# Thread: What power is needed to cut thin foam?

1. ## What power is needed to cut thin foam?

Hi,

having built a CNC router, I'm now looking to expand it's use. For wood working I will continue to rout, but I often cut (now by hand) Depron, a 3 or 6 mm sheet of some polysomething foam, from which one can build small RC planes (parkflyers). Now my idea is to start of using a laser from a DVD (200 mW, if my research is correct). But is there a theoretical way to guestimate the necessary power? If the prices of the necessary laser is beyond the budget, I might just forget about this for a while...

Thanks,

Hugo

2. I imagine a power density of 5-10 W/mm^2 would be adequate for foam, at least for CO2.

I ran through some quick calculations, but I'm wondering if I missed a decimal place (or five). A DVD laser diode has a wavelength of around 640nm... good optics might get you to a spot size of around 10-15um. My in-the-head calcs say this is a beam density of 390MW (yes, that's mega!) at that spot size... the advantage of this semiconductor laser over a typical CO2 laser is the wavelength, which allows you to focus to a smaller dot size by a factor of 1,000 (and hence have a higher power density by a factor of 1,000^2).

Can you achieve that? I don't know, never tried, but I imagine the focal point is going to have a very short length. I'm merely looking at it from a math standpoint, and I have no idea if the power will translate in this way, particularly at a different wavelength than CO2.

3. Originally Posted by Witsenburg
Hi,

having built a CNC router, I'm now looking to expand it's use. For wood working I will continue to rout, but I often cut (now by hand) Depron, a 3 or 6 mm sheet of some polysomething foam, from which one can build small RC planes (parkflyers). Now my idea is to start of using a laser from a DVD (200 mW, if my research is correct). But is there a theoretical way to guestimate the necessary power? If the prices of the necessary laser is beyond the budget, I might just forget about this for a while...

Thanks,

Hugo
Hello
We have developed a Plotter with a special knife system that cuts 2.5 -3 mm foam. We are now trying to develop a 6mm blade. This is a little more dificult. The 3mm cuts very well with clean edges and fast. The machine and software will be about \$1400 for a 24" machine x any length.

4. B4 my laser crapped out, I was cutting 1/4 bluecor (fan-fold foam) at 60 ipm at something between 20-40 watts Co2 flowing gas laser.

5. ## CNC mounted 250mw 635nm Diode

I have sucsessfully etched woods and plastics (the more matt the surface is the better) with a tiny little DVD-R diode.

The diode is focused to approx 0.07mm.

I have just cut some 3mm thick foam (medium density and dark grey in colour) at about 200mm/m. Not the fastest beast in the world. But it worked

Could cut thicker with multiple passes.

Have attached scan of some Tufnal about 100mm x 70mm, It had a pretty glossy surface but still etched well at about 300mm/m