Full Version: Anodized Aluminum

From: jeff (JCHUMBLEY) [#1]
 20 Feb 2006
To: ALL

Can an anodized piece of aluminum be reanodized after being hit with the laser?

 

Jeff

EDITED: 11 May 2006 by DGL

From: Harvey only (HARVEY-ONLY) [#2]
 21 Feb 2006
To: jeff (JCHUMBLEY) [#1] 21 Feb 2006

Usually you do very little damage to the anodize unless you overpower the cut. It burns out the dye. You can blast out the anodized coating, (aluminum oxide), with too much power.

If you mean to undo the engraving and match the color, that will be a problem. It is dyed in boiling dye and it must be the same dye, same temp and same time. Even then it probably will show a little bit. Then you will have to delve out the dyes and parameters, a very unenvious task.

From: jeff (JCHUMBLEY) [#3]
 21 Feb 2006
To: ALL

Thanks. Didn't really think there was a chance to save them.


Jeff

From: laserman (MIKEMAC) [#4]
 21 Feb 2006
To: jeff (JCHUMBLEY) [#3] 21 Feb 2006

Jeff,

We have stripped them and re anodized them with out any problems. Its just about the cost and if it is worth the expense.

Any metal plater can do this.

From: RALLYGUY (RALLYGUY1) [#5]
 22 Feb 2006
To: ALL

I have talked to an anodizer about this in the past..........

They can strip the anodic layer and dye pretty easily..... It would have to go through that as well as the re-anodising them....Once stripped and re-dyed...I highly doubt you would ever know they had been lasered. I would be able to get clarification from this anodizer if it was necessary.

Best bet would be to talk to an plating house that does anodizing. I'm betting they could be saved.

Brian G.

EDITED: 22 Feb 2006 by RALLYGUY1

From: Bill (BILLC) [#6]
 22 Feb 2006
To: ALL

If you are going to strip anodizing just be sure that the parts you are stripping do not have any critical or real tight dimensions. The stripping process will remove some of the base metal. If they are precision parts they may be out of tolerance after re-plating.

From: Boz (CHEDDARHEAD) [#7]
 23 Feb 2006
To: ALL

Unless you are just powering your way through the anodization, you are not removing any material by using a CO2 laser engraver. With less than 50 watts, you are actually bleaching the pigments of the anodized coating. That's why laser engraving on anodized aluminum will pass the 25 year outdoor sign standards. You do not leave any raw aluminum exposed, unless you cut your plates to size after anodizing.

EDITED: 23 Feb 2006 by CHEDDARHEAD

From: Stunt Engraver (DGL) [#8]
 23 Feb 2006
To: Boz (CHEDDARHEAD) [#7] 24 Feb 2006

Rob,

The engraving may pass the 25 year outdoor standard, but I've never seen an anodized surface that can pass the same test. :-) 

From: Boz (CHEDDARHEAD) [#9]
 24 Feb 2006
To: ALL

That is an interesting point. Since we don't do engraving, just enough to test machines, we have very little practical knowledge of how the products are used. So have you had customers requesting outdoor signage made of anodized aluminum? And from your experience, the anodized coating goes bad after years of being exposed? Or the base metal comes through and corrodes?

From: Stunt Engraver (DGL) [#10]
 24 Feb 2006
To: Boz (CHEDDARHEAD) [#9] 11 May 2006

Rob,

I can't say I have "extensive" experience with anodized aluminum, for outdoor applications.

My comment was based on a sign (black anodized alum.) I engraved for a "Memorial Garden." It seems the anodized surface is either wearing away or fading. The engraving itself, since it was lightly routed into the metal, is very legible.

The surface of the metal itself is now a silver/gray. The sign comes around from time to time, for updating.

I can't remember exactly how long the sign was exposed to the elements, before the affects of "Mother Nature" became apparent.

I'd say about 6 months.

From: Harvey only (HARVEY-ONLY) [#11]
 24 Feb 2006
To: Stunt Engraver (DGL) [#10] 24 Feb 2006

The material below the anodize will oxidize, (anodize), in outdoor conditions. This causes a graying effect.

From: Mike (MIKEN) [#12]
 10 May 2006
To: Stunt Engraver (DGL) [#10] 11 May 2006

I have had some experience with black anodized in outdoor use and find it to be quite durable. I've had signs that I know are more than 6 years old and outside year round and still look good.

The Missouri Botanical Garden (one of the country's largest) uses exclusively anodized aluminum and I'm sad to say they bought their own laser engraving machine just about the time I was ready to take over their sign making.

From: Stunt Engraver (DGL) [#13]
 11 May 2006
To: Mike (MIKEN) [#12] 12 May 2006

Mike,

How dark does the black anodized finish stay, over time?

Maybe all finishes aren't created equal, but the signs I've made and see, as they come back for updating, are gray and eventually a lighter shade of gray.

From: Harvey only (HARVEY-ONLY) [#14]
 11 May 2006
To: Stunt Engraver (DGL) [#13] 11 May 2006

Chewbarka dips the tags after dying them. I would think that would increase their longevity quite a bit. Anything that prevents oxygen from entering, UV resistant or not, would certainly give an edge.

From: Dave Jones (DAVERJ) [#15]
 11 May 2006
To: Stunt Engraver (DGL) [#13] 11 May 2006

Not all anodized aluminum is created equal. There are special dyes used for exterior signs that are fade resistant. Plus the method of sealing and even the alloy of aluminum all are factors for exterior use.

From: Stunt Engraver (DGL) [#16]
 11 May 2006
To: Dave Jones (DAVERJ) [#15] 11 May 2006

Dave,

I've only had experience with the typical anodized sheet stock, sold through engraving supply houses, i.e. Gravograph.

From: Dave Jones (DAVERJ) [#17]
 11 May 2006
To: Stunt Engraver (DGL) [#16] 11 May 2006

I've been having aluminum custom anodized for about 20 years, for the enclosures on my electronic equipment. The better anodizing companies ask all sorts of questions about what alloy it is, indoor vs outdoor, flat vs glossy, normal or extra hard surface, etc... There are several variations in the process, and a selection of chemicals used for different applications. Only some of the dyes are considered fade resistant in sunlight.

From: Stunt Engraver (DGL) [#18]
 11 May 2006
To: Dave Jones (DAVERJ) [#17] 11 May 2006

Good info Dave.

Much more to it, than meets the eye.

Thanks,

From: sprinter [#19]
 11 May 2006
To: Stunt Engraver (DGL) [#18] 11 May 2006

I stopped buying standard anodized aluminum sheets several years ago. I now buy 4'x8' sheets of T6 6061 aluminum which the metal supply house cuts to size and then have it anodized with a harder finish and a UV dyes. It works out to be about the same price as standard anodized aluminum sheets.

EDITED: 11 May 2006 by SPRINTER

From: Stunt Engraver (DGL) [#20]
 11 May 2006
To: sprinter [#19] 12 May 2006

What are your main uses of the anodized material?

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