A design method for plastic gear transmissions
Turning plastic gear design from rules of thumb into a documented method, with safety factors validated against tests.
- Industry
- Automotive actuators
- Year
- 2025
- Sheet
- 5 / 7
- Client
- Tier-1 automotive supplier
- Duration
- 4 phases
- Tools
- KISSsys, KISSsoft, Minitab, MATLAB, FEM
- Standards
- VDI 2736
Plastic spur gear pair (true involute geometry) and the S-N curve that sets its fatigue limitSchematic, not to scale
The question
Plastic gears are light, quiet and cheap to make, but their strength depends on temperature, humidity and the moulding process. The customer wanted a repeatable design method, with safety factors it could defend in front of its own customers.
What the customer received
- Validated KISSsys models and DOE reports
- Correlation report for the selected test cases
- Recommended safety factors and a design handbook for plastic transmissions
- Definition of the material test campaign
Services: Design methods and validated models, Testing and model correlation, Gear and transmission calculation
What we did
- Reviewed the state of the art and the customer’s existing transmissions, and defined the design space.
- Built parametric KISSsys models and ran design-of-experiments studies across the design space.
- Validated the models against four test cases, with a critical analysis of every deviation.
- Defined the material tests to VDI 2736: S-N curves, wear coefficient and friction coefficient, plus guidance on how moulding parameters change crystallinity.
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