Brass engraving

[Kev Williams]

With all due respect, saying brass is no problem for a fiber laser is akin to saying water is okay to drink; as with water, it all depends on the ingredients--

this is a screenshot of a PDF list of grades of brass and bronze,
brass-bronze spec pic.jpg
brass-bronze specs.pdf <and this is the PDF

Some of these will lasers, some won't. Which will, which won't-- good question!

[John Lifer]

I would hazard to guess that the brass and bronze that contain non metal of a significant amount wont engrave well. Now what is significant? Who knows.

[John Kleiber]

John, what power are you running at? I wonder if those that were not able to engrave on brass simply didn't have the power needed available.

Michael, I revised my video from last week and incorporated EZCAD2 settings along with the specific type of brass as per the machine shops original drawing. I will post it up shortly.

-John

[John Kleiber]

Brass is not a problem for fiber. Here are some brass split rings I marked yesterday.
The specs required light etching of a part #/weight limit to be place on each side diametrically opposite of each other.
Once marked the machine shop will split the rings leaving 2 halves with the same mark.

Light marking is all I have ever done with brass. Tooled engraving would be far more practical for engraving where significant depth is desired.



-John

[Scott Shepherd]

I have brass that won't mark with a fiber at all. You can't make it even make a faint mark. The brass shown above is free machining brass. Some sheet brass that is used for forming over dies will not mark. I have 50 caliber shells that won't mark under any conditions with the fiber. I set it at 100% power and .1 on the speed and it won't leave a single mark. All the way from 20KHz to 80KHz.

[Kev Williams]

When I was playing with a piece of pure copper, I found that, while lower speeds/low freqs/high power work great for hogging out aluminum, with copper power is the least important of the 3 settings. The ratio of speed to frequency was very important. I forget the settings, but I do remember that when I did find settings that marked, if I went like plus or minus 5 digits with the frequency the engraving stopped. I also found I could change the speed/freq any way I wanted, AS LONG AS the ratio of speed to freq remained the same. Changing power had little effect at all...
like this example (and this is where the spot diameter 'feature' is your friend)--
First, I have speed set at 1000 and frequency at 30k...
1-30.jpg
-note the spot overlap graphic--

now I've doubled the speed and frequency to 2000 and 60k-
2-60.jpg
--and the spot overlap is identical...

This overlap seems to be the critical factor with pure copper, and I would assume brass--
in this sample I changed the freq (only)from 60k to 65k, and note the overlap-
2-65.jpg
not a lot different, but whereas (to my eye) at 60k the overlap is slightly less than 50%, at 65k looks to be slightly above 50%-- this could be the difference between marking and not marking. Again, these aren't my copper settings, just examples. But playing around with slight speed/freq changes, and using the spot graphic as visual, you may find a spot where that pesky brass will mark - or not

--if you do, get out the calculator and figure out the slowest possible speed and freq ratio and enter those, and that will give you the biggest power spread you can apply...

[Scott Shepherd]

Red brass won't mark either. I had a batch of Buck knives and they used yellow brass to make the ends but red brass for the 1/4" diameter pins that held it all together. It would engrave the yellow brass and not leave any mark on the red brass. I ended up having to make masks and sandblast them.

[John Kleiber]

Scott / Kev,

I guess I'm just lucky. Based on all the conversation about marking ammo brass, yesterday I decided to laser engrave a .308 brass case.

My settings were:
Loop: 3
Speed:160
Power: 100
Freq: 20

Hatch .02 @ 45/90/315

Since Kev mentioned spot diameter was possibly a factor, my Spot Diameter was set to: 0.050mm at the time.

I marked the phrase "BRASS 308 CASE" along the side and the only letter that had an issue was the "E". I assumed the taper of the case wall caused an out of focus issue and it was a little lighter. Aside from the middle part of the "E", the rest was a nice deep mark.

-John

[John Lifer]

If you can consistently mark any brass, consider your machine blessed. I engraved a couple of shell casings when this post was first put out. I thought i had it wooped. So I changed the the and try another..... Nothing like that first couple! Lighter, fainter, junk! Tried a couple of more and just decided it was going to be inconsistent....

[John Kleiber]

Red brass won't mark either. I had a batch of Buck knives and they used yellow brass to make the ends but red brass for the 1/4" diameter pins that held it all together. It would engrave the yellow brass and not leave any mark on the red brass. I ended up having to make masks and sandblast them.

Scott,

Is the red brass you are referring to sort of pink in color when compared to the yellow brass?

-John