european report
Milling cutters boost productivity at
Audi AG Mould And Die Ingolstadt
THE Mould and Die Division of Audi AG, operates
from three sites, Ingolstadt and Neckarsulm in Germany
and Györ Hungary. It’s one of the largest in the auto
industry with a staff of over 1,400 and a net output of 300 million Euro.
The headquarters in Ingolstadt is also a Centre of Excellence for mould
and die-making and body manufacturing for the entire VW group. Inhouse
production and processes are constantly subjected to close scrutiny,
with the main objective being to shorten the cycle times and increase
value-added activities. That may sound obvious but in this type of mould
and die-making with the demands for individual and one-off production,
that’s not so easily achieved.
Head of Machine Technology in the Mould and Die Division, is Anton
Habermeier whose primary objective is to increase the proportion of un
manned machining. So far this has been doubled over the last two years
and is continuing. Anton Habermeier outlines the strategy. In the
manufacture of body dies for car shells, large body parts and combined
tools for cutting and forming milling tool plays a very important role, and
the type of work pieces machined shows why. The importance of stable
cycle is critical. ‘We take the approach’, says Habermeier, ‘that virtually no
further finishing should be necessary after machining.’ Every
interruption in the finishing cycle inevitably results in a visible mark on
the work piece that requires further attention.
At the start of the year an increasing number of dies for hot stamping
processes, such as those for high-strength body panels had to be machined.
This meant that the tool life is especially important when milling the
freeform surfaces of these work pieces. The parts have a hardness value up
to 60 HRC, they contain deep cavities, sometimes with difficult transitions
from the hard to the soft material. The cycle times for finishing are up to
20 hours and in order to achieve a perfect surface finish, it required the
operation to be completed in a single uninterrupted cycle.
Audi Mould and Die Division was forced to take action. The milling
tools used up to that time weren’t able to meet the requirements. ‘It wasn’t
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The flowing surfaces of Audi body panels require long life dies- which
in turn means efficient machining using the most capable tooling.
possible’, says Alexander Schiffner, responsible for tool pre-adjustment in
the Tool and Die Division, ‘to completely finish machine these dies in one
cycle.’ Initial tests with the SRF ball nose cutter from Mitsubishi Materials
achieved the breakthrough. The first milling tests were already so positive
that the finishing cutter - actually intended for hardened and pre-hardened
steel - was also used on cast steel and cast iron dies. When these tests
were also successfully completed the application engineers ventured into
the roughing cycle. Schiffner concludes: ‘We were amazed at the tool life
achieved even under the changing conditions that the contours generate
and especially the boundary between hard and soft material. It is
interesting to note that independent of these trials Audi Mould and Die
Division in Neckarsulm also achieved similar results.’ Antonio Abrantes,
head of Mitsubishi’s European Technical Department was delighted: ‘The
milling cutters proved their efficiency even during roughing cycles where
cutting depths were up to three millimetres’.
The SRF cutter used VP10MF grade MIRACLE coated carbide inserts.
The substrate material for the insert is an ultra fine micro grain carbide,
which is extremely wear resistant and very hard. However it also possesses
a tough characteristic due to the uniformity throughout the tool structure.
The S-shaped cutting edge has positive geometry and is designed for
smooth cutting. This results in low cutting resistance and allows an
optimised temperature to be maintained during machining, especially in
the centre of the cutting edge. This is an essential element when using air
cooled dry machining techniques. Inserts are held in carbide shanks. The
advantage over steel shanks is their high resistance to vibration which
ensures an extremely smooth cut - also key element in preserving tool life.
As in most complex moulds the workpieces contain many deep fissures
with extreme differences in height.
www.mitsubishicarbide.com
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