Anodizers are service providers of the anodizing process, creating anodized metals with increased wear and corrosion resistance. Anodizers are able to provide increased resistance by thickening the surface layer of the metal with a non-conductive oxide film, while reducing the overall weight of the metal.
While anodizers most frequently work with aluminum alloys, due to the decreased corrosion resistance that results from the addition of the alloyed elements such as copper, iron and silicon, they also work with various other metals including niobium, tantalum, magnesium, zinc, titanium and tungsten. As a result of the variety of workable metals, anodizers are able to provide metal materials and parts to a wide range of industries including: industrial manufacturing, for anodized bars, rods, angles and profiles used in various processing applications.
These applications include electronics, for protective encasings of a variety of electrical equipment; automotive, for use as the trim and the body of the vehicle; military, for small parts such as fine aluminum wire as well as large military aerospace parts; and medical, for surgical instruments and implants, to name just a few.
In addition, several industries have certain standards that anodizers should ideally adhere to such as the American Architectural Manufacturers Association (AAMA) standard 611-98, for anodized architectural aluminum.
Anodizers can use several different anodizing processes, ranging from the common to the experimental and obscure. The main difference between many of these processes is the type of acidic solution that is used. The two main types of acids used are chromic acid and sulfuric acid. Chromic acid refers to the H2 CrO4, which is an oxidizing acid family that the Environmental Protection Agency has placed restrictions on. The uses of certain types of this acid have been classified as a human carcinogen.
While emissions resulting from sulfuric acid, which refers to a strong mineral acid that is very similar to chromic acid, are also restricted by the EPA, it is considered less dangerous than the emission of chromic acid. However, there are some new developments in chromic acid that are much more environmentally-friendly. Additional acidic solutions used by anodizers include citric acid, phosphoric acid, boric acid and organic acids.
The two main types of anodizing processes that anodizers use are bath anodizing and anodic painting, although bath anodizing is more common in industrial applications. In bath anodizing the metal is fully immersed in the acidic solution, while in anodic painting the metal ferrule of a paint brush is dipped in the acidic solution and then used to apply it to the metal. As a result, anodizers typically use bath anodizing for mass production and anodic painting for smaller projects.