The Difference between Anodizing Type II And Type III

In the previous article I have said that as a large-scale CNC machining factory, One of the biggest advantage is that we have our own anodizing workshop, can do normal anodizing and hard anodizing, which also called type II and type III , now I will focus on introduce these two kinds of anodizing.

In fact, aluminium billet is a kind of corrosion-resistant metal, it is especially easy to generate aluminium oxide by chemical reaction with oxygen in the air, but because the naturally formed oxide film is not uniform, resulting in the surface of aluminium alloy with different shades of colour, which is rather unsightly; on the other hand, the naturally formed oxide film is very thin, easy to scratch, and the corrosion resistance is relatively weak. So we usually choose to do normal anodizing after CNC machining, the artificial anodized film generated, uniform, dense and more corrosion-resistant.

On the other hand, the hardness of aluminium alloy can not be compared with steel. After anodizing of industrial aluminium profile surface is very hard, the hardness of the oxide film can reach 300HV, so it is very wear-resistant and not easy to scratch.

Finally, as aluminium alloy fittings are mostly used for decorations and handicrafts, which require high aesthetics, anodic oxidation can provide colourful colours, high-grade and exquisite, mainly for decoration.

Hard anodizing is called Type III, It's film thickness is usually 20um at least, hard anodizing of the film has 50% penetration in the aluminium alloy, 50% attached to the surface of the aluminium alloy, so hard anodizing of the external size of the product becomes larger, smaller holes,  we will also pay attention to the tolerance in the process of CNC machining, abrasion resistance will be better than the Type II; But the colour of hard oxidation is not as easy to oxidize as Type II, the price will be more expensive than type II. type III is mainly used for function, generally used for wear-resistant and electricity-resistant occasions, such as military products, aerospace parts