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  1. #1
    Join Date
    Jan 2005
    Posts
    36

    drilling copper

    i've been having problems at times drilling some holes in copper. i got some 110 electrolyte copper, and i need a bunch of .160 holes in it. right now i'm at 1525 rpm, and a feed of 3.5 ipm. i've tried both straight drilling, and now peck driiling, but i still have problems with drills breaking. the copper is 1/2" thick and i need to go thru it with hss .160 drill. any suggestions. it doesn't happen with every part, but enough where i can't use the part because if i don't hear it break it tries to drill without a point, and ruins the part. thanks for any help.

    hardinge vmc 1000

  2. #2
    Join Date
    Apr 2003
    Posts
    1876
    Copper is very gummy.

    Try increasing the chip load, peck drill, and use lots of coolant.
    Matt
    San Diego, Ca

    ___ o o o_
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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  3. #3
    Join Date
    May 2005
    Posts
    1810
    Flatten the face of each flute with a small facet - this will keep it from grabbing by creating a neutral face angle. Positive rake angles dig while neutral angles push.

    Scott
    Consistency is a good thing....unless you're consistently an idiot.

  4. #4
    Join Date
    Apr 2003
    Posts
    1876
    Quote Originally Posted by mxtras
    Flatten the face of each flute with a small facet - this will keep it from grabbing by creating a neutral face angle. Positive rake angles dig while neutral angles push.

    Scott
    Good idea.

    Also consider using 135° vs 117° drills. Steeper angles work better in softer mat'ls.
    Matt
    San Diego, Ca

    ___ o o o_
    [l_,[_____],
    l---L - □lllllll□-
    ( )_) ( )_)--)_)

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
    Join Date
    Jan 2005
    Posts
    36

    thanks, i'll try :wee:

  6. #6
    Join Date
    Aug 2005
    Posts
    34
    We have a lot of success (1/16" diameter drills) using 135 degree Guhring polished parabolic drills. Use straight oil, not soluble.

  7. #7
    Join Date
    Aug 2011
    Posts
    0
    try drilling at 300 to 450 rpm and use cow's milk as a coolant.

  8. #8
    Join Date
    Jul 2006
    Posts
    735
    Chances are the chips are not clearing.

    +1 on the coolant. Try doing a full retract pecking (so that the chips get brought out and the coolant gets in) and keeping the peck depth between 2/3 and 1/2 the bit diameter (so that not too much accumulates). Once it is all working reliably you can try to squeeze some time back. The RPM and IPM seem to be okay, if anything I would bump the RPM to 1660 (70 sfpm).

    Good luck!

  9. #9
    Join Date
    Feb 2009
    Posts
    6028
    I hate it, but...
    Every shop I used to go in to that did almost all copper, used cutting oil, not coolant. I used to machine a lot of OFHC and it was all done with oil as well.

  10. #10
    Join Date
    Jun 2007
    Posts
    3757
    Cutting oil.
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

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