspection.

Results

PM gerotors provide an efficient and cost-effective alternative to crescent gears. Near-net lobe formation avoids the excessive material removal and expensive machining that subtractive production would require for this large matched set.