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Electropolishing

Electropolishing is a chemical and electrochemical process used to smooth and polish metal surfaces by selectively removing material from a metal part through the application of an electrical current. This process improves surface finish, reduces surface roughness, and enhances corrosion resistance. It is often referred to as “reverse plating” because, unlike electroplating where material is deposited onto a surface, electropolishing removes material.

The metal part to be polished is submerged in an electrolytic bath, typically an acid mixture. The metal part acts as the anode (positive electrode) while a cathode (negative electrode) is placed in the bath. A direct current is applied, causing material to dissolve from the metal surface. Electropolishing removes microscopic peaks and irregularities from the surface, making it smoother at the microscopic level. The process is more aggressive on protruding (high current density) areas, creating a more uniform surface.

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SERVICES

Electropolishing Services

I.D. Electropolishing Conforming Cathode Electropolishing

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Applicable specifications

Specification	Type/Class/Limitations	Description
Electrolurgy EPS-502
ASTM B 912, Passivation of Stainless Steels Using Electropolishing

Frequently Asked Questions

THE ELECTROPOLISHING PROCESS:

Electropolishing is accomplished by connecting the metal part to be processed to the positive side (the anode) of a DC power supply. The part is then immersed in a heated electrolytic (acidic) bath that contains metal plates connected to the negative side (the cathode). The electrical reaction causes an ionic conduction resulting in the removal of particles of metal from the anode.

During the process, the products of this anodic metal dissolution react with electrolyte to form a film at the surface of the metal. This film essentially conforms to the general contour of the surface of the metal and therefore is thinner over the micro-projections and thicker at the micro-depressions. The result is more rapid dissolution of the micro-projections causing micro-leveling at the surface.

The amount of metal removed is influenced by the composition of the metal part to be electropolished, the temperature and agitation of the electrolytic bath, the spatial and area relationships of the anode and cathode, the current, and the length of time the current is flowing.
ELECTROLURGY’S ELECTROPOLISHING CAPABILITIES:
- Electropolish 300 and 400 Series, 17-4 PH
- Perform I.D. Electropolish (Requires Conforming Cathode)
- Typical Thickness Removal 0.0001 to 0.0003 Inches, up to 0.002 (Two Thousandths) possible
- Part Length Up to 4 Feet, 75 Pounds
- Masking available for selective polishing
- In-house salt spray testing per ASTM B 117
- Non-Destructive Testing (NDT) Available
BENEFITS OF ELECTROPOLISHING:
- Improved surface finish, results in a highly smooth, reflective, and uniform surface.
- Corrosion Resistance, passivates the metal, making it more resistant to corrosion.
- Deburring helps remove small burrs and sharp edges from metal components.
- Enhanced Cleanliness creates a surface that is easier to clean and less likely to harbor contaminants.
Electropolishing is commonly used on metals such as stainless steel, aluminum, titanium, copper, and nickel-based alloys. The process is precise and can be controlled to achieve specific surface roughness and aesthetic requirements.
TYPICAL APPLICATIONS OF ELECTROPOLISHING:

Medical Devices: Used to improve the biocompatibility and cleanliness of surgical instruments, implants, and other medical devices.

Food and Beverage: Enhances the cleanliness and corrosion resistance of stainless-steel equipment.

Aerospace and Automotive: Improves fatigue resistance and appearance of metal components.

Semiconductor Industry: Polishes and cleans parts used in high-tech applications requiring ultra-smooth surfaces.

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