Disclaimer: Please note that Graepels does not provide finishing services directly. These services are handled by third parties. The information provided here is intended as a guide to offer an overview of the available finishes and other relevant details.

Understanding Electropolishing

Electropolishing, otherwise known as ‘Anodic’ or ‘Electrolytic Polishing’, is an electrochemical process whereby the surface metal is removed by anodic dissolution. Micro material particles are removed thus smoothing the surface of the material.
Electropolishing is sometimes referred to as ‘reverse plating’. This is because the process starts by removing the high points within the microscopic surface texture. Removing the high points of the surface metal results in a smoother more reflective surface finish.

Benefits of Electropolishing for Perforated Metal

Improved Surface Finish:

Smoothness: Electropolishing removes a thin layer of material from the surface, resulting in a smooth, mirror-like finish. This is particularly beneficial for perforated metal, as it reduces rough edges around the perforations and enhances the overall appearance.
Aesthetics: The process provides a shiny, clean surface that is visually appealing and often required for decorative applications.

Enhanced Corrosion Resistance:

Oxide Layer: By removing surface impurities and contaminants, electropolishing helps to form a uniform and protective oxide layer, particularly on stainless steel. This layer significantly improves corrosion resistance, which is crucial for applications in harsh environments.

Improved Cleanability and Hygienic Properties:

Smooth Surfaces: The smoother surface achieved through electropolishing is easier to clean and less likely to harbor contaminants or bacteria, making it ideal for industries such as food processing, pharmaceuticals, and medical devices.

Reduced Friction and Wear:

Surface Quality: The removal of microscopic burrs and surface irregularities reduces friction, which can enhance the performance and lifespan of components subjected to mechanical movement or contact.

Stress Relief:

Microstructural Benefits: Electropolishing can reduce residual stresses in the surface layer of metals, potentially improving the mechanical properties and performance of the metal in demanding applications.

Non mechanical processes: The process for electropolishing requires no tools, which means there are no marks created during the polishing including that of directional polishing lines. The material is left with a microscopically smooth surface

Corrosion resistance: Electropolishing offers up to 30 times more corrosion protection than the standard mill finishes.
Uniform finish: Unlike other metal coatings, Electropolishing offers a uniform and regular finish that is bright and reflective micro finish.

Micro finishes: Electropolishing, although aesthetically pleasing, is also functional. Superior micro finishes improve seals, lower friction, reduce real surface area, provide easier sanitation and improve light and heat reflection. Electropolishing is not a surface coating. There is no risk of the surface distorting or pealing over time.
Complex and Fragile Components: can be electropolished to ensure they are not damaged. Other methods for removing points and projections can involve grinding or vibration, whereas electropolishing is a non-mechanical and softer approach to polishing particularly where complex and fragile parts are concerned
Surface Preparation: Electropolishing effectively prepares the surface of a material for further processing or finishing like plating, anodizing or welding

Issues and Challenges in Electropolishing Perforated Metal

Material Considerations: Not all metals are equally suitable for electropolishing. Stainless steel and aluminum are commonly electropolished.

Cost Factors: The set-up and maintenance of electropolishing equipment can be costly. Additionally, the process itself can be more expensive than other finishing methods like mechanical polishing or chemical passivation.

Thickness Uniformity: Electropolishing generally provides a uniform finish, however perforated metals can present challenges in achieving uniform thickness removal, but this is usually the case if the perforations vary in size and distribution. Consistency in perforation spec should avoid this.

Subsurface Defects: While electropolishing enhances the surface finish, it cannot repair or mask deeper surface defects such as scratches, pits, or inclusions. Such defects need to be addressed before electropolishing.

Electropolishing Process

Electrolyte Bath Preparation
Composition: Prepare the electrolyte bath, typically a mixture of acids such as sulfuric acid and phosphoric acid. The exact composition can vary depending on the material being electropolished.
Temperature: Maintain the bath at the required temperature, usually between 50-90°C (122-194°F), to optimize the polishing action.

• Current Application: Submerge the metal in the electrolyte bath and apply a direct current. The metal to be polished acts as the anode, and a suitable cathode material is used.
• Dissolution: The applied current causes metal ions to dissolve from the surface, preferentially removing high points and resulting in a smoother surface.
• Time Control: Control the duration of the process to achieve the desired level of polishing without over-polishing, which could thin the metal excessively.

Typical Applications of Electropolishing

• Food Processing Equipment
• Medical Equipment
• Pharmaceutical Processing Equipment
• Automotive Industry
• Architectural
• Chemical Plant & Equipment