More about Electropolishing

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The electropolishing process is used on metal surfaces. It is the reverse of electroplating in that it uses an electrolytic circuit to remove material from the surface rather than deposit it. When a metal work-piece is electropolished, it is placed in an electrolyte bath and connected to a DC power source. This creates a DC electrolytic circuit that uses the work-piece as the anode. Here, an anode is the component of an electrolytic circuit that gives off electrons due to the chemical reaction activated by the electric voltage—it is where oxidation occurs.

As the current is sent through the circuit, a minute layer of material is stripped from the surface. Any layer removal of more than a thousandth of an inch ceases to be cost-effective, and other finishing services may be a better choice. For the right surfaces, however, especially those that were somewhat smooth before undergoing electropolish, the process can create an ultra smooth finish. During the electropolishing process, the size and placement of the cathode has significant bearing on the operation.

Although now used to polish a variety of stainless steel and metal products, electropolishing was first used to prepare various metals for microscopic observation. In some steel surfaces, electropolishing leaves an extremely fine, chromium-enriched layer. This passivates the surface, thereby providing an added benefit to the process. It also improves surfaces by smoothing peaks and cavities, and provides a stress and occlusion free polish. Electropolishing is a good option for odd shapes that are otherwise difficult to finish, as well as for high-precision components that need a near perfect surface.

Among the other benefits of electropolishing is that it emits no toxic fumes or chemicals, and electrolytic baths are well controlled by service companies. The process dates back more than 45 years, and significant improvements have been made during the time since its inception. Newer electrolytes have made it possible to perform the operation on a wider variety of metals, and have helped increase production capabilities.