What is Type II Anodizing and What are its Benefits

Anodizing is an electrochemical process using which aluminum is being turned into aluminum oxide on the surface of a component. Anodizing is done to raise the thickness of the natural oxide layer on the surface of metal parts. Since Type II anodizing is common, die casters can make a porous surface finish, which can accept the die easily.

Although dying is not mandatory for successful coating, the dies can be added for coloring the metal parts in anodizing. The anodizing process includes pre-treatment, rinsing, etching, desmutting, anodizing, coloring, and sealing in aluminum die casting. The aluminum coating will be grown from and be turned into the surface of aluminum dies.

The process is simple and comprises of an anodizing solution usually comprising of sulfuric acid. Sulfuric anodizes are formed via an electrolytic solution of sulfuric acid at room temperatures and a voltage density of 15 to 22 amps per square feet. A cathode will be connected to the negative terminal of a voltage source and be placed in the solution in Type II anodizing.

When the circuit gets on the oxygen in the anodizing solution will be freed from the molecules of water and will combine with the aluminum on the component forming an aluminum oxide coating. The process tends to take around half an hour or an hour based on the alloy used.

Certain conditions like electrolyte concentration, acidity, solution temperature, and voltage can be controlled to permit the formation of a consistent oxide layer. Thicker films will be made by dilute solutions at low temperatures with high voltage. The film thickness may range from under 0.5 micrometers for cosmetic effects, to up to 150 micrometers for architectural applications.

Anodizing will increase corrosion resistance as well as wear resistance of aluminum parts and will provide better adhesion for glues and paint primers than bare metal. Anodic films are used for cosmetic effects, either with thick porous coatings, which will absorb dies, or with thin coatings that will add interference effects to reflected light.

Anodizing is a post-treatment process in aluminum die casting and is considered safe for the environment. Anodizing is also used to make dialectic films for electrolytic capacitors or to impart anti-galling properties on the threaded parts. Black hard anodizing makes the aluminum alloys corrosion resistant.