Before

CNC-machined cobalt chrome femoral implant before polishing, showing matte surface with visible machining lines

Surface metrology scan of cobalt chrome femoral implant before polishing with Ra 30.468 µin

After

Cobalt chrome femoral implant after polishing with mirror-like reflective finish

Femoral Implant Surface Scan – After (Ra: 1.2887 µin)

Objective

To find an optimal polishing method for CNC-machined cobalt chrome femoral implants that meets or exceeds the customer’s “rough polish” benchmark, defined by a previously approved target part.

Part DescriptionFemoral (Knee)
IndustryMedical/Pharmaceutical
Fabrication MethodCNC Machined
MaterialCobalt Chrome
Process TypeElectropolishers, Multiple Methods, Polishing, Superpolish/Ultrapolish
Equipment TypeCentrifugal Disc Finisher, Centrifugal Barrel Finisher/Harperizer

Solution

Bel Air tested multiple finishing methods to replicate and improve upon the customer’s reference part. Using either a Centrifugal Barrel Finisher/Harperizer or Centrifugal Disc Finisher, the cobalt chrome femoral components were polished to achieve a consistent rough polish across the curved geometry. In some cases, electropolishing was evaluated as a complementary or alternative step, depending on final surface specifications. Each method was validated to maintain dimensional accuracy while delivering the desired aesthetic and functional finish.

If you are unsure what equipment and media you require to achieve your desired surface finish, send us your part, and we will evaluate it and provide you with a detailed metrology report.