The electropolishing process, when applied to stainless steel, polishes, passivates, and deburrs, removing imperfections and leaving a smooth, uniform finish. The process not only extends the life of the metal, but offers cosmetic benefits as well.
Once electropolished, stainless steel is rust-proof. For this reason alone, the electropolishing process is commonly employed in the marine, aerospace, and pharmaceutical industries, among others.
In addition, many of the chemicals and nature-based solutions used in newly improved methods for the electropolishing process are relatively environmentally-friendly, especially when compared to those used in the metal plating industries.
Electropolishing, as a process, is fairly simple and straightforward, even though its results make it seem nearly magical. The process consists of a piece of metal being immersed in a temperature controlled bath of electrolyte and connected to the positive terminal (anode) of a DC power supply with the negative terminal being attached to an auxiliary electrode (cathode). An electrical current is then passed through the anode where metal on the surface is oxidized and dissolved in the electrolyte. At the cathode, a reduction reaction, normally hydrogen evolution, takes place. The results are amazing and the benefits numerous, but as you can see, the process is almost unremarkable.
Basically, electropolishing is electro-plating in reverse. But instead of depositing a coating of another material on a surface, the action of electropolishing removes a surface layer, typically 20-40 microns in depth in the case of stainless steel. This removal of an often contaminated surface layer and the electrochemical action of micro-smoothing results in electropolished stainless steel surfaces being bright and highly reflective and the advantages are many.
As the result of electropolishing, the passive oxide layer — which is essential in preventing stainless steel from corroding — is optimized. This optimization or micro-smoothing means that the total surface area has been reduced and that contaminants and/or unwanted debris are less likely to adhere to the finish. This means products not only stay cleaner, but that surfaces that do get dirty can be cleaned more easily. In addition, surface friction is reduced and the mechanism of preferentially removing surface high spots makes electropolishing ideal for eliminating fine burrs. Aesthetically, the highly reflective bright finish achieved through electropolishing is ideally suited for decorative applications, particularly where the shape of the item requiring polishing is extremely complex.
Today, many industries benefit from the advantages electropolishing provides. Some of these industries are:
- Food and beverage
- Paper and Pulp
- High Vacuum