584,798 active members*
4,259 visitors online*
Register for free
Login
Results 1 to 9 of 9
  1. #1
    Join Date
    Jul 2013
    Posts
    3

    Milling a plastic with a CNC 770 milling machine

    I am currently doing microfluidics research and kind of stuck on this situation.

    I am using a 0.79mm or 1/32 inch tool to mill a "bean" shape that is 1.2mm wide on a Polystyrene sheet.
    However, my tool keeps breaking after milling one "bean" shape on a polystyrene sheet.

    I used 7000rpm and 250 mm per min.

    Can anyone of you give me a tip or method that I should take to successfully mill without breaking the tool?

  2. #2
    Join Date
    Dec 2004
    Posts
    783
    What's your depth of cut?

    Sent from tapatalk

  3. #3
    Join Date
    Jul 2013
    Posts
    3
    The depth is 0.5mm, I did some research online and apparently I need a faster RPM, but my milling machine can only go up to 10200RPM
    Can you recommend ideal RPM and feed rate ?

    Thank you!

  4. #4
    Join Date
    Apr 2008
    Posts
    1577
    How many flutes are on the tool?

  5. #5
    Join Date
    Jun 2004
    Posts
    6618
    Ideal would be like a router. Maybe 25000 RPM.
    You may be breaking the tool due to heat by going that slow and that low on rpm.
    That is about 10 IPM, which is very slow for plastics.
    Put some coolant on it and speed it up as fast as you can on RPM and I'd say at least 25 IPM. Maybe 50 IPM.
    Lee

  6. #6
    Join Date
    Jul 2013
    Posts
    3
    4 flutes

  7. #7
    Join Date
    Dec 2004
    Posts
    783
    Switch to two flute, your probably melting the plastic.

    http://pages.ebay.com/link/?nav=item...d=380655997877

    precisebits has a nice write up on finding ideal feeds and speeds for small bits too.

    Sent from tapatalk

  8. #8
    Join Date
    Dec 2004
    Posts
    783
    Also, of you can switch to delrin or abs, they both machine better than polystyrene.

    I have cut 500+ parts (5x15mm dimension)from 1.5mm abs and delrin sheet on the same bit. 18000-24000 rpm 15-30 ipm.

    Sent from tapatalk

  9. #9
    Join Date
    Apr 2008
    Posts
    1577
    I suspect the 4 flute tool is your problem. Try a double as suggested or possibly even a single flute endmill (although at that size it may be very easy to break).

    You can machine plastics with lower speed but the finish will suffer slightly, just keep your speeds and feeds relative - keep that tool moving and ejecting the hot shavings.

Similar Threads

  1. CNC Milling Machine Packages and Bespoke CNC Milling Machines
    By worldofcnc in forum News Announcements
    Replies: 0
    Last Post: 05-27-2010, 02:20 PM
  2. New to milling plastic
    By Shocker in forum Glass, Plastic and Stone
    Replies: 3
    Last Post: 04-12-2010, 01:34 PM
  3. Anyone milling plastic?
    By oxford in forum Benchtop Machines
    Replies: 19
    Last Post: 07-13-2008, 03:54 AM

Posting Permissions

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