| Anodizing uses controlled electrolytic oxidation to develop an aluminum oxide coating on the surface of an aluminum sheet or finished part. The resultant coating is dense, and file-hard. Anodized coatings are integral to the substrate: they form by "growing down" into the metal (about 1/3) and by superficial deposit (about 2/3). Anodizing substantially increases resistance to corrosion, scratching and wear, provides insulation, maintains high reflectivity, and enhances appearance: coatings are transparent to gray and resist staining. Anodized surfaces can be used alone, or can achieve a variety of color and texture effects through dyeing, electrocolor or interference color. 
The enhanced performance of an anodized surface is also the equivalent of pretreatment used in conversion coating: anodized coatings are part of the metal, but have a porous structure that allows secondary infusions. Thus, anodizing can often replace traditional conversion coating pretreatment, providing a high-quality base for paint, powder coating, electroplate, adhesives or lubricity agents. High purity alloys, and higher-density aluminum castings are most suitable for anodizing. Varieties of AnodizingType I, also known as CAA or Chromic Acid Anodize, was the first commercial anodize process. It is primarily used to generate a thin film, (.05 to .1 mils) on parts with complex geometries and exceptionally tight tolerances. Type I anodize is compatible with most alloys and is widely used in aerospace and defense, and wherever critical components have lap joints, recesses, crevices or other features which can trap electrolyte. (Chromic acid, if entrapped during anodizing, will not substantially attack aluminum or aluminum alloys.) Other key advantages of Type I anodize include preservation of the metal's fatigue strength, and minimal dimensional changes. Type I chromic acid anodize provides a minimum 336 hours of 5% salt spray resistance per ASTM B117. A version of CAA anodize, called "sealed chromic acid anodizing," is used to improve adhesion characteristics. Type II, SAA, or Sulfuric Acid Anodize is the most frequently used anodize alternative for aluminum. It produces coatings up to 1 mil for conventional coatings and up to 4 mils for hard coatings. Conventional coatings are primarily decorative or protective; hard coat anodizing are processed at higher voltages and current densities and are mostly used for engineering applications. Surfaces that have been treated with sulfuric anodize have greater durability than surfaces treated with type I. Type II anodize is compatible with intense color dyeing and is often used for decorative and architectural applications. Sulfuric anodize provides a minimum 336 hours of 5% salt spray resistance per ASTM B117. Type III, HCA, or hardcoat anodize, generates the highest wear performance generally Rockwell 60-70C, the smoothest surface, and the darkest coloring. Electrical insulation rating for hardcoat anodize is 800 V/mil. This lower-temperature process is the most versatile of anodize technologies. Highly recommended for 5000 through 7000 series alloys. PAA, phosphoric acid anodize is also Boeing's BAC5555 process. It is used for structural adhesive bonding, per ASTM-D3933, and substantially improves performance in high-humidity environments. BSAA, Boric Sulfuric Acid anodize, The Boeing Company developed this process as a chromic acid anodize replacement for non-critical fatigue parts. Known as BAC 5632, its acceptance grew as environmental laws increasingly favored the use of chrome-free chemistries. Paint adhesion is equal or superior to chromic acid, and the process is more energy-efficient than chrome-based processes. Anodize Systems: Type I Chromic, Type II Sulfuric, Type III Hardcoat Anodize; PAA Phosphoric and BSAA Boric Sulfuric AnodizeRack Line processes parts mounted on racks - High production capacity
- Auto or manual operation
- Tank sizes to 100´ or longer
- Fixed, flexible fixed or random timeways
- Hoist speeds from 100 fpm to 750 fpm
- Load tilt option
- Many load and unload options
- Pre-piped modular design
- Reporting options available with automatic controls
Split Rail return type rack processing - High Production Capacity
- Automatic Operation
- Fixed Cycle
- Hydraulic Lift and Transfer
- Floor Mounted Chassis Structure
- Individual Tanks
- Optional Parallel Processing
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WALGREN COMPANY 
