Esuter

Topic: Problem with 7075 T6 forging

My company is not a product finisher but we supply a lot of brass and aluminum parts that eventually get anodized/plated. We currently have an issue with a customer complaining of "outgassing". The suspect part is a 7075 aluminum forging taken to the T6 HT condition. The customer machines the part, then sends out for blast finish and hard anodize.

The parts appear as though the anodize is not adhering where some sanding was done to remove raised metal from stamping. The blasting did not completely remove the grind lines and these "valleys" are where the anodized is flaking off. The other item is "outgassing" on internal machined features. Although we have had some past issues with surface conditions for anodizing, we have never had one show up where it was thought to be a void inside the forging.

Not being an anodizer, I am looking for direction on what the most common causes for this would be. Is the term "out-gassing" in an anodizers world common to forgings?

Any help would be greatly appreciated.