Case Study: Hydraulic Valve Actuator Mechanism

Process: Conventional Powder Metallurgy

Material: SS-316H-20

Secondary Operations: Turning and Specialized Deburring

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End Use and Function

This award-winning component acts as the spring seat of a hydraulic valve actuator mechanism. It was originally designed as a plastic injection molded part. However, the plastic softened in the operating environment causing the part to fail.

Fabrication

The tooling concept for this two-level part consists of a straight-walled die, a flat lower punch, a formed upper punch, and a core rod. The part is made from SS-316H-20 and is compacted to a green density of 6.5 g/cm³ prior to sintering at 1,150 ºC (2,100 ºF) in a pure-hydrogen atmosphere. The sintered parts have a density of 6.6 g/cm³ and the nitrogen content is kept below 0.03 wt.% to ensure good ductility for the part and the durability required for the cyclical loading of the hydraulic actuator. The five blades of the component are 6-mm (0.25-inch) long and too thin (0.66 mm [0.025 inch]) to be compacted to net shape directly, so extra material is added in the region of the blades.

A low-cost turning operation is needed to achieve the final part geometry. Post machining includes a specialized deburr and careful handling to prevent any part-to-part contact.