Breaking Chips with HSS Drills
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    Default Breaking Chips with HSS Drills

    I'm wanting to improve my drilling technique. I run HSS drills- mostly in aluminum.

    So let's look at the current job- 5000 holes with an X drill and 5000 more with a 3/32" drill. All holes .25" deep. I'm getting ok chips on the X but would like them to be smaller- drilling straight thru, no peck- 200SFM, .010 IPR. The 3/32" is running at 150 SFM and .005 IPR, peck drilling. The chips are long and stringy.

    Any advice on how to better achieve small broken chips would be great. Thanks.

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    Use G73 instead of G81. Adjust you "Q" peck amount to suit. Or, increase the feed.

    [/endthread]

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    With that many holes I would look into a material specific carbide drill, try Guhring,Walter etc. You will be surprised how much time you ll save

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    I know I could switch to a different drill, but the point I'm after is that I want to learn how to get better, broken chips with HSS drills. The current job is just an example.

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    Quote Originally Posted by biglord4ever View Post
    I know I could switch to a different drill, but the point I'm after is that I want to learn how to get better, broken chips with HSS drills. The current job is just an example.
    So your question is, "How do I get excellent results when using the wrong tool?"

    Get yourself an M A Ford 3fl super twister, run it as fast as the machine will go, and don't worry about it

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    Quote Originally Posted by Larry Dickman View Post
    So your question is, "How do I get excellent results when using the wrong tool?"

    Get yourself an M A Ford 3fl super twister, run it as fast as the machine will go, and don't worry about it
    So are you saying its impossible to break chips with HSS drills?

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    Quote Originally Posted by Jashley73 View Post
    Use G73 instead of G81. Adjust you "Q" peck amount to suit. Or, increase the feed.

    [/endthread]
    Agree fully with this.

    Also, in my opinion you're a little light on SFM. I run HSS in aluminum starting at 250...all drill sizes.

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    Quote Originally Posted by biglord4ever View Post
    I know I could switch to a different drill, but the point I'm after is that I want to learn how to get better, broken chips with HSS drills. The current job is just an example.
    I agree with Larry, not only philosophically, but with that exact Drill too.

    But for the sake of conversation; the old formula for determining chip load for HSS Driil is Diameter*.0156----per flute. Bigger Drills take more abuse. As far as your SFM goes you're running one Drill slower than the other!!! The SFM shouldn't change, same material, same tool material.

    But we don't even know what alloy you're working with. If 6061 or 7075 or 400 series. So really no one can tell you how to break the chip, other than pecking.

    Again the Twister will blow your hair back. Unless you don't have enough feed to keep up with 5000 SFM. You literally run them as fast as you can.

    R

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    If you figure out how to not make a stringy chip in 6061, please let me know.

    Only luck I have had is with a Guhring drill going full RPMs and a ridiculous feed rate. The chips come out looking like a fluid rather than a chip, but no bird's nest, and they remarkably hold dimension very well.

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    Parabolic drills?

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    Why would parabola make the chip break?
    I don't think so. Length is more important to me than flute design. And parabolic drills are jobber length.

    R

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    Use a chip breaker cycle instead of full retract


    Sent from my iPhone using Tapatalk Pro

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    If you are using a poor quality 6061 like any Chinese or USA Service Center junk, chips can be harder to break and very inconsistent.

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    Quote Originally Posted by biglord4ever View Post
    So are you saying its impossible to break chips with HSS drills?

    Quote Originally Posted by Jashley73 View Post
    Use G73 instead of G81. Adjust you "Q" peck amount to suit. Or, increase the feed.

    [/endthread]

    It's "Difficult" to break chips with conventional HSS-Jobber drills. A lot depends on your material. Low carbon steel, soft low-strength aluminum alloys, will almost never give satisfactory chip-breaking with conventional HSS-Jobber drills. Cast-iron, certain tool-steels (D2), brass will give good chip-breaking without any effort. So the material will play a big part in chip-breaking if you're using HSS-Jobber drills.


    If you want premium performance, you need to go to specialized drills. Often times these are made from solid carbide, but there's some "premium" drills made from cobalt-HSS and powdered-HSS as well. The one thing that all of these drills have in common, is that they're designed with special attention to the flute shape, tip geometry, etc.. In other words, they're designed from the get-go to be high-performers. HSS-Jobber drills are not, and they never will match the performance of "premium" drills.



    Now, HSS-Jobber drills will perform well in aluminum in terms of speed & tool-life just fine. You're not getting bad advice here when people say to run them as fast RPM/feed as possible for your machine. But, understand that these drills were never designed to offer superior chip-breaking in soft aluminum alloys. If so, they would suck for drilling carbon steel using a drill-press. HSS-Jobber drills are designed to be just that - a drill that works OK in every material, in every machine - and they fit that jack-of-all trades role very well. Just understand that they're a master-of-none as well...


    If you want to continue using HSS-Jobber drills for your aluminum/volume job, and you want better chip-breaking, you'll have to use a G73 chip-breaking drill cycle to get satisfactory chip-breaking. You can probably also max your machine on RPM & increase feed to match, to compensate for any lost cycle time.

    The nice thing about using G73, is that it's EASY. You simply change the G81 in your program to a G73 and then add a Q.25 to that same line. The Q tells the machine to retract slightly every .25" of drilling-depth in order to break a chip. Alter the "Q" value as needed to suit your needs. The amount of retract/peck is determined by, and can be changed in parameter #5114 (in the case of Fanuc 0i series & similar controls) and every machine I've ever seen has been set around .01" retract/peck distance. See attached for explanation.

    g73.jpg




    If you want to continue to used G81 continuous drilling, then do like others have suggested, and go with a premium drill.


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