fire , pulses problem!!

[Hussain ZAKARIYA . Kuwait]

hello every one
please i try to cut 10mm acrylic but the finishing is not ok there is a many of reflaction pulses on the sheet with the cutting table , and how can i make control on the fire while cutting ? every 5 sec i have to puase and start again !!

i try to put some peaces under the sheet it`s ok to remove the pulses but it`s increase the fire !!

any one help ??

( sorry for my english it`s not ok )
any one help?

[David Fairfield]

Yes the edge will be a little rough. The laser cuts by shooting pulses and you will see the results on the edges of the material. The manual will explain settings for optimal cutting of acrylics and show you how to increase frequency. There are ways to treat the edges, after cutting, to make them more smooth. In my opinion, its usually not necessary.

You really need to be extra careful when cutting acrylic, it will ignite. Especially when you aren't looking-- Murphy's law is always a factor. Use air assist as a flame damper.

Dave

[Joe Pelonio]

10mm may be pushing it for a 50 watt machine. If you have to go very slow it's going to flame more.
You must use air assist, and it will also help to apply transfer tape to both sides and dampen it with water before cutting.

[David Fairfield]

Ah, now I understand. You are getting marks on the backside of the material from the reflections off the grid. Like Joe says, tape works. Also you can fine tune your settings so the power is low enough to just cut through with minimum reflection. Or try cutting in two passes. Experiment with lower power & higher speed. You can also elevate the material a little on pins or blocks. Keep a record of your good results for each type of material and manufacturer.

Dave

[Scott Shepherd]

You have to get the work off the table. Take some scrap acrylic and cut some small pieces. Place them around the table, then place the 10mm on those. Make sure you change the focus to allow for the 10mm thick spacers. It'll eliminate the "tick" marks caused by flashback from the grid. Also, you need air assist as mentioned earlier.

I've cut 3/8" many times with a 45W so you should be okay. It's not lightening fast, but it'll do.

Also, focus about .060" down into the work as well. Don't focus on the top of the material.

[Hussain ZAKARIYA . Kuwait]

thanks all
i have manual air assist and i`m adjust it to 25psi also i have fire , i will try to put tabe with some water maybe it will work with me

i will reply after try

thank every one for help

[Scott Shepherd]

I cut a load of 1/2" thick letters a couple of years ago. I sat at the machine and watched it cut all the time. At the time, I would get the flare up every so often. I spend hours trying to determine what the exact cause was and how to stop it. It was a completely random event. I could cut letters out, an entire sheet, no problem, but the next piece in, run the same exact file, 2nd letter, flare up. Next piece, 5th letter flare up, next piece, no flare ups, next piece, many pieces flare up. I could never figure out the cause, well, at least from a resolution perspective. I know what causes it in general, but trying to resolve the issue, I never could put anything in place to change it.

I ran from 10psi to 40psi during all of those, trying to see if anything worked any better. I found low pressure to work better, but it did not stop the flare ups.

Also, I tried with paper on the back, wet and thought it was working well, then the next sheet, it wouldn't. So I can't tell you that I found a fix for it at all, and I did try a lot of things at the time. I even tried with air on and air off. Air off gave me some clean cuts, but it didn't resolve the issue either.

What speed/PPI/Power are you running?

[Hussain ZAKARIYA . Kuwait]

i try speed 0.5% and 100 power and 1000 ppi
just now i try alot of things , i try cut with both the paper (that acrylic come with) i make it wet with water and it`s fire from down and i lost the sheet, i try second time with remove just one face of the paper ( down ) and it`s work great with me without too little fire , i put air pressure 19 psi, and about the pulses ( reflection ) i put a pieces 10 mm acrylic under the sheet and it`s work ok , and the z axis 19.9 from the home point i reduce 0.1

Generally i will not use 10mm for a piece with details becuase the last job take 1 hour and 52 min !!


thank you guys it`s really helpful site and i`m honored to join you

[Scott Shepherd]

Take the paper off both sides if you can.

Also, that may be too slow for that material. I had a setting of .5 speed for the 1/2" thick with 45W. If you go too slow, it will flame up. Test a piece and keep bumping up the speed until it doesn't cut through and then slow it back down a click or two.

When you remove the paper from the top side, the material will act as a wave guide if it's clear acrylic, so it will require less to get through.

If it's colored acrylic, then you are probably right in line with the speed.

Also, make sure your Vector Performance setting is set to "Quality" (all the way to the left of the slider bar), and make sure your Image Density is set to "6" for all vector cutting. I know that's a "Raster" setting tab, but it does impact it.

So 1000PPI, Image Density to "6", and Vector Performance set to "Quality", no paper on either side if possible (sometimes the customer wants the paper left on).

[Mike Mackenzie]

I would suggest what Scott said only I would remove the original protective paper and re mask with lo tack application tape. I would also raise it above the honeycomb surface. I use 1/4 x 1 lag bolts and i position them in the area that will not get cut the 1/4 inch bolts go right into the honeycomb cells so you can move them around as needed.

I have found that most of the flame comes from the adhesive that protects the acrylic.

[Hussain ZAKARIYA . Kuwait]

thanks you all for your advices

i hate to work with 10mm because it`s take too time