The purpose of thick anodic hard oxidation is to make aluminium and aluminium alloys highly wear- and abrasion-resistant with a skin hardness of approximately 400/600 Vickers, according to the alloys and thicknesses used. As this treatment is not a material facing but an actual surface change to the corresponding aluminium oxide, the layer resulting from the process will develop approximately half way inwards and half way outwards and evenly extend to the whole part surface. Therefore, in the part design phase in particular, dimensional changes must be taken into account in connection with the required thickness to treat.

To be able to obtain hard oxidation, the minimum required thickness is 25-30 microns and the ideally required thickness is 45-50 microns according to the alloy used. Hard oxidation is a self-colouring treatment, the obtained colours range from grey to bronze and to anthracite black, according to the alloy and thickness used. Hard oxidation can be completed with a PTFE (Teflon®) impregnation treatment to considerably improve the hard oxide friction coefficient.

This treatment becomes impregnated in the hard oxide layer without affecting the dimensions. The PTFE treatment is considered non-toxic, therefore, it can be safely used for parts intended for the food-processing and pharmaceutical industries. Hard oxidation can always be black coloured and in some cases, it can also be green, red or orange. In case of special customer tolerance requirements, a special protection can be applied before the actual treatment. This technique has a wide range of applications, from production to racing cars, from Formula 1 to motor boating, from Moto GP to off-road motorcycles, and from the aerospace to the packaging, pharmaceutical, textile, food, cycling and many other industries.