Cutting MDF with a Laser - request for advice

[Chris Terrell]

I've recently started using a Chinese-made laser cutter (50 or 60W tube, can't recall right now). I'm trying to find the right settings for cutting 9mm MDF cleanly and minimising the amount of charring that I have to sand off afterwards. So far I've found that it took about 8 repeats of the cutting operation, initially at 100% power and speed of about 100cm/minute for 3 runs, the rest at 50% power as it began to ignite a section (it was salvageable).
The job was done and the item - a tool carrier - is ok but there is deeper charring in the central part of the board thickness due to overheating. I'm wondering if this would have happened anyway in thicker material or if it needed a cooling time between repeats?

Does anybody have any advice on good settings for cutting MDF without this amount of burning?

I haven't had time available to do a full calibration test to find this out for myself, though a quick test implied that a lower power setting and speed, plus repeated cutting, would be better.
I'm wondering too if the beam/mirrors might need realigning and if this would make any difference?
The cutter has a reasonably effective air assist, but I'm not sure it projects the air very deep into a narrow cut in thick materials.

I've been told that this machine should be able to cut 12mm MDF.... over a few days perhaps!!?? At the moment I'm thinking it may be better and quicker overall just to use the laser to mark out the pattern and cut it using a bandsaw, coping or fretsaw and hole cutters.

Any thoughts and suggestions welcome, I'm already impressed by the amount of useful stuff I'm learning through this forum, so thank you in advance!

Best wishes and Happy New Year to you all.
Chris:)

[Rich Harman]

I cut 5mm MDF at 10mm/sec, 95% power. It will cut faster but that speed insures that it will cut through everywhere on the table.

Alignment will absolutely be a factor if it is not correct. Also make sure that your focus is good.

[George M. Perzel]

Chris;
Try setting your focus to the proper depth for the lens you are using, then raise the table or lower the head by about 1/2 of the depth of the material you are cutting-although 9mm mdf will be tough for one pass at 50 watts.
Best Regards,
George
Laserarts

[Lee DeRaud]

Just as with plywood, all MDF is not created equal: you may want to try a different supplier.

I use a lot of 1/4", and discovered that my local plywood distributor has two types: cream-colored stuff that the laser zips right through and some slightly darker stuff that behaves as you describe.

[Michael Hunter]

Clean cutting of MDF that thick with that power could be a bit of a challenge.

As well as the other suggestions, you could try lowering the frequency, pulses per inch, dpi or whatever your control software calls it.
I find the optimum for wood about 500 to 700. It can give a "little perforations" look to the cut edges, but does reduce the charring compared with higher rates.

[Chris Terrell]

Thanks to all of you for your replies, that's very helpful and I'll try these out when I'm back at the school in January.

[Zvi Grinberg]

Creek Friends,

Most MDF boards are made with toxic resin and pollute Formaldehyde fumes.
If you still decide to challenge your health, at least care for excellent fume extraction from you space.

I would also be concerned about corrosion of the machine's components.

Zvi