Electropolishing, sometimes referred to as "reverse plating", is an electrochemical process that uses an electrical current combined with a formulated bath of chemical electrolytes to remove imperfections, burrs and impurities from the surface of metal parts. It will level microscopic peaks and high points on the surface of the substrate creating a smoother more reflective finish. The finished surface is clean and bright. In many cases Electropolishing can take the place of more labor intensive and costly mechanical polishing operations. Electropolishing cleans the surface of the part and improves the corrosion resistance of the material. In addition, it is very effective at removing any discoloration on the surface caused by heat-treating or naturally occurring oxidation. Electropolishing can transform the surface of a dull, matte part and give it a highly polished, decorative appearance.
THE PROCESS:
Electropolishing is accomplished by creating an electrochemical cell in which the material to be polished is the anode. A cathode is formed to mirror the geometry of the work-surface and the two are submerged in a heated electrolyte bath. When current is applied, the electrical charge forces metal ions to be dissolved from the stainless steel work-surface.
The key to the electropolishing process is the difference in current density across the surface and the rate of the process is directly proportional to this current density. The increased current density at the raised points forces the metal to dissolve faster and levels the surface material. After the electropolishing treatment, the work-piece is passed through a series of steps to neutralize, rinse, clean and dry the surfaces.
Electropolishing delivers a smoother, more reflective surface that reduces product adhesion and improves surface clean ability. Electropolishing dissolves free iron, inclusions, and embedded particles from the surface of the part. This process improves the surface chemistry of the material, and promotes the formation of an improved corrosion resistant surface layer.
BENEFITS OF ELECTROPOLISHING:
Aesthetically appealing.
Polishes areas inaccessible by other polishing methods
Electropolishing improves surface reflectivity and brightness by leveling micro peaks/valleys
Removes impurities from the surface improving corrosion resistance of the part.
Can be used to chemically deburr a part.
Provides a clean and smooth surface that is easier to sterilize.
Improves the micro finish of the critical surfaces to improve sealing and fit.
SPECIFICATIONS:
ASME BPE Standards for Electropolishing Bioprocessing Equipment
SEMI F19, Electropolishing Specifications for Semiconductor Applications
ASTM B 912-00, Passivation of Stainless Steels Using Electropolishing
ASTM 1558, Standard Guide for Electrolytic Polishing of Metallographic Specimens
