Case Study: Output Pulley
Process: Conventional powder metallurgy
Density: 6.3 g/cm³
End Use and Function
This output pulley goes into an electric reclining mechanism in a minivan-rear-seat application. This powder metallurgy (PM) component offers a lot of functionality in the small-footprint mechanism—the groove for cable retention, the cam for radial movement, and stops at both ends. To enable the manufacture of this component, the density needed to be equalized in all sections of the part.
Designing the output pulley as a net-shape component, which includes an undercut radial groove, entailed the development of what the fabricator calls “extreme forming,” a proprietary tooling concept requiring four levels controlled by CNC logic. No secondary operations were used to create this component, other than a traditional tumble deburr and a coat in a rust preventative.
This component is another example of the benefits of finding a parts fabricator to work with early in the design process. Net forming the groove eliminated the time-consuming milling operation that would otherwise have been required with a machined steel part, and which would have increased its cost by about 50% and resulted in additional waste. Designing the part for fabrication at a density of 6.3 g/cm³ resulted in a 20% weight savings over a fully-dense machined part. The output pulley is produced at an annual quantity of 500,000 units.