I have a 10W laser (4.5cm focus) and still new to laser cutting. I have no problem cutting black polyethylene foam (can go 600mm/minute) and have made several tool + accessory holders. But my understanding is "white" PE foam is too transparent and will pass through and scatter too much light. I tried several susceptors to absorb the energy.
All experiments used 60mm / minute travel speed and 15mm cut depth @ 5mm depth of cut per pass
1. talcum powder
This works well for the top pass. It cuts a swath 1 to 2mm wide, depending on how thick the powder coat is. But it only partly cuts the next layer. The 3rd pass seems to do nothing at all since the measured penetration is ~10mm, compared to the 15mm expected.
The square on the left is cut without any susceptor. Only 5mm penetration. The square on the right used talc.
2. 70% water and 30% talc by volume
The idea was for the mixture to flow into the cut for the next pass. Unfortunately, this is even worse than nothing - no penetration at all. It seems the water both absorbs and reflects too much of the energy. Also, the thickness of the liquid is much more than the thin layer of talc in #1, so the amount transmitted will drop off exponentially with thickness (Bouguer-Lambert law).
3. black India ink
This worked well and cut all the way through. You could see the ink seep into the channel and burn.
But it leaves an ugly residual
Maybe there's a light colored liquid that only absorbs around 450nm and can be easily ablated. It's not clear what color it should be because 2 materials with the same perceived color can have different spectrums.
Any other ideas?
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