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Thread: Drill Speed

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  1. #1

    Join Date
    Jun 2020

    Drill Speed

    I want to put twist drill of dia 21.5 and 23.5 on my machine. My daily requirements would be more than 1000 holes per day. Have majorly used has drilling on radial drills and annular cutter on magnetic drills.
    Annular cutters are not suitable in cases where stacking is preferred. HSS twist drills are not so fast.
    I am currently developing a CNC drill machine, and I need to find the right speed(s) options that I need to design for.

    Drill dia 21.5mm or 23.5mm
    Material Steel low carbon, BHN around 150, normalised.
    Drill Type HSS twist drill.

    What if I upgraded to a carbide tip twist drill, something like Sandvik Coro 870. What speed would these like at the same diameter?


  2. #2
    Join Date
    Jun 2015

    Re: Drill Speed


    hss drill requires torque @ lower rpms, while carbide requires higher rpms

    hss feed/revo may be > carbide feed/revo, but because carbide can operate at higher rpms it will achieve a higher linear feed, thus in the end, feed/min will be higher with carbide

    you can not compare hss and carbide, for the same tool diameter, at identical rpms, simply because hss and carbide operate at differents rpms, because their cutting speeds are not identical .... in short, hss requires more torque at low rpms, while carbide is the oposite

    if you wish to improve stability with carbide, switch to u-drills : their inserts are less $$$, life spam is ok, they will go over missalignments more easy, and they require less spindle torque compared to classical indexable drills

    however, there is a catch with u-drills : they do not handle well depths>7D, and the u-drills with inserts with 4 cutting edges do not run as smooth as those with only 2 cutting edges

    how does your fixture look ? and what is the depth of the hole ? kindly
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