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Odd problem - aluminum identification

I'm doing some occasional work for a friend who manufactures machines that puts hangers on plant pots for greenhouse applications. He just made a bunch of parts of what he thought was 6061-T651 aluminum. Some of the parts 'might' have been 2024-T3.

When he got the parts back from the anodizer, some of the parts were eaten away as if they had been dipped in acid and left for a long time. As much as 3/16 thickness had disappeared on some of the finer details. The anodizer claimed that they had all been treated the same. Most of the parts were fine, only a few were affected.

I guess the question is: How do you tell the different types of aluminum apart and even if he had, why the big difference coming out of the anodizer?

Earle Rich Mont Vernon, NH

Reply to
ERich10983
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snipped-for-privacy@aol.com (ERich10983) wrote in news: snipped-for-privacy@mb-m22.aol.com:

The alloy used determines, to a large extent, the flow rate, current and time, used to obtain a desired layer thickness. The alloy can also contain metals that the acid reacts with much more readily than the aluminum.

Reply to
Anthony

Mixing the two alloys when anodizing is a serious mistake. I have had like results. I can only assume that the same properties that render 2024 not weldable also render it not well suited for that particular method of anodizing. There is a process that works, but it is different from the one used on the 6000 series of aluminum. As I recall, hard anodizing can not be performed on 2024.

The difference in machining between those two alloys is profound. Anyone that has any experience with each of them should be able to tell them apart with no trouble, just as you should be able to identify 7075-T6 from other aluminum grades. 2024, especially T351 or T4, cuts very different from

6061-T6. 2024 always cuts with what could best be described as a powdery surface, never shiny. In a way, it resembles the surface of machined fine grained cast iron, but not the same color. 6061, when lubricated properly, always cuts with a shiny surface. The chips from 6061 are tough and tend to string if no chip breaker is used, whereas the chips from 2024 tend to be somewhat crumbly. 2024 responds to dry machining far better than does 6061, which tends to weld to the cutting tool when cut dry.

It's always a good idea to color code material if it is not otherwise marked for identity. In defense work, that's mandatory. Without certs and traceability, the material would not be useable.

Harold

Reply to
Harold & Susan Vordos

Greetings Earle, When I asked the anodizer I use they told me that 2024 may accept the dye different than 6061. Thus the color shade may not be the same. But, I have had 2024 black and blue anodized along with 6061 parts and not told the platers. That's because they would have charged me an extra $85.00 if I had. Slight shade differences would have made no difference to the customer. As it turned out there was no difference in the color of the parts. I have also had 2024 hard anodized. When getting parts hard anodized and dyed black there was no color difference from 6061. When getting 2024 hard anodized and not dyed the grey color was different than 6061 treated the same. Because of my experience I think the anodizer of your friends parts did not treat all the parts the same. Eric R Snow, E T Precision Machine

Reply to
Eric R Snow

Agreed. I would use a different plater. No excuse for the loss of material you mentioned.

michael

Reply to
michael

Thanks for the opinions. The parts have been made over and the anodizer will do them again gratis. It's probably a combination of screwups on both parties. It won't happen again, I'm sure.

Earle Rich Mont Vernon, NH

Reply to
ERich10983

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