The anodizing process can only be performed on aluminum and its various
alloys. Anodizing is not an applied coating such as paint or zinc
coating.
Anodizing is an electro chemical process. The parts are submerged in an
electrolyte bath. DC current is passed through the parts causing the
surface of the aluminum to build up a layer of aluminum oxide. The oxide
layer penetrates the aluminum and builds on the surface in equal amounts.
This subsurface bonding is how anodizing creates a very durable layer of Aluminum Oxide. Aluminum Oxide is a very inert element and does not react to the atmosphere. The anodizing acts as a barrier between the aluminum and the environment around it.
Commonly used units of measure for anodizing coating thickness.
- Decimals: .001”
- Mils: 1.0
- Microns: 25.4
Equivalents:
.001” equivalent and equal to 1.0 Mil also can be expressed as 25.4 Microns.
Liberty Anodizing processes two types of anodizing commonly referred to as Type II (Sulfuric Anodizing) and Type III (Hard Coat Anodizing)
Type II anodizing is used for corrosion resistance. The clear anodizing
has a .4 – .8 mils coating thickness.
Type II is the base process for colored anodizing, which requires a
thicker layer of .7 – 1.2 mils.
Type III anodizing is used for wear and abrasion resistance. The Hard Coat
process builds up a thicker and denser coating it has a 1.2 – 1.8 mils
coating thickness. The abrasion resistance in measured by using the Taber
Abrasion Test.
Various types of castings can also be anodized, such as die castings, sand
castings and permanent mold.
Liberty Anodizing offers five dye baths, all with high rating of lightfastness.
Black Blue Gold Purple Red
(Natural or clear is not dyed)
Aluminum Alloy Reference For Anodizing
| Series (AA)* | Alloying Constituents | Metal Properties | Properties |
|---|---|---|---|
| 1XXX | None | soft conductive |
10 – 27 ksi |
| 2XXX | Copper | very strong hard low elongation |
27 – 62 ksi |
| 3XXX | Manganese | strong small grain |
16 – 41 ksi |
| 4XXX | Silicon | strong fluid |
25 – 55 ksi |
| 5XXX | Magnesium | strong ductile fluid |
18 – 51 ksi |
| 6XXX | Magnesium and Silicon | strong ductile |
18 – 58 ksi |
| 7XXX | Zinc | very strong | 32 – 88 ksi |
*AA – Aluminum Association