Speckling in Al7075 Black Anodized Parts
We make a number of parts out of Aluminum 7075 T6511 – in this case from 2 in. dia. extruded bar. These parts are then finished to Type III Class 2 Black Anodize (Hardcoat). Occasionally we get a batch of parts that show speckling – usually not as bad as the latest batch. This is not aesthetically acceptable to our customer. Unfortunately we do not uncover this issue until we have finished machining and anodizing an entire lot of parts. Some of the tight tolerances create problems historically when we try to strip the parts/reanodized. Does anyone have any suggestions on root cause/how to avoid this issue?
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