Milling Expanded PVC on CNC Equipment

Bit choice, feed speeds and RPMs for cutting cellular PVC. November 10, 2006

I'm looking for recommended feed speeds and RPMs to cut expanded PVC, 3/4" thick - same stuff they use for exterior trim.

Forum Responses
(CNC Forum)
From contributor A:
I'm away from work and don't have access to feed rate data, but we have experimented with several types of bits and the "O" flute bits work the best by far. The expanded PVC has a molecular density rather like pine lumber, so you can run faster than you would, say, in a sheet of plywood or melamine.

From the original questioner:
Thanks. I am going to go with a 1/4" O-flute upshear. I've been told with the wrong feed/spindle speeds, the material can kind of "melt" back into itself, ruining your cut.

From contributor J:
Try starting at 200 feed 100 plunge 18500 RPM climb mill.

From contributor G:
A 1/4" diameter cutter is a bit small for that gauge of material, but it will work. Go with a minimum 3/8" diameter "O" flute or upspiral. Single flute will remove the chip better and double flute will give you a better finish.18000 rpm's at 450-600 IPM. You can run slower if you prefer. In 15 years of cutting that stuff, I've never run into a melting problem with expanded PVC like you would get with other plastics.