Case Study: One-Way-Clutch Wedge Washer

Process: Conventional Press & Sinter (PM)

Material: FL-4400 prealloyed steel (1.4 wt.% copper addition)

Density: Part 1: 7.25 g/cm³, Part 2: 7.1 g/cm³

2 parts sinter-brazed into 1 component

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End Use and Function

The novel electric selectable one-way-clutch wedge washer facilitates seamless gear changes and regenerative braking.

Fabrication

The wedge washer is created through a sinter-brazing process, joining two compacted PM parts with precise tolerances. Density challenges in the legs/pins were addressed by adjusting press controls and tooling design, achieving 7.25 g/cm³. The second part faced density issues in the cam feature, resolved through improved tooling and press control, reaching 7.1 g/cm³. Both parts are made from prealloyed FL-4400 with 1.4 wt.% copper and undergo carburizing heat treatment.

Results

A selectable one-way clutch reduces shift times and enhances consistency. In the low/reverse position, it saves space, minimizes spin loss, and lowers complexity and costs. In hybrid transmissions, it significantly boosts fuel economy without the drawbacks of friction-clutch systems. Additionally, manufacturing the part from wrought steel would lead to substantial material waste during machining.