What Is Electropolishing?

Electropolishing is an electrochemical finishing technique for stainless steel and many other alloys that accomplishes a number of unique specific benefits. Essentially it is the opposite of electroplating, rather than depositing a metallic layer, metal is removed from the surface on a microscopic level.

The metal work piece to be electropolished is immersed in a temperature controlled electrolytic bath of a specifically blended acid formula and connected via a fixture or rack to the positive terminal of a DC power supply, making the part itself anodic (+). A series of stainless steel or copper  plates in the bath are installed to the negative side of the power source making them cathodic (-). When direct current is applied, the electrolyte acts as a conductor to allow an electrical circuit and metal ions on the surface of the positively charged part are oxidized and dissolved by being attracted towards the negatively charged cathode. Electric fields naturally focus on microscopic peaks, increasing the local removal rate over that of the valleys, resulting in a significantly smoother, brighter more reflective surface even with minimal material removal (5-10 microns). Also while ions are drawn to the cathode, gassing in the form of oxygen occurs at the metal surface, furthering the cleaning process.

In addition to the improvement of surface topography, electropolishing improves the surface chemistry of stainless steel. Not only does it remove embedded particles and inclusions, elemental iron is removed preferentially leaving the surface with a higher relative concentration of chromium. Upon exposure to oxygen, this improved surface will form a thicker and more uniform chromium  oxide layer achieving dramatically enhanced corrosion resistance properties. This makes electropolishing in many cases superior to traditional passivation.

In order to realize these results and the associated benefits, electropolishing must be properly executed. There is excellent, mediocre and poor quality electropolishing. To achieve the excellent,  correct maintenance of the electrolyte, fixturing, current density and timing, pre-cleaning (degreasing) and post rinsing, cleaning and drying, are just some of the critical steps to the art and science of  electropolishing. We have been achieving the excellent since 1993 while still meeting the the very strict environmental regulations of California, the Bay Area and Silicon Valley (San Jose-Santa Clara). We have the expertise, experience and of course all the necessary facilities and equipment to guarantee optimum results at a reasonable cost and timely delivery.