Freedom Offers Several Choices for Anodizing:

There are three primary methods of anodizing Aluminum ‑ sulfuric acid anodize (SAA), hard coat anodize (HCA) and chromic acid anodize (CAA) ‑ each has a unique set of properties and applications.

SAA produces a coating that will readily take dye to color it, as well as provide the aluminum with moderate corrosion protection. HCA is very dense and provides the aluminum with excellent corrosion and abrasion resistance. CAAprovides the aluminum with a very thin, very dense anodic coating.

For SAA and HCA, the anodic coating that is formed penetrates into the aluminum, as well as grows outward from the surface of the aluminum on average at a 50-50 ratio. This is a big factor since many industries have tight dimensional tolerances that have to be met.  If a part is slightly over-anodized then the process has to be stripped and redone.  Some parts simply cannot be stripped and regain their dimensional requirements.

SAA anodic thicknesses usually ranges from 0.0003 – 0.0007 inches while HCA ranges from 0.0018 – 0.0022 inches.  A thickness gain of .2 to .4 mils can be significant especially in the case of diameter changes on shafts or holes as well as threaded features.

For CAA, the anodic coating is immeasurable to standard thickness measuring practices and the anodic coating is very dense. The downfall from this application is that Chromic Acid is an environmentally hazardous chemical and is highly regulated by water and air quality personnel.  Furthermore, the resulting coating is somewhat fragile and is not rated for abrasion resistance.

Dye Matching

Freedom has Dye Matching services for Anodizing and we currently have black, grey, brown, green, blue, and red.