Rubberized Crankshaft Sprocket

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by Lisa Lester

Case Study: Crankshaft Sprocket

Process: Conventional Powder Metallurgy
Secondary Processes: Induction heat treatment and tempering of the teeth for durability
Materials: FC-0208 and FL-4405

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Rubberized Crankshaft Sprocket
2016 Award of Distinction: Rubberized Crankshaft Sprocket

End Use and Function

These three components, a rubberized crankshaft sprocket and two rubberized oil pump sprockets—a drive and a driven—go into a General Motors Generation II High-Feature V6 Engine, currently installed in the Cadillac CT6 and ATS, GMC Acadia, and Chevrolet Camaro.

Fabrication

The crankshaft and oil pump drive sprockets are made of FC-0208 (teeth are induction hardened and tempered) while the driven sprocket is warm-die compacted (teeth at 7.1 g/cm3) and made of FL-4405. The patented rubber design used on the crankshaft sprocket provides improved noise, vibration, and harshness (NVH) characteristics that exceed the engine manufacturer’s demands.

Results

  • Fabrication via PM provides an estimated 30% savings over parts machined from steel bar or forgings.
  • The annual production of 700,000 sprockets is projected to reach two million in 2018.
  • While it would be possible to create these components using alternative processes of machining from wrought steel or steel forgings, powder metallurgy offers a solution at a lower price with better material utilization.