Hard Anodize

By: Mil A 8625  09-12-2011
Keywords: Abrasion Resistance

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.

Keywords: Abrasion Resistance