Bit Wear in PVC with Applied Laminate

Cutting small parts in hard material can be rough on tooling. Here is advice about feed speeds and RPMs, as well as some thoughts on hold-down methods. June 4, 2012

I am having difficulty cutting 1/8" PVC/Celtec that has been glued to laminate. I am cutting with a 1/4 double flute upshear router bit and they have been wearing out after every sheet! Does anyone have any ideas? I am looking for spindle speed, feed rate, and the best tool for cutting on a CNC nesting table.

Forum Responses
(CNC Forum)
From contributor D:
I use O-flute bits with slower rpms 12000-15000 at 200-400 IPM. What are your speeds and feeds? Heat kills bits - you want flakes (chips), not dust and keep the cut cool!

From the original questioner:
16000 to 18000 at 150 IPM and actually we only run it at about 70%. The problem is, I am cutting a 4X8' sheet, and the parts are 4" square. We had trouble with parts moving so slowing it down seemed to help. How would you handle a job like this?

From contributor W:
Parts moving is a vac or hold down issue. I recently had to cut a large volume of .0625 aluminum in 6x6 squares and I pre-programmed some hole locations for screw holes and placed some screws in the middle of the sheets to prevent this.

From contributor D:
I've done a lot of experimenting, and have finally settled on the perfect (for me) speeds and feeds. Single downshear O-flute, 1/4" and 1/8" bits in 1/4" PVC 14K at 150ipm. It is only slightly hot, but it leaves just the right pack density in the groove to help hold the small parts in place. I adjust the rpm’s up or down slightly with the reostat depending on how close it's getting to reweld temps. It varies slightly as the bit dulls. I usually run these bits for a good 40 hours before tossing them.

From contributor Y:
Vibration of the material will wear out tooling faster than cutting marble. Adjust the density of the fixture gasketing to the cubic weight of the material. Adjust the size of the vibration absorbing sealant to the size of the finished part. If you want to play around with softer sealant just ask.