Heat Issues when Cutting MDF with Compression Bits

It's tricky to adjust cutter speeds for good chip load and cool cutting in MDF. May 15, 2008

I just purchased a 4 flute compression finisher/rougher combo bit from Vortex called the tornado bit. Does anyone have experience with this bit? I am trying to get the right feed rate and RPMs. The bit seems to be getting hot after the cuts, so I feel like I am not cutting at the right speeds.

Forum Responses
(CNC Forum)
From contributor K:
I have found Vortex to be very good with helping in this area.

From contributor M:
Don't know what you are cutting, but you will have to cut fast without a lot of short moves. With short moves you will have a lot of accel/decel times that will give you a smaller chipload creating more heat versus the longer cuts. If you cannot keep the speed up, use a three flute tool instead of the four. If you don't understand chipload, search this forum or ask the good people at Vortex.

From contributor O:
Contributor M is correct.... run your machine's axis motion as fast as you can, then reduce the spindle rotational speed down till you eliminate dust and burning.

From the original questioner:
I am cutting 3/4 MDF.

From contributor B:
I have not had good luck cutting MDF with a compression bit. You are right - they heat up really fast because the MDF is abrasive. Try cutting with a 1/2 in. down shear 2 flute bit about halfway through 16000 @ 420 ipm, then finish with an upcut same speed/feed. You should get chips and very little dust. Slow down the RPM if heat builds.

From contributor E:
I've not used the tornado bits, but I have used the 4 flute 1/2" finisher from Vortex. I took a roughing pass leaving .25mm stock at 14,000rpm and 21m/min (826 ipm) and 17.5mm deep. Then followed that with a finish pass at 18000rpm and 30m/min (1181 ipm). I used two passes to keep the parts from moving and to give a better finish. The parts were 2'' wide in some areas (a window grid). Cheap lower quality MDF is usually much denser and more difficult to cut than a super-refined or double-refined MDF (such as Plum Creek, or GP's Synergite or Hollyhill). We routinely cut the Synergite 5/8" and 3/4" MDF 1 pass at 24,000rpm 30m/min with a Vortex 3 flute 1/2" compression.