Hard anodizing (hardcoat) is anodizing to produce a coating where high wear resistance or microhardness is its primary characteristic. It is used mainly for engineering purposes. Examples of hard anodized products can be valves, sliding parts, hinge mechanisms, cams, gears, swivel joints, pistons, pulleys, valve blocks, rod ends and food chutes.
Secondary treatment such as impregnation with solid film lubricants and coloured dyes can be applied.
Anodic oxidation coatings consist of aluminium oxide and are hard and wear-resistant. They can scratch glass. This means that anodized aluminium resists abrasion and erosion to a greater extent than most metals, which makes it ideal for many engineering applications.
Important product quality criteria include:
- visible defects
- coating thickness
- wear resistance
- final dimensional tolerances
Protection against corrosion of the aluminium and friction coefficient after lubrication can also be important depending on application.
The inspection of QUALANOD-licensed anodizing plants includes the testing of samples of anodized products to verify that the correct quality is being achieved.