Aerospace, Medical, Food and Beverage and many other industries require reliable metal surface finishing methods.

In order to achieve the highest quality surface finish, manufacturers often choose electropolishing, which delivers precise, consistent, and repeatable results.

Electropolishing removes surface flaws from metal parts with microscopic precision using a rectified current and a chemical electrolyte bath.

The following alloys can be electropolished:

• 200-300 Series Stainless Steels
• 400 Series Stainless Steels
• Precipitating Hardening Grades
• Unusual Stainless Steels
• Copper Alloys
• Tool Steels
• Aluminum
• Titanium
• Nitinol
• Specialty Alloys
• Nickel Alloys
• Specialty Steels
• Carbon Steels

Are your metal surfaces experiencing any of these common problems?

Surface defects caused by machining operations include burrs, microcracks, staining, debris, and other imperfections. As a result, parts may perform less well, especially in assemblies involving metal surfaces. During electropolishing, imperfections are smoothed out to reveal a clean and bright surface that is defect-free.

A few of the most common surface problems that electropolishing can resolve are listed below.

The Electropolishing Solution for Metal Surface Defects

Burrs – Microdeburring can be effectively accomplished using electropolishing.

Surface Roughness – As a result of metalworking operations, contaminants and anomalies can be left behind. The process of electropolishing removes the outer skin of material from the part and improves its microfinish by up to 50%.

Staining, Peeling, Abrading – Electropolishing cleans surfaces and leaves them non-coating, non-distorting, stain-resistant, and brighter.

The susceptibility of a material to corrosion – Comparing electropolishing to passivation, electropolishing improves the chrome to iron ratio by 4%, resulting in 30X better corrosion resistance.

Reduced Lifespan – The electropolishing process has become a common method of improving the cycle life of metal parts that bend, twist, and flex.
Inadequate fit – Metal can be removed to within .0001″, improving the fit and function of critical metal components.

Electropolishing

Electropolishing is simply electroplating in reverse. Instead of depositing a coating of another material on a surface, the process of electropolishing is to remove a surface layer, typically 20 – 40 micrometres in depth, in the case of stainless steel.

Electropolishing requires a source of electrical current and a rectifier to convert from alternating current (A.C.) to direct current (D.C.). With the aid of busbars, the D.C. is transmitted to the job and cathode bars suspended over a tank containing an electrolyte solution, normally a mixture of acids.

Metal cathode (negative) sheets are suspended from the cathode bars into the electrolyte. The job to be electropolished is suspended from the anode (positive) bar into the electrolyte and adjacent to the cathode sheets.

When the current is switched on, metal removal from the component surfaces takes place in a controlled manner with micro-peaks being eroded preferentially. This results in a smoothing of the affected surfaces, whilst the macro-profile of the surfaces remains unaltered.

Careful selection of the process electrolyte solution allows electropolishing to be carried out on special metals such as titanium, copper and duplex materials, but it is in the treatment of stainless steel that it has found its greatest commercial application.

Benefits of Electropolishing

In many cases, electropolished stainless steel surfaces are bright and reflective. This results from the removal of an often contaminated surface layer and the electrochemical action of micro-smoothing.

The passive oxide layer, which is essential to prevent stainless steel from corroding, cannot be improved upon following electropolishing.

By reducing the total surface area, a result of micro-smoothing, unwanted products are less likely to adhere to an electropolished finish. In the same way, surfaces can be cleaned and kept clean more readily.

Friction is also reduced and the mechanism of preferentially removing surface high spots makes electropolishing suitable for eliminating fine burrs. The highly reflective bright finish is also suitable for a number of decorative applications, particularly where the shape of the item requiring polishing is extremely complex.