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Aluminum Anodizing and Hard Coat Anodizing

Aluminum Anodizing

Aluminum Anodizing

Anodizing aluminum is an electrochemical process that produces a clear oxide layer on the surface of the metal. This oxide layer is extremely hard and porous, allowing the metal to accept color. The pore structure when viewed under a high-powered microscope looks like a honeycomb or metal sponge.

Dye, ink or paint can then be deposited into the pore structure and sealed to lock in the color and stabilize the surface. Colors are deeply embedded in the aluminum, not simply applied to the outside. The color actually becomes a part of the metal and won't chip off.

The formula for anodizing varies, but is basically controlled by time, temperature and current density. Anodizing insulates the surface and makes it non-conductive. For specific applications, engineers might design a part to have a dual purpose - areas that are anodized (non-conductive) and areas that are conductive for electrical contact.

Hard Coat Anodizing

Hard Coat Anodizing

Hard Coat Anodizing is different than conventional anodizing. Lowering the temperature and increasing the current density can build a thicker more compact layer on the surface of the metal. This process is ideal for parts that need extra protection under extreme conditions.

Hard Anodizing penetrates the metal as much as it builds up on the surface. The term "thickness" includes penetration and builds up. A typical hard-anodized job will increase a diameter by .002" (50 microns) - .001" penetrations and .001" build up. It is sometimes confusing to machinists who are more familiar with plating. In plating that same part would increase in dimension by .004". For specific questions on closer tolerance requirements, please contact our production manager.

The Benefits of Aluminum

This technical information has been contributed by
Alexandria Metal Finishers

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