Page 1 of 2 12 LastLast
Results 1 to 12 of 18

Thread: Feed/speed for aluminum

  1. #1
    Registered
    Join Date
    Nov 2008
    Location
    USA
    Posts
    5
    Downloads
    0
    Uploads
    0

    Default Feed/speed for aluminum

    Hey guys, total newbie here ...

    I'm looking to get my first CNC mill. Right now, I'm planning to get Grizzly's version of the Super X3 and CNC it with CNCFusion's kit.

    I'm going to working almost completely in 7075 aluminum. From what I've read, aluminum should be milled at far higher spindle speeds than the Grizzly's top speed of 1750 rpm, which seems to limit it to about 20 ipm.

    My budget is limited, but I need to able to produce parts in a reasonable amount of time. Right now, simulations at 20 ipm are coming in at several hours. How can I improve the mill's performance? I have a 5hp motor lying around, can I simply install a bigger motor and change the gearing or will that blow out the bearings? Can I feed at at higher rate by using carbide or adding a flood coolant system?

    Is there a better choice for the mill? I really can't swing more than $3500 or so for the mill, motors, and control, so I can't simply go buy some monster mill.

    Any advice would be greatly appreciated.

    Cliff

    Similar Threads:


  2. #2
    Gold Member
    Join Date
    Feb 2006
    Location
    USA
    Posts
    5075
    Downloads
    0
    Uploads
    0

    Default

    You don't indicate what type of work you will be doing, and what size tooling you'll be using most. RPM is determined by tool material, tool diameter, and work material. If you'll be using 1/2" HSS tools in aluminum, you *want* to be turning about 3100 RPM, and feeding at 10-15 IPM, faster for shallow cuts. If you'll be using 1/8" HSS tools in aluminum, you *want* to be turning about 12,000 RPM, with about the same feed rates (maybe a bit less).

    So, yes, 1750 RPM will SERIOUSLY increase your machining times. Except for larger tools, you don't need more power, you need more RPM. you can probably get away with perhaps doubling the RPM by changing motors (get a 3-phase motor and VFD, which will allow you to double the motors base speed, and give you variable speed), or gearing (a LOT more work). Better still, get a mill that already has higher speed capability. Syil has an X4 mill with, IIRC, a 24K RPM spindle. But, it may be vaporware.

    I can't for the life of me understand why all these small mills have such low speed spindles, as it is a serious performance limiter. Of course, given their limited rigidity, you aren't likely to reach the above rates on other than very shallow cuts anyway. $3500 just doesn't buy you a very heavy duty CNC machine.....

    Regards,
    Ray L



  3. #3
    Registered
    Join Date
    Nov 2008
    Location
    USA
    Posts
    5
    Downloads
    0
    Uploads
    0

    Default Taig instead?

    So, would I be better off going with a Taig? Their machines have a top speed of 10,000+ rpm. The parts I'm machining will all be fairly small, 12"x6"x4" max.



  4. #4
    Registered
    Join Date
    Jan 2007
    Location
    USA
    Posts
    634
    Downloads
    0
    Uploads
    0

    Default

    Except for larger tools, you don't need more power, you need more RPM.


    Shhhhh. Don't start in with all these newfangled ideas that use that strange "logic" stuff! You'll rile the natives. Remember the chant, "if it weighs more, it must work better".
    Sheesh. Next you'll try telling us that TruckNutz don't actually add 50 extra Horsepower, or that the Earth goes around the Sun or something else equally silly.
    Jeez, kids these days...



  5. #5
    Registered ImanCarrot's Avatar
    Join Date
    Nov 2005
    Location
    UK
    Posts
    1468
    Downloads
    0
    Uploads
    0

    Default

    [quote]Remember the chant, "if it weighs more, it must work better"

    lol, I like that

    Gonna print that out and stick it on my lab wall.

    I love deadlines- I like the whooshing sound they make as they fly by.


  6. #6
    Gold Member
    Join Date
    Feb 2006
    Location
    USA
    Posts
    5075
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by cliffaddy View Post
    So, would I be better off going with a Taig? Their machines have a top speed of 10,000+ rpm. The parts I'm machining will all be fairly small, 12"x6"x4" max.
    You definitely want to find a machine with the fastest spindle you can. A Taig might be a good choice - I'm not sure what it's actual usable work envelope is. I suspect the size you specify may be pushing it. The Taig is a pretty flexible machine, which means you won't be doing any heavy cutting, but you would be able to move fairly fast with small cutters. You might also look at the Syil X4. There is a model with a high-speed spindle (20K RPM, IIRC), though it's a bit outside your budget. As in most things - You can have good, cheap, fast - pick any two.

    Regards,
    Ray L.



  7. #7
    Gold Member hoss2006's Avatar
    Join Date
    Apr 2006
    Location
    United States
    Posts
    7574
    Downloads
    0
    Uploads
    0

    Default

    Himmy can attest to the logic that a larger machine can take MUCH bigger DOC's
    getting your part finished much sooner than a tiny machine that has to tickle away
    even with it's higher rpm.
    Do a search, someone posted a simple upgrade to the X3 to increase the rpms.
    Even at only 1800 and corresponding SFM, you can see it's capable of a decent feedrate.

    Attached Thumbnails Attached Thumbnails -speed-feed-120sfm-jpg  
    http://www.hossmachine.info - Gosh, you've... really got some nice toys here. - Roy Batty -- http://www.g0704.com - http://www.bf20.com - http://www.g0602.com


  8. #8
    Registered
    Join Date
    May 2007
    Location
    US
    Posts
    779
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by HimyKabibble View Post
    I can't for the life of me understand why all these small mills have such low speed spindles, as it is a serious performance limiter.
    Lawyers and liability.
    When selling to a commercial shop the manufacture has some protection and can reasonably assume the person operating the machine has some level of qualification. Also cost is not as big an issue as it is at the hobby level, so the manufacture can put proper shielding and safety switches on the machine to make sure the doors are closed.

    Selling to the hobby market the operator could be some 14 year old kid with no experience, no guidance, and no common sense. Sooner or later someone is going to put a fly cutter in the spindle, spin it up to 30,000 and the 1/4 HSS tool bit is going to end up buried in the wall after passing thru the kids guts.



  9. #9
    Gold Member hoss2006's Avatar
    Join Date
    Apr 2006
    Location
    United States
    Posts
    7574
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by Andre' B View Post
    Lawyers and liability.
    When selling to a commercial shop the manufacture has some protection and can reasonably assume the person operating the machine has some level of qualification. Also cost is not as big an issue as it is at the hobby level, so the manufacture can put proper shielding and safety switches on the machine to make sure the doors are closed.

    Selling to the hobby market the operator could be some 14 year old kid with no experience, no guidance, and no common sense. Sooner or later someone is going to put a fly cutter in the spindle, spin it up to 30,000 and the 1/4 HSS tool bit is going to end up buried in the wall after passing thru the kids guts.
    Good point!
    We have signs posted on all our equipment at work forbidding usage by unauthorized personnel, with their jobs at risk if they do.
    Protects them and us from machinery that could kill.
    The hobby machines have to build in the protection to keep the maiming to a minimum.

    http://www.hossmachine.info - Gosh, you've... really got some nice toys here. - Roy Batty -- http://www.g0704.com - http://www.bf20.com - http://www.g0602.com


  10. #10
    Gold Member
    Join Date
    Feb 2006
    Location
    USA
    Posts
    5075
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by hoss2006 View Post
    Himmy can attest to the logic that a larger machine can take MUCH bigger DOC's
    getting your part finished much sooner than a tiny machine that has to tickle away
    even with it's higher rpm.
    Do a search, someone posted a simple upgrade to the X3 to increase the rpms.
    Even at only 1800 and corresponding SFM, you can see it's capable of a decent feedrate.
    A 1/4" tool running a 0.005" chipload will not live very long at all. Running a 4-flute 1/4" tool in aluminum will clog in a few seconds, unless perhaps making very shallow cuts. That 36 IPM feedrate would work only on a very shallow cut anyway, and you'll end up with a whole drawer full of endmills that are dull on the tips, an unused over most of their length. Any reasonable depth of cut on a small mill, and the vibrations will beat the tool to a pulp in very short order. The best way to get your money's worth out of tooling is to keep the RPMs and chiploads reasonable, and bury the tool as deep into the work as you can, so you're using as much of the length of the tool as possible. Slow down the feed until you're just short of breaking the tool, and/or stalling the spindle.

    Regards,
    Ray L.



  11. #11
    Registered
    Join Date
    Jun 2008
    Location
    USA
    Posts
    197
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by HimyKabibble View Post
    A 1/4" tool running a 0.005" chipload will not live very long at all. Running a 4-flute 1/4" tool in aluminum will clog in a few seconds, unless perhaps making very shallow cuts. That 36 IPM feedrate would work only on a very shallow cut anyway, and you'll end up with a whole drawer full of endmills that are dull on the tips, an unused over most of their length. Any reasonable depth of cut on a small mill, and the vibrations will beat the tool to a pulp in very short order. The best way to get your money's worth out of tooling is to keep the RPMs and chiploads reasonable, and bury the tool as deep into the work as you can, so you're using as much of the length of the tool as possible. Slow down the feed until you're just short of breaking the tool, and/or stalling the spindle.

    Regards,
    Ray L.
    Dammit so I bought my X3 for nothing then since I bought it primarily for 5/8" x 5" x 10" aluminum milling? Most of my cutting will be done with a 3/16" endmill. What should I do? What's the max DOC, speed and feed I can expect from it?

    Rick



  12. #12
    Gold Member
    Join Date
    Feb 2006
    Location
    USA
    Posts
    5075
    Downloads
    0
    Uploads
    0

    Default

    Rick,

    I can only tell you what I do on my knee mill. I run 3/16" endmills at 8200 RPM, about 10-15 IPM, 0.100" DOC, with mist coolant. I haven't spent a great deal of time optimizing the DOC and feed, since I don't do a huge amount of cutting with small tools. But, I don't think I'm terribly far from the limits. With an X3, I think you're limited to 2000 RPM, so your feed would be roughly 1/4" that. You can push it harder, but tool life will suffer.

    Regards,
    Ray L.



Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum from DIY CNC Machines to the Cad/Cam software to run them. The site is 100% free to join and use, so join today!

Follow us on

Facebook Dribbble RSS Feed