Case study: Thermoplastic gears make starter motors lighter

DSM’s high-performance polyamides suit demanding stop-start applications

DSM’s high-performance plastics for automotive gears help improve engine efficiency, reduce fuel consumption and reduce production costs.

Plastic annulus gears for starter motors are built to last with Stanyl® polyamide 46 (PA46). This high-performance portfolio of thermoplastics meets the lightweight and efficient needs of the automotive industry by providing exceptionally low wear rates in demanding under-the-hood environments, all while significantly reducing system costs.

With the adoption of demanding start/stop starter motors, annulus gears are subjected to an enormous increase in load cycles. While conventional starter motors see up to 40,000 engine starts or 13 million load cycles per gear tooth, the newer start/stop starter motors see an increase up to 350,000 starts or 45 million load cycles, all under higher temperatures than ever. Stanyl PA46 was engineered to have high durability and low wear, even at operating temperatures up to 170°C.

Working together with a leading manufacturer of starter motors, DSM developed new gear designs that reduced weight by 46 percent over metal gears, while cutting costs in three ways: reducing the part count from five to one, eliminating assembly steps and reducing injection molding cycle times.

The result: Decreased overall system costs and lower carbon footprint (less weight and more efficient engines equals less fuel consumption).

Further information on improving efficiency in engines and part production: