JEC COMPOSITES MAGAZINE - Issue #102 - January/February 2016 - 30

thermoplastic

Fig. 5: Organic sheets based on UD tape fabrics

loom machine to produce a fabric with a
plain-weave fibre architecture. The singlelayer UD tape fabric can be fixed, by a
pressing process, to a single-layer organic
sheet with two reinforcing fibre directions.
As shown in Figure 5, stacked single-layer
fabrics or sheets can be translated into an
organic sheet that can be processed into
the final structural component in a subsequent thermoforming process.
Owing to the thin UD tapes, undulation
within the textile architecture is lower
for the thermoplastic UD tape-based
fabrics than for a conventional textile
fabric. In-plane mechanical performance
is therefore increased. Nevertheless, fabric
architectures typically result in lower
in-plane mechanical properties than a
unidirectional layer. But SGL was able to
show that the low undulation level of the
thermoplastic UD tape-based fabrics leads
to a performance loss of less than 10%
compared with a unidirectional laminate.

Fig. 7: Left: injection moulding compounder; right: front end using the Thermoplastic Material Toolbox

This can be accepted if other process and
mechanical parameters can be positively
influenced. The textile behaviour of the
thermoplastic UD tape-based fabric enables controlled draping during the thermoforming process. This controlled and
regulated draping results in an optimized
fibre architecture in the final geometry,
thus promoting optimized lightweight
design with respect to load path-oriented
laminates [4]. In addition, the toughness
of fabric architecture-based laminates
is higher than unidirectional laminates.
This results in higher energy absorption
and therefore higher crash and impact
performance.

process using LFT materials. The areas
with significant stress were reinforced
locally using UD tapes and organic sheets
based on UD tape fabrics. All the materials
based on Nylon 6 (PA 6) as thermoplastic
matrix were machined together in a single
process step. This example shows the
capability of the Thermoplastic Material
Toolbox for cost-efficient and lightweight
optimized components in a high-volume
production approach. Together with an
optimized structural design, this will lead
to further market penetration of thermoplastic composites in different industries
and applications.

Long fibre-reinforced
thermoplastics (LFT)

Carbon fibre-reinforced thermoplastics
should be seen as a comprehensive material system and material toolbox respectively. Based on heavy tow fibres with
customized sizings, UD tapes, organic
sheets and LFT materials can be used in
automated processes in order to enable
cost-efficient high-volume composite
applications. n

Mechanical stiffness can be generated by
superior materials or by an advanced geometrical design using ribs or crimps. As
shown in Figure 6, ribs can be processed
using press and injection materials such
as LFT. In order to gain the benefit of a
customized sizing and an economic fibre
base, SGL developed LFT semi-finished
materials using 24k and 50k heavy tows -
Sigrafil C T24-4.8/240-T140 and Sigrafil
C T50-4.0/240-T140. These carbon fibres
can also be used in a direct LFT process
(D-LFT). Both the semi-finished materials process and the D-LFT process enable
the production of components with a
high geometrical stiffness and material
performance.

Application example

Fig. 6: LFT-based ribs in combination with other
thermoplastic semi-finished materials

SGL Group demonstrated the Thermoplastics Material Toolbox on a front-end
automotive component. As shown on the
left side of Figure 7, the component was
manufactured in an injection moulding

30 jec composites magazine / No102 January - February 2016

Conclusion

References:
[1] G. W. Ehrenstein;
"Faserverbund-Kunststoffe: Werkstoffe,
Verarbeitung, Eigenschaften",
2nd edition, Hanser, München, 2006
[2] H. Schürmann; "Konstruieren mit FaserKunststoff-Verbunden", Springer Verlag, 2007
[3] A. Erber, S. Spitko; "Customized Sizing Solutions for Carbon Fiber reinforced Polymers";
I.C.S. Conference; March 2014; Paris
[4] A. Erber, S. Spitko; "Expanded role for
thermoplastic composites"; Journal of Reinforced Plastics; Volume 58, Issue 4, July/
August 2014
More information:
www.sglgroup.com

http://www.sglgroup.com

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #102 - January/February 2016