Electropolishing – sometimes also referred to as reverse plating or reverse electroplating – is a finishing process that improves the overall quality and durability of a wide range of machined metal parts. Most machining processes leave surfaces with imperceptible defects, while others occur naturally in the material. These tiny cracks, bumps, and burrs can greatly affect part performance, resulting in shortened product life or unpredictable component failures.
Unlike more abrasive metal polishing methods, electropolishing removes these defects entirely, leaving a smooth and even surface that’s completely free of blemishes—even at the microscopic level. This level of surface quality makes electropolishing an increasingly popular finishing process for many industries.
The Electropolishing Process
Electropolishing specifically refers to the process of positively charging a metal object and submerging it in an electrolyte-rich acid. Once in the chemical bath, a current is applied to the bath, and the electrolytes in the chemical solution react to the current to remove ions from the surface of the part. Any flaws in the surface of the object are peeled away by this process, revealing a fresh and flawless new surface.
This process is commonly used for:
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Deburring
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Increasing corrosion resistance
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Extending part life
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Microfinishing
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Improving aesthetic value (by creating more attractive surfaces, removing discoloration, etc.)
Electropolishing Benefits
Electropolishing offers significant advantages over passivation, as well as other more abrasive metal polishing techniques. These benefits include:
Smooth Surfaces
The primary benefit of electropolishing is the removal of imperfections. Even when a surface has only microscopic burrs, or when bumps and cracks exist only at a microscopic level, these blemishes can impact the function of parts, reduce part life, or lower conductivity.
Corrosion Resistance
While passivation – another chemical bath finishing technique – also increases corrosion resistance, electropolishing does so more effectively. Meanwhile, abrasive techniques often leave surfaces uneven or scratched, or push defects further into the material, leaving the door open for corrosive elements to enter the metal down the road.
Physical Appearance
Electropolishing provides a new, reflective surface that often looks even better than it did in its original mill quality.
No Contamination
Electropolished parts and surfaces no longer have microscopic crevices for bacteria or chemicals to get trapped in. This also means that electropolished surfaces can be cleaned without the risk of contamination by cleaning chemicals.
Better Functionality
Because electropolishing reduces surface drag and friction, electropolished parts enjoy a longer service life and increased functionality.
Flexibility
Unlike many metal finishing processes, electropolishing can be applied to small parts or parts with hard-to-finish corners. The process works the same regardless of the shape or size of the metal being finished.
Electropolishing Applications
Electropolishing has begun to gain traction across a wide variety of industries as manufacturers and their customers recognize its beneficial effects on their equipment. Electropolishing has become common in the following industries:
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Aerospace
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Semiconductor
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Electronics
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Automotive
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Appliances
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Scientific research
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Food and beverage
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Medical/dental equipment
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Pharmaceutical
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Lasers
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Agriculture
While these industries seemingly have little in common, in the end, they all require parts that are long-lasting, resistant to corrosion and contamination, or easy to sanitize and clean—all with an unparalleled surface finish. The unique benefits of electropolishing make it an ideal finishing technique for a broad spectrum of applications.
It may not be the best-known name in metal finishing processes, but electropolishing will no doubt continue to grow in popularity as industrial stakeholders recognize its benefits. If you use finished metal parts in your operation, electropolishing is definitely worth exploring.
Resources
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http://highlandequip.com/surfacefinishes.html
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https://www.mining-technology.com/contractors/machining/metal-science-technologies/pressreleases/what-is-electropolishing/
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https://www.mmsonline.com/blog/post/understanding-electropolishing
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http://www.machinedesign.com/materials/electropolishing-best-path-passive-parts
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http://www.ableelectropolishing.com/resources/common-applications/
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https://www.thefabricator.com/article/finishing/electropolishing-applications-and-techniques
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https://www.delstar.com/electropolishing-applications-guide
Image Credit: Akimov Igor/Shutterstock.com
