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Topic: Anodizing sand blasted parts

Hi, can someone please help with anodizing aluminum that has been sand blasted. We use Type II anodizing with organic dyes from Clariant. I have a customer who is interested in anodizing aluminium castings. Apparently the parts are cast then finished machined to proper shape. After that the customer says the supplier requires that the parts be blasted to increase the structural properties of the part. This does not sound right to me but I am not an expert. The customer was also told by his supplier that the material is 6061, which is a spec for wrought alloy not cast. The main issue is that the customer is very particular as to the appearance of the parts and we have done blasted parts before with terrible results. Is there a way to anodize these parts so that they have a perfect finish? Would electropolishing help? Thank you very much for your help.

LeoH

Re: Anodizing sand blasted parts

You are right about 6061, it anodizes well but it is not a casting alloy.  Casting alloys contain silicon which is a problem for anodizing.  A strong acid fluoride deox will remove the silicon but it will never be a perfect finish.  There are some casting alloys that are based on zinc bu he die casters don't prefer them.  Not sure what they could mean about blasting improving the metal, sounds bogus.

Sometimes the blasting media imbeddes ino the metal which can cause finishing problems.  I don' think that electropolshing will help.