[gtoshihiko]

Hello,

I've recently been tasked with cutting polypropylene sheet on a CNC router. I'm using a 3/8" 2-flute upcut spiral at 16000 RPM and 300 IPM. The problem I'm having is in 3/4" thick material where I'm taking 1/4" passes and the chips are getting stuck in the groove left behind the tool path. This only happens on the 2nd and 3rd passes. When I say stuck I mean really stuck. High pressure air sometimes does not work to eject the chips. The stuck chips are being re-cut by the tool and causing a poor finish. I cut 3/4" thick polyethylene and even 1/2" thick polypropylene without this issue. Any advice is appreciated. Thanks in advance.

[ckelloug]

Compressed air to blow the chips out and cool the tool would be my first guess. My second would be that your spindle speed is too high. I haven't ever done this task myself however so hopefully someone with more experience will comment.

[ger21]

Cut your spindle speed to 10,000 - 12,000, or increase your feedrate.