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Thread tools \ Technical introduction – thread tapping

Short, 2–3 turns
for blind holes and generally for aluminium, grey cast iron and brass
C (2-3)

Medium, 3.5–5 turns
for short through holes
D (3,5-5)

Extremely short, 1.5–2 turns
for blind holes with a very short thread run-out; avoid if possible
E (1,5-2)

Screw tapping designs

We distinguish between two fundamental designs
for screw tapping. DIN 371 with reinforced shank
well as DIN 376 and DIN 374 with continuous
shank. DIN 371 reinforced shank DIN 376 and DIN 374 protruding shank

Usage conditions and clearance angle

The size of the clearance angle has an effect on the service life and guiding properties of the
screw tap.
A large clearance angle minimises friction and increases the service life; a smaller clearance
angle improves the guidance of the screw tap.
In principle, spiralised screw taps for blind holes have a smaller clearance angle than straight- CNC/conv.
grooved screw taps. If the clearance angle were too large, the chips would jam during the
reverse motion, leading to breakage of the screw tap.
conv.
CNC/Synchro

1
2
① guiding properties ② service life

CNC/conv. conv. CNC/Synchro

CNC/conventional Conventional use CNC/synchro
These screw tap types are designed for both con- These threaded drill types are suitable for conven- In comparison with the conventional CNC types,
ventional and CNC machines, and they represent tional machining in the small and medium quantity these screw taps are characterised by a minimal
a compromise between the ideal guidance and an range in unstable clamping conditions. Its very long guide part and a very large clearance angle. Their
increase in the service life through increasing the guide part and the low clearance angle make these very free geometry ensures a long service life
clearance angle. screw taps ideal in unstable machining conditions in the medium to high quantity range. However,
This mixed type is the most common and the best on old machines with a standard length compensa- correct tool clamping must be ensured
solution for the majority of machining tasks. tion chuck or cutting by hand. in the synchronous chuck or as a rigidly clamped
By moderate machining conditions, we mean e.g. tool. In addition, the thread must be created on a
cutting of threads on a CNC machine in a length synchronous CNC machine with low play. These
compensation chuck or a synchronous chuck. With screw taps are all equipped with an H6 shank in
this machine tap type, for example, a thread can order that they can be clamped rigidly in a surface
also be cut on a conventional drill with a length chuck or shrink-fit chuck.
compensation chuck.

Source: Hahn+Kolb Werkzeuge GmbH
Technical data subject to change. www.iconridge.com 173
Availability subject to country specific rules and regulations.