How Deep? Engraving Metal with a Laser

[matthew knott]

I was just using a 50 watt fiber today for deep engraving, its pretty tasty, In simple terms most pulsed fiber lasers (the ones you guys will be looking at for engraving anyway) are around 1mJoule, doesnt matter if its a 20,30, or 50 watt. What this means is the maximum pulse on all the lasers is the same, the way power comes into effect is as follows
20w laser gives 1mJ @ 20khz
30w laser gives 1mJ @ 30khz
50w laser gives 1mJ @ 50khz

So what does this mean, well running a 20 watt at 2.5 times slower will give exactly the same results as a 50 watt, on our 20 watts we normally use a speed of 200mm/second for deep engraving, we can now run at 500mm/second and get the same result.
(this all assumes the M2 values of the lasers are the same, and they tend to get worse as the power goes up)
I would like to get a higher mJoule laser as for deep engraving this makes a big difference but cost is an issue.

Just as important is getting the correct focus lens, the shorter the lens the higher the power density, but also you get a smaller working area so its a trade off, i would recommend a 163mm lens as its a good all-rounder and will do a 120x120mm square.
Prices are coming down all the time and galvo machines are great value when compared to only a few years ago, but beware spending lots of money wont necessarily get you a better machine (just a more expensive one)

[matthew knott]

I was just using a 50 watt fiber today for deep engraving, its pretty tasty, In simple terms most pulsed fiber lasers (the ones you guys will be looking at for engraving anyway) are around 1mJoule, doesnt matter if its a 20,30, or 50 watt. What this means is the maximum pulse on all the lasers is the same, the way power comes into effect is as follows
20w laser gives 1mJ @ 20khz
30w laser gives 1mJ @ 30khz
50w laser gives 1mJ @ 50khz

So what does this mean, well running a 20 watt at 2.5 times slower will give exactly the same results as a 50 watt, on our 20 watts we normally use a speed of 200mm/second for deep engraving, we can now run at 500mm/second and get the same result.
(this all assumes the M2 values of the lasers are the same, and they tend to get worse as the power goes up)
I would like to get a higher mJoule laser as for deep engraving this makes a big difference but cost is an issue.

Just as important is getting the correct focus lens, the shorter the lens the higher the power density, but also you get a smaller working area so its a trade off, i would recommend a 163mm lens as its a good all-rounder and will do a 120x120mm square.
Prices are coming down all the time and galvo machines are great value when compared to only a few years ago, but beware spending lots of money wont necessarily get you a better machine (just a more expensive one)

[Paul Phillips]

when building explosive lenses for thermonuclear weapon implosion systems.

Aha! I knew it! That's exactly what I suspected you do as (one) part of your top secret government side work Dave!

[Matt Geraci]

So the hammers have the same power they just hit at a faster rate?