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ISSUED THE TÜV SE AL OF SAFE T Y
Every pressure cooker lid produced by WMF is tested
under high pressure. The forces involved in the
test are many times stronger than what a lid would
be subjected to during regular use. But only if
the lid functions perfectly under these extreme
conditions is it issued the TÜV seal of safety.
HIGH TECH UNDER HIGH PRESSURE
Every pot is given its shape, a process whereby a
circular blank is deep-drawn under up to 300 tonnes
of pressure. WMF developed Cromargan® especially
for this purpose back in 1927.
mixture of chromium, nickel and stainless steel especially
for this: Cromargan®. It is a rust-proof material with ideal
deformation properties. This means that the pot body can
be
drawn
without damaging the material.
During one of the last steps in the process, the blank is
given another essential quality feature: the TransTherm®
universal base. It’s not just embedded in pressure cookers
but in every WMF pot. An aluminium core is embedded be-
tween the pot body and a magnetic stainless steel circular
blank. The base, which is pressed with a force of up to 1300
tonnes at temperatures of over 500 °C is especially robust
and suitable for all kind of hobs. The way it is designed also
creates the optimum heat distribution inside the pot.
DESIGNED FOR ABSOLUTE PERFECTION
This is the final step in the manufacturing process, but the
pots are far from being ready to hit the shelves. They are then
given the so-called sun-brushed finish in one of the biggest
interlinked robotic grinding machines in cookware production
in the world, which gives the pots their unique elegance.
“There’s no way a machine
could do this job.”
The quality control carefully checks that it has been applied
100 percent. “There’s no way a machine could do this job,”
explains Matthias Moll, process engineer at WMF. Even the
slightest irregularity would cause the pot to be rejected. “Here
at WMF, we’re perhaps a little bit too critical in this respect,”
explains Moll. “The customer wouldn’t even notice such tiny
flaws, but that’s exactly the kind of thing that goes to show
that we strive for absolute perfection.”
Only now are the grip handles welded on and the base
cambered. The base of the pot is pressed slightly inwards by
a robot using a wooden stamp. If, for example, a pressure
cooker is heated up at a later stage, the cambering offsets
the expansion of the material in the base so that the pot
doesn’t shake. During the final step, an employee then fits
the handles and carries out a final and comprehensive test
of the functions and safety features. This involves putting
the lid on a specially prepared dummy pot and placing it
under high pressure. The forces at work during the test are
several times higher than what the lid would be subjected
to during normal everyday cooking. Only when the lid also
functions perfectly even under these extreme conditions is it
given the TÜV seal of safety. Incidentally, every pot is clearly
marked with a batch number that has been assigned to it.
This way, the entire batch can be recalled in the event of any
quality defects. However, this has never happened even once
in the long and successful history of WMF.
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K NOW- HOW
by WMF
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