Electropolishing

Electropolishing combines a chemical bath with an electrical current that precisely removes a uniform layer of surface material from the part. It works to remove contaminants and microscopic imperfections such as cracks, burrs, jagged edges and more — for improved roughness average (Ra) up to 50%.

Electropolishing is the Swiss army knife of metal finishing in that it can eliminate the need for additional metal finishing processes like hand deburring, tumbling, sanding and other mechanical processes.

Passivation

During passivation, stainless steel parts are placed into a basket and submerged into a nitric or citric acid bath. Depending on the alloy, acid concentration, temperature and time can be adjusted to effectively remove free iron and other contaminants on the part’s surface.

By increasing the thickness of the oxide layer on the part surface, passivation improves corrosion resistance while also removing surface contamination. Parts are typically passivated in a bulk process.

Which is better?

While passivation is useful for removing free iron and contaminants from metal parts, electropolishing offers a wider range of benefits:

• Electropolishing is 30 times more effective than passivation in preventing corrosion (see salt spray test below)
• Electropolishing improves pathogen resistance and cleanability for food and medical parts by removing microcracks and surface defects that create issues with effectively cleaning
• Electropolishing can be used on far more metal alloys than passivation. This includes all stainless steels, aluminum, copper, brass, Nitinol, titanium and many more
• Electropolishing provides a bright, clean and uniform appearance

Side-by-side comparison

Figure 1: A side-by-side comparison. Source: Able Electropolishing

Corrosion protection

Below are results from an independent lab’s testing of eight stainless steel alloys after 24 and 888 hours of ASTM B-117 salt spray testing. The test was performed on unpolished and passivated coupons, passivated coupons and electropolished coupons. See the results below.

Figure 2: Results from an independent lab’s testing of four stainless steel alloys after 24 and 888 hours of ASTM B-117 salt spray testing. Source: Able Electropolishing

What materials can Able passivate?

Figure 3: What materials can Able passivate. Source: Able Electropolishing

See it in action

Watch the video on electropolishing versus passivation to see the metal finishing processes in action.

Electropolishing for precise, consistent and effective metal finishing

Electropolishing is an electrochemical process for improving the surface finish of metal parts. This is achieved by precisely removing the outer layer of metal, improving the Ra value up to 50%. Able can apply this process to nearly any metal, including Nitinol and titanium. Don’t trust critical parts to anything less.

Want to learn more?

• Send a sample part for free electropolishing
• Attend a webinar
• View case studies
• Speak to electropolishing experts