Many customers ask us the difference between Electropolishing and Passivation so we wanted to take a moment and dispel some of the myths.
Electropolishing is a subtractive electro chemical process which removes material from a metallic product. It can also be called electrochemical polishing or electrolytic polishing but the process is the same. It is used to polish, passivate, and deburr metal parts and is used instead of abrasive processes for metal finishing. The end result is a cleaner, smoother and shinier finish on metal parts. Passivation is done to stainless steel to make it less "passive" or in other less affected by outside element and corrosion. It is a light coat of material, such as metal oxide to protect against the elements. Often passivation is a smaller part of the electropolishing process.
Electropolishing is almost always going to cost more. Due to the electrochemical process involved in electropolishing each part needs to be attached individually to an electricity passing fixture. In passivation, the parts can be group batched into a system. In almost all passivation cases, the parts must be agitated so that the whole part is exposed to the passivation fluids. Since the parts do not need to be individually fixtured, passivation is more affordable.
The finish difference between passivation and electropolishing can be seen with the naked eye. Electropolishing has a shinier surface which you can see visually. Under a microscope you can also see that parts are smoother after electropolishing. Passivation adds is a light coat of material, such as metal oxide to protect against the elements. It makes the wire more passive.
We can't really answer that question. Depending on your industry and product there are a variety of standards which must be achieved. Often, passivation will be the "minimum" needed to achieve your standards. Electropolishing tends to be more suited to the marketability and appearance of your product. Double check your ASTM standards to see whether or not both Electropolishing and Passivation are needed for your product.