Remove paint from steel/ablating parameters for fiber

[Maxim Pernatiy]

Hello,

We have Raycus 50w with 200*200 and need to remove completely black paint from stainless steel, so at the end there should be no black residue or black dots - just clean metal.
I'm tryed using Tykma settings, but have the black residue and black dots remaining, even after 8 repeats.
Thanks in advance.

[John Lifer]

Sometthing wrong with a 50 watt and can't remove paint. try the settings for metal cleaning, 135degree, .02mm hatch (I forget the power and freq). If that doesn't work, something wrong.

[James Minick]

I start with a low 50khz freq and 80% power to blast away material (I blast carbon build-up). Then use a higher freq 100khz and lower power 50% to finish. Check/adjust focus.

[Kev Williams]

About 'smooth finish' and the cast iron I see you're engraving-- If you're goal is a smooth, FLAT bottom after lasering, that's never going to happen in cast iron. The best you can hope for is a smoothER finish. The reason is simply because your laser beam is only .001" or so in diameter, with no form of depth control... the surface of cast iron is very mottled, with endless peaks and valleys. When you attack those peaks and valleys with a laser beam that removes metal, not only will the metal removal make the peaks shorter, it will also make the valleys deeper; net result, just a deeper version of what you started with. And the laser itself creates its own peaks and valleys. The good news, since there's less metal in the peaks than in the valleys, the bottom will become flatter with subsequent passes. But depending on the surface you're starting with, that could be a LOT of passes. I have a gun barrel engraving routine that will engrave to .006" deep with a very smooth surface edge when finished- the routine consists of 3 cross-hatch 'dig' runs, each hatch different and run 4x, a second identical run but at different settings, and a final 'cleanup' cross-hatch run 6x. That's 60 separate hatch runs in just ONE pass. And until last night, I was running 38 PASSES to complete one engraving- 60 hatches, x38 times that's 2280 separate passes! 2 nights ago I engraved "6.5 CREEDMORE" engraved in .188" high characters, it took 18 minutes. Last night after doing some tweaking, which amounted to raising power and speed settings, I was able to cut the 38 passes to 22 passes to get virtually the same results, down to 'only' 1320 passes, that is significant! A similar engraving last night took just over 12 minutes. I was VERY happy, as previous tweaks didn't go so well... One might think 12 minutes is too much time- but not really; tool engraving requires securing the barrel in a clamp, with enough force to keep it from moving but not enough to damage it. And barrels aren't 'straight', clamping angled parts requires shims. (2-3 minutes) Then the engraving alignment procedure to the barrel (1 minute), then sharpening the tool (2 minutes, and one tool is good for 2-3 engravings before it needs sharpened again), then the on-screen setup (2 minutes) then the actual engraving, usually 2 passes (2-3 minutes). So we're at around 9-12 minutes.

--not that different. And setting up a barrel to the fiber is, grab 2 V-blocks, set the engraving area under the red dot, do the on-screen setup (equal time either procedure), redlight the engraving, push start...and I've never had to sharpen a laser beam! :D

The moral of this story: The less passes the better, but sometimes literally thousands of passes may be needed; laser machining is far from perfect; and after 3 years experience with fiber lasers, I'm still tweaking years-old job settings, which sometimes works, sometimes not. Running these machines is a continual learning process, which can be very frustrating, but also very rewarding when you find a solution that can reduce engraving time by 30%, like I did just yesterday ;)

What works for us won't necessarily work for you, we're just 'starting points'. Have patience, try new settings, it'll happen :)

[Scott Shepherd]

I've seen your issue before and it's been color related. I had items that worked beautifully, then a new color came in from the same place, same process. It would NOT remove all the color. I don't recall how many times I ran it but it was more than 10, probably more than 20, and in the end, it would never remove all of that color. Put any other color in and it did it in 2 passes. There was something in that color that must have been organic that the fiber wavelength did not like.