The weight saving trend in the automotive sector is not only unbroken; it is becoming increasingly important as the year 2020 approaches – this is when the fleet CO2 emissions of European automobile manufacturers must comply with significantly more stringent requirements.
Thermoplastic materials, with both short and long fiber reinforcement, have made a major contribution to lightweighting today, because with their help innumerable metal production components were replaced by equally capable plastic counterparts. In the meantime, these plastic components and materials are starting to reach their fundamental limits. The next big advance in metal substitution in vehicle construction will succeed only with a technological leap, namely, using continuous-fiber reinforcement of injection molded structures, i.e., with thermoplastic composites. Once fully established, thermoplastic and thermoset composites will account for a market volume of about €2 billion in the long term.
New line of semi-finished laminate and tape products
For this reason, BASF is now expanding its activities in the field of engineering plastics to include a completely new approach called Ultracom™. This is a package of three components: continuous fiber reinforced semi-finished products, adapted overmolding compounds and the complementing engineering support. The key innovations in this new approach are laminates based on woven fabrics and unidirectional (UD) tapes that are fully impregnated with Ultramid® or Ultradur®, the polyamide and PBT materials from BASF. These thermoplastic composites are being enhanced in a development cooperation together with TenCate, the globally active fiber-reinforced composites manufacturer, and Owens Corning, the leading supplier of glass fibers.
The second component of the Ultracom package consists of the overmolding materials that have been developed specifically for use with these laminates. These materials are also from the Ultramid and Ultradur product lines, this time in the form of compounds. By using them in combination with the laminates and tapes, it is possible to injection mold complex parts that have very high mechanical reinforcement by use of continuous fibers at precisely defined locations while simultaneously incorporating specific functions as the result of overmolding.
First commercial Ultracom packages
At the K 2013, BASF will already be able to offer first commercial Ultracom product packages. For customer projects requiring parts of high stiffness, the package consists of an Ultralaminate™ based on polyamide 6 (or an Ultratape™ if highly directed reinforcements are needed) in combination with Ultramid G12 COM with 60 percent glass fiber reinforcement as overmolding compound. For crash loaded applications with a special need for impact strength, BASF offers a package which is optimized for high energy absorption. This package consists of Ultralaminate and Ultramid ZG7 COM. In this case the tape version Ultratape exists for local reinforcement, for example as required in seat structures. It can be overmolded with the same Ultramid ZG7 COM. For the time being, the orthotropic Twill-2/2 structure familiar from technical textiles and polyamide 6 will be used for the laminates. The first pre-production parts realized by Ultracom will be displayed at the K-Show 2013.
Also included: simulation, process support and testing laboratory
The third component of the Ultracom package is of great importance for developers of parts made from composites: It covers the extensive engineering support provided by the BASF application engineering group. This includes not only assistance in the form of designing the part on a computer with the aid of the universal simulation instrument Ultrasim®, but also support when it comes to processing the material and manufacturing the part. For this purpose, BASF has added a fully automated pilot line combining an injection molding system with automated laminate feeding at its technical center. The numerous opportunities available at the BASF part testing laboratory complete the package.
Engineering support – the third component is essential
This third component of the Ultracom package, the engineering support, is not just an option that can be used when necessary, as it was in previous lightweighting projects: It is an essential component of all customer projects. Without the ability to optimize design and production and to describe the behavior of the composite materials and the parts numerically via integrative simulation as in the case of the conventional short and long fiber-reinforced thermoplastics, a successful full scale market launch would be difficult to achieve. In recent years, the Ultrasim® simulation tool from BASF first made it possible to develop and design many new parts such as transmission cross beams, engine mounts, engine supports and metal-free front ends. Laminate- or tape-based thermoplastic composite parts will be a viable solution for high-volume production only if integrative simulation is supplemented by new material models and underlying experimental findings. The first Ultramid® production application on the basis of overmolded thermoplastic laminates – at that time, still produced externally - appeared in 2012 in the form of the seat pan for the Opel Astra OPC. For this application, it was already possible to use the expanded capabilities of Ultrasim. They are now available to all customers in the context of joint development projects.
Fits like a glove
On the material side it is a prerequisite and at the same time a challenge to ensure an optimum combination of fiber and polymer on the one hand and tape or laminate and overmolding compound on the other hand. They must match each other perfectly like a lock and key: The fibers must have a surface sizing formulated for the specific polymers that they are impregnated with – and vice versa. Overmolding materials, in turn, must satisfy the typical requirements for injection molding while simultaneously permitting optimum bonding/adhesion of ribs to the laminates in a fast process.
Joint learning curve – the best of two worlds
At present, the greatest technological obstacle is the development and introduction of highly automated and robust process technologies at all partners along the value-added chain, which will also lower the process costs. Currently integrated systems consisting of injection molding machines, molds, automatic positioning equipment and heating structures are not available off the shelf, neither are the individual elements matched to one another. When they become available, thermoplastic composite parts reinforced with continuous fibers will, in the near future, provide the best possible combination of weight savings, cost efficiency and performance for body and chassis components. Fiber laminates or tapes permit production of injection molded parts that are reinforced locally along the existing load paths while simultaneously incorporating additional functions and modularization via conventional injection molding. In this way, the highly efficient injection molding process and the custom reinforcement required in the part in the form of continuous fiber structures will be combined in an optimal manner.
Laminate or Tape?
The two different types of semi-finished products fulfill different functions: while thermoplastic laminates are fiber fabrics impregnated with thermoplastics, unidirectional tapes require layered arrangements that must first be produced from the fully impregnated fiber tapes to create structures. Thermoplastic laminates are thus better suited for quasi-isotropic hybrid parts with a large surface area, while tape-based inserts are more suitable for local reinforcement of injection molded short glass fiber-reinforced parts with anisotropic properties.
Consolidation and high investment – time is of the essence.
Working together with customers in the automotive sector, the experts at BASF are giving themselves three years to develop production concepts for thermoplastic composites with continuous-fiber reinforcement for body and chassis parts. All partners in the industry must build up know-how together to develop the materials, the process technology and the market. For its part, BASF intends to spend a high two digit million euro sum on research and development in its composite activities in the next three years. Some customer projects are already ongoing. BASF is ready right now to contribute its expertise in the formulation and processing of engineering thermoplastic and thermoplastic-impregnated fiber fabrics to additional customer projects.
Additional information on UltracomTM materials from BASF is available by sending a message to the email address [email protected] or by calling the telephone number +49 (0) 621 60-78780.