Machining Aluminium

Hi Guys,

I would really appreciate some help on machining Aluminium on my Pacer CNC machine.

I am going to cut a casting mold out of a 250 x 250 x 32mm slab. ( i purchased 3 grades to test the quality - 5083, 6032 and ecocast)

I have a 6mm 30mm cut twin flute and a 4mm 40mm cut twin flute aluminium tools to do the job.

My machine has a 2KW air driven spindle (pacer compact cnc) on an auto tool change system, and a misting spray system installed.

What feedrates would i need to use, and what pass depths could i get away with?? do i need a high spindle speed, the max i can go is 240K. I need to achieve a high quality finish, all my design work is carried out in aspire.

Again i really do appreciate all your help.

Cheers

Steff

[QUOTE=Steff;38127]Hi Guys,

I would really appreciate some help on machining Aluminium on my Pacer CNC machine.

I am going to cut a casting mold out of a 250 x 250 x 32mm slab. ( i purchased 3 grades to test the quality - 5083, 6032 and ecocast)

I have a 6mm 30mm cut twin flute and a 4mm 40mm cut twin flute aluminium tools to do the job.

My machine has a 2KW air driven spindle (pacer compact cnc) on an auto tool change system, and a misting spray system installed.

What feedrates would i need to use, and what pass depths could i get away with?? do i need a high spindle speed, the max i can go is 240K. I need to achieve a high quality finish, all my design work is carried out in aspire.

Again i really do appreciate all your help.

Cheers

Steff



UPDATE:

Ive been cutting the aluminium today and im not getting on well, been using a Belin single flute 6mm upward spiral. Running at 21k spindle speed, 2 m/min feedrate, 2mm pass depths.

The first cut is flaring the alu outwards, not cutting clean like you would expect. im pocketing down to 25mm and on each pass the edges are getting rougher. I tried to slow the spindle speed but this made very little effect. I changed the feedrate down and this too made the job worse. i was running at 21k rpm at 2.4 m/min and then my tool snapped :( , this is still under the cnc cutter guide stated at 3mm pass depth --- 2.5 m/min --- 21k spindle speed.

Any advice would be highly appreciated right now!

Thanks again

steff

Hi Steff,

PM sent.

Quote:

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The first cut is flaring the alu outwards

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sounds like that would be in some part down to the one of the qualities if the material your cutting (it can be a bitch)
im not sure if its down to it being rolled as cast seems to machine better (more brittle because of the way it crystallizes I think but dont hold me to it)
the chip clings to the tool, gets dragged back in re-cut and before you know it its cutting more material than it can clear boggs down and snaps

i think your being a tad ambitious with your depth of cut for a router... id stick with the recomended feed n speed and reduce the depth of cut even if it means going to 0.5mm... slow and painful but will get you there in the end :)

im assuming you use WD40 ?
if not dabbing plenty WD40 or maybe paraffin and brushing the chips clear as you go will improve things markedly

I have no experience of cutting at 21,000 rpm, I have dabbled with tiny tooling at 6,000 rpm. I will be curious to see if you succeed.

Soft aluminium alloys have a bad habit of extruding when they should be cutting. I find that when I drop below 8mm tooling I have to be careful when cutting soft extrusion if I don't want to snap tooling and that's with a good flow of suds to carry the chips away. I think things get a bit bendy at 6mm and below, the tool lacks the rigidity to insist on the cut.

Only a suggestion, but this stuff takes a deep T6 temper Blackburns Metals Limited - Mould Plate - Alumec

Quote:

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the tool lacks the rigidity to insist on the cut

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you have a way of putting things that really gets to the nub :)

With a 2 flute 6mm alu-power (cutwell tools) try around 12,000rpm and a feed of 1200mm/m at a depth of 1mm to start with but you will need to get some good cooling on it.

See what I've posted here, it's basically the same as what you're asking:
http://www.mycncuk.com/forums/genera...html#post38181