Fiber + Copper = 0

[Kev Williams]

Got a potential order of 14,000 pieces, which would be really cool...
The pieces are copper-- And I'm finding that my fiber does not play well with copper...

anyone else concur with this?

To wit- I test engraved 3 pieces. Two engraved nice, one was a bit light...

Customer liked, but his customer wants bigger logo.

Pieces are curved, I did several passes on one piece, all resulted in nice dark engraving...
...several passes on second piece and the laser barely touched it even in the precisely focused areas. Even slight out of focus resulted in the dust on the copper being vaporized. Watching it run in these spots, only the red light was visible, the copper was unmarked.

After the second run, I was worried my laser might be the problem. But nope, put the first piece back in and it engraved just like before.

To look at the pieces there's no difference. I tried cleaning with alky, Fantastik, turpentine, nothing changed..

So next up is diamond drag, which for these parts may be fine. I hope, I could use a big order like this...

So I'm curious if this is typical of copper? About 2 weeks ago I tried to engrave the back of a brass nameplate (engravers brass) and the laser would barely touch that too. Brass pocketwatch cases on the other hand, engrave like stainless. Probably the nickel content...

[Mike Null]

I had to opportunity for a big job a while back and got even worse results than you. Also tried brass cartridges with zero success. I had these engraved by experienced people but just couldn't get results.

[Kev Williams]

update on this-- these things are copper plated. And that's why the variation. I did stumble upon some settings that work okay on 'solid' copper, as long as a light etch is sufficient. Because that's as good as it gets, at least with my 30 watts and 160mm lens! The variation happened because some of the pieces are lightly plated, some heavily. The light plate burns off real easy, and what's beneath goes black. The heavy plated, the laser can't burn thru it. And since I wasn't using optimal settings, I was only getting minimal penetration in some spots and none in others...

Trying to etch copper also taught me a lesson about engraving speed-- whereas with a C02 laser, if you need more engraving depth or 'burn', you can just slow the cut speed down...
-Doesn't exactly work that way with a fiber... ;)

[Mike Null]

I should add that we did get a black mark on the brass cartridges but it took so long as not to be feasible.

[Keith Winter]

I'm surprised you got 2 of the 3 to come out, I've had little luck with copper. What settings are. You using? Photo?

[Kev Williams]

500 speed / 100% power / 35 freq / dead on focus... Actually, using copper should be a fantastic way to find your len's exact focus length

Also, beware the beam when hitting copper, because it WILL reflect it- I got hit with a blast of heat while standing over it when the laser wasn't digging in. Glad my glasses were on..

Anyway, very small adjustments to speed and freq may give better or worse results. Much bigger than small adjustments results in nothing! Very finicky...
--this is as good as it gets, nothing dark about it--

342645

[Gary Hair]

You could try slower speed Kev, 500 is still pretty fast. Some steel parts I engrave at 100 speed, 100 power and 30 freq, .02 hatch at 135 and 45 degrees - those settings should give you about as much power as you would want to hit one spot. If you have a large area to engrave then you'll want to avoid too many passes in a row, or avoid touching the part after more than a pass or two...

[Kev Williams]

This brings back what I mentioned above about speed changing... :)

If I just slow down the speed, the actual cutting frequency increases, and I get less dig. Going from 500 to 100 speed results in just barely a cut. The best results I get is 550 speed and 36 freq, that gives me a nice, bright-ish, consistent mark.

Gary-- You know the button with the 4 red circles I asked you about? What you see when clicking that is the "actual" cutting frequency you're putting down based on your speed and freq settings. A C02 pulses the laser in specific pulses per inch, a fiber pulses in specific pulses per second. Ergo, a C02's 'actual' cutting frequency never changes, so speed changes up or down equal less or more cutting power... But if you run a fiber laser slower but don't change the frequency, the 'actual' frequency increases. Messing with this copper I've learned the 2 settings most definitely go hand in hand! Since I'm at the bottom of the freq range, I can't go much slower or the laser won't dig because the cut frequency's too high. That's why going to 100 speed had negative results.

All of you with EZcad, make your settings 500/100/35 and click on the red circles button. Note the overlap. Now, move the speed slider down, and the overlap increases. Move the speed faster, overlap decreases... The overlap at around 500 speed and 35 freq is what copper likes. Vary much around that and not much if anything will happen!

Now for the fun part-- Moving speed and freq settings higher, you can achieve the same overlap, and get the same cutting results! The compromise is power applied will be less due to increased speed. How much is anyones guess, but---

I did a test, and by dam it works.. You guys need to try this--
Since my copper engraved nicely at 500 speed/35 freq, I doubled my settings to 1000 speed and 70 freq, which results in precisely the same overlap... And I got precisely the same engraving results...!

So I doubled again to 2000 speed and 140 freq-- and again I got the same results! Since that put the settings at the top of the frequency range, there's not much faster to go before running into the max frequency.

So it turns out that 4-red-circle button is a lot more important than I thought!

-- but all bets are off when you add 'wobble' ... ;)

[Kev Williams]

Another weird finding-
regardless of the multiples in the speed/freq ratio working, copper really seems to like the 34k to 37k frequency setting. 33k and the dig starts to fall off. 38k it starts to fall. at 30 and 40k, it the marking is very minimal. At 35 and 36k, I was getting good burn at pretty much any speed I entered, even 7000 speed worked good...

Just when I think I have something figgered out... http://www.engraver1.com/gifs/banghead.gif

[matthew knott]

Unfortunately increasing the frequency also reduces your pulse energy! so you cant just increase speed and frequency to get the same result, you need to add more power !!! careful with copper, you can damage your machines , the gavlo mirrors are normally the first bit to go, you burn a spot onto them! interestingly an old school yag will outperform a fibre easily on copper! I have a 60watt SPI WITH A 100mm lens and its still worries me on copper

[John Kleiber]

This is an interesting thread. For the longest time I have had mixed results with brass.
Lasering of some items seems to result in merely a light bright minor etching.
The red laser of our 50w fiber simply dances on the surface with only minor pinpoint scorching.

Sheets of Home Depot sheet brass Fiber poorly, however solid brass keys laser great.

With the Home Depot sheet brass, I have sand blasted, chemically cleaned and scored the surface with similar poor results.

At this point, if the item is "solid brass", engraving is definite, sharp, deep and clear.
However, items from Home Depot described as brass sheet or other items like "brass finish", "brass like" or "brasslite" are problematic.

-John