Is 30 watt enough for cutting .50" acrylic?

[Richard Rumancik]

What results have you had cutting .50" acrylic with a 30 watt? The LaserPro NA site says their machines can cut half inch in a single pass with a 30 watt. I have a Mercury 30 watt and have been marginally successful cutting .375 thick acrylic. Even at that, the edges are so striated that the finish is unsatisfactory. What results do you get on similar Epilogs and ULS machines?

[Joe Pelonio]

I have an Epilog 45W and the manual puts the maximum at .375". I can cut it nicely at speed 2 power 100%. I once did 1/2" in 2 passes but it did had a rougher than normal edge. If they say it will do it, have them demonstrate in front of you.

[Mike Mackenzie]

Richard,

Laser Mfg's state that you can cut 1/2 inch with 30 watts but it is so slow that you could probably do it faster with a butter knife. The other issue is that it is a very dangerous fire hazzard and I can't believe they advertise it that way. I would rather be safe than sorry.

[Dave Jones]

I have a 45W Epilog and have cut 1/2" aircraft plywood with it in one pass (slow and a fair amount of char). I've only tried 1/4" acrylic.

I suspect my next one will be 60W. The 45W is great for rastering most things but slow for vector cutting. A 30W will be even slower for vectoring.

Also using Cermark can take a lot of power depending on the metal. I haven't been doing that yet but in reading the posts about it 30W is on the low edge for doing Cermark.

[Bruce Volden]

I have a 45W Epilog and have cut 1/2" aircraft plywood with it in one pass (slow and a fair amount of char). I've only tried 1/4" acrylic.

I suspect my next one will be 60W. The 45W is great for rastering most things but slow for vector cutting. A 30W will be even slower for vectoring.

Also using Cermark can take a lot of power depending on the metal. I haven't been doing that yet but in reading the posts about it 30W is on the low edge for doing Cermark.

I beg to differ on the Cermark 30W comment. I use my 25W 75 power / 12 speed 300 dpi and have done thousands of knives! Works absolutely beautifully, I think the "trick" is in experimenting in the proper thinning of the metal mark.


Also, on the 1/2" acrylic~~I agree with Joe. Most of our lasers use "flying optics", the power is attenuated with each mirror it has to bounce off. I read somewhere (long ago) the attenuation factor could approach 3-8 % per mirror. Maybe todays better optics have lowered that???


Bruce

[Dave Jones]

Bruce, it depends on the material being marked. Some materials are better conductors of heat and require more power. Sean Weir (aka "Mr. Science") who works at Ferro in the R&D laser lab says, for example, that for marking on gold they recommend having at least 35W and 50W works a lot better.

Some materials will work with less power, but you have to go at such a slow speed that it can take a long time to get a large marking done. One guy said recently on another forum that it took almost a full hour to mark a motorcycle head with a large design because of how slow he had to set the machine to get the cermark to stick. With a more powerful machine it could go a lot faster and not tie up the machine for such a long period.

[Bruce Volden]

Bruce, it depends on the material being marked. Some materials are better conductors of heat and require more power. Sean Weir (aka "Mr. Science") who works at Ferro in the R&D laser lab says, for example, that for marking on gold they recommend having at least 35W and 50W works a lot better.

Some materials will work with less power, but you have to go at such a slow speed that it can take a long time to get a large marking done. One guy said recently on another forum that it took almost a full hour to mark a motorcycle head with a large design because of how slow he had to set the machine to get the cermark to stick. With a more powerful machine it could go a lot faster and not tie up the machine for such a long period.

Dave, I wholeheartedly agree! The knives I mark have a good carbon content and I can NAIL them. Chrome...I run the other direction, I have yet to get a consistent mark. If I do, it tends to fail after a few months ,aluminum is another I won't do. I've tried other metals and find them a hit/miss so I stick with my knives. Also as long as we're on the subject of metal marking, what's your views on the new fiber lasers??? I had a couple samples sent to me from "nationally known" laser mfgrs. and am TOTALLY NOT impressed with what I've seen. I will put Cerdec against the samples I've seen any day!!


Bruce

[Joe Pelonio]

With a more powerful machine it could go a lot faster and not tie up the machine for such a long period.

Of course the same can be said for cutting any material, and engraving of most materials other than standard Rowmark/IPI laminate, the more power you have the faster you can go, and the faster you go the less charring
and flaring. I decided on 45 watts because I didn't expect to be cutting over 3/8" material, but knowing what I do now, especially with the production jobs I get, I'd have probably gone for something with at least 60 just to save time.

[Michael McCullock]

Bruce

The "average" beam absorption rate should be more along the line of 0.4% per mirror.

Michael

I beg to differ on the Cermark 30W comment. I use my 25W 75 power / 12 speed 300 dpi and have done thousands of knives! Works absolutely beautifully, I think the "trick" is in experimenting in the proper thinning of the metal mark.


Also, on the 1/2" acrylic~~I agree with Joe. Most of our lasers use "flying optics", the power is attenuated with each mirror it has to bounce off. I read somewhere (long ago) the attenuation factor could approach 3-8 % per mirror. Maybe todays better optics have lowered that???


Bruce

[Rodne Gold]

30w "should" easily cut 1/2" acrylic, however cutting this thickness is not only a function of power , it is a function of the beam. A normal 2" lenses beam converges and diverges above and below the focal point , and albeit acrylic is a waveguide type material (makes the beam "straight"), the depth of beam above and below the focal point that has enough power density to cut is no where near 1/2 an inch. Using a longer lens will help , however the spot size increases and power density decreases and thus 30w is just not enough. 8mm is about the limit you can cut well with a 30w and a 2" or 4" lens. Striations are cos your air assist is not set correctly. Air assist pressure should be set so that it just stops flaming and the direction is critical so as to eject melt. Striations are cos of bad ejection of melt and the pex resolidifies.