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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 fl utes.
Advantages: Disadvantages:
high machining speed clamping problems with very deep threads
cost-eff ective tools screw tap breakage with diffi cult materials
simple tool handling and well-known procedure average surface quality
broad fi eld of application risk of axial cutting (taper)
use on simple machines possible of the thread
regrindable tools 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 fl ow through the polygon shape of the thread former. The
fi bre pattern is not interrupted.
Advantages: Disadvantages:
Very high working speed and process reliability Higher torque
Very high surface quality Special pre-drilling diameter with tight
One tool for through hole and blind hole tolerance
No clamping problems Incomplete moulding of cores (claw)
Higher thread strength Minimum expansion of tool must be ensured
Tools are easier to use Regrinding not possible
Long service life, less breakage Lubrication essential
Deep threads 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:
right-hand and left -hand thread can be manufactured machine requirements (XYZ axes)
with a tool machining times generally longer in
thread milling cutters cover diff erent threads with the series production
same pitch limited experience of the user in
for partial thread profi les, a wide range of threads can be thread milling
produced with a cutting insert
Advantages, process reliability:
Extremely high process reliability with very expensive
components
Reliable process solution for problem materials with
poor chip breaking and diffi cult chip formation
First choice with thin-walled workpieces or unstable
clamping operations
High thread quality
Thread can be made right to the base of a blind hole
Radius compensation programming enables thread P
tolerance to be adjusted easily
Source: Hahn+Kolb Werkzeuge GmbH
Technical data subject to change. www.iconridge.com
Availability subject to country specific rules and regulations. 154
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