Feed Rates and cutters for wood panels

[jimbo_cnc]

I just knew I shouldn't have mentioned the machine or ballscrew design. It's removed now.

This thread is part of my research into feed rates.

Everywhere I look I get a different answer, but most of them are 6000mm/min plus.

I want to know if I can get away with 3500mm/min given the cutting does not need to be at the economic sweet spot for tool life or machine productivity.

[jimbo_cnc]

6mm 2flute down spiral
0.15mm chipload
10k rpm
= 3000mm/min

That might work ?

[Shinobiwan]

Hi jimbo,

If 3500mm/min is the max rapids of the machine then I doubt you'll be cutting with any decent DOC at 3m/min. For me that's too close for comfort to the performance headroom. I might be wrong and they can run the machine at 5m/min or whatever and just choose 3.5m/min to be conservative.

I can tell you cutting MDF slowly quickly dulls TCT bits and I wouldn't even bother with HSS as they'll last even less.

I cut around 6-7m/min with 6-9mm DOC in MDF but really depends on your machine. Spindle speed and the number of flutes is important too. If your really going to cut at slow speeds then definitely stick to single flutes. Don't thrash the shit out the spindle either. MDF doesn't need 24k rpm and the slower you go the less rpm you'll ideally use. There's a point where you'll run out of torque on your spindle though so I've found 10-12k rpm is fine for the feeds I mentioned above.

You can get away with cutting at slow speeds such as 2-3m/min but make sure your using the right cutter and keep you spindle speed as low as you can otherwise the cutter rubs rather than cuts and that leads to burning and short tool life.

For wood people think speed is a luxury but having had a machine that cuts at similar rate to what your looking at and now one that cuts it how its supposed to I can tell you its world of difference.

[jimbo_cnc]

OK thanks.

You are correct, I need single flute to get the chip load OK. They are a bit harder to find and more expensive than 2 flute it looks like.

For 19mm MFC I think I need 22mm or 25mm cutting length? I have seen some 20mm length is that too short?



6mm 1flute down spiral
0.3mm chipload
10k rpm
= 3000mm/min feed
= 3.1 m/s cutter speed

Is that getting better. Now I've lost the cutter speed tables I saw earlier.

[gavztheouch]

OK thanks.

You are correct, I need single flute to get the chip load OK. They are a bit harder to find and more expensive than 2 flute it looks like.

For 19mm MFC I think I need 22mm or 25mm cutting length? I have seen some 20mm length is that too short?



6mm 1flute down spiral
0.3mm chipload
10k rpm
= 3000mm/min feed
= 3.1 m/s cutter speed

Is that getting better. Now I've lost the cutter speed tables I saw earlier.

What about a compression cutter to prevent chipping that melamine facing?

[jimbo_cnc]

Isn't compression cutter just a different name for down spiral?

[Shinobiwan]

Compression cutters have both up cut and down cut flute patterns.

[gavztheouch]

If you really are just cutting for an hour every week then the this machine should do you fine. The feedrates of 22m/min in 18mm birch you were quoting are for big industrial routers that have big spindles, servos, vacuum systems and possibly tooling ( You can only push a 6mm cutter so fast) Any small scale machine is not going to match that performance in terms of 1. cut quailty 2. Last any time before something breaks/shifts/loosens/bends.