Electropolishing smooths the microscopic surface of stainless steel objects by removing metal from the object’s surface through an electrochemical process, leaving it bright, clean and microscopically smooth.
Our Electropolishing Service
We are proud to offer our electropolishing service direct from our Ormeau factory, located on the Gold Coast, Queensland.
Process of Electropolishing
Electropolishing is the reverse of electroplating.
During electropolishing, metal is removed ion by ion from the surface of the stainless steel object. Electropolishing is most advantageous when replacing traditional mechanical finishing such as grinding, milling, blasting and buffing as the final finish. However, depending on the condition of the stainless surface these traditional methods are more often than not required prior to electropolishing in order to gain a better electropolished finish.
During electropolishing stainless steel is immersed in an electrolyte solution and subjected to a direct electrical current. The object is maintained anodic, with the cathodic connection being made to a nearby metal conductor. The stainless being electropolished becomes sacrificial while the electric current removes and smooths its surface.
Smoothness of the metal surface is a primary and very advantageous effect of electropolishing.
During the process, a film of varying thickness covers the surfaces of the metal. This film is thickest over micro-depressions and thinnest over micro-projections. Electrical resistance is at a minimum wherever the film is thinnest, resulting in the greatest rate of metallic dissolution. Electropolishing selectively removes microscopic high points or “peaks” much faster than the corresponding rate of attack on the corresponding micro-depressions or “valleys.”
Benefits of Electropolishing
Better Physical Appearance:
- No fine directional lines from abrasive polishing
- Excellent light reflection and depth of clarity
- Bright, smooth polish; uniform shaped parts
Better Corrosion Protection:
Electropolishing yields maximum tarnish and corrosion resistance in many metals and alloys. Stainless steel contains metallic and non-metallic inclusions, which are unavoidably included during manufacture. Mechanical polishing not only fails to remove inclusions, but also tends to push them further into the surface and even increase them by further pick-up of abrasive materials. These inclusions eventually can become points of corrosion
Ease of Cleaning:
- Substantially reduces product contamination and adhesion due to the microscopic smoothness of an electropolished surface (much like a glass surface)
- Decreases cleaning time. Electropolished surfaces are much easier to clean than a surface that has not been electropolished
- Improves sterilisation and maintenance of hygienically clean surfaces for food, drug, beverage and chemical processing equipment
- Provides the best passivation of stainless steel
- Removes cold-worked metal oxides
- Simultaneously deburrs sharp edges as it polishes. This is at the microscopic level. Sheet metal still need to be manually deburred before Electropolishing
- Polishes areas inaccessible by other methods
- Reveals flaws in metal surfaces undetectable by other means. Electropolishing is one of the most effective inspection tools for inspecting metal surfaces
Enhanced Mechanical Properties:
- Less friction and surface drag
- Increased production in process equipment. Electropolishing greatly reduces fouling, plugging, scaling and product build-up
- Surface retains the true grain structure and properties of the bulk metal
- Fatigue strength is not reduced. Electropolishing allows the true fatigue strength of a part to be accurately determined
- Higher fatigue strength can be promoted by particle-blasting the surface to reintroduce compressive stress without losing electropolishing’s advantages
- Stress-relieving of the surface
What metals can be Electropolished
Most metals can be electropolished successfully, but the best results are Obtained with metals with fine grain boundaries that are free of non-metallic Inclusions and seams. Those metals having a high content of silicon, lead or sulphur are usually difficult.
Stainless steels are the most frequently electropolished alloys. Wrought alloys will generally have a better finish than castings which polish to a bright finish but not to the same brightness or smoothness. Other Commercially Electropolished
- Low and High Carbon Steels
- Tool Steels
- High Temperature Alloys (Molybdenum, Nimonic, Waspaloy, Tungsten)
- Leaded Steel (Low-Lead)
- Nickel Silver
- Beryllium Copper
- Silver and Gold
It is not common for many of the above metals to be electropolished as set up costs and the need to perform in polishing in large batched can be extremely costly.
Southern Stainless has an in-house Electropolishing facility incorporates an Electropolishing Bath that is 4m Long x 1.1m Wide x 1.7m Deep which is set-up for Electropolishing stainless steel only.
If you require items longer than 4mts to be electropolished we are able to “double dip”. When this occurs and there is an overlap on the material that in-turn get polished on two occasions there may be slightly more shiny effect on this location.
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