Aluminum Anodizing Services
At Alexandria Metal Finishers, we take on unique aluminum anodizing projects that competitors cannot undertake due their size or complexity. Quality and innovation combined with a 50 year history in the plating and finishing industry sets us apart among metal finishing and plating providers. We provide chromic acid (Type 1) as well as both Type II and Type III sulfuric anodizing of all sizes of aluminum components.
Aluminum anodizing is accomplished by immersing aluminum into a tank filled with an acid electrolyte bath and passing an electric current through the solution. Cathodes are mounted to the inside of the tank and the aluminum acts as the anode. Anodizing converts the metal surface into a durable, corrosion-resistant, aluminum oxide finish. The surface of the finished product is very porous and allows for subsequent dyeing and/or sealing. We set up our own tanks and have the ability to modify our system when necessary. Please contact us for more information on our anodizing capabilities.
Chromic Acid Anodize
Type I or chromic acid anodizing is used primarily by our aerospace customers in precision applications, as it is the thinnest form of anodizing and does not appreciably change a part's dimensions. Chromic acid anodizing can be used for inspection of aluminum forgings or castings by noting evidence of chromic acid bleed out from laps, cracks, seams, etc. The resulting color from chromic acid anodizing will vary from light gray to dark gray depending on the alloy. Type 1 is not as readily dyed as sulfuric anodize.
Sulfuric Acid Anodize - Type II
Type II aluminum anodizing is performed using a sulfuric acid bath to create the anodic aluminum oxide surface. This method is often referred to as "conventional anodizing" for good reason. Type II anodizing is very versatile and provides an ideal surface for dye application. The resulting color will vary with alloy composition. Aluminum with low alloying elements will show practically no color change. This means Type II can be dyed practically any color or shade (black, blue, red, gold, orange, green etc.)
Sulfuric Acid Anodize - Type III
Type III sulfuric acid anodizing is commonly referred to as "hardcoat anodizing" as it is used to protect aluminum parts in harsh wear applications. Hardcoat anodizing creates a denser anodized layer that may reach up to 0.002" in thickness. Type III is dyed easiest of all because of the deep pores created. The hardcoat process darkens and alters the base metal enough so that the color is dramatically different than Type II, i.e. red dye on Type II is fire engine red while on Type III it is dark burgundy.