Fiber Laser on Copper

[Tim Bateson]

Wanted to pass along something that seemed to really work for me. My 50w Fiber was having trouble engraving Copper... no surprise. As I had a large job and not enough time to do it, at the rate it was going I decided to experiment.
Based on a thread here that mentioned a fan blowing on copper had helped. I took it one step further and placed the copper blanks in the freezer for 15-20 minutes and took a few out at a time to laser. Got me much cleaner/deeper results and faster too. It reduced the laser time by at least 25%.
This initial cost estimate put the customer off a bit, but they needed this job done ASAP. This experiment enabled me to reduce my cost enough, I now have a customer that comes back over & over.

[John Lifer]

Really that much difference. I wouldn't have thunk it. 40-50 degree reduction made that much of a difference.

[Tim Bateson]

Before I used the Freezer, these blanks were too hot to touch after engraving. Copper holds the heat for a good long time. Now after engraving they are just warm to the touch. Much easier to work with.

[Kev Williams]

Interesting that the temp would have any bearing on the engraveability of copper, but I'm a believer in 'anything's possible'!

Me, to this point in my engraving life I've come to the conclusion that how copper engraves via my fiber is directly proportional to absolutely nothing.

Right now my BIL is running some copper bracelets on the fiber rotary, and he's all but pulling his hair out in frustration... 4 or 5 will engrave fine, then one or more will act like the laser's not firing, some of those require 4 or 5 passes, some require a complete power settings change. Some burn too dark. Some engrave fine, not at all or too dark all on the same part.

A while back I ran some tests on what I know to be pure copper, and I found a very narrow speed and frequency range that reliably created a light etch. Power didn't seem to matter much, got the same results from just enough power to make the mark to full power. And I also found that as long as the speed-to-frequency ratio was the same I got the same results-- as in, 800 speed/50 freq or +50% to 1200 speed and 75 freq

This job we're doing now is the first copper job in a long time, and is a one-off quickie. But one of these days I need to drag out that piece of copper and dial it in again- then write down the numbers :D

[Tim Bateson]

These parts are electrical in nature. They stamp the aluminum ones, but copper is too soft for that process. They kept crushing them. Thus lasering was the solution.

[Jacob John]

So theoretically speaking, this would work for All Metals when you're attempting to cut since the whole point is to keep the heat isolated in that single spot correct?

[Gabriel Holmes]

Copper is always fun since it is working against you two-fold as a great thermal conductor as well as having an absorption rate of <3% (typical) in the 1064nm range. Welding copper was always chore as well, even with using a dual laser setup (1064 YAG @500W just to pre-treat copper followed by a 532nm 12w green laser for welding, even then, only around 30% absorption).

I'd be interested to see how copper marks if submerged in liquid nitrogen for several seconds. Any welding gas supply shop should have it readily available for fairly cheap.