Pre-Treatment: Cleaning is done in a non-etching, alkaline detergent heated to approximately 145 degrees Fahrenheit. This process removes accumulated contaminants and light oils.
Rinsing: Multiple rinses, some using strictly de-ionized water, follow each process step.
Etching (Chemical Milling):Etching in caustic soda (sodium hydroxide) prepares the aluminum for anodizing by chemically removing a thin layer of aluminum. This alkaline bath gives the aluminum surface a matte appearance.
Desmutting: Rinsing in an acidic solution removes unwanted surface alloy constituent particles not removed by the etching process.
Anodizing: Aluminum is immersed in a tank containing an electrolyte having a 15% sulfuric acid concentration. Electric current is passed through the electrolyte and the aluminum is made the anode in this electrolytic cell; the tank is the cathode. Voltage applied across the anode and cathode causes negatively charged anions to migrate to the anode where the oxygen in the anions combines with the aluminum to form aluminum oxide (Al2O3).
Coloring: Anodic films are well suited to a variety of coloring methods including absorptive dyeing, both organic and inorganic dye stuffs, and electrolytic coloring.
Sealing: In all the anodizing process, the proper sealing of the porous oxide coating is absolutely essential to the satisfactory performance of the coating. The pores must be rendered nonabsorbent to provide maximum resistance to corrosion and stains. This is accomplished through a hydrothermal treatment in proprietary chemical baths or by capping the pores via the precipitation of metal salts in the pore openings.
anodizing Quality Assurance Scope
The Lab Department at the Haomei aluminum, anodizing facility provides quality assurance testing as requested by customers. Our facility is now ISO 9001:2000 certified! All lab equipment is calibrated, operated, and maintained as specified in the Haomei Aluminum. ISO 9001:2000 written procedures and work instructions. All of the following tests are written into the AACOA, Inc. ISO 9001:2000 work instructions.
Coating Thickness
ASTM B244 Measurement by Eddy-Current Instruments
Coating Weight
ASTM B136 Measurement of Coating Mass Per Unit Area
Gloss
ASTM D523 Measurement of Specular Gloss
Abrasion Resistance
ASTM D4060 Measurement by Taber Abraser
Seal Quality
ASTM B136 Measurement by Stain Resistance
Acid Dissolution Tests
ASTM B680 Measurement by Acid Dissolution
BQ 007-02 Ford Laboratory Test Method
GM 4472M General Motors Engineering Standard (Section 3.3)
LP-461A-241 DaimlerChrysler Laboratory Procedure