Amanda Jacob

Toyota's Lexus LFA to use Toho Tenax carbon composites

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The Lexus LFA.
The Lexus LFA.

Toho Tenax, part of the Teijin Group’s carbon fibre business, reports that 65% of the Toyota Lexus LFA’s cabin will be made with carbon fibre reinforced plastic (CFRP). The cabin will weigh 100 kg less than a comparable aluminium cabin, yet still maintain high rigidity.

CFRP also will be used for the diffuser, speed-controlled rear wing and interior components.

Toho Tenax supplies its materials to most of the CFRP components used in the Lexus LFA.

Toho Tenax developed the components in cooperation with Toyota group companies, parts manufacturers and the Teijin Composite Innovation Center (TCIC).

The Toyota Lexus LFA was unveiled at this year’s Tokyo Motor Show and will begin marketing at the end of 2010. Only 500 LFA cars will be built. 

Lexus LFA carbon fibre construction

The LFA employs a carbon fibre reinforced plastic (CFRP). A trio of CFRP moldings comprise 65% of the cabin by weight, yielding a curb weight of 1485 kg. This CFRP technology is primed for future mass production in other Lexus models.

Keeping the car’s overall weight to a minimum was a fundamental requirement. So early in the development process, the team switched from aluminium construction to a CFRP body, yielding a weight saving of 100 kg (220 lbs).

In total, CFRP represents 65% of the cabin structure with aluminium alloy braces supporting the engine and suspension, representing the remainder. Within the LFA structural design, three different CFRP moulding processes were used:

  • prepreg is primarily used to form the main cabin frame;
  • resin transfer moulding (RTM) is used on the transmission tunnel, floor panel, roof, and hood;
  • carbon fibre reinforced sheet moulding compound (C-SMC) is used on the C-pillar and the rear floor.
For the LFA the CFRP structure was developed entirely in-house. An example of the benefit of this approach was the development of an automated weaving process with laser thread sensors that ensures fabric integrity along with dramatic production-time savings. A three-dimensional carbon fibre loom was developed specifically for the LFA programme, and the LFA team also developed a joining technology to bond carbon fibre and metal components. Conventional joining processes use a threaded aluminium insert that is wrapped in the CFRP. However, the LFA uses a system that required no insert or direct CFRP contact by employing a flanged aluminium collar to link the two materials, overcoming inherent weaknesses in such joints.