JEC COMPOSITES MAGAZINE - Issue #82 - July 2013 - 44

seats

combination of parts produced by injection moulding of high impact resistance
PA6GF30. In this application, it was found
that the use of CFRT was not necessary to
meet the specifications. The total number
of parts is reduced to 15 (including screws
and rivets) for a weight of 1,665 g, i.e. close
to 50% reduction in the number of parts
and a 35% weight reduction. The benefits
of the multifunctional seat pan include:

Fig. 2: Composite process comparison for cycle time and fibre length after processing

posites combine high specific strength,
average specific modulus and elevated
impact resistance which make them a good
candidate for interior parts. Carbon fibre
composites have superior properties but
their cost is still prohibitive for automotive
applications.
The processes used in automotive applications should have a cycle time of 1 minute
or less. Figure 2 shows the wide spectrum
of composite processes that can be used
with thermosets and thermoplastics. Some
thermoset processes are close to 2 minutes
and are compatible with medium series
production. However, thermoplastics
(TP) are preferred to thermosets (TS) in
car interior applications for the following
reasons:
- lower cycle time,
- higher impact resistance,
- easier process control (no chemical
reaction in TP),
- better recyclability,
- volatile organic compounds emission and
odour are less problematic.
The targeted processes for a one-minute
cycle time combine:
- thermostamping to form a continuousfibre-reinforced thermoplastic (CFRT)
insert for the structure, and
- an injection moulding step to overmould
the CFRT insert with chopped-fibrereinforced thermoplastics (for function
integration).

Multi-functional seat pan
A multi-functional seat pan made of
injection-moulded, high impact resistance PA6GF30 was developed jointly by
Faurecia and Solvay Engineering Plastics
(formerly Rhodia Engineering Plastics).
The project focused on the function integration and weight reduction potential of
reinforced thermoplastics. The case study
concentrated on the front seat cushion
cross-member of an electric seat with tilt
and cushion length adjustment functions.
An existing steel design for this perimeter
is presented in Figure 3. It is composed of
28 assembled parts (including screws and
rivets) and weighs 2,750 g.
The new multifunctional seat pan is a

- function integration (15 parts instead of
28),
- 35% weight reduction (1 kg),
- lower investment for injection-moulded
parts than for steel parts.
The parts were designed jointly by Faurecia and Solvay, making an extensive use
of simulation tools including integrative
simulation techniques developed by Solvay (MMI ConfidentDesignTM). They used
an advanced database on the mechanical
behaviour of polyamide matrices, a Digimat MX material database and, in parallel,
an injection moulding simulation of glass
fibre orientation that was then mapped
from the moulding mesh to the structure
mesh. The data was used to simulate the
crash performance of the multi-functional seat pan. Prototypes of the assembly
shown in Figure 3 were injection moulded
with a high-impact PA6GF30. Full validation of the prototypes was successfully
performed and included frontal crash, rear

Fig. 3: Comparison of the multi-functional seat pan and the reference seat

44 jec composites magazine / No82 July 2013
JEC COMPOSITES MAGAZINE - Issue #82 - July 2013

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