Aluminum is used more and more today due to the reasonable cost, ease of machining and light weight. The only negative issue that arises with aluminum is the limited metal finishing options. Unlike stainless steels, you cannot passivate aluminum in order to remove the contaminants on the surface. In addition, there are few options for improving microfinish after machining. Electropolishing is an effective means for providing a part that has an enhanced surface finish and clean surface. Many companies use the electropolishing for parts that are assembled in a clean room, such as laser components.
Aluminum is generally separated two main categories: casting and wrought alloys. Casting alloys are comprised of high amounts of silicon. This lends the casting alloys their low melting points and decent fluidity. But at the same time, lessens their desirable smooth finish.
Wrought alloys have significantly different compositions and microstructures from casting alloys. A wrought aluminum part that has been electropolished will exhibit an improved surface and will be contaminant-free. The surface will also display a shiny finish.
Common aluminum alloys and the results that can be achieved through electropolishing:
| ALUMINUM | COMMENT |
|---|---|
| 1008 | Good Bright Finish After Electropolishing |
| 1100 | Excellent Mirror Type Finish After Electropolishing |
| 2014 | Satin-Pitted Finish – Not Suited for Electropolishing |
| 2024 | Bright Finish After Electropolislhing (Slight Pitting) |
| 3003 | Good Reflective Finish After Electropolishing |
| 4032 | Gray Finish – May Come Out Better With More S/R |
| 5052 | Good Reflective Finish After Electropolishing |
| 5086 | Good Bright Finish After Electropolishing |
| 5350 (Cast) | Bright Finish After Electropolishing (Pitted) |
| 5657 | Good Bright Finish After Electropolishing |
| 6061 | Good Bright Finish After Electropolishing |
| 6082 | Good Bright Finish After Electropolishing |
| 6105-T5 | Excellent Finish After Electropolishing |
| 6463 | Bright Finish After Electropolishing (Some Pitting) |
| 7050 | Good Bright Finish After Electropolishing |
| 7073 | Good Bright Finish After Electropolishing |
| 7075 | Good Bright Finish After Electropolishing |
| Al Cu 31 | Bright Finish After Electropolishing (Pitted & Rough) |
| Al EA70-2 | Very Bright Finish After Electropolishing |
| ALUZINC | Good Finish After Electropolishing (Some Pitting) |
| 2011 | (Bright Finish After Electropolishing (Slight Pitting) |
Why electropolish aluminum? Corrosion always begins on or near the metal’s surface. Unfortunately, all handling and fabricating procedures will eventually degrade the surface integrity and properties. Surface contaminants, including metallic particles, iron, dirt, and grease are a fundamental part of welding, machining, and other fabrication procedures. Mechanical polishing, cutting, handling, and polishing tend to result in extraneous iron and other abrasive particles that are embedded within the surface of the material. These surface contaminants break down the aluminums’ naturally occurring corrosion resistant oxide layer and are often the site where corrosion begins. The electropolishing process dissolves a minute layer of surface material and contaminants, thus freeing embedded particles and increasing the part’s lifespan.
Ultimately, electropolished aluminum will increase the part’s resistance to pitting, localized galvanic corrosion, surface corrosion, crevice corrosion, cracking, stress corrosion, and microbiological corrosion.
At Able Electropolishing, we perform our signature electropolishing treatment on a variety of metal alloys, including aluminum. Following our treatment, parts have an enhanced corrosion resistance, improved microfinish, and are clean and free of harmful contaminants. Along with the commonly used 6061 aluminum, our process is suitable with other alloys such as 1100, 3003, 5002 and 7075.
Contact us to see how we can utilize our metal finishing capabilities for your aluminum parts.
