Cutting 4 mm birch in a 80W Laser

My 80W laser takes around 4 passes to cut a 4 mm birch at 70% of it’s power and the speed would be as low as 10mm/sec Is it actually normal or there’s something wrong with my laser.Please share your expertise .

I cut several wood test pieces from random scrap with a 60 W (claimed) OMTech laser:

The 5 mm oak plywood required one pass at 10 mm/s and 70% power, with 8 mm plywood a little slower at 6 mm/s.

Perhaps your laser is misaligned, defocused, or has crud on the optics?

mirrors are aligned …I checked recently …what does defocused mean…how to deal with the same…I’ll clean the optics once again

The focal point of the lens should be at or very slightly below the surface of the material. If the focal point is much higher (= the material is too low) or much lower (= the material is too high), then the beam energy is spread over a larger area and doesn’t deliver enough power to get the cutting done.

If the beam is properly focused through clean / aligned optics and it still doesn’t cut, then something else is wrong.

Is a new problem on a laser you’ve been using for a while or is it an entirely new laser that never cut very well?

it used to cut the same material in 2 passes at 50% power

Then the “something else is wrong” includes expensive items like a worn-out tube or a one that has stopped lasing in what’s called TEM00 mode.

Tubes do wear out after a few years, due to changes in the gas mixture and suchlike. If it’s more than a few years old then it may be time for a replacement.

Searching the forum for keywords like “laser mode” and TEM00 will show how to test for that problem. Basically, a low-power pulse on a paper target at the first mirror (as you do when aligning the mirrors) should produce a clean round dot, rather than a ring or a couple of misshapen spots.