Case Study: Fan Clutch Assembly Components
Process: Conventional Powder Metallurgy
Yield Strength: 380 MPa
Ultimate Tensile Strength: 410 MPa
Secondary Operations: Machining
End Use and Function
This high-performance fan clutch assembly is used in cooling systems in semi-tractors and other large diesel-engine vehicles. Composed of six powder metallurgy (PM) components, these components replaced a machined assembly.
The assembly is composed of six PM parts including a bushing-tensioner retainer and an index coupler. The former, a six-level component, required two-upper and three-lower punches for compaction on a CNC servo-controlled press. The index coupler has nine holes formed during compaction, and 29 different identifying letters and numbers for functional operation in the assembly. Tapping the holes was the only machining operation. All six parts are made from FC-0208-50 with a yield strength of 380 MPa, ultimate tensile strength of 410 MPa, and tensile rupture strength of 860 MPa. This material offered a superior combination of properties in the as-sintered (non-heat treated) condition, since some of the components required machining for tolerance or shape requirements.
Physical property requirements dictated that the components be made from metal. The net-shape PM processing opportunity saves an average of 30%–40% raw material usage over machining. The PM process was selected as the only cost-viable metal-working process, offering a 60% cost savings over machining and even greater over casting or forging.