50W co2 laser cutting everything I throw at it but not MDF ?

Hi,

I got a 50w 40x40 co2 laser from china a while ago (maybe 2 year) and upgrade it a bit, I added a true air assist (adjustable 5 to 35 psi), installed an ampmeter, a hood switch and water flow sensor, a water chiller (compressor type), adjusted the power supply output below 20ma (came adjuster at 22) and replaced the tube a few month ago because I had doubt about the power of the tube since some people with the same machine claimed to cut material I had trouble with and that solved all the problem I had.

The problem I am facing today is bugging me, I can cut thick acrylic (1/2 inch), 6mm plywood in single pass at 10mm/s 80% power ,and 12mm in 3 pass at the same setting, I tried cork and gasket maker sheet, engraved glass and wood, cut 10mm birch plank and never had a single problem ! But today I tried cutting 1/4 inch MDF and even at 5mm/s and 5 pass the laser just wont go trough ! At 6 pass the laser start to pierce in some spot but not enough to separate de piece from the sheet. I suspected the laser and I double chececked everything, mirror alignement is perfect, all mirror and the lense is clean. tried cutting birch plank and plywood and all is good so the laser is not dying, I tried upping the air assist pressure but that did not help. If i slow the laser to a crawl at 3mm/s at 90% it get trough after 4 to 5 pass but the part is so charred all around that it is unusable. I went to the store ( following all coronavirus precaution, gloves mask and all that) and got another sheet of mdf from another company, this one seem a bit lighter in color, same thickness, but that wont cut either and when it does its more burned than cut !

So I guess my question is, any of you got experience with cutting MDF ? Plenty of people here seem to cut it with k40 without problem and I just can't figure what I'm doing wrong ! Maybe some additive or the glue used in the MDF I got have are the culprit ? maybe some magic laser setting I never messed with ? I would really like to use MDF for some future project.

Man made wood composites can be difficult to cut due to the glue. I’d buy samples of mdf from different sources to see what cuts. Slowing it down just creates a charred mess


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Originally Posted by Dean448

Man made wood composites can be difficult to cut due to the glue. I’d buy samples of mdf from different sources to see what cuts. Slowing it down just creates a charred mess


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Yeah, I found some other sample at various hardware store that are still open in my area and not a single one of them seem to cut well. I will probably try again after the pandemic is over, because washing everything every time after I come back home is making my wife give me nasty look !

I have cut MDF, but have found that it is not a good material to use with a laser. I have a 180W machine. The heat thatt is generated make MDF a poor material, backside burns badly.

I found one type that would cut. but like robertlroberts said, it made a sticky burned mess on the backside, guess I'll use plywood instead. Thanks everyone !