Aluminum Anodization FAQs
What is aluminum extrusion, fabrication, and anodization?
Aluminum Extrusion refers to a process of creating shapes with an aluminum billet or log by forcing it to flow through a shaped opening in a die. Aluminum can be extruded into standard shapes or specific designs depending on a customer’s preference.
Aluminum Fabrication refers to building aluminum components by cutting, mitering, notching, piercing, forming, bending, CNC machining, mechanical assembly and welding.
Aluminum Anodization is an electro-chemical process of coating aluminum with a thin layer of oxide to increase corrosion resistance and harden the surface. Aluminum also can be dyed with various anodizing colours, which in most cases, are resistant to sunlight.
What are the types of anodizing systems?
There are three types of aluminum anodization: Type 1 Chromic Acid Anodizing (CAA) and Type II & III Sulfuric Acid Anodizing (SAA).
Type I: Chromic Acid Anodizing (CAA)
Chromic Acid Anodizing represents the oldest anodizing process. It produces thinner films with a thickness of 0.5 µm to 18 µm that are softer, elastic, and to a degree self-healing. They are harder to dye, and that they could be applied as a pretreatment before painting.
Type II & III: Sulfuric Acid Anodizing (SAA)
Sulfuric Acid Anodizing is the most commonly used system. Type II anodizing refers to coatings of moderate thickness, 1.8µm to 25µm while Type III refers to coatings thicker than 25µm. Thick coatings require more process control, and are produced in a refrigerated tank near the freezing point of water with higher voltages than the thinner coatings. Hard anodizing can be made between 13 and 150 µm thick. Anodizing thickness increases wear resistance, corrosion resistance, ability to retain lubricants and PTFE coatings, and electrical and thermal insulation.
*Dajcor performs Type II aluminum anodizing
What are the benefits of acid etch anodizing?
- minimizes or eliminates striations, shadow lines, flow lines, surface defects, minor corrosion and die lines.
- uses fluoride ions that attack the microstructures of the aluminum extrusion, resulting in a significant reduction or elimination of surface defects, providing a superior matte finish.
- acid etch provides a greener alternative to conventional etching processes, reducing the amount of waste sludge by 90%, which results in less sludge going into landfills.