Metal Pickling vs. Electropolishing

Metal pickling and electropolishing are both metal finishing treatments that can remove surface impurities and contaminants. However, electropolishing continuously proves to be the leading treatment for metal parts made from both specialty and common alloys. Read on to learn about metal pickling and electropolishing, as well as why electropolishing is the most beneficial treatment for parts.

WHAT IS METAL PICKLING?

Metal pickling is a metal finishing process that utilizes acids, generally hydrochloric or sulfuric acid, to remove surface impurities. This finishing process can remove stains, rust, scale and contaminants. However, it is often too corrosive for some metal alloys and causes the surface to become etched and can lead to intergranular attack.

How does Electropolishing Work?

Electropolishing is highly effective metal finishing treatment utilized by various industries, including medical, automotive, food service, dental, pharmaceutical and more, as the “final step” of the manufacturing process. This “reverse plating” treatment utilizes an electrolyte bath and rectified current to remove a uniform layer of surface material from parts. To begin the process, an electropolishing specialist submerses parts in a phosphoric-based electrolyte chemical bath.

A power source will then convert AC current to DC at low voltages and metal ions are removed from the parts’ surfaces. Parts are then rinsed and dried. Electropolishing is a suitable treatment that provides long-lasting benefits to metal parts of a variety of common and specialty alloys, including titanium, copper, stainless steels, carbon steels, Nitinol, aluminum, tungsten and more.

Exceptional Benefits of Electropolishing

Overall, metal pickling cannot provide the same level of metal finishing that electropolishing can. Electropolished parts have superior improvements for a variety of aspects, including:

  1. Corrosion resistance—Untreated metal parts can develop rust over the course of time. Electropolishing is one of the most effective metal finishing treatments to improve corrosion resistance. Because electropolishing removes a uniform layer of surface material from metal parts, it also effectively eliminates initiation sites for corrosion.
  2. Microfinish value—Metal parts that have not undergone electropolishing may have micro cracks that, while not immediately concerning, could prove to be a threat to parts performance and their life span. To proactively prevent part failure, many companies submit parts for electropolishing for microfinish improvement.
  3. Deburred edges—Metal parts may have burrs or jagged edges that are unsuitable or unsafe for various applications. Electropolishing can create smooth edges by removing a thin layer from parts’ surfaces.
  4. Ultracleaning—Electropolishing removes the amorphous layer on metal parts, which eliminates any embedded contaminants and impurities. After treatment, metal parts can be used for applications that require sanitary or sterile objects, such as those in the food service or medical industry.
  5. Decorative finish—Untreated metal parts may be dull or aesthetically displeasing. Electropolishing produces a bright, shiny surface that adds an additional benefit to parts.

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Pickling vs. Passivation

Along with electropolishing, passivation is a commonly used process to form a more polished metal surface. Passivation is different from pickling in that it doesn't utilize acid. However, when it comes to the battle of pickling vs. passivation when determining which process to use to form smoother parts, electropolishing is still the best solution in many cases. Passivation doesn't often effectively deburr metal parts, only leaving a superficial polish compared to electropolishing's more thorough process.

Ultimately, if you want to successfully deburr and polish your metal parts, electropolishing is often ideal compared to both pickling and passivation processes.

Want to learn more about the advantages of electropolishing vs. pickling? Contact the specialists at Able Electropolishing today.

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