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.
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.
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
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.
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