Electropolishing: Alloys & Benefits

International Trade & Business

Jul 23, 2024

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Manufacturers of mission-critical parts that lives are dependent upon, from aerospace vehicles to surgical implants to equipment that handles food, there little margin for error. A single, microscopic imperfection can lead to part failure, infection or other disasters.

Cold working and machining causes a wide variety of these imperfections that are often invisible to the naked eye: microcracks, microburrs and other surface defects that can compromise the finish, fit, function, and durability of critical metal parts. Free iron, heat tint, oxide scale, alpha case, EDM recast layer, and other stains/issues may also need removal.

Electropolishing is also known as electrofinishing, electrochemical polishing, electrolytic polishing, and e polishing. Whatever you call it, electropolishing eliminates metal surface defects by removing a microscopically precise layer of surface material. This degree of precision and consistency plus being able to remove a variety of surface imperfections all in one process is why electropolishing is a required finishing process for critical metal parts – and is 30 times more corrosion resistance than passivation (though parts are passivated as part of the electropolishing process).

Electropolishing eliminates the need for a variety of mechanical metal finishing processes, including deburring, tumbling, and cleaning.

Metal Alloys That Can Be Electropolished

Electropolishing is most commonly used on 200, 300 and 400 series stainless steel but also works well for a variety of common and specialty alloys:

Aluminum
Brass
Carbon Steel
Copper
Elgiloy
Hastelloy
Nickel
Niobium
Nitinol
Tantalum
Titanium
Tungsten

Benefits of Electropolishing

Because it’s suitable for a wide range of metal alloys, electropolishing is specified by engineers in the world’s most demanding manufacturers: aerospace, automotive, food and beverage, medical devices, semiconductors, surgical implants, and many more because of the following benefits.

Deburring

Because electropolishing removes surface metal from a part, it eliminates burrs on the surface as well. This process is frequently used for deburring delicate on intricate parts and is effective on a variety of metal hardnesses.

Corrosion Resistance

By removing surface imperfections and embedded contaminants, electropolishing significantly improves long-term corrosion resistance as revealed in salt spray tests when compared with both raw and passivated parts.

Thorough Cleaning

Electropolishing removes embedded scale, rust, grinding compounds, foreign debris, and oils, creating a bright, uniform finish that does not peel or abrade. As a result, corrosion resistance and weldability are improved without reducing surface hardness or stressing your parts.

Microfinish Improvement

Electropolishing improves microfinishing on complex or fragile parts that are not well-suited for methods like grinding, lapping or harperizing. It reduces the microscopic peaks caused by metalworking operations like stamping, welding, and forming, reducing microfinish values and improving part performance.

Part Life

Electropolishing has become a common metal finishing process used to help improve the life of metal parts that flex, cycle, twist and bend. By removing surface imperfections on the surface of metal parts, engineers have found electropolishing to greatly improve the life of components that function as springs.