Electropolishing Case Study: Complex Shaft Assembly Used in Kidney Dialysis

Industry

Medical: Manufacturers of portable dialysis equipment

MFG/METHOD

Shaft Assembly comprised of a weldment of machined components

ALLOY

316L stainless steel

PROBLEM

The 316L stainless steel shaft has two 316L stainless steel tabs that are welded on the outside of the shaft. This causes weld discoloration, a contaminating oxide. The Shaft Assembly is an important part in an assembly for a portable blood dialysis machine. The tip must be sharp to puncture a carton containing a solution pre-mixture of powder and liquid. The fluid is dispersed through the portable dialysis machine. The inside must be clean and the surface must be smooth.

SOLUTION:

Our customer electropolished several samples. After electropolishing the outside and inside Shaft Assembly they found that electropolishing solved several problems. By removing a controlled amount of material, the ground burr around the puncture area was removed. This exposed the true sharpness, which allowed a smooth puncture into the container. Secondly the inside surfaces are smoother and the microfinish was improved. The better inside surface finish means less micro-crevices and inclusions for bacteria to harbor. The discoloration from the welded tabs was cleaned. Overall, the Shaft Assembly is bright passive and ultraclean with a smooth finish on the inside.

Electropolishing is the finish of choice for this important medical device.

Note to engineer: Able has processed literally thousands of different parts for the medical industry since 1954. Please contact our technical representatives for questions on process acceptance in the industry.