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This article discusses several current practical applications of electropolishing and/or passivation. The emphasis is not on these processes alone, but rather in combination with conventional mechanical finishing, i.e. abrasive belting, polishing/buffing, and blasting. More specifically, this paper examines ways mechanical finishing combined with electropolishing provides levels of smoothness, cleanliness, and corrosion resistance beyond that of mechanical finishing alone. This discussion is limited to stainless steel base materials. Areas of interest include recent trends in electropolishing, quality considerations, costs, packaging, off-site or field applications, and environmental considerations.
Electropolishing has been practiced commercially since the 1930’s. The first widespread use of electropolishing was primarily to add cosmetic appeal to consumer goods such as cookware and fountain pens. In recent years, the emphasis has shifted to engineering applications, especially in the food, medical, pharmaceutical and semiconductor industries.
Electropolishing is the electrochemical dissolution of a metal surface to improve the smoothness, reflectivity, cleanliness, passivity, or some combination of these surface characteristics.
Electropolishing is a “micro” metal removal process as opposed to conventional mechanical finishing processes, which are “macro” metal removal/distortion processes. As such, it can easily complement mechanical surface finishing processes such as rolling, grinding, blasting, and polishing and buffing.
While the reflectivity, sparkle, and shine produced by electropolishing are obvious to the eye, some of the more subtle effects are apparent only through more sophisticated examination, such as surface chemical analysis, profilometry and in-service performance trials.
Nearly all metals and alloys can be electropolished, but in actual practice, stainless steel accounts for the greatest majority of commercial electropolishing. The inherent strength and corrosion resistance of stainless steel makes it the material of choice for process equipment and many consumer products.