Page 721 - Iscar

USER GUIDE
TAPS

Tap Surface Treatments and Coating Types

The high speed steels we use grant high wear resistance TiAIN-COATING – TiAIN
and toughness.
For machining certain materials, various surface This is a special coating for machining abrasive materials
treatments are an advantage. such as: grey cast iron, alu-alloys with silicon, fiber
reinforced plastics, etc., or machining under high
Steam Tempered (ST) temperatures, which means with insufficient cooling, or
The steam tempered is a Fe O oxide coating which high speeds ≥ 600m/min. The TiAIN has a hardness of
4
3
reduces the friction between the tool and workpiece and approx. 3,000 HV and is temperature resistant up to
prevents cold welding. approx. 800°.
Color: Violet-grey coefficient of friction against steel : 0.4
Nitriding (NI)
Hardslick-COATING – Hardslick
Recommended surface treatment for machining hard
wear/abrasive materials such as grey cast iron, Hardslick combines in a novel way the advantages of an
extremely hard, thermally stable TiAIN-coating with the
aluminum alloys with high silicon percentage (more
than 10%). sliding and lubricating properties of an outer
WC/C (Tungsten carbide/carbon) coating. The hardslick
TiN Coating (TI) coating has a hardness of approx. 3,000 HV and is
temperature-resistant up to approx. 800°.
The TiN coating has a hardness of approximately 2,300
HV and is temperature resistant up to approximately Color: Violet-grey coefficient of friction against steel : 0.2
600°C. This is an excellent golden colored coating Tolerances According to DIN EN 22857
for general applications.
For taps with ISO metric threads.
TiCN-COATING – TiCN
The following chart gives a comparison between
TiCN takes place of TiN when the conditions require the
coating to have a different the new standard DIN EN 22857 and the withdrawn
hardness and toughness. standard DIN 802 part 1. An important change is
The TiCN brings an advantage to machining very difficult the re-classification from tap tolerance to tap
steels or cutting application class.
interrupted bores.
The TiCN-coating has a hardness of approx. 3,000 HV,
but is temperature-resistant up to approx. 400° only. That
means TiCN needs excellent cooling for long service life.
Color: Blue-grey coefficient of friction against steel : 0.4

Application class Tolerance class to Allotment of the
for taps to withdrawn standard tolerance zones of the nut thread
DIN EN 22857 DIN 802 part 1 to be cut
Class 1 ISO 1 4H 4H 5H - - -
Class 2 ISO 2 6H 5G 5G 6H - -
Class 3 ISO 3 6G - - 6G 7H 8H
- - 7G - - - 7G 8G
A suitable transition period is to be expected.
Codes for tolerance classes 7G/8G and <X>
tolerance zones have yet to be standardized
within DIN EN 22857, and the values
from DIN 802 part will remain valid.

717
717