Case Study: Pump Rotor

Process: Conventional powder metallurgy
Secondary Processes: Turning, milling, and resin impregnation
Density: 6.95 g/cm³
Tensile Strength: 105,000 psi (725 MPa)
Yield Strength: 55,000 psi (380 MPa)
Hardness: 89 HRB

End Use and Function

This part is a powder metallurgy (PM) diffusion-alloyed steel rotor that operates in an industrial rotary gear pump for handling fluids like wastewater or chemicals. Part of the challenging surrounding the development of this part included requirements such as passing a crush test on the tooth/hub joint and having a break strength exceeding 6,000 pounds.

Pump Rotor
2011 Award of Distinction: Pump Rotor

Fabrication

Fabricated to a density of 6.95 g/cm³, the rotor has a tensile strength of 105,000 psi, yield strength of 55,000, and 89 HRB hardness. The part is resin impregnated for leak prevention and machinability improvement. All inside and outside diameters are turned to size. Tooth flanks are milled for the required fit with other pump components.

Results

Using PM for this part resulted in:

  • a cost savings estimated at 22% over alternative processes such as machining rolled bar and casting;
  • higher material utilization;
  • reduced transportation costs.