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available from Ø0.9mm and provide superior
rigidity and optimal coolant flow rates.
As a result of being made of solid carbide,
when compared to brazed versions, these
gundrills can work with up to 100% higher
feeds and speed parameters. ISCAR's experts
offer a very wide variety of gundrill geometrical
shapes, which are designated for different
drilling rates, hole accuracy and surface finish
quality. The drill's shape, together with its
profile must be matched to the workpiece
material. In fact, this is exactly what our
specialists did in this particular case. However,
selecting the correct gundrill geometry is only
one important step towards a successful result.
A suitable cutting edge treatment (rake face
polishing and edge honing to the right size)
enhances the surface finish even more. It also
improves the drill's performance and prolongs
tool life. In addition, the gundrill body itself is
being polished. It becomes very smooth and
enables the chips to slide easily inside the
gullet on their long evacuation.

The best results in gundrilling hollow valves have
been achieved by using one of ISCAR's finest
submicron carbide grades IC08 that is protected
by a AlTiN nano-layer PVD coating.

Camshaft
A relatively new concept for making much lighter
(up to 45%) and remarkably cheaper camshafts,
in comparison to the traditional method of
machining from cast or forged bar stock, is
assembling camshafts from modules. This
system uses thermal expansion as the process
principle, some OEMs fix pre-heated individual
cams on to a pre-cooled precision steel tube.
Others fix individual cams on to the steel tube
then, by using hot air pressure to expand the
tubes diameter in the places where it engages
with the cams. In both cases, the lobes of
each individual cam are precisely arranged in
accordance with the geometry of the camshaft.

The individual cams are produced either from
pressed and sintered powder metal or from

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