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Hybrid Lightweight Technologies News

Less is more

Frankfurt, August 4, 2016 – At the leading plastics trade fair “K”, which takes place in Düsseldorf from October 19 to 26, 2016, lightweight construction is an important topic. Here, the focus is on materials made of fiber-plastic composites.

Lightweight construction has been around for some time, and for aircraft construction especially, engineers started reducing fuel consumption early on and thus saving tremendous costs by reducing weight. For this reason, carbon, or more accurately carbon fiber-reinforced plastics (CFRP) are being used here more and more often. Savings from using this lightweight material were even high enough to offset its high costs, but it was still limited to a niche existence, since aircrafts are not built in mass production. Over the past few years, this has been changing. Now, everyone in the industry is talking about lightweight construction, mainly because the automotive industry was the first industry to jump on the bandwagon that produces in large quantities and in series.

Today, the automotive industry is the driver for lightweight construction, not in the least because the industry itself is being driven. As part of the EU's climate policy, the industry is obligated to reduce the pollutant emissions of its vehicles. The associated EU regulation specifies that CO2 emissions are to be reduced step by step until 2030. In 2020, the CO2  emissions will already need to be limited to an average of 95 grams per kilometer. Not complying with these goals entails severe penalties.

Apart from the motor and aerodynamics, this goal can also be achieved by reducing the weight of the chassis. “The savings potential of lightweight construction is tremendous. Weight accounts for approximately 22 percent of the overall fuel consumption of a modern vehicle,” says Matthias Graf, Head of Technology and Business Development – Business Unit Composites at the mechanical engineering company Dieffenbacher. “Aerodynamics have already come a long way, which is why improvement potential in this area is limited. In lightweight construction, on the other hand, we are just getting started,” says Graf. However, we have already come far in this area since 2010. For example, it was possible to fully automate the manufacturing process for CFRP components and thus make it suitable for large series production.

The EU emission goals have given a strong boost to lightweight construction in the automotive industry. But the topic was not entirely new either; if lightweight construction had not been a priority in the past, modern cars would be significantly heavier. “Modern vehicles include much more safety technology, more electronics, more comfort, but their weight has increased comparatively little,” sums up Peter Egger, Director of the Center Lightweight Composite Technologies at the injection molding machine manufacturer Engel Austria. 

A contribution to sustainability
If a component's weight is reduced, less energy is needed for it to move. Therefore, the lightweight construction approach based on CFRP is already a contribution to sustainability in and of itself. The requirement, however, is that the production process for a lightweight composite is ideally configured in terms of energy use. “If too much energy is needed for production, the overall result in terms of sustainability becomes worse,” says Peter Egger from Engel.

CFRP is still at a slight disadvantage when it comes to recycling. If the carbon fibers are embedded in a thermosetting plastic, this composite will be difficult to separate into its original components later on. There is currently no large-scale technology for recycling in the sense of separating the fibers from the plastic and reusing the individual components. The pyrolysis needed for this is simply too expensive at the moment. However, the problem of recycling is already being tackled from various angles. “At Engel, we largely use thermoplastic systems when it comes to fiber composites. They can be recycled excellently. Often, the material can be regranulated and reused in the injection molding process. Using it for joining technology is easier as well,” Egger reports.

The recycling problem can be easily cut back by using fewer CFRP components but still using lightweight construction. “We need to think about the increased use of pure plastics in cars – those that we can recycle 100%,” says Klaus-Peter-Welsch, Sales & IT Manager at Geiss AG. He thinks that plastics have a great deal of untapped potential. In his opinion, the share of plastics used in cars could be increased even more, making them significantly lighter. Consider the increased use of nonwoven fabrics, for example. A nonwoven in the wheel housing does not rattle and is lighter than other traditional materials such as steel or aluminum. Nonwovens also have the benefit of sound insulation. They consist of pure polypropylene fibers, which are not woven and are 100% recyclable.

Fields of application nearly endless
Even outside the automotive industry and aircraft construction, fiber composites and their potential for lightweight construction are in high demand. For example, a comparatively new field of application is the building industry. The federal government created a joint project for promoting carbon and concrete composites. It focuses on concrete reinforcement through carbon fiber non-crimp fabrics. The carbon fiber constructions are significantly lighter and have higher load bearing capabilities than the usual steel reinforcements. Carbon fiber reinforced concrete facilitates free construction and shaping, and a minimum concrete thickness as corrosion protection for the steel becomes obsolete. This is a considerable contribution to resource conservation, as large amounts of concrete are saved.

The textile machinery manufacturer KARL MAYER is involved in the project. “We focus on manufacturing biaxial non-crimp fabric structures for reinforcing concrete components,” says Jochen Schmidt, CEO of KARL MAYER Technische Textilien GmbH. The biaxial fabrics have a lattice-like structure. The load bearing carbon fiber is placed at an angle of 0 degrees as the warp and at a 90 degree angle as the weft and then is fixed with the weft knitting machines in one step. “With this, we are also doing some fundamental research in concrete,” says Schmidt.

If you are restoring a bridge for example, this is usually done by adding an additional layer of concrete that had been reinforced with steel mats. Using carbon in place of steel saves a great deal of weight and materials. “This means that restoring the bridge can be done at the same or even lower cost,” explains Schmidt.

Fiber composites are not limited to carbon
There have been high growth rates of CFRP over the last few years. However, this material's share in the composite market is still low, constituting only about one percent. With 95 percent of worldwide production volume, glass fiber-reinforced plastic (GFRP) clearly ranks first. Germany is the largest producer in this area. For example, an important application includes the vanes of wind turbines made of composite components primarily made of glass fiber-reinforced plastic. Such a vane would be much too heavy if it were made of steel. If non-fiber-reinforced plastics were used, the vane could not endure the forces it is exposed to. The fiber non-crimp fabrics absorb the extremely high centrifugal forces of a rotating vane and ensure stability in the long term.

Great potential for half the cost
Carbon fiber-reinforced plastics have great potential for lightweight construction, but they are still quite expensive. For this reason, development is geared towards achieving better material properties through component engineering. Furthermore, tremendous potential is also seen in reducing production waste and increasing energy efficiency of the processes. Up to now, the cost comparison often only factored in the material cost per kilogram. “Looking at the costs from the perspective of fulfilling a function and savings through function integration as well as savings made through the reduced weight during use paints a different picture,” says Graf from Dieffenbacher. “I believe that we will succeed in halving the production costs of a CFRP component over a period of ten years,” he says, fully convinced.

This overview of lightweight construction focuses on the development and use of fiber composites, a key topic at the leading plastics trade fair “K”. The second part focuses more strongly on hybrid lightweight construction, the combination of composites with aluminum, steel and other materials. The second part will be published prior to the COMPOSITES EUROPE trade fair, which takes place simultaneously with the ALUMINIUM trade fair in Düsseldorf from November 29 to December 1, 2016.


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