MarkC;
Aluminum wire enamellers often use ultra sonic wire cleaners. I was a field service engineer starting up enamelling systems once in my life and between the pay off and the pre-annealer some of the aluminum wire systems had an ultra sonic cleaner. I did a search and found: www.hielscher.com/ultrasonics/wire_03.htm

From the explanation, it is very similar to what was used way back when (mid-70's) but I am certain that the technology and equipment is better today.

rb