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Thread tools \ Technical introduction – thread tapping

Screw tapping

Screw tapping produces extremely high torsional forces. Particularly when producing blind holes in
long-chipping materials, the chips must be broken at the changeover point. The following procedure for blind
hole tapping illustrates the relationship.

The thread is in the cut- a er reaching the thread The chip must now be The chip is now broken
ting process and guides depth the switching broken off through the off and the torque is
the chips to the top. process follows, in which back of the screw tap. drastically reduced.
the forces return to The forces reach maxi-
almost zero. mum level.
For this reason, primarily HSSE and HSSE-PM cutting materials are used for screw taps. These cutting materials can work with all material groups except hardened
materials. Solid carbide is only used as a cutting material in a few tapping applications.
If the material hardness is too high, such as in hardened material above 55 HRC, solid carbide must be used. However, solid carbide is also used as a cutting material
with short-chipping materials, since torsion forces are low in these applications. The following graphic shows the various machining tasks and the appropriate
cutting material for the application.
Steel Stainless steel Cast metal Non-ferrous Special alloy Hardened steels
metals

HSSE ISO ISO ISO ISO
P M K N

HSSE- ISO ISO ISO ISO ISO
PM P M K N S

ISO ISO ISO
VHM
K N H

Coatings and surface treatments for tapping

Coatings form a protective layer between the workpiece and the cutting tool. Through the use of coatings and surface treatments, the following properties are
achieved.
 Higher wear resistance  Higher cutting speed and feed rate  Reduced friction
 Increased hardness  Corrosion protection  Higher temperature resistance
We diff erentiate between the following coatings and surface treatments:

titanium nitride Titanium aluminium nitride
universal layer for universal machining. TiN Universal layer for high-performance machining TiAlN
 Vickers hardness: 2200–2300 HV with high cutting speed.
 Friction coeffi cient: 0.5  Vickers hardness: 3200 HV
 Temperature resistance: 500–600°C  Friction coeffi cient of steel: 0.55
 Colour: Gold  Temperature resistance: 700-800°C
 Colour: Dark blue grey

Titanium carbon nitride ULTRA HL
Its high level of hardness and excellent wear TiCN This modern layer has been specially devel- ULTRA
resistance make the TiCN layer suitable for ma- oped for thread machining and is currently the HL
chining diffi cult materials. highest-performing layer due to being extremely
 Vickers hardness: 3500 HV smooth and very heat resistant while at the same
 Friction coeffi cient of steel: 0.2 time exhibiting low thermal conductivity. Particu-
larly in processing stainless steel.
 Temperature resistance: 400°C
 Colour: Blue grey (anthracite)  Vickers hardness: 3000 HV
 Friction coeffi cient of steel: 0.15–0.20
 Temperature resistance: 800°C
 Colour: Dark grey

Source: Hahn+Kolb Werkzeuge GmbH
Technical data subject to change. www.iconridge.com
Availability subject to country specific rules and regulations. 156

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