Johnson Controls achieves 40% lighter seats

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  • Symbiosis between steel, FRP, carbon fiber non-woven and thermoplastic tapes
  • Attachment parts reduced from 12 to one
  • Part of the CAMISMA lightweight project

Johnson Controls received this year’s CLEPA Innovation Award in the category “Green” for its work in the CAMISMA research project. Together with project partners from industry and science, the company, working with a newly developed seat structure, succeeded in drastically reducing the use of steel and light alloys by replacing
them with multi-material systems. With equivalent performance in terms of safety, the CAMISMA seats are more than 40% lighter than conventionally manufactured seat structures made of metal. Johnson Controls has now manufactured and successfully tested the first functional prototypes under conditions similar to those in series production.

CAMISMA’s goal: cost-efficient, sustainable access to carbon-fiber-based materials

With the CAMISMA project (Carbon-Amide-Metal-based Interior Structure using a Multi-material system Approach), which was subsidized by the German Federal Ministry of Education and Research, the project partners Johnson Controls, Evonik Industries, HBW Gubesch, Toho Tenax Europe, and RWTH Aachen University, have been pursuing a holistic approach since 2011: “With CAMISMA, our goal is to create cost-efficient, sustainable access to carbon-fiber-based materials.” says Andreas Eppinger, group vice president technology management at Johnson Controls Automotive Experience.

To overcome the CFRP drawbacks

The carbon materials group (CFRP) offers outstanding characteristics, such as high strength and design flexibility. However, it is still considered as too expensive for large-scale series use in vehicle production. Due to high costs for the source materials and the expensive, time-intensive manufacturing processes, carbon-fiber components cannot compete with present metal-forming methods. In addition, until now, there have not been any satisfactory solutions for integrating metal parts, such as seat adjusters, which have to be strongly attached to the seat structure.

Symbiosis between steel, FRP, carbon fiber non-woven and thermoplastic tapes

Immediately following the start of the project in 2011, the focus was on development of the multi-material system. The team worked with four different components: steel and fiberglass-reinforced plastic (FRP), as well as carbon fiber non-woven and thermoplastic tapes made of carbon filaments.

The four materials are combined in a complex, multilayer structure: In a thermoplastic forming process, which was also newly developed, carbon fiber is used to produce the basic form of the seat. Carbon filaments reinforce defined zones within the structure in order to provide the required strength, as does the FRP injection-molded rib structure. In addition, fasteners for the foam, seat covers, and safety devices such as airbags, are integrated into the rib-shaped FRP parts. Specially layered steel adapter components, which are first inserted into the tool and overmolded, are used to mount the two seat adjusters. The adjustment mechanisms are then fastened to the seat in a separate work stage by means of laser welds.

In September 2014, the project team reached a key milestone: The results of an initial physical crash test, which was designed to simulate a rear impact, demonstrated that the seat prototype satisfied the strength requirements. For the test, the CAMISMA seat prototype was attached to a conventional seat sub-structure. A current seat with a metal structure from large-scale series production, including the relevant strength values served as a reference. The company was able to confirm the virtual dynamic stress tests with the results from the physical test.

40% lighter & number of attachment parts reduced from 12 to one

The advantages of this lightweight structure are obvious: According to the current project status, CAMISMA seats are more than 40% lighter than conventional seats made of metal. Through functional integration, the manufacturing steps required in assembly are also substantially reduced through the number of attachment parts needed (from 12 to one, compared with the reference seat), which in turn compensates some of the additional cost.

An industrial manufacturing process, whose volume can be estimated at about 200,000 units per production line and year, now for the first time allows the efficient use of carbon fiber, which in the non woven is planned to be mainly composed of recycled raw materials. Going forward, an attempt will be made to cover the visible surfaces of CAMISMA seats during the production process and thus to enable attractive design and differentiation possibilities in the interior (read also Automotive seat covers printed by an inkjet process). According to current planning, the product should be available to customers in 2019 models.

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