JEC COMPOSITES MAGAZINE - Issue #107 - August/September 2016 - 27

New injection moulding process
Focus
Through its plastics research division, which evolved out of the Deutsches Kunststoff Institut DKI (German Plastics Institute),
Fraunhofer LBF provides its customers with support and advice along the entire added-value chain, all the way from polymer
synthesis to the material and its processing, product design, and to the qualification and validation of complex, lightweight,
safety-critical construction systems. The research division specializes in the management of full development processes. Highperformance thermoplastics and composites, thermosets, thermoset composites and assemblies, and thermoplastic elastomers
play a key role. The plastics division is a skills centre that specializes in issues around additives, compounding and hybrids. It has
extensive expertise in the analysis and characterization of plastics and how their properties change during processing, and in the
development of time-resolved processes.
For its customers, Fraunhofer LBF develops, assesses and implements tailored solutions for mechanical components and systems,
in particular those that are safety related. Application areas include vibration technology, lightweight construction, reliability, and
polymer technology. In addition to the evaluation and optimized design of passive mechanical structures, the Institute designs
active mechatronic-adaptronic functional units and implements them as prototypes. It also develops appropriate forward-looking
numerical and experimental methods and testing techniques. Customers are from industries like automotive, railway, shipbuilding, machine and plant construction, power engineering, building & construction, medical technology, chemical, and others. They
benefit from the technical expertise of more than 400 employees and highly advanced technologies accommodated on more than
11.560 square meters of laboratories and test surface area at the Bartningstrasse and Schlossgartenstrasse sites.

material costs. Also, the injected structures
form an assembly joint for which the junction with the organosheet constitutes a potential failure point.

Fig. 2: Sand-blasted
laminate showing
3D glass bridges
structures

tions and ribbing, in a single step. The advantages of this technology include low material costs while guaranteeing high part strength
and more firmly integrated functions, which
are uniformly connected to the core. The
manufacturing process is cost-effective, since
the production cycle time for this type of
functionalized sandwich composite is very
short. This is why the process is especially
well adapted to mass part production.

Eliminating the defects of
overmoulding technology
New processes have been developed in recent years that combine the thermoforming
of organosheets with the integration of functions and ribbing. The ribs are sprayed onto
the hot organosheet in the injection mould
(overmoulding technology). The disadvantage is that semi-finished fibre-matrix products often have to be used, resulting in high

The technology developed at the Fraunhofer
LBF avoids the two flaws of overmoulding technology. It is based on an injection
moulding process in which very thin-walled
(and therefore more cost-effective), semi-finished fibre-matrix products are placed along
the edges (which are subject to heavy flexural stress during bending) of a fibre/plastic
thermoplastic composite. The relatively unstressed core is filled by the molten thermoplastic compound, which also forms the integrated functions and ribbing at the surface of
the sandwich component in a single step. For
this, the functions and ribbing are formed
uniformly from the core and through the top
layers, without creating an assembly joint.

No107 August - September 2016

More information:
www.lbf.fraunhofer.de
Contact:
anke.zeidler-finsel@lbf.fraunhofer.de

/ jec composites magazine

http://www.lbf.fraunhofer.de http://www.mikrosam.com

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #107 - August/September 2016