Questions About Engraving Speeds and Laser Power

Discuss laser machine here freely.

Moderator: baker

Post Reply
kanaedes
Posts: 2
Joined: Thu Aug 27, 2015 12:56 am

Questions About Engraving Speeds and Laser Power

Post by kanaedes »

I’m new to CNC laser engraving / cutting and I have a TON of questions, all of which have likely already been answered somewhere else. But since the last few days of trolling through previous threads has more or less left my head spinning, I’m just going to ask for some info and advice one thread at a time. :?

First, a little background: I recently bought a cheap piece-of-junk 40 watt Chinese CO2 laser engraver. In spite of its many minor problems, glitches, and technical issues, not to mention unholy abomination that is Moshidraw, I’m actually rather pleased with it. And I think I have discovered a niche product I can make with it. :x

Without going into too much detail, the material I’ve been working with comes out quite well with two passes engraving at 16-18 cm/s at the full power of my 40 watt laser. The substrate I’m working with is somewhat heat sensitive, and a single pass at half the speed deposits too much energy into the material. Two passes allows it to cool slightly.

Now what I’d LIKE to do is use a more powerful laser tube and engrave at a higher speed. I am ASSUMING that using an 80 watt laser at a rate of 32-36 cm/s will produce the same results, or a 120 watt at 48 cm/s. But I have also heard it said that higher wattage CO2 lasers are better suited for cutting than engraving. Logically it makes sense that higher power and higher speed would have an identical effect as lower power and lower speed, but I’m not sure if there are some outside effects of influences that I am missing.

So, my first handful of questions: Can I just increase laser power and engraving speed linearly and get the same effects? Is there some threshold where laser power becomes less suitable for engraving? What is the maximum speed one can engrave at with reasonable quality results (let’s say for argument’s sake, somewhere around 300dpi resolution.) And does anyone have any experience with engraving at high speeds?

Thanks for the help!
Plixo
Posts: 1
Joined: Sun Sep 06, 2015 5:53 am

Re: Questions About Engraving Speeds and Laser Power

Post by Plixo »

Hi Kanades,

Basically, yes it's more or less linear.

However, for engraving, I would not recommend to go higher than 80W, at least with Chinese tubes, for the following reasons:
1) The bigger the tubes are, the bigger the beam and the lower the beam quality
2) Price of tube is not linear, above 80W, climb fast
3) The bigger the tube, the longer it take to start the beam so you will have difficulty achieving 300 DPI resolution. In addition, the life of the bigger tube is greatly reduce with engraving [I personnally blow up a US$1.5K 150W tube doing a 16+h continuous engraving !!!]
4) The bigger the tube usually the bigger the machine thus slower max speed and lower accuracy which is the key point for engraving

In addition, to avoid having to go for two passes, I highly recommend to upgrade the air assist by using a real compressor with dust/air/oil filters, at least 20 PSI will give you nice cooling and sharp edges. Depending on your material, you can also try to preapply masking tape, will avoid color-burn edges and reduce/eliminate post-cleaning process.

Hope this helps.

Alexis Martial
Main Scientist
Plixo Pte Ltd
http://www.plixo.com.sg
kanaedes
Posts: 2
Joined: Thu Aug 27, 2015 12:56 am

Re: Questions About Engraving Speeds and Laser Power

Post by kanaedes »

Thanks for you help.
Or that higher power lasers perhaps do not cycle on and off as quickly and smoothly as lower powered lasers? I’m just assuming that there’s SOMETHING I’m not accounting for in my
Post Reply