Anodizing cast aluminum

[JackOfDiamonds]

I routinely anodize 6061 aluminum, but I'm working on a project now that uses Alcoa "MIC6" cast aluminum tooling plate. I would like to anodize this because it's just so much nicer than raw aluminum, especially screw threads, but I don't know if it will "take". Has anyone tried it?

 

[CapriMikeC]

If you are anodizing simply for corrosion protection, then yes it works well. Especially with Type III hard anodize it will give a kind of olive/gold color.

Any threads that get anodized need to be slightly oversized since the pitch diameter will shrink with the anodize buildup.

 

[mike93lx]

Not sure if you Googled at all, but I saw this. Maybe it's helpful

Problem clear anodizing MIC-6 material

Problem facing with MIC-6 material for anodizing process

www.finishing.com

 

[PCustoms]

Mechanically/chemically it will work.

Cosmetically it's a tossup, and will likely be blotchy to to the variations on the casting. I've got a lot of cast parts that get a non-cosmetic anodize and the finish is all over the place.

 

[klxrcr]

I’ve had mic6 anodized that had what appeared to be “flakes” that didn’t take the dye. It was pretty noticeable when anodized black. You should use alca-5 tooling plate if you want to anodize it, it’s a 5000 series aluminum so slightly less yield strength but it looks better and I found it to cost less than mic6.

 

[JackOfDiamonds]

My other option is "Gleich g.al C250". It's another cast aluminum but the website seems to indicate it's a 5000 series alloy. I'll have to read up on what 5000 series actually means. I gather the problem with MIC6 is the high silicon content.

G.AL® C250 - GLEICH USA

The two sides precision machined G.AL® C250 Precision Plate with a protective PVC film is GLEICH’s Cast Tool & Jig Plate in alloy EN AW-5083

gleich-usa.com

EN AW-5083 [AlMg4,5Mn0,7 – 3.3547]

 

[MoonRise]

5000 series aluminum refers to the aluminum alloy 'family'. 5083 is obviously in the 5000 alloy family.

5000 series has magnesium as the main alloying additive, and is a non heat treatable aluminum alloy, but the alloy can be hardened/strengthened via strain hardening or cold working. It is a "wrought" alloy and not a "casting" alloy (the casting alloys use/follow a different alloy designation format with three digits instead of the four digits used to designate the wrought alloys. The casting alloys with magnesium as the main alloying additive would be a 5xx designation compared to the 5xxx designation for the magnesium wrought alloys.)

Alcoa MIC-6 plate is listed as a 7000-series aluminum. One data sheet says that it is able to be anodized and welded, but other data sheets recommend Alca-5 because it is a little STRONGER (18 ksi yield versus 15 ksi yield, and 41 ksi UTS versus 24 ksi UTS) and anodizes better than MIC-6. And is supposed to be 5% lighter too, if that matters.

Comparing Alca 5 vs. Mic 6 Cast Aluminum - IMS

Dive into Comparing Alca 5 vs. Mic 6 Cast Aluminum and optimize your metal operations. Whether it's supplies or best practices, find what you need here!

industrialmetalservice.com

Alca 5 Aluminum | Cast Aluminum Tooling Plate Suppliers | Howard Precision Metals Inc

Alca-5 is a 5083 certified cast plate that has superior anodizing response and a density of 5% less than Mic-6 allowing for the purchase of 5% less weight per part. To purchase Alca 5® cast precision plates, fill out a Request for Quote form.

www.howardprecision.com

Alcoa MIC-6 data sheet:

https://www.yarde.com/docs/products/mic-6_brochure.pdf

claims that MIC-6 can be anodized successfully to a dark grey but often shows color and/or texture variations in the anodizing from the casting process. But that dying it black after anodizing usually results in a good cosmetic appearance.