Our shop cuts doors and drawer fronts from 2-sided HPL on 11/16 pb using a 2 flute 3/8 compression bit. They are cut good side down, as the CNC does the machining for the European hinges we use, as part of the milling process.
The laminate is so abrasive that we experience chip-out on the bottom after cutting only 2 5x8s of sheet goods. At this point, we lower the Z offset to get a sharp edge to cut with. We get approximately 6 sheets per bit, as well as using up a sacrificial 1/4 MDF spoilboard.
Anyone else have experience with this?
I have seen the same problem. I use a solid tungsten "up-cut" spiral for this. I also have an up+down cut with interchangeable tips that gives a good finish on both edges.
The key to cutting more sheets of two-sided plastic laminate material is the proper combination of spindle speed, feed speed and number of flutes on the router bit and its diameter.
The other issue that causes problems with compression bits and good two-sided material is the lead-in that your post processor provides. A straight plunge lead-in even when it is not along the actual finished edge of the work piece will quickly dull the bottom cutting edge of a compression bit. To get the best performance from compression bits you need a ramp lead-in with a lateral move into the finished edge of the work piece. The ramp minimizes the heat buildup on the tip of the bit. The lateral move into the finished edge keeps the tip of the bit that has an up cut and tends to chip on entry away from the finished edge of the work piece. The point along the finished edge where the compression bit entered the side that was up and plunged through on the side that was down is where I had a problem with chipping, even with a new bit.
Iíve cut as many as twenty sheets of 5 x 8 two-sided hpl material with a bit that had already cut thirty five sheets of 5 x 8 melamine covered particleboard. At twenty sheets I started to see some chipping on both sides of the board. In this case, I was cutting standard grade plastic laminate, not vertical or post form grade.