Case Study: Retainer Weight

Process: Conventional powder metallurgy
Secondary Processes: Tooling, steam treatment
Density: 6.7 g/cm³
Tensile Strength: 284 MPa
Yield Strength: 490 MPa
Hardness: 97 HRB

Retainer Weight
2014 Award of Distinction: Retainer Weight

End Use and Function

The award was given to a sinter-hardened steel retainer weight that operates in the transmission of large motorcycles, controlling the on/off position of the clutch. Dimensional accuracy was a large part of the challenge with this component.


The challenge of attaining dimensional accuracy in a component with such a thin, large-diameter shape was overcome with process optimization and the choice of steam treatment. Wear resistance and durability were also key for a successful part.

The parts have a density of 6.7 g/cm³, a tensile strength of 284 MPa, a compressive yield strength of 490 MPa, an elongation of 0.3%, and a 97 HRB hardness.


This redesign of a previous PM part achieved a 17% weight reduction with increased dimensional accuracy.