6.10.4 Coating thickness. Thickness

6.10.4 Coating thickness. Thickness of the heavy Type Ill coat.ing c~n becontrolled to extremely close tolerances. Anodized coating can be obtainedwith tolerances of as little as ± 0.0001 inch (O.l mil). With all anocizingprocesses used primarily for engTneering ra:her than for decorative purposes,a number of highly specialized techniques are used for operation control. Onemethod that may be employed is to carefully measure the coated part whilestill wet and replace it in the bath for a fixed period of treatment.Calculations based upon a calculated Fate of coating per unit of processingtime may be used as the basis for determining the exact duration of processingrequired for the specific alloy being coated.6.10.5 Coating dimensions. Table IV gives typical thickness ranges ofaqodic coatings tna: can be applied on aluminum and aluminum a]loys, kllanodic coatings are harder than the substrate material. If interference isrequired for assembly, and is accomplished by force fitting, Type I, IB, IC,I~B, and some Type II coatings are too thin and too brittle to withstandabrasive damage during such assembly. With Type I l l coatings assembly may beaccomplished by grinding, lapping or otherwise removing the surplus coating.All anodic coatings are brittle and may crack and spall due to force fittings.