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Anodizing/Finishing 380 Die cast Aluminum

Q. I am rather unfamiliar with the anodizing process and am seeking information. We have a part that is made of a 380 die cast aluminum and from what I have read, this is high in silicon which makes anodizing difficult or impossible.

We are just trying to give some reasonable corrosion resistance when subject to the elements, and the finish is of less importance. If possible, a dull black finish would be just fine.

Is there an option for anodizing this type of part or do I have to look at alternate finishing methods? If so, what is a typical specification, i.e., coating thickness & standard that I should have on the drawing?

Dan Beilke
engineer - St Paul, Minnesota, USA
2004

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A. 380 die castings are not difficult to anodize - we do it all of the time. The only thing difficult is to get a good looking finish. We anodize many, many 380 die cast parts & they are done for the properties of the anodize coating, not for appearance purposes. The finish will come out a dull grey usually. If you try & dye them black, you will probably not have much luck. David A. Kraft - Long Island City, New York 2004 A. Aluminum die castings can be anodized and hardcoated. It is much more difficult to do and the resultant coating is not as hard nor as corrosion resistant as comparable anodic coatings on wrought alloys. The appearance of anodize on diecastings is a dirty looking brownish gray. Chris Jurey, Past-President IHAA Luke Engineering & Mfg. Co. Inc. Wadsworth, Ohio 2004

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Q. What is the recommended pretreatment for anodizing 380 Al castings ?

Should alkaline or acid etch be excluded?

N. Zaki
- West orange New Jersey, USA
March 14, 2016