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Thread tools \ Technical introduction – female thread production

                    Thread production process at a glance


                                            Screw tapping          Thread forming           Milling cutter
        Process reliability                     ○                       +                      ++
        Surface quality                         ○                      ++                      +
        Machining speed                         +                      ++                      ○
        Service life                            ○                      ++                      +
        Flexibility/universal use               ○                       +                      ++
        Thread depth                            ○                      ++                      ++
        ○ = limited suitability |  + = well suited  |  ++ = very well suited

                    Tolerances for threads




        standards ensure that male and female threads of the desired form fit together. depending on the application, the appropriate tolerance must be taken into account
        for the screw tap or thread former. in thread milling, the tolerance can be produced as desired using radius correction. the graphic shows the different tolerance
        classes and their use.

                DIN EN 22857                             DIN 802 part 1
          Application class of the screw tap  Tolerance range of nut thread to   Tolerance class  Technical application
                                          be cut
           Name      Identification                      of the screw tap
           Class 1     ISO 1      4H  5H                     4H                Screw connection with little play
           Class 2     ISO 2               6H                6H                 Standard screw connection
           Class 3     ISO 3                   6G            6G               Screw connection with a lot of play
            –            –                          7                  As a preventive measure against warping in heat treatment

        The graphic shows the position of the tolerance field of the nut thread in the   µm
        different tolerance classes, such as 6H (highlighted in grey). The blue tolerance
        fields show the position of the tolerance field for the corresponding screw taps   280   1
        or thread formers.                                                                         256
        It can be advantageous to produce screw taps and thread formers in a different   240
        tolerance class.  This tolerance is indicated by an X after the tolerance class (e.g.   1
        6HX instead of 6H). The X represents a manufacturer-specific tolerance and can   200  212
        differ between manufacturers.                                      1
        Tough materials have recoiling properties. To counteract this effect, the X range   180        2
        is used in the ATORN thread cutting programme for these tough materials. Screw  160              154
        taps for titanium and nickel alloys, for example, are produced in the X range.     2     7G   7GX
        Where abrasive materials (those with friction or a grinding effect) are concerned,  120  1  6G  6GX 126  126
        it also makes sense to produce tools in the X range. This results in a longer   112  2         7G
        service life, because the screw taps are still within tolerance even having been   2  6H  6HX  98  98  98
        subject to wear. The red ring screw tap for cast and short-chipping non-ferrous   80  70  70  6G  70
        metals is produced in this tolerance range.            4H   4HX         6H
                                                           40          42         42
                                                                     4H  14                         32
                                                            3
                                                          ① Nut thread tolerance field  ② Screw tap tolerance class ③ Tolerances

                    Cutting materials and cutting process during thread cutting

        The following list of cutting materials is used for   SC — solid carbide
        female thread machining in the screw tapping,   ƒ Very high level of hardness
        thread moulding and thread milling processes.                             VHM
        The graphic shows the toughness/breaking   ƒ Cutting material for applications up to 65 HRC
        strength parameters in comparison to wear   ƒ Very high cutting speed, high precision
        resistance/hardness.                                                               HSSE-
                                       HSSE-PM — high speed steel, powder metal
                                       ƒ Cutting material for applications up to 1300 N/mm   2  PM
                                       ƒ Medium to high cutting speed
                                       ƒ High elasticity, high cutting speed
                                                                                                      HSSE
                                       HSSE — high-speed steel
                                       ƒ Cutting material for applications up to 1300 N/mm   2  1
                                       ƒ Low to medium cutting speeds          2
                                       ƒ 5% cobalt content
                                       ƒ Very high elasticity                  ① Hardness/wear resistance/cutting speed
                                                                                 ② Toughness/breakage resistance





              Source: Hahn+Kolb Werkzeuge GmbH
        170   Technical data subject to change.                                           www.iconridge.com
              Availability subject to country specific rules and regulations.
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