Inner door trim
Interior paneling of side doors in automobiles - or door panels for short - serve not only for optical and haptic aspects, but above all to seal the vehicle interior with regard to acoustics, moisture and air permeability.
In the past, door panels were mostly made of cardboard only and usually only covered part of the door . In modern vehicles, on the other hand, it is mostly a matter of plastic or leather-covered carrier parts made of plastic, which are usually formed as a continuation of the dashboard . In recent times, the mostly invisible support parts have increasingly been made from natural fiber composites and are now one of the main areas of application for this class of materials.
In modern vehicles, door panels are mostly upholstered and shaped as a continuation of the dashboard . Door panels house the door opener , door locks , armrests , door handles, buttons for power windows , mirror adjustment and central locking , loudspeakers , side airbags , storage compartments, can holders, ashtrays (mostly only in the rear), as well as the air outlet nozzles on some vehicles such as the BMW 5 Series .
Materials used
The natural fibers used are mostly flax or hemp fibers native to Central Europe , but other subtropical and tropical fibers such as jute or kenaf are also used. Depending on the model, the amount used is around 1.2-1.8 kg of natural fibers for front doors and around 0.8-1.5 kg for rear doors per automobile. The polymers used are usually thermosetting resin systems such as polyurethane or phenolic resin , although thermoplastics such as polypropylene and polyethylene have also been increasingly used in recent years .
Door linings made of natural fiber-reinforced plastics can be found at almost all well-known automobile manufacturers. They are used, for example, in the 3, 5 and 7 series by BMW or by Daimler and Audi .
Advantages of natural fiber reinforced plastics
The reasons for this use are numerous; In addition to ecological reasons, which were primarily in the foreground in the 1980s and 1990s, it is now the favorable mechanical properties and production costs that make their use attractive. Natural fiber composite materials have a lower density than glass fiber reinforced or talc-filled plastics, which results in a weight saving of 10 to 30%. This in turn leads, in addition to a better ecological balance in production, due to the use of renewable raw materials, also to lower fuel consumption and thus an improved CO 2 balance.
In addition to the good mechanical properties, these materials usually also have very good acoustic properties. In addition, they have a very low tendency to splinter, which must be taken into account when selecting the material from a safety perspective.
Due to the relatively low price of natural fibers, door linings made of natural fiber reinforced plastics are also an alternative to products made of glass fiber reinforced polymers in terms of price. When used with thermoplastic polymers, there are also improved recycling options, which, taking into account the EU end-of-life vehicle regulation, which stipulates the recyclability of 85 percent of all parts of a car by 2015, is another advantage of these materials.
Manufacturing process
By far the most frequently used process for manufacturing door panels is compression molding , especially in the production of high-quality door concepts. For models that are as inexpensive as possible and that are produced in large numbers, injection molding is particularly suitable , a process which nowadays can also be used to process natural fiber granulates .
Since the natural fiber reinforced plastics often do not meet the requirements of automobile manufacturers in terms of optics and haptics, they are usually covered with foils. Another problem with these materials is a specific odor development during production, which is often perceived as unpleasant. This is controlled by certain additives and adjustments in the manufacturing process, whereby many solutions are not judged to be completely satisfactory.
Individual evidence
- ↑ Archived copy ( Memento of the original from June 7, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
literature
- Hans-Hermann Braess, Ulrich Seiffert: Vieweg manual automotive technology. 2nd edition, Friedrich Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig / Wiesbaden, 2001, ISBN 3-528-13114-4
- Kim L. Pickering (Ed.): "Properties and performance of natural-fiber composites", Woodhead Publishing Limited, Cambridge, 2008, ISBN 978-1-84569-267-4
- Amar K. Mohanty, Manjusri Misra, Lawrence T. Drzal, (Eds.): “Natural fibers, biopolymers, and biocomposites”, Taylor & Francis Group, Boca Ranton, FL 2005, ISBN 084931741X
- Michael Carus, Christian Gahle, Cezar Pendarovski, Dominik Vogt, Sven Ortmann, Franjo Grotenhermen, Thomas Breuer, Christine Schmidt: “Study on the market and competitive situation for natural fibers and natural fiber materials (Germany and EU)” Agency for Renewable Resources (FNR), 2008
- M. Karus, M. Kaup, "Natural fibers for the European automotive industry", nova Institute, 2002
- AK Bledzki, O. Faruk, VE Sperber, "Cars from Bio-Fibers." Macromolecular Materials and Engineering Edition 291, 2006, pp. 449-457
- G. Marsh, "Applications feature: Next step for automotive materials", Materials today, Issue 6, 2003, pp. 36-43