Electropolishing

Electropolishing

Macfab’s precision machining operations are further enhanced by our electropolishing process. Performing this process internally reduces issues that might be caused due to handling and transport, and the vertical integration allows us to deliver finished ready to use parts to our customers.

While tumbling, vibration, and hand deburring are effective processes of deburring and generating marginal improvements in surface finish, electropolishing is a superior method to ensure microscopically precision finish and burr removal for parts – only tight tolerance and precision machining facilities such as MacFab utilize. Electropolishing was developed in the 1950s. During the years since its development, it has also been called electrochemical polishing, anodic polishing and electrolytic polishing.

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The Value of Electropolishing

Excellent machining or grinding operations can still leave imperfections invisible to the human eye: micro burrs, microcracks, heat tint, oxide scale, and heat tint – fortunately all these can be addressed by electropolishing. It is an electrochemical process that removes a small layer, 0.001 to 0.0025 inches from the surface of the work piece – think of it as the reverse of an electroplating operation. This process is typically performed on stainless steel (series 300 or 400) machined or welded parts as Macfab specializes; however, aluminum and Nitinol materials can also benefit from this finishing process as well. The parts are left bright, clean, and microscopically smooth with a Ra of 8 to 16 microinch finish achievable. The process eliminates burrs and microcracks and leaves the parts with an improved corrosion resistance, fatigue life, and pathogen resistance too. Corrosion resistance is up to 20 times greater than passivation processes such as allodizing as it only removes contaminates left on the surface of the part.

The Electropolishing Process

Focusing in more detail on the electropolishing process and how it delivers such broad enhancement to parts, the parts are first loaded onto a metallic tree or fixture where they have good electrical contact. The fixture is then connected to the positive side of a Direct Current (DC) circuit making the parts the anode of the reaction. A second metallic plate is submerged in the tank and connected to the negative side of the DC circuit. The tank is filled with an electrolytic solution that is matched to the material of the part – for Macfab that is Stainless Steel. Once the work piece has electricity applied to it, the solution breaks the bonds of the stainless steel atoms. Imagine the burr or high points on the surface of the part have a small bolt of lightning pass through it. What is left is a metallic salt and the parts free of burrs and with improved surface finish at the same time.

Below are a few of the industry standards covering Electropolishing that we at Macfab refer to in developing and controlling our electropolishing process.

ASME BPE

Standards for Electropolishing
Bioprocessing Equipment

SEMI F19

Electropolishing Specifications for
Semiconductor Applications

ASTM B912

Passivation of Stainless Steels Using
Electropolishing

Learn more about Macfab’s Specialty Finishing Services including Electropolishing.