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Thread tools \ Technical introduction – female thread production

                      Female thread creation: Screw tapping


         When creating a thread by tapping, a core hole and counterbore must be made in the material. The
         screw tap carries out the cutting motion. Thus, the thread pitch determines the feed rate. Material is
         cut out and the chips are removed via flutes.

         Advantages:                    Disadvantages:
         ƒ high machining speed         ƒ clamping problems with very deep threads
         ƒ cost-effective tools         ƒ screw tap breakage with difficult materials
         ƒ simple tool handling and well-known procedure  ƒ average surface quality
         ƒ broad field of application   ƒ risk of axial cutting (taper)
         ƒ use on simple machines possible  ƒ of the thread
         ƒ regrindable tools            ƒ tapping chuck required










                      Female thread creation: Thread forming (thread tapping)

         In contrast to tapping, where sections are cut out of the material, the process of thread forming does
         not involve cutting. The material is made to flow through the polygon shape of the thread former. The
         fibre pattern is not interrupted.

         Advantages:                    Disadvantages:
         ƒ Very high working speed and process reliability  ƒ Higher torque
         ƒ Very high surface quality    ƒ Special pre-drilling diameter with tight
         ƒ One tool for through hole and blind hole  tolerance
         ƒ No clamping problems         ƒ Incomplete moulding of cores (claw)
         ƒ Higher thread strength       ƒ Minimum expansion of tool must be ensured
         ƒ Tools are easier to use      ƒ Regrinding not possible
         ƒ Long service life, less breakage  ƒ Lubrication essential
         ƒ Deep threads                 ƒ Where used in the food or medicine industries,
                                         there is a risk of germ build-up in the area of
                                         the moulding recess.






                      Female thread creation: Milling cutter


         The development of computer-controlled machines has made the thread milling procedure another
         option for creating female threads. The thread is produced by the helical diagonal immersion of a
         rotating tool. In the process, the axial movement of the tool in one revolution produces the pitch. For
         this procedure, a CNC machine with at least three axes is required (XYZ).

         Advantages, tool cost minimisation:  Disadvantages:
         ƒ right-hand and left-hand thread can be manufactured   ƒ machine requirements (XYZ axes)
          with a tool                         ƒ machining times generally longer in
         ƒ thread milling cutters cover different threads with the  series production
          same pitch                          ƒ limited experience of the user in
         ƒ for partial thread profiles, a wide range of threads can be   thread milling
          produced with a cutting insert
         Advantages, process reliability:
         ƒ Extremely high process reliability with very expensive
          components
         ƒ Reliable process solution for problem materials with
          poor chip breaking and difficult chip formation
         ƒ First choice with thin-walled workpieces or unstable
          clamping operations
         ƒ High thread quality
         ƒ Thread can be made right to the base of a blind hole
         ƒ Radius compensation programming enables thread                                     P
          tolerance to be adjusted easily





              Source: Hahn+Kolb Werkzeuge GmbH
              Technical data subject to change.                                           www.iconridge.com  169
              Availability subject to country specific rules and regulations.
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