How to Anodize CNC Aluminum Parts?
What is anodize?
Anodizing is an electrochemical process that converts the surface of the metal into a long-lasting, high performance aluminum oxide finish.
Anodizing creates a hard coating that is great for many applications. Anodizing increases resistance to corrosion and wear, and provides better adhesion for paint primers and glues than bare metal does.
We usually anodize to blue, red, silver, grey, gold, or black colors.
How does it work?
First, the aluminum parts need to be sandblasted, in order to remove all the machining marks. We usually blast #120 sand onto the parts.
The second anodizing process is holding the parts with the jigs and racks during the whole process. This is very crucial step because if the parts are not racked well they may fall into the tank.
The next step is cleaning the parts to remove the machining oils. This is accomplished by submerging the aluminum into an alkali or acid based detergent tank. Removing the oils leftover from the extrusion process is critical to ensure that there is no spotting or uneven etching of the metal surface. Then rinsed in preparation for the next step.
After then, etching the parts to prepare the anodizing progress to remove a little bit of a thickness on the part. As we know the anodize coat is adding the thickness. This step is to create a uniform surface. Then rinsed again in preparation for the next step.
Then go to the next step is desmutting to remove the inclusions like zinc.
The main step is anodizing that immersing the aluminum into a tank of sulfuric acid electrolyte while passing an electric current through the medium. A cathode is mounted to the inside of the anodizing tank while the aluminum extrusions act as an anode.
The next step is coloring. After anodizing, the surface is porous structure, and the dissolved metal salts or organic dyes can be introduced into the open pores to create various shades.
The final step is to seal the porous surface using a solution of nickel acetate sealing closes the pores proving a uniform sealed surface.
