CNC-Routing PVC Sheet Material

Bit choice, speeds, and related issues for routing Sintra and similar materials. February 17, 2006

Can anyone recommend a good router bit/feeds/speeds for routing sintra? I'm using a Porter Cable 3 1/4hp router on my CNC and I would like to get the best edge quality I possibly can as the client is a theme park. I did a part run and had a lot of trouble with re-welding and some chattering along the edge. Any help would be greatly appreciated.

Forum Responses
(CNC Forum)
From contributor F:
An Onsrud bit for acrylic will work fine (1/4" upcut o-flute for acrylic). Actually, a lot of cutters will work fine. Sintra is about as easy as it gets - however, how thick are you cutting? If the cut is too deep in one pass (over 3/8") then re-welding might be a problem. Try a 2 flute upcut solid carbide metal cutting bit if you can't get the Onsrud or similar quickly. I don't go any higher than 200 IPM for feed rate, and even that depends on the smoothness of your machine.

From contributor G:
Can you slow the Rpm's down? What's causing the re-welding is the chips are being re-cut prior to the chip evacuation. This will also cause the tool to dull quicker. A single O will work, but if the parts are small, it will tend to lift the material. I would then advise you to use a 2 flute slow helix.

From contributor D:
Sintra cuts better in a clockwise direction. Pay attention to which side the chip sticks to. If the scrap is clean but the part is re-welding, reverse the cut direction. We use 1/4" O-Flute Straight bit from Onsrud and get great results. You won't get a great edge and it tends to be very porous.