Mil-A-8625 Ty 3 Hard Anodize Class 1(Non Dye) or Class 2 (Color Dye)
Successful
use of anodic coatings, especially hard anodize, depends on proper product
design. Because of the manner of formation, anodic coatings will develop voids
at sharp corners and edges. Sharp edges and corners are difficult to anodize
satisfactorily and in general should be avoided. All edges and inside corners
should be radiused prior to anodizing. Chamfering should not be used unless
resulting sharp edges are radiused.
Nominal
coating thickness: .002 inch (2.0 mils) +/-20%. Allowance must be made for
dimensional increase. An increase in dimension, equal to ½ of the coating
thickness, can be expected for each surface. In the case of small holes and
tapped holes, coating thickness can vary from no film to full thickness. In
general, holes over ¼ inch should be anodized. Major and minor thread
dimensions will be increased by 2 x’s the build up thickness.
In
general, all anodic coatings are harder than the substrate material. The
abrasion resistance does not increase with increasing coating thickness.
Abrasion resistance will decrease as the coating thickness approches 3 mils.
Hard Anodize is usually not sealed when the main function of application is to
obtain maximum wear abrasion resistance. Sealing will improve corrosion
resistance.
Anodizing Industries 
Successful
use of anodic coatings, especially hard anodize, depends on proper product
design. Because of the manner of formation, anodic coatings will develop voids
at sharp corners and edges. Sharp edges and corners are difficult to anodize
satisfactorily and in general should be avoided. All edges and inside corners
should be radiused prior to anodizing. Chamfering should not be used unless
resulting sharp edges are radiused.
Nominal
coating thickness: .002 inch (2.0 mils) +/-20%. Allowance must be made for
dimensional increase. An increase in dimension, equal to ½ of the coating
thickness, can be expected for each surface. In the case of small holes and
tapped holes, coating thickness can vary from no film to full thickness. In
general, holes over ¼ inch should be anodized. Major and minor thread
dimensions will be increased by 2 x’s the build up thickness.
In
general, all anodic coatings are harder than the substrate material. The
abrasion resistance does not increase with increasing coating thickness.
Abrasion resistance will decrease as the coating thickness approches 3 mils.
Hard Anodize is usually not sealed when the main function of application is to
obtain maximum wear abrasion resistance. Sealing will improve corrosion
resistance.