Aluminum Anodizing

Anodizing is a process in which, a thin film of oxide is formed over the aluminum. This is in fact grown out of the metal, which is likely to peel from the substrate. This film is known as Aluminum oxide, a very rigid, corrosion resistant and hard shielding layer. For this reason aluminum oxide layer makes it the ideal and often considered as the number one choice for the restorer of vehicles with aluminum trim etc. Due to the resistance of the Anodize finish, it is perfect for areas where scraping from road grit is likely to create a trouble. It can be considered permanent or long lasting if the part is polished before the process is carried out. The polish can be finished to appear like a chrome plate, and no further buffing will be necessary.

Aluminum anodizing is generally carried out in an acid solution that gradually dissolves the aluminum oxide that results in the formation of a coating with microscopic pores. These pores permit the electrolyte solution and current to access the aluminum substrate and carry on the growth the coating to larger thickness beyond what is formed by autopassivation. On the other hand, these pores will later on allow air or water to contact with the substrate and begin corrosion if not sealed. These pores are often filled with colored dyes before sealing. Since the dye is only applied on the surface, the underlying oxide may persist to offer corrosion protection even if minor scratches may break through the dyed layer. Anodized aluminum surfaces are more hard and rigid than aluminum but have low or moderate resistance, though this can be enhanced with sealing and thickness of the layer.

The other benefit of anodizing aluminum is the ability of colored anodizing dye. Colored dye trickles into the infinitesimal pores of the anodized layer and colors it. The layer is then preserved and the color become visible as part of the aluminum metal itself. This can be utilized to cool, creative and artistic effect, which may produce aluminum element with outstanding and vivid colors to gild motorbike or, more typically, a telescope.

Aluminum anodizing is practically a simple process, and provided that you can lay your hands on the exact chemicals that include sulfuric acid, it is quite undemanding to do simple anodizing aluminum at home or at any work place. But it should be kept in mind that aluminum anodizing at home is limited to fairly small amounts - if you desire to anodize a big item you need a lot of electrical power and plenty of acid, so if you wish to do an intact bike frame in one go, it is better to contact an aluminum anodizing company for assistance.

Most of the aluminum anodizing kits is designed to provide a professional finish to aluminum substrates for a diversity of products. These aluminum-anodizing equipments are ideal for small objects such as motorcycle crankcases, electrical components, vehicle trims, boating accessories, household objects, etc.

The most extensively used aluminum anodizing specification that is MIL-A-8625, describes three kinds of aluminum anodization:

Type I Chromic Acid Anodization
Type II Sulphuric Acid Anodization
Type III sulphuric acid hardcoat anodization

Other anodizing specifications include MIL-A-63576, ASTM B580, ASTM D3933, ISO 10074, AMS 2469, AMS 2470, BS 5599 etc. None of these specifications define an exhaustive process, but a set of tests and quality assurance procedures that the anodized product must require.