Case Study: Worm Gear

Process: Metal injection molding

Density: 7.55 g/cm³

Material: MIM-17-4 PH stainless steel

Gear Quality: Helical in nature

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End Use and Function

This component is a worm gear used in the locking mechanism of commercial vehicles to activate the park function. MIM technology was used due to the complexity of the helical teeth and adjacent cylindrical shaft geometry to transmit torque to the mating assembly.

Fabrication

The worm gear was made by MIM using a single cavity injection mold. Three interlocking slides were used to produce the complex gear teeth geometry. The gear teeth are helical in nature and required special design to function with the mating part. The material used was a MIM-17-4 precipitation hardened stainless steel. This part did not require secondary operations to be functional with the mating assembly. The ability to produce conforming gear components without post sintering steps speaks volumes regarding the MIM technology.

Results

This part is sustainable, utilizing a process that combined several functional geometries into a single cavity mold. Based on the overall size and complexity, MIM is the only reasonable cost-effective technology to produce the parts. The combination of the helical gear geometry, internal shaft diameter, specified material, and production volume make this part difficult to produce by any other technology.