Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. The anodic oxide structure originates from the aluminum substrate and is composed entirely of aluminum oxide. This aluminum oxide is not applied to the surface like paint, but is fully integrated with the underlying aluminum substrate. It has a highly ordered, porous structure that allows for secondary processes such as coloring and sealing.
Anodizing is accomplished by immersing the aluminum into an acid electrolyte bath and passing an electric current through the medium. A cathode is mounted to the inside of the anodizing tank; the aluminum acts as an anode, so that oxygen ions are released from the electrolyte to combine with the aluminum atoms at the surface of the part being anodized. Anodizing is, therefore, a matter of highly controlled oxidation the enhancement of a naturally occurring phenomenon.
Anodized Aluminum, whether sulfuric acid anodize type II or hard coat anodize type III, is the most effective way to finish aluminum components. A large benefit of specifying an anodize finish, is durability. Since anodizing is a reacted finish that is integrated with the underlying aluminum, the impact and corrosion resistance is superior. For the same reason, the adhesion is unmatched by other finishes as well. It will not crack, chip, peel etc.
Color and gloss stability, with exposure to UV rays is also very good, with repeatable color ranges. Since, selection, matching and measuring color is a full subject for discussion on it’s own, I recommend contacting Forge Metal Finishing to discuss.
Often used in the defense and aerospace industries for several reasons. Not the least important of which is speed. Many complex components can be finished quickly with few steps and handling. This establishes predictable delivery schedules with consistent quality results.
Medical and dental equipment are also markets served by aluminum anodizers. Anodized products and components are used in a large number of applications in medical and dental equipment manufacturing, including blood handling equipment, regulators, oxygen equipment, hospital and emergency room apparatus, instruments durable enough to be sterilized repeatedly, and many more.
In my mind, the most important benefit of an anodize finish, is the ability to maintain dimensional integrity. Depending on the requirements of the component, a thickness range or a 0 change can be achieved and measured, to satisfy the contract manufacturer and the OEM.
It is also important that an anodizer is selected using a recognized quality system in place, such as having NADCAP accreditation.