Aluminium Cutting

[Katoh]

Good Evening to All
Its been quite a while since my last post, just goes to show when you build a good Mach machine nothing really goes wrong, True to a point, since last time I posted anywhere, I have added a 4th axis to the big router, and actually worked out how to use it, still trying to learn how to alter a 3d file but that is a different matter entirely.
Ok enough rambling from me, My next project is to make a 23' Aluminium boat, the panels I am hoping to cut using my CNC router, I can already hear shrieks out there, apparently it can be done. The thickest material will be 6mm and the rest will be 4 and 3.
The machine has a 5HP Fimec motor speed range from 7 to 14.700 rpm and cuts max speed 3000mm/min comfortable, can go a lot faster but scary at high speeds! I don't want to use mist lube on the cutter I have made up a concentrated compressed air fitting to blow onto the cutter, but I don't want oil going all round the joint.
I will probably use either a 3mm or 6mm cutter cut down, smaller the better.
Now the Crunch, What I would like to know What is be best cutter to use? speed/feed rate? rpm? and cut depth?
Has anyone got experience?
Cheers Katoh

[Hood]

I cut lots of 5083 and wouldnt dream of doing it without flood, you may be lucky and get away with air only but.... well  I have never had much luck. Then again I only have 4000rpm spindle on the mill so maybe getting the spindle speed and the feed cranked up will help. Get a cutter specifically designed for Alu and you may stand more of a chance.
Why do you not want oil on he cut?

Hood

[Katoh]

Hi Hood
You probably don't remember my Machine but its a great big flat bed router, know with a 4 axis down one end, the work sits on a timber base and its all contained with timber surrounds. Ok I chop up a plate with mist, mist floats around soaks into the timber, next time I use the router to shape a $1000 stick of walnut for someone oil starts leaching into the job from the base and destroys the job, I see this get upset, grab a gun and shoot the router. This is a very dramatic recreation of what could happen, but I really prefer not to go down that path if you know what I mean.
Katoh

[Hood]

Ha ha OK I see now why you dont want oil and coolant there
Suppose you are just going to have to try and see how you get on but as said I would definitely go with a cutter specifically designed for Alu, they are usually sharper and have a high helix and can be fed fast if you have the spindle speed, and you do
Hood

[ger21]

You can get router bits for cutting aluminum dry from www.onsrud.com. They won't be cheap, though.

[Katoh]

Thanks Hood and Gerry
I will look at the onsrud site maybe also cmt might have something, but it would be nice to talk to someone how actual does it with the same sort of machine, little tips and tricks are at times invaluable.
Katoh

[ger21]

RPM and feedrate will be critical. Onsrud should be able to steer you in the right direction.

[HimyKabibble]

Good Evening to All
Its been quite a while since my last post, just goes to show when you build a good Mach machine nothing really goes wrong, True to a point, since last time I posted anywhere, I have added a 4th axis to the big router, and actually worked out how to use it, still trying to learn how to alter a 3d file but that is a different matter entirely.
Ok enough rambling from me, My next project is to make a 23' Aluminium boat, the panels I am hoping to cut using my CNC router, I can already hear shrieks out there, apparently it can be done. The thickest material will be 6mm and the rest will be 4 and 3.
The machine has a 5HP Fimec motor speed range from 7 to 14.700 rpm and cuts max speed 3000mm/min comfortable, can go a lot faster but scary at high speeds! I don't want to use mist lube on the cutter I have made up a concentrated compressed air fitting to blow onto the cutter, but I don't want oil going all round the joint.
I will probably use either a 3mm or 6mm cutter cut down, smaller the better.
Now the Crunch, What I would like to know What is be best cutter to use? speed/feed rate? rpm? and cut depth?
Has anyone got experience?
Cheers Katoh

I don't see any reason you shouldn't be able to do what you suggest.  I'd probably use a carbide endmill rather than a router bit.  I do my aluminum roughing using a 1/2" carbide 3-flute endmill, 0.125" DOC (~3mm), 6000 RPM, 75 IPM.  It'll do that all day long with just a strong blast of air to keep the chips clear.  In general, with aluminum, if your feed is too slow, you'll find the tool heats up, and chips weld to the tool.  The natural reaction when you see a hot tool, and chip welding, is to slow down, but that's exactly the wrong thing to do.  You want to maintain the heaviest chipload you can get away with (which is a function of your machines stiffness and spindle power), as a thick chip will carry heat away from the tool.  If the machine stiffness prevents running the desired chipload, reduce RPM, reduce feedrate accordingly, and try again.

Regards,
Ray L.

Regards,
Ray L.

[elpablito]

Using onsrud or amana carbide single O flute 1/4" diameter you can cut at 15000 rpm and 0.003 to 0.006 per tooth (45 to 90IPM) full diameter (eventhough i never cutted more than 3mm aluminum in a single pass)
I use a cool air gun and lub myst.

[Katoh]

Gentlemen
Thank you ever so much for the advice, I will buy a couple on the O flute bits in sizes from 3-6 mm and at least know iI have a starting point, run the router at around 75ipm and speed around 13-14k rpm used air jet on the cutter and play around with a scrap piece of 6mm plate till I tweak it just right. Then start cutting out this boat, Cant Wait!
Thanks Again
 Katoh