What You Should Know About Anodized Aluminum

Anodized aluminum machined parts are often an inexpensive way to harden the surface of the metal. The anodized parts are used in a variety of commonly seen devices including those in the medical field, art, handrails, appliances and jewelry. With all the uses, here is a little more information about what the anodization process entails.

Anodization Process

The anodization process requires submerging aluminum machined parts in an anodizing tank of sulfuric acid. The bath thoroughly coats the parts for a fully integrated coating. The hard surface has a thinner finish than other coatings such as powder coat. The process makes for a good electrical insulator, provides corrosion protection and long-lasting durability on a variety of common items including roofing.

Anodizing Types

Machined parts that are anodized come in two common types. Type III Hardcoat is a more expensive process using lower temperatures to create a harder, thicker coating. Type II uses regular sulfuric anodizing to create very head coatings. Type II usually has a coating around 0.002” thick versus Type III’s 0.006”. Type II anodized specifically for architectural purposes features a metallic ion dying.

Metal Defects

Common defects in the aluminum to be anodized include extrusions, poorly machined surfaces, welds and cold or hot-worked areas. These issues can cause problems with the anodization process due to the nature of the conversion coating. In order for the proper formation of the anodized layer, the aluminum finish should be fully exposed, consistent and clean to avoid negative effects during the anodization process.

In addition to the standard silver color, architectural equipment uses a 2-step electrolytic dying process for a fade-resistant coloring. Anodized parts resist corrosion and are extremely durable but must be cleaned using mild soaps or alcohol. Anything with lye or ammonia should be avoided as strong acids can damage the metal. The metal is a great material to engrave markings.