What is Electropolishing?
Electropolishing is an electrochemical and reverse plating process that removes the outer layer of “skin” on a metal part to address microscopic imperfections within its finish—instead of electroplating, which deposits metal onto the finished surface.
Electropolishing will smooth and streamline the microscopic surface of most metal objects, improve surface finish, improve corrosion resistance and achieve passivation—typically stainless steel or similar alloys. Electropolishing typically takes off between 0.0002 and 0.0003 of an inch from the surface of an object.
The process may improve the surface finish of your metal part by 10%-40% (depending on part tolerances and surface finish) or more—rendering the surface of the metal microscopically featureless and void of any tiny imperfections. Often, during a standard run, total material removal is limited between 0.0002” to 0.0003” per surface—but the removal rate can be adjusted depending on a part’s tolerances.
It’s important to note that electropolishing only improves the surface of a metal part on a microscopic level. Any macroscopic textures or surface scratches will only result in a smoother texture or smoothed scratch if taken through the electropolishing process. For macroscopic surface imperfections, mass finishing is the more appropriate process for the job.
How do we do it? We first load the parts onto racks, which we dip into a tank filled with a phosphoric and sulfuric acid solution. The tank is lined with metal plates that function as cathodes so we can run a positive electric current through the bath.
We can adjust the removal rate to a specified tolerance, and we check throughout our process to ensure we are meeting the targets we set. This is especially important during electropolishing of large batches of parts, so we ensure that our quality is consistent from the first part to the last.
Can Electropolishing Achieve Passivation? Yes.
Passivation is the removal of free iron from the surface of a part. Electropolishing will remove free iron, as well as de-burr and deeply clean the surface. This can be especially important when you have small parts with trace amounts of free iron and micro-burrs.
To learn more about Electropolising, please watch the video on this page.
before and after examples
High Treated Machined Parts
Our small part electropolishing process will remove heat scale and contaminates on a parts’ surface while keeping material removal to a minimum (.0001-.0002” precision).
Electropolishing removes weld discoloration while producing a mirror finish that is corrosion resistant.
Oxide is removed through Electropolishing creating a mirror finish.
Small Electropolished Rings & Tubes
OD and ID finishing of High Purity Ring-Internal Ra 8.
What is Electropolishing?
Electropolishing is an electrochemical and reverse plating process that removes the outer layer of skin on a metal...
The Electropolishing Process
The electropolishing process is initiated by immersing a metal part into a temperature-controlled bath of electrolyte...
How Much Material Does Electropolishing Remove?
Electropolishing, when done properly is a highly controllable process which removes as little as...
How Much Will Electropolishing Improve the Surface of my Part?
Ra and RMS are both representations of surface roughness. Ra is calculated as the roughness average of a surface’s...
What is ASTM B912?
ASTM B912 is an industry standard for the passivation of stainless steel alloys through electropolishing...
What is ASTM A967
ASTM A967 is an industry standard specification for the chemical passivation treatments for stainless...