Electropolishing has become a common metal finishing process used in the aerospace industry to help improve the overall quality of metal components. These components come in many forms including high-performance fasteners, fittings, nozzles, housings, and welded assemblies. In order to maintain reliable performance, these components must be precisely manufactured and have an impeccable surface finish that is free of burrs and other contaminants.
Three key benefits of electropolishing are examined below.
One of the most valuable benefits of electropolishing is resistance to environmental hazards such as corrosion. Because the process removes a thin, uniform layer of surface material, it creates a passive, clean exterior, free of the iron deposits that can appear after welding or other secondary operations. Deterioration resulting from premature corrosion can change the metallurgical structure of a component, weakening its interior and damaging or loosening adjacent parts. Electropolishing, therefore, is specified to inhibit or retard corrosion and increase overall wear resistance. Electropolishing leaves a stainless steel part with a chromium-rich, passive surface that is much more resistant to corrosion. While electropolishing is often used to inhibit corrosion on stainless steel, it can be used on many other alloys as well. Numerous companies use the procedure to delay or hinder the corrosion properties of aluminum, copper, brass, carbon steel, and more.
Fatigue Life Improvement
The most significant benefit that aerospace engineers experience from electropolishing is fatigue life improvement. Metal parts used in helicopters and airplanes must be able to withstand stress and corrosion with long-term use and must meet highly demanding cycle life specifications. Whether the parts are machined or stamped, they will most likely exhibit surface anomalies that can lead to premature failure. These residual defects from manufacturing, often in the form of micro-cracks or pits, can become initiation sites for crack propagation or corrosion. By removing these imperfections on the surface of metal parts, engineers have found electropolishing to greatly improve the surface quality of components, which in turn leads to significant fatigue life improvement. Improving overall cycle life for flight-critical components is crucial for the industry.
The electropolishing process is suited for use on nearly any alloy and removes a uniform amount of material from the surface. It’s an effective solution for deburring and maintaining part integrity. It can remove the most marginal amount of metal from parts and adhere to precise specifications such as keeping corners sharp or preserving sealing surfaces and other critical features. It’s critical that the components used in the aerospace industry be free of contamination so as not to interfere with the functioning of the assembly. Premature failure due to the presence of foreign material can lead to equipment being idle or even critical in-flight problems. Electropolishing effectively removes any flecks of metal or contaminants that may be present from machining operations.