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@PHDTHESIS{Schacht:979701,
author = {Schacht, Andreas},
othercontributors = {Bobzin, Kirsten and Hopmann, Christian},
title = {{T}hermisch gespritzte {H}eizschichten für das
{K}unststoffspritzgießen},
volume = {77},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Düren},
publisher = {Shaker Verlag},
reportid = {RWTH-2024-01772},
isbn = {978-3-8440-9361-2},
series = {Schriftenreihe Oberflächentechnik},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2024; Dissertation, RWTH Aachen University, 2023},
abstract = {Plastic injection molding is the most important process in
plastics processing and is characterized by short cycle
times and high cost-effectiveness. The productivity of the
process is achieved in particular by cold-temperature molds
for rapid solidification of the injected polymer melt.
However, an excessively high temperature gradient can lead
to premature solidification of the polymer melt and thus to
reduced part quality. This effect is counteracted by
variothermal temperature control of the mold. While internal
systems can be controlled at any time, they are slow due to
the thermal mass of the mold. External systems can achieve a
higher level of dynamics by heating only the mold surface,
but this requires the mold to be open. By applying a heating
element of a few micrometers thickness directly to the mold
surface, the heat can be generated precisely where and when
it is necessary. Such a heating element was developed using
atmospheric plasma spraying (APS), a process variation of
thermal spraying. The coating system consists of a
TiOx/Cr2O3 heating coating embedded in two Al2O3 insulation
coatings. The development was carried out in three different
technology readiness levels. In the first stage, the
relationship between the APS process parameters and the
dielectric strength of the insulation coatings as well as
the resistivity of the heating coating was identified and
quantified using a design of experiments. Thereby, the
dielectric strength showed certain independence from the
process parameters, whereas the resistivity is significantly
determined by the electric current, the H2 secondary gas
flow as well as the spray distance. For the second stage, a
test rig was developed to emulate the thermal stress of
plastic injection molding. Thermal cycles were applied to
the heating coating systems. The heating coating system was
capable of highly dynamic temperature changes on the surface
and was subjected to over 20,000 thermal cycles without
damage. In order to be able to control the heating coating
within a closed mold, a contacting solution was designed
which allows a power supply from the back. In the third
stage, heating coating systems were applied on mold inserts
and tested in plastic injection molding. Final
investigations of the molded parts showed the positive
influence on warpage and shrinkage.},
cin = {419010},
ddc = {620},
cid = {$I:(DE-82)419010_20140620$},
pnm = {SFB 1120 A12 - Experimentelle Analyse thermomechanischer
Eigenschaften thermisch gespritzter Beschichtungen (A12)
(405697953) / SFB 1120: Bauteilpräzision durch Beherrschung
von Schmelze und Erstarrung in Produktionsprozessen},
pid = {G:(GEPRIS)405697953 / G:(GEPRIS)236616214},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2024-01772},
url = {https://publications.rwth-aachen.de/record/979701},
}
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