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  1. #1
    Join Date
    Aug 2010
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    0

    Peck drilling with carbide

    Someone recently told me that carbide drills are not meant to be used with peck drilling cycles. True ?

  2. #2
    Join Date
    Jul 2005
    Posts
    12177
    Sort of true. Probably more correct to say peck drilling is not needed with carbide drills running in the manner they can be run. That is high rpm and fast feed which tends to efficiently eject the chips making pecking unnecessary. The other reason for pecking which is to allow the drill to be cooled by coolant and let coolant into the hole doesn't apply because coolant should not be used with carbide drills.

    Of course if you are trying to cram a carbide drill as deep as its flutes will allow then problems are likely to occur and pecking can be tried. But this is not really the correct way to use a carbide drill. I don't have any literature about carbide drills available right now but I seem to recall the recommended maximum depth is 1-1/2 to 2-1/2 the diameter.
    An open mind is a virtue...so long as all the common sense has not leaked out.

  3. #3
    Join Date
    May 2004
    Posts
    4519
    Quote Originally Posted by rcs9250 View Post
    Someone recently told me that carbide drills are not meant to be used with peck drilling cycles. True ?
    Totally true. Not "meant" to be. But in machining, you have to do whatever works to make good parts in a timely manner and get them out the door and make money while doing it. I have used carbide drill with peck drilling many times with great results, especially in 6061 aluminum where chip control was an issue.

  4. #4
    Join Date
    Aug 2010
    Posts
    0
    Thanks guys. We have pecked with them too, mostly on deeper holes where chip problems occurred.

  5. #5
    Join Date
    Jul 2009
    Posts
    2
    There are a lot of really good posts online about this subject and I suggest you research it in depth, few people really understand what is really involved during an actual drilling cycle, including speeds and feeds for specific materials/cutting tool materials.
    I highly suggest against pecking with coolant through carbide, period.
    I also suggest against pecking with carbide unless dire circumstances call for it. If you're not seeing results (regardless of material) and do not wish to do the research contact your tooling supplier and get the proper speeds and feeds or ditch the brand.
    Otherwise you're going to end up reducing/ending life of an expensive drill when you could have possibly been better off with a $2 HSS piece of Chinese junk.
    On a horizontal anything, rule of thumb (for me) is program a dwell only long enough to thin/break the chip.

  6. #6
    Join Date
    Mar 2006
    Posts
    21
    Interesting....If we did not us carbide to peck drill we would not drill! I understand it can cause problems but you just have to work around them. You don't want the drill to rapid in on top of a chip or oops! You have to make sure you have good clearance for the tool. The G74 is a bad peck for this as it does not bring the drill completly out of the hole to remove the chips or allow coolant to flush the chips from the hole and the flutes. I use an incrimental cut and paste that will go any depth.

    (PECK CYCLE)
    G0Z.100
    G1Z-.1(-.100)
    G0W.125
    G04X1.0
    G0W-.1
    G1W-.125(-.200)
    G0W.125
    G04X1.0
    G0W-.1
    G1W-.125(-.300)
    G0W.125
    G04X1.0
    G0W-.1
    G1W-.125(-.400)
    ...........................and so on.....

  7. #7
    Join Date
    May 2005
    Posts
    2502
    xyzer is right, it's all about exactly how the peck works, and most of the canned cycles are not helpful with carbide.

    Check out the Hole Wizard in G-Wizard Editor's Conversational CNC module for a simple way to create highly customized drilling cycles:

    G-Wizard Editor is Helping Folks Move Ahead « CNCCookbook CNC Blog CNCCookbook CNC Blog

    Best,

    BW
    Try G-Wizard Machinist's Calculator for free:
    http://www.cnccookbook.com/CCGWizard.html

  8. #8
    Join Date
    Jan 2011
    Posts
    0

    pecking with carbide?

    carbide -peck drilling

    To get an answer, you should narrow your question by:
    -material
    -hole depth
    -lathe/mill

    For example, a 20XD hole can easily be drilled in eco-brass with no coolant and no pecking, except an occasional in-hole dwell, using HSS Guhring GT100 parabolic flute drills. Driiling stainless may call for pecking with same drill.

    I encourage the poster who said he had success with pecking carbide to give further details, since an ounce of experience is worth a ton of opinion.

    jb

  9. #9
    Join Date
    Dec 2011
    Posts
    316

    Carbide - Peck - Coolant

    I recently completed a job which called for 600, 13mm holes, 1.5" deep in 6061. There were 5 groups of 4 holes each per part times 30 parts.

    I used a Titex carbide bit, G73, full coolant and 1700 RPM.

    G73 R 0.1 X 1.0 Y 0.0 Z -1.5 P.01 Q.075 F7.5 L4

    I realize that this runs contrary to conventional wisdom however it works well.

    I can only assume that a constant supply of coolant:
    1. Prevents shock cooling,
    2. Provides adequate lubrication
    3. Prevents chip welding.
    4. Provides chip evacuation

    There's theory and there's what works.

    John

  10. #10
    Join Date
    Jul 2005
    Posts
    12177
    6061, barely 3 x diameter deep, carbide drill, 1700rpm, 7.5ipm.

    Isn't that a bit slow?

    I would go faster than that using a spiral point cobalt drill and expect it to easily last 600 holes.
    An open mind is a virtue...so long as all the common sense has not leaked out.

  11. #11
    Join Date
    Dec 2011
    Posts
    316
    Geof

    Blame it on a conservative old fart and a medium size hobby mill < 2 H.P.

    Bit is hardly used and will drill many more holes. Prefer the Titex cabide as it is rigid (no wandering) and no center drill is required.

    Not out to set any land speed records (applies to the drill as well as me).

    Post was only to demo that carbide drill bit can peck and use coolant.

    John

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