Electropolished

Electropolished refers to a metal surface that has undergone electropolishing, an electrochemical finishing process used to produce a smooth, bright, and uniform surface. In the process, the workpiece is made the anode in a controlled electrolyte bath, often containing sulfuric and phosphoric acids with water and additives. When current is applied, material is dissolved preferentially from microscopic peaks rather than valleys, producing a leveling effect that reduces roughness and removes embedded contaminants.

Common materials treated by electropolishing include stainless steel (notably grade 304 and 316), aluminum, nickel alloys, titanium, and copper alloys. The resulting surfaces are typically described as ultra-smooth and highly uniform, with improved cleanliness and aesthetic appearance. Electropolished finishes are widely used in industries where corrosion resistance, hygiene, and ease of cleaning are important, such as food and beverage equipment, pharmaceutical and medical devices, semiconductor hardware, and aerospace components.

Advantages of electropolishing include reduced surface roughness, improved corrosion resistance due to a more uniform passive layer, and enhanced cleanability and sterility. It can also improve surface integrity by removing micro-pores, inclusions, and surface defects that act as initiation sites for corrosion or bacteria adhesion. Disadvantages include higher cost and equipment requirements, potential dimensional changes on thin or delicate parts, and the need for proper waste handling and post-treatment steps such as passivation for stainless steels.

Electropolishing is differentiated from mechanical polishing by its material-removal mechanism and its ability to produce a consistently smooth, defect-free surface across complex geometries.