Light weight powertrain components

Important results from the project

The objective was to combine steel and heat treatment process to develop concepts for weight efficient transmission components to achieve a weight reduction of at least 20% by increased performance. Also shorter development time is addressed while a higher performance facilitate manufacturing of new products without major redesign. 57% of the tested combinations gave a strength increase that was 40-80% higher compared to the reference material, steel 21NiCrMo2, in gear root fatigue. For a gear it´s possible to achieve up to 50% less weight depending on selected concept.

Expected long term effects

In the project small and large gears, rotating-bending-testbars and contact fatigue rings have been manufactured, heat treated and evaluated in a corresponding test rig. Performance has been evaluated regarding bending and contact fatigue. The result is a systematic comparison of the performance for different combinations of steel and heat treatment as well as any post treatment. Further optimization is also possible, since this was not included in the study. Analysis were made regarding potential for weight-saving, cost and environmental load for the manufacturing of gears.

Approach and implementation

41 combinations of steel, heat treatment and post treatment has been included and evaluated. Both slightly higher alloyed steel grades compared to the steel grades more commonly used in the industry today, as well as steel grades expected to result in a significant higher fatigue performance were included. The intention was to create as wide a base as possible. This also applies to the performance evaluation made by bending fatigue (rotary bending and gear root fatigue bending) and contact fatigue testing.