The hard anodizing is also known as hard coat anodizing or anodizing type III.

There is no essential difference between the principle of hard anodizing of pure sulfuric acid type aluminium alloy and ordinary anodizing. The main purpose of hard anodizing of aluminium parts is to improve various properties of aluminium and aluminium alloy. Such as corrosion resistance, wear resistance, weather resistance, insulation and adsorption. The anodizing type III is not only suitable for deformed aluminium alloy, but also for die casting aluminium alloy parts.

Hard Anodized As Machined

Generally, the thickness of hard anodizing  film is ranging from 13- 150μm. 

Regarding to the hard anodizing films which thickness are less than 25μm, they will be used for the parts of tooth keys and spirals. The thickness of the Hard anodizing film for wear resistance or insulation is about 50μm. Under certain special process conditions, it is required to produce a hard anodizing  film with a thickness of 125μm or more. However, it must be noted that the thicker the hard anodizing  film, the lower the micro hardness of the outer layer can be, and the roughness of the film surface will increase.

Usually, our standard thickness of the aluminium alloy hard anodized film is 25-50μm.

Matt Black Hard Anodized with sandblasted