Electropolishing FAQs

What is Electropolishing?

Electropolishing is an electrochemical process that uses both chemicals and electricity to remove microscopic imperfections, delivering a clean and smooth surface finish.

Does Electropolishing improve surface finish?

It is possible to achieve a reduction up to 50% of the average surface roughness dependent on the base material and the pre-polishing techniques applied.

What are the benefits of Electropolishing?

  • Appearance – Depending upon the initial surface finish and the quality of the stainless steel, electropolished surfaces can range from smooth and deburred to bright and shiny, often reflective. Aesthetically pleasing, uniform luster.
  • Smoothness – Levels peaks and valleys on a microscopic level. Provides up to 50% improvement in surface roughness (Ra). Does not stress or fracture the crystalline metal surface. Removes fissures and cracks from the microstructure.
  • Deburring – Removes small pieces of displaced surface material that can snag and break.
  • Cleanliness – Creates a clean surface easy to sterilize. Removes embedded contaminants that can lead to corrosion. Reduces friction of parts in constant motion. Reduces galling on threaded parts.
  • Complexity – Polishes areas that are inaccessible by other polishing methods without causing damage. Effectively polishes tiny surfaces on complex components.

What metals can be Electropolished?

While most metal alloys can be electropolished, Allegheny Surface Technology specializes in 300 series stainless steel. Stainless steel is one of the most popular alloys to electropolish because it combines desirable mechanical properties with a known and proven corrosion resistance.

What is the difference between Electropolishing and Electroplating?

Electropolishing and electroplating are both electrochemical processes that involve the application of chemical and electricity to a metal object. However, they work in opposite directions. Electropolishing removes metal from the surface whereas electroplating adds metal to the surface.

Is Electropolishing better than Mechanical Polishing?

In many cases, electropolishing is best used to complement mechanical polishing. Electropolishing operates in the micro range, smoothing and leveling defects to a few thousandths of an inch in depth. Larger defects may never be removed by electropolishing, warranting a mechanical prefinishing step to complete the process. Electropolishing may smooth the part by up to 50 percent. To reduce the microfinish, you may need to mechanically polish before electropolishing.

What is the difference between Electropolishing and Passivation?

Electropolishing is the greatest form of passivation, but it has added value than just passivation. Passivation improves the chemistry of the surface (increases the Cr/Fe ratio) while electropolishing removes surface damage, improves the surface profile and cleanability, or smoothes the surface.

What is ASTM B912?

The ASTM B912 specification “covers the passivation of stainless steel alloys in the 200, 300, and 400 series, and the precipitation-hardened alloys, using electropolishing procedures.”

How large of a part can you polish?

Our capabilities allow us to process components of all sizes. While most process equipment may fit within our processing baths, we have developed proprietary techniques in order to electropolish components larger than our tanks. These proprietary techniques allow us to process equipment of any size at our facility or in the field.

Can you Electropolish at my facility?

Yes! Allegheny Surface Technology specializes in field services including electropolishing, mechanical polishing, passivation, and tank repair and modification. The repair and/or alterations of pressure vessels are performed to meet the requirements of the National Board inspection code and/or ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.

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