CPT International 04/2017

An essential task, however, is the design
of a protective capsule that is suitable
for both the casting process and
the component. This protects the chip
from the high temperatures of the molten
metal as well as from the high densification
pressures of the die casting
until the casting has solidified.
What potential is there for RFID chips
in castings?
Wöstmann: The state of technology
for the identification of castings comprise
barcodes and data matrix coding
(DMC). These are applied to the surface
of the casting and are optically read to
identify the component. Should there
be any contamination or damage,
however, this type of coding is no longer
identifiable. Processing or painting
the surface also affects the readability,
such as with laser coding, as do the aging
of e.g. adhesive labels or the corrosion
of engraved DMC codes. RFID
technology is based on wireless technology
and thus escapes the disadvantages
of optical coding. The chip can,
similar to barcodes and DMC, be applied
to the surface. If the RFID chip
is directly embedded, then this offers
the advantage of coding at the earliest
possible point, as early as manufacture;
thus, from creation to destruction
the component is individually marked.
The greatest potential to add value lies
in the so-called “tracking and tracing”
of the castings throughout the production
steps. Through the individual
identification of each single component,
all production data are assigned
at all times, which is the fundamental
basis of Industry 4.0. Furthermore, also
retroactively, for example in the event
of a complaint, all data are available for
each individual component and thus
a retrospective quality control can be
conducted. In addition, any component
recalls will be limited to the parts
actually affected and will not apply to
entire batches, as is necessary using
current identification methods.
Aluminum die casting involves high
temperatures. How can the embedded
chip withstand the casting process?
Wöstmann: It won’t by itself! We
therefore developed a protective encapsulation
which enables the transponder
to withstand the temperature
peak. The geometry of the protective
capsule also enables simple and automatic
handling and positioning into
the high pressure die. At our current
state of technology, we have already
developed a simple and robust blank
in which the transponder, the protective
capsule, and a positioning aid are
included.
Do all the chips withstand the process?
Wöstmann: A 100 % read rate is mandatory,
as each non-readable part is
automatically rejected. Therefore, the
careful selection of the “right” transponder,
in combination with the protective
capsule design, is of equal importance.
Within the framework of an
EU project, we conducted a test run
in conjunction with Audi in which
all embedded transponders without
exception survived the die casting
process.This means we were able to
achieve a 100 % read rate under serial
conditions.
Where did the test run take place and
what exactly did it look like?
Pille: The test run took place at Audi Ingolstadt’s
experimental foundry. The
aim was to test inline the RFID chips
selected by Fraunhofer IFAM, the protective
capsule developed for the Audi
demonstrator, and the read/write
hardware under serial-like conditions.
In addition, a special gripping arm was
developed and tested, which automatically
grasped the RFID capsules and inserted
them into the tool.
What challenges needed to be overcome?
Pille: Certainly the greatest challenge
was precisely the “serial-like conditions”.
The demonstrator, a shock
tower, had an existing geometry for
which we needed to design the RFID
chip and protective capsule. In addition,
the casting did not occur in a
laboratory setting, where the capsules
could have been manually inserted
and locked; rather, it was necessary
to ensure that the operation was both
processsafe and automated.
Is the process suitable for all materials?
And if not, are further developments
planned?
Wöstmann: Regarding the process, we
have optimized the system for high
pressure die casting applications, as
these involve relatively short temperature
effects. However, we have already
started working on solutions for low
pressure die casting and gravity die casting.
Also, we intend to venture further
into higher temperate ranges, such as
in copper, iron and steel casting, in order
to be able to offer an identical solution
for all casting applications. As for
further development,we have in parallel
expanded our activities to include
the direct embedding of sensors, e.g. in
order to detect the occurrence of overloading
or misapplied loads in the casting.
Such sensors can naturally be combined
with transponder technology in
order to transmit the data wirelessly
from the casting.
Following the casting process, many
castings undergo further comprehensive
processing. Are the embedded chips
not destroyed during these work steps?
Pille: The embedded chips have shown
themselves to be extremely robust; and
precisely this was the original intention
of the technology, namely integrating
the identification into the component
itself in order to achieve a more robust
labelling that can also withstand mechanical
damage to the casting surface,
that is not affected by corrosion or other
environmental influences, and that
has no adhesive labels which would be
released by the cooling lubricant. However,
one challenge remains: a subsequent
heat treatment where the temperatures
last for a longer period and
thus make the protective capsule ineffective.
T5 heat treatments can – depending
on the transponder – be overcome,
however T6 heat treatments will
cause the protective capsule to fail and
the transponder to be destroyed.
What effects on quality and productivity
in foundries do you expect
through the implementation of embedded
RFID chips?
Wöstmann: Regarding productivity,
I expect no direct increase stemming
Casting Plant & Technology 4 / 2017 7