Chipping Anodize?

[Jessica Cleary]

Hello all! Hope you all are having a wonderful day! This is my first post so please let me know if I do not provide enough info!!

I have attached some pictures they are taken with a microscope so hopefully you can see what I am talking about. I am running 7075 Aluminum with a Type III anodize hard coat. I am using a 35 Watt Fiber laser made by TYKMA laser systems called a "Minilase". Here are my settings: 7 passes @ 90 degrees; Speed 1500 MM/Sec; Power 100%; Frequency 35 KHZ then 7 passes @ 270 degrees; Speed 1500 MM/Sec; Power 100%; Frequency 35 KHZ; and finally 6 passes at 135 degrees; speed 2000 MM/Sec; Power 100%; Frequency 75 KHZ. I have about 250 pieces in this order. About 45 pieces it seems as though the anodize is chipping off around the laser marking. I believe this to be an anodize issue as opposed to a laser issue, however, I have only been running a fiber laser for about a month now so I could be way wrong. I am having to go about .010" deep into the material in order to clean up the anodize when I really only need about .003" so it is really a lot of wasted time. If I only go to .003" then there is what looks like dried out salt in the marking. This "Salt" can actually be removed from the marking with a fingernail or knife point so if you run your hand over the marking some of the "salt" moves into the surrounding anodize and makes it look really fuzzy. Maybe this is two different issues but I am hoping you guys can help me sort it out!!

Thank you all in advance for your help! I look forward to hearing from you!
Jesse

[Kev Williams]

The problem IS the anodizing, but, it's not because of 'bad' anodizing. It's simply because the anodized surface is now converted to aluminum oxide, which is literally as hard as, and as brittle as stone. Typical anodizing is around .001" thick, and usually engraves nicely. I get anodized parts that my customer insists on the colors being 'deep', so they sit in the tank longer than usual and the anodizing gets to be .002-.003" thick. I've been tool engraving these parts for 8 years and I've fought the same problem. However, since I got my fiber, they engrave much quicker and easier, and look great.

But you're dealing with HARD anodize, which is VERY thick. I have another customer who has parts hard anodized, and it took like 10 passes at 1500 speed before I got thru to the bare aluminum, and the anodize (the army-greeny-gray looking stuff) didn't look as bad as yours, but I'm not even bothering with them on the fiber, the C02 marks them just fine.

That all said, I'm not sure of what advice might help--- if it were me, I'd ditch the hatch fill and run a very tight island fill, like.02mm or less. The laser bumping into the edges during hatch filling may be causing some of the chipping, an island fill would at least test that theory...

[Jessica Cleary]

Thank you Kev! I appreciate the feedback. I will absolutely try changing the fill to get the marking to come out cleaner. I am not having much luck on the Co2 lasers on this anodize either. I have a Trotec Speedy 100 45 watt and a Speedy 300 60 watt and on both some parts come out marbled in color. With some spots white and some spots dark grey to brown. No matter how many passes I do with the CO2s I cannot get the marbled ones clean up while others come out a perfect white on the first try. Would this most likely be the same issue?

[Kev Williams]

marbled look from a C02 is new to me. All the hard anodized I've ever done comes out consistent. My only issue with C02ing anodized is some anodized just won't lighten up will. A sheet metal shop I engrave for has some guy anodize these small plates (does it at home) and a dark blue is sometimes all I can get. With those parts, I've found less is more- like 20% power will lighten them up more than 80 or 100%. And if I try a second run even at low power, they go darker.

But again, consistent.

The closest to "marbled" I've ever gotten is when the laser blasts thru parts of the anodize and hits bare metal, but not ALL the anodize. I HATE when that happens because there's no fix. I've always considered this to be caused by faulty anodizing, too thin or the aluminum not prepped right, not really sure. Could be you DO have a bad batch of anodizing... More pics if possible.. :)

[Jessica Cleary]

Thank you so much for all your help and ideas Kev!! I have not tried less power I have increased power and lowered the speed. I will try lower power and see if I can at least get a consistent mark. Here are some more pictures. Taking the pictures with the microscope pretty much answered my question about the marbling though. As you can see there are some pits in the material that still have color in them. The CO2 obviously cannot go deep enough to clean that up. Maybe I just need to do it all on the fiber? Let me know if you see anything else I may have missed or if you have any ideas on how I can clean these up with the CO2 laser. Thank you again!!

[Mark Sipes]

I it possible the material is powder coated and not anodized ?

[Kev Williams]

THIS I'm having a hard time with--

This is your pic 3 within the "D", which I blew up and went crazy with the contrast--
This stuff next to the arrows looks LIQUID-- Just wondering if that's something
YOU left there after cleanup or such, or if that's a result of the engraving?
345778

[Jessica Cleary]

WOW! Thank you for putting in so much effort!! I really appreciate the help!! I see what you are talking about it sure looks like something is in there. However, nothing has been done to the part after laser with the CO2 so I am not sure what would be in there? These parts are anodized. The sample with the chipping is only anodized while the second set of pictures I am told does have a paint over anodize finish. I don't have any discolored ones right now that are just anodized and marked on the CO2 laser. Would the CO2 liquefy the paint or would the fiber for that matter?