PVC chip load?

[rigo430]

I've got some pieces i need to make out of PVC and i was wondering what kinds of speeds and chip loads people like to use to get good finishes.

[stevespo]

Without knowing what type of machine you're using, or the type of tooling you have available - here's some generic advice for plastics.

Look at what the tool manufacturer recommends for chipload. Some companies publish charts, so use it if you have it.

Without a handy chart, I tend to use 2% chipload, and then I plug the values into feedrate calculator. You may need to adjust it faster or slower, depending on the variables - this is a good middle of the road.

I'm using a high speed spindle on a wood router. I slow down the RPM (12K) and increase the feed rate (IPM) to avoid overheating and welding the plastic. A mist system, or compressed air will also help.

I tend to use a single flute cutter. It gives the chip room to eject and helps with cooling. The "O" type cutters, in a straight flute or spiral work nicely in most plastics. The Onsrud 63-750 series is a great choice for soft plastics.

So, with a 63-775 (.250" diameter) tool at a .008" chipload, and 12K RPM, I'd probably start around 80-90 IPM. Faster RPM will probably require faster IPM. Naturally it depends on what your machine is capable of. You might be able to go quite a bit faster, or slower if your machine is not rigid or smooth enough.

This is just my experience. YMMV.

Steve

[rigo430]

I plan on using either a HAAS VF8 or VF2 super spindle. As far as tooling goes I've got tools meant for aluminum or some router bits i could probably use.

[stevespo]

Lucky you. You're not going to have any issues with vibration or precision, and you've got a high speed spindle as well (what do those support 8-10K RPM max?).

The finish (and feedrates) will be better with a dedicated tool because the geometry is designed for the material.

Give it a shot with the router bits, or a 2 flute end mill - it will certainly work. If you're not happy, try one of the Onsrud cutters.

Steve