[Nissim6811]

Hi There


I have a cnc machine but very little experience.

I want to cut 3mm alumiuim with a pattern on the surface (non slippy pattern )
I tried 6mm end mill tool
I set the speed to 6000

The tool snapped after a few minutes

Can someone please advise me what is best bit to use ?
What speed shall I set the machine
Do I need to oil bit during the cut ?

Many thanks in advance

Nissim

[Superman]

Hi There


I have a cnc machine but very little experience.

I want to cut 3mm alumiuim with a pattern on the surface (non slippy pattern )
I tried 6mm end mill tool
I set the speed to 6000

The tool snapped after a few minutes

Can someone please advise me what is best bit to use ?
What speed shall I set the machine
Do I need to oil bit during the cut ?

Many thanks in advance

Nissim

More info
- what are the cutter specs ?, how many flutes ?, is it an alum cutter (HSS, carbide, coated, not coated.....it needs to always be sharp ) ?
- what feedrate ? what depth of cut ? width of cut ?
- how are the chips removed ?
- what is available to you to use in the way of air, coolant, etc to remove chips ?
- guards to limit swarf & coolant spray ?
- what machine are you using ?

Generally, you need to get the chips away from the cutter, by using air, air/coolant, or straight coolant.
- the coolant could be a proper soluble oil emulsion, WD40, kero, or a mix with water to stretch it out ( this also helps to limit the material sticking to the cutter )
- the feedrate depends on a lot of factors, ie width/depth of cut, # of teeth, tool "stickout", work holding method...... just to name the main ones

Your RPM is too slow ( cutting speed works out to be 113 m/min...which is for steels ), what is the max RPM of your machine ?
- alum is roughly 4x the cut speed of steel,

You may have gotten the tool too hot, & possibly it packed up with chips....causing the tool to not being able to cut any material....
- I guess you got a fairly decent burr where the tool ended up breaking ?

[InMesh]

Feeds there a good thing too.

[squirrel_41]

Okay I know that if you use G-Wizard the feeds and speeds will be very high I have never been able to use the feeds and speeds calculated by G-Wizard even with Flood cooling the ally still melts and sticks to the tool.
I just finished cutting some 3mm Marine grade alluminium useing a 6mm 4 flute Hss tool
These are the feeds and speeds that worked really good I was also useing flood coolant just water with some soluble oil added
Spindle RPM = 3000
Feed rate = 160
Plunge rate = 50
full width cut i.e 6mm
depth = full depth i.e 3mm
Leave 1 mm for the clean up

Finish pass I used calculation from G-Wizard
Spindle RPM = 17465
Feed rate = 1349.7
Plunge rate = 251
but I think i would slow down the feed a little to maybe 1200
these feeds are all mm per min

And just to add all those tools that get the ally melted to them just drop then in a jar off Hydrochloric acid overnight and they will be good as new in the morning.

[Nissim6811]

Thank you very much for your help

I attached photos

[Superman]

Thank you very much for your help

I attached photos

Feedrate looks a little toooo high ( 6x )
you need to slow your feedrate down ,,,, say,,,,, 0.10 to 0.15mm / tooth,,,,, after you get it cutting, then, increase your speeds & feeds


Some equations you need to learn
RPM = ( Cutting speed / ( cutter Ø x Pi ) ) x 1000

Feedrate / RPM / number of teeth = Feed per tooth
so, you aye using
9000 / 12000 / 1 = 0.75mm

to go the other way
RPM x feed per tooth x # of teeth = feedrate
12000 x 0.10 x 1 = 1200 mm/min
12000 x 0.15 x 1 = 1800 mm/min

[Nissim6811]

Thank you so much !!

I followed your advice and set up the feed speed
Its perfect now

Thanks again
Nissim

[RCaffin]

The reality is that the treadplate you are trying to mill is a horrible alloy and very unsuitable for CNC milling. It is just too soft and too sticky. I think, from memory, that it is a 5000-series alloy. Very cheap compared to the better 6000-series alloys.
Yes, you can machine it with great care. Air blast and an oily mist to keep the cutter WET.
If you get any Built Up Edge (BUE), you are seconds from disaster.

Cheers
Roger