Troubles with fiber laser engraving copper

[Marianne Rusche]

Hi everyone,
I have been trying to deeply engrave on copper with my 30w fiber laser. What happens is it seems to only go so deep and it won’t go any deeper. I saw an Ezcad video that showed you should have 3 hatches and the middle one should be parameters that will get rid of the slag build up. Unfortunately the video was kind of tough to understand. Should I have some kind of a clean up hatch in the middle? Is that the reason it just won’t engrave any deeper? I ran a small graphic almost a half hour and it hardly engraved at all. Does anyone have any suggestions as to the parameters needed to deeply engrave copper using the Ezcad software with a 30w fiber laser?
Thanks, Marianne

[Julian Ashcroft]

When I want to go deep I find that after a few passes the noise the laser makes eating into the metal gets quieter which indicates not much is happening, so I wind the focusing wheel down a bit until the noise builds up again.

[Kev Williams]

Fiber lasers don't engrave pure copper very well, if at all. I have a thin 8" x 32" pure copper sheet, my fiber won't do a thing to it, just reflects off (which is dangerous!). But my laser will mark copper pipe, which likely has something else in it, like tin, zinc, etc...

[Marianne Rusche]

Thanks, I’ll try to refocus and see if that helps!

[Marianne Rusche]

Thanks Kev, yes I’m really struggling with both copper and brass. I might just end up not using copper as much!

[Jeff Watkins]

What lens are you using? That will play a major role in the results you get. The smaller the focal length the smaller the beam will be with higher power density. I use a 100x100 (f160) lens when I'm working with copper and certain types of brass. I try and arrange the artwork towards the back of my week area to limit reflections and scatter. Most of the time my 200x200 lens sits on the machine but I do change it when needed. Sort of like having a favorite camera lens but you still need the right lens for the job.

I've been looking at the 70x70 (f100) lens for awhile and saw Kev recently bought one. I'm ordering one this week for tougher materials and a little time savings.

[Tim Bateson]

I had posted a couple months ago about having trouble with electrical Copper cubes. I placed a few in the freezer for a short bit. When cold, they not only lasered deeper, but faster & cleaner. Not sure about the science behind it, but I've used that trick a couple times and it's been very beneficial.

[Marianne Rusche]

What lens are you using? That will play a major role in the results you get. The smaller the focal length the smaller the beam will be with higher power density. I use a 100x100 (f160) lens when I'm working with copper and certain types of brass. I try and arrange the artwork towards the back of my week area to limit reflections and scatter. Most of the time my 200x200 lens sits on the machine but I do change it when needed. Sort of like having a favorite camera lens but you still need the right lens for the job.

I've been looking at the 70x70 (f100) lens for awhile and saw Kev recently bought one. I'm ordering one this week for tougher materials and a little time savings.


I believe its 290mm focal lens. So maybe the beam isn’t small enough to handle copper. That’s frustrating!

[Marianne Rusche]

I had posted a couple months ago about having trouble with electrical Copper cubes. I placed a few in the freezer for a short bit. When cold, they not only lasered deeper, but faster & cleaner. Not sure about the science behind it, but I've used that trick a couple times and it's been very beneficial.

Wow that’s crazy! I never would have thought to put the copper in the freezer. How did you even think about giving that a try? I’ll give it a try... thanks!

[Kev Williams]

A thought on focal length concerning fiber laser lenses...

There's 3 'focal lengths' that are in play:
1- the lens "F=" number,
2- the lens working area,
3- the lens actual focus length from lens to work...

Most lenses are sold/advertised based on working area, a "110mm lens" means you have an approximate 110mm working area. But the lens F-number for a 110 lens is typically 160mm, which is the approximate outer-limits of the lens's full scan area.

someone on the board taught me this (forget who, but thanks! ;) ) - to find the scan area of a lens, take it's F number- say 160mm, and draw a circle that big. Now draw a box that fits perfectly within the circle. According to Corel, a 113.128mm box will fit perfectly into a 160mm circle :)

I have 3 lenses, F numbers are 100, 210 and 300... The working area's calculate out to 70.7mm, 148.48mm, and 212.115mm respectively- These lenses are advertised as 70, 150 and 210mm lenses, so the box in the circle thing does work as a rough calculation...

I don't know how to calculate focus length, other than to test the lens manually, there may be a math calculation?

That all said, if you're indeed using an F-290mm lens, you're getting a lot of working area but the compromise is lower beam power density. A 110mm lens will focus to a much smaller spot and will likely more than double the beam power, which may get your copper to better...

[Floyd Siegal]

The math to figure out your actual working area: Example... F-theta mm number (210mm) divided by the square root of 2 (1.414213562373095) = 148.49mm
Anyway, just remember to divide the lens mm x 1.414.

[toni plaza]

copper - either green marker 532μm or even better uv 355μm. Fiber marker is not for copper marking. Regards.

[Kev Williams]

well, that depends ;) --My 30w Triumph fiber has a hard time with even marking copper-- My new 30w ebay laser will cut clear thru copper it if I want to...

I don't understand it really, I guess lasers are like a box of chocolates... ;)

[toni plaza]

There is a reason why they are called markers, because they are for marking. You are using fiber which uses visible wavelength and causes heat damage to material for which fiber is not design to mark. Marking is not cutting, this is why you have different kind of knives, scissor, screwdrivers, tools in general etc.... First you need to know what material you will be working on before applying a specific tool to it. This is why you have different lasers green uv, yvo4, fiber, hybrid, etc. "like a box of chocolates..." If you understand material spec and how it works with light, it really is not that complicated. Copper is marked 30 times better - let me repeat - 30 times better in quality/visibility/results by green laser and 60 times better by UV - fiber is only 1/30th of green and 1/60th of UV. Regards.

[Bill George]

Really? When I had my fiber laser I marked copper and brass. I think your confusing a diode laser with the ones used and discussed here. Kev and Gary have owned fiber lasers forever.

[toni plaza]

If you did not see the difference what markings are left by green or uv you will force your fiber view, if numbers 30 times and 60 times cannot explain the quality/visual difference, I cannot help. I did not get these numbers out of thin air, but not seeing green or uv marking on copper and not being able to open up a little bit above fiber that's interesting. Try different lasers it will be good for the perspective. Try Japanese markers which have 1µm and 2µm resolution and not 50µm like fiber you have. That's 25 to 50 times better resolution. Maybe you will be able to change your view. Regards.

[Kev Williams]

To be sure: I'd LOVE to have a 532 or 355nm laser, I've seen full data-matrix codes marked on plastics that are less than 3mm square done by a 355, which is amazing, and I'm sure that's tip-of-the-iceberg stuff...

but realistically speaking, *for me*, spending the money on a such a laser based on my laser needs, would be like buying a Bugatti to use for Uber... ;)