The processing and functionalization of thermoplastic continuous fiber-reinforced semi-finished products, such as thermoplastic fabrics or UD tapes, using the Engel organomelt process will be one key focus at Engel's trade fair stand this year at Composites Europe 2018. The world's first large-scale application has been launched in the US. Valeo Front End Modules manufactures front-end carriers with integrated air ducts for a renowned German OEM in Smyrna, Tennessee, believed to be Volkswagen in Chattanooga, Tennessee. In July of this year, the structural components won an Automotive Award from the Society of Plastics Engineers (SPE) for their innovative production based on organic sheets and its outstanding properties. The parts contain a high organic sheet fraction, resulting in significant weight savings and improved crash performance. In addition, it was possible to integrate the air ducts directly into the support using a double-shell structure.
The fully automated, large-scale production system solution supplied by injection machine builder Engel consists of a duo 1700 injection moulding machine with 17,000 kN clamping force, three easix articulated robots for the preparation of multiple metal inserts as well as for the handling of the organic sheet, a viper 90 linear take-out robot and a size 5 IR oven. Engel provides this cell as a system solution all from a single source.
The consolidation press can be seamlessly integrated into the overall process, which significantly increases efficiency in the production of tailor-made tape solutions.
The tape stacking cell developed by Engel uses high-resolution camera technology to produce precise stacks from tape blanks.
The two half-shells are produced in the same mold in a one-shot process. For this purpose, the two organic sheets are simultaneously heated in the IR oven, inserted into the mold, shaped there and directly “functionalized” by means of an injection molding process taking place in the same mold. The Tepex dynalite type organic sheets provided by Bond Laminates are based on glass fibers in a polypropylene matrix. Glass-fiber reinforced polypropylene is also used for overmolding.
This reproducible thermoplastic approach enables integration of the forming process and functionalization, and to merge the supporting structure and functional elements in an adhesive manner. "The fully automated one-shot process contributes considerably to the low unit costs required by the automotive industry," emphasizes Christian Wolfsberger, Business Development Manager Composite Technologies at Engel's headquarters in Schwertberg, Austria. A further benefit: the exclusive use of thermoplastic polymers simplifies the development of recycling strategies with the aim of returning the components to the material cycles at the end of their service life. "We can see that thermoplastic-based composite lightweight design is increasingly becoming the focus of product developers, both in the automotive and aircraft industries," stresses Wolfsberger.
Besides organic sheets, Engel’s organomelt technology is also suitable for unidirectional (UD) glass and/or carbon fiber reinforced tapes with thermoplastic matrixes. Tapes make it possible to design semi-finished products in line with requirements and thus make even better use of the components' lightweight design potential. The components are either partially reinforced with just a few tapes or are produced from tape stacks several millimeters thick.
To be cost-effective in large-scale production, the stacks must be made and consolidated inline and within the cycle of the injection molding process. As a system supplier, Engel is in a position to offer integrated and fully automated solutions for the entire process – from individual tapes through to functionalisation in the injection moulding process – from a single source.
Two systems are used for the production of the blanks. A pick-and-place tape stacking cell with optical image processing and a consolidation press, which Engel will be presenting for the first time at Composites Europe. "With this new development, we have succeeded in consolidating stacks of fiber-reinforced thermoplastic tapes in the injection moulding cycle," says Dr. Norbert Müller, head of Engel’s center for lightweight composite technologies. "The consolidation press can be seamlessly integrated into the overall process, which significantly increases efficiency in the production of tailor-made tape solutions."
The consolidation press developed by Engel in cooperation with its partner Fill (Gurten, Austria) can be used to consolidate fiber stacks with deliberate fiber orientation and different wall thicknesses. All process steps are automated. All told, the consolidation process integrates inserting the fiber stack into the mould, transferring the closed mold to the heating press, heating, transferring the mold to the cooling press, consolidation, cooling and transferring to the initial station, where the mold is opened, the consolidated semi-finished product (blank) removed and a new fiber stack inserted so that the cycle can start again.
The tape-stacking cell was developed by Engel. In order to achieve the shortest possible cycle times here too, it relies on the pick-and-place principle. This means that tapes can be deposited and spot-welded together at three-second intervals. Since the quality of the stack depends on the accuracy of the tape positioning, Engel has equipped the stacking cell with a measuring system comprising high-resolution camera technology. The measuring system delivers data that is used for actively intervening in the depositing process, thus guaranteeing the greatest possible depositing accuracy.
Pick-and-place stacking technology with optical image processing offers highly flexible use. The tapes can have almost arbitrary widths and contours. Because the stacks obtain their shape required for the component during stacking, consolidation can be followed by forming and functionalisation in the injection moulding step without the need for intermediate trimming. Engel is already using this kind of solution for the manufacturing of its own products. The rotation arm of the e-pic robot consists of carbon fiber reinforced tapes.