This is by far the most important quality of Hard Anodised coatings. All reputable companies should have the equipment to check abrasion against a recognised standard. These two methods are used by us and we are experienced with them.
THE TABER TEST
This method of abrasion resistance testing is dealt with in both the latest BS5599 and the U.S. AMS-A-8625.
It involves preparing a test piece of representative material, usually a disc about 100mm diameter, 3-6mm thick and hard anodising with a batch of production work. After suitable preparation the disc is weighed and then placed on the rotating table of the equipment. Two abrasive wheels bear down under a specified load onto the rotating test piece and after a specified number of cycles the test piece is weighed again. The results are quoted as a weight loss in mg. There are different acceptable values for weight loss for different alloys, as an indication the acceptable weight loss for a 2000 series (copper) alloy is 21/3 times higher for that of 1000, 3000 and 6000 series alloys.
WEAR COMPARISON - TABER ABRASER
| MATERIAL | SPECIFIC WEIGHT LOSS | HARDNESS (VPN) |
| Untreated aluminium alloy 6082 | 4 | 100 - 120 |
| Hard Anodised alloy 6082 | 0.3 - 0.35 | 400 - 460 |
| Stainless Steel | 2.2 | 300 - 350 |
| Mild Steel | 1.1 | 200 - 220 |
THE ABRASIVE WHEEL TEST
This method, depending on the design of the machine used can be more convenient than the Taber Test in that the test area can be a small flat surface on a non-critical part of a component. The SUGA method uses an abrasive strip mounted on a wheel, which bears under load on the sample surface. The wheel is not allowed to rotate but is pushed forward and retracted about 30-40 mm causing abrasive action on the surface. After each reciprocation the wheel is allowed to rotate through a small angle to reveal fresh abrasive. Once again a before and after weighing method is specified by the relevant standards and results are compared with a standard sample anodised to certain specifications. It is also possible to measure thickness loss very quickly using an eddy current meter, very useful for comparison.
