CNC Bits for Cutting HPL Laminate

High Pressure Laminate is rough on tooling. Here's advice for choosing a bit that might last a little longer. November 27, 2012

Have you been successful cutting laminated sheets on the CNC? I've followed chart recommendations and have used diamond tooling, but cannot get past the excessive wear on my tools. I believe it's a feed/speed issue, but haven't found the right combination.

Forum Responses
(CNC Forum)
From contributor J:
When you say laminated sheets, are you talking HP laminate, and what substrate? I cut HP laminate with carbide bits.

From contributor K:
2 flute compression XP spiral from Vortex, run at 950 ipm and 18,000 rpm (tweak it from there). We cut a lot of HPL on particleboard and this is the best combo we've found.

From contributor J:
Yes, I am talking about HPL glued to particleboard core melamine. I've run Onsrud 2 flute compression bits at 16750 rpm going 600ipm with bad results; it will chip the bit right at the laminate line. I was told by a tool rep that possibly it's the glue we are using to adhere the HPL to the melamine. I feel strongly that it's a feed/speed issue, so I will try your suggestions and see what result I get.

From contributor S:
Increase the flutes, decrease the RPM, program speed to achieve the correct chip load.

From contributor G:
The problem is not the glue, but the laminate. Our customers use a 3+3 compression. Use the same speed as your current settings, and you should achieve 70+ panels prior to dulling.

From contributor C:
Contributor G has a point about 3x3 carbide compression bits with lower RPM and reasonable feeds. Our baseline is 3/8" 2 flute compression, 18000rpm at 850 ipm, and we yield 30-40 good clean sheets. Compare to 3/8" 3 flute comp at 12000rpm at 850ipm, and a yield of 50 to 60 good clean sheets.

The killer of carbide is heat. We have dulled many bits prematurely by not cutting deep enough through the layer of laminate on the spoil board. Normal through cut for us is .005", however on small parts we onion skin before the through cut and sometimes the onion skin cut is cutting part way into the laminate and will dull a bit rapidly. We have tried an increasing depth of cut profile (Routercim) as the through cut is made around the part. That simply consumed the spoil board faster, but did keep the bits sharper for a little longer.

Try increasing the depth of cut on your through cuts by a couple of thousandths. This may help with getting the heat away from the tips of the tool.

From contributor B:
Use a 1/2" straight carbide tipped end mill.

I had to cut 50 sheets of Wilsonart HPL laid up 2 sides on an 11/16 fir PB core. My Onsrud 1/2 compression bits, which have excellent tool life in melamine particleboard, began chipping the laminate after only 5 sheets, and after 10 sheets or so the tool edge was completely destroyed where it was hitting the laminate. I tried dropping the bit .030", but that did not help much, and ate up the spoilboard. After burning up 2 $80 bits, I did not want to eat up another one. So I tried a cheap 1/2" straight carbide tipped bit. Bingo! Still cutting clean after 30 sheets of HPL.

I think the cutting angle on compression bits is too sharp for HPL - great for getting smooth edges on wood, but awful for cutting super hard materials like HPL. The cheap, straight carbide tipped bits have a lower angle cutting edge. Think about it - a compression bit edge is very sharp, like a wood chisel, and straight carbide tipped bit edge, not so sharp, like a cold chisel. HPL is very hard and brittle, like stone. To cut stone you use a cold chisel, because the edge on a wood chisel would be ruined after a few blows.