Frankfurt, Monday, June 10, 2016 – Lightweight construction is essential for a resource-saving, energy-efficient environment. By 2020, lightweight construction around the world is expected to total EUR 140 billion for the transport sector alone, with growth rates of seven to eight percent. With this in mind, VDMA has established the Working Group Hybrid Lightweight Technologies. Mechanical engineers and representatives from user and supplier industries use this platform to exchange information and ideas on opportunities, technologies and materials for lightweight construction. VDMA hears from some of the experts of lightweight construction in a series of interviews.
Interview with Klaus-Peter Welsch, Sales & IT Manager at Geiss AG and member of the Board of the Hybrid Lightweight Technologies working group
Mr. Welsch, everyone talks about carbon being the material of choice for lightweight construction. How do you see it?
Klaus-Peter Welsch: Carbon fiber is the phrase on everyone’s lips now that the car industry has started using it in a big way in its efforts to reduce weight. Given all the advantages of this material – its comparably low weight being undoubtedly the biggest – its key disadvantage is usually swept under the rug. The problem with carbon fiber reinforced plastics and other fiber reinforced plastics is how to recycle them. Some people claim that this problem is already solvable or even that it has already been solved, even in high volumes, but this is currently only possible under laboratory conditions. In practice, attempts are currently being made to shred, press and reintegrate the offcuts that arise during production. 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.
Could the recycling of CFRP components be improved by using duroplastics instead of thermoplastics?
Welsch: No. It is not possible to melt the thermoplastic out of a carbon fiber, especially not when it is woven. The melting temperatures are so high that it is very likely that the structure of the carbon fibers would change or that the properties of the fibers would at least be affected. Also, the liquid plastic would never drain out completely. Imagine soaking a cloth in butter and then trying to get the butter out again. The fat would drip out when heated, but the cloth would still be oily. A similar thing would happen with the residues in the carbon fibers, making reuse only possible to a limited extent.
So what should the car industry do to reduce the weight of the vehicles?
Welsch: CFRP can be a useful choice in the case of certain requirements for the rigidity of a component. But we at Geiss believe that it is important not to stand still with CFRP and to move the technology on. We need to think about the increased use of pure plastics in cars – those that we can recycle 100%. Plastics have a great deal of untapped potential. We can still increase the proportion of plastic – pure plastic – in a car and we can make them even lighter.
What kind of new uses of plastics are you thinking of?
Welsch: Think about the increased use of nonwovens, 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 – pure plastic fibers that are not woven. This material is 100% recyclable. Every material has its own significance. We just have to use it in the best possible way.
But other materials are still essential when it comes to load-bearing parts, aren’t they?
Welsch: Rigidity values that are unimaginable today will be possible in plastics. One example is in the construction industry, where plastic boards are already used in some cases for partition walls, instead of wood or plasterboard. These plastic boards consist of two thin films that are molded and welded. They are much lighter than plasterboard and similar materials. A board measuring two by 1.25 meters can hold the weight of a person without even bending. And the entire board can be recycled.
How important is lightweight construction for Geiss?
Welsch: Thermoforming technology is our bread and butter. It is a small niche in the huge field of plastic processing. We use the process to produce plastic technical components for our customers, usually large-scale parts in small batches. Producing them using injection molding is extremely uneconomical. In thermoforming, the material thickness is crucial. Our main aim here is to achieve low cycle times, in order to reach a high level of productivity. The cycle time is mainly influenced by the heating and cooling processes. The thinner the board we are molding, the shorter the cycle time. The area is far less important. We have therefore always been interested in the ability to work with the thinnest possible materials. The thinner they are, the better.
Do you expect your business to benefit from the growing importance of lightweight construction in industry?
Welsch: We certainly do anticipate more business, for two reasons. The first is the weight reduction thanks to the increased use of plastics. This is an urgent issue, and not only in the automotive sector. The other reason lies in the drastic rise in product variety. An example: Hard-shelled suitcases are now available in many different colors, and can even be customized with the name of the owner. But this does not change the number of suitcases sold. In order to offer more colors, more color mixtures have to be prepared in the injection molding process, the machines have to be cleaned more often, and so it goes on. The production costs rise. For us as thermoformers, it doesn’t matter whether you form three boards over a mold or 20. It does not take any modifications to the machine, so no additional costs arise. The product variety means that we have gained a large portion of the former injection molding market.
Could one say that hybrid lightweight construction is only the beginning, and in the future will be just one lightweight construction solution among many?
Welsch: Progress continues, of course. That is why we founded the working group. We cannot stand still now, and we cannot be afraid of the amount of work involved in further improvements.
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