Melting Acrylic/Plastic

[Dwayne Dibbley]

I have been trying a 6mm single flute carbide bit @ 21000 RPM 400mm Feed and 2mm depth, but the subject always gets to hot see pic:-



should i try faster feeds? slower spindle ? deeper cut ? or some form of coolant / lube ? to resolve the heat build up.

Thanks

[dazza]

Id say its too fast(rpm)try knocking the spindle speed down by 1000 rpm increments jogging back and fourth on a bit of scrap acrylic.

[Jonathan]

Id say its too fast(rpm)try knocking the spindle speed down by 1000 rpm increments jogging back and fourth on a bit of scrap acrylic.

Agreed - the chipload is too low so you need to decrease the spindle speed and/or increase the feedrate.

[JAZZCNC]

Acrylic as a very narrow chip load range and thats why it melts so easliy. I'd be going for higher feed rate first as 400mm/min is way to slow. Try 18000rpm and 900-1200mm/min then play around with both. Thou i'd be going higher on feed not slower. You'll definatly be wanting to at least double your original 400mm/min. I'd also cut with more DOC start with 50% cutter Diameter but it's not unusual to cut at 100% cutter dia.

The type of acrylic also plays a big part to how it cuts.! Extruded can be a pig to cut and Cast tends to be better.

[Ger21]

I'd go down to about 12,000 rpm and 2000mm/min. I've used similar numbers on acrylic in the past.

[JAZZCNC]

I'd go down to about 12,000 rpm and 2000mm/min. I've used similar numbers on acrylic in the past.

Last Cast acrylic I cut was 10mm thick and I cut it single pass with 8mm spiral upcut cutter at 24000rpm and 1200mm/min and it left a lovely finish but I thought these figures might scare him. . Lol . . . . Funny stuff acrylic and I find the larger the cutter the better finish I get.!!