Increasing cost pressure in the automotive industry is making it necessary to use even more efficient production processes. This is why system supplier ArvinMeritor of Dietzenbach, Germany, relies on outsert molding with Ticona engineering plastics to produce modern sunroof systems. With this process, it is possible to manufacture sophisticated components that combine a high degree of functional integration with excellent precision. Significant cost advantages can be gained over conventional production methods through the reduction in the number of components and assembly steps achievable with outsert molding.
The use of outsert molding can cut the number of components by up to two-thirds, which also enables overall processing costs to be considerably reduced. At the TB&C Outsert Center in Herborn, Germany, complete modules are produced for ArvinMeritor and other customers in a single operation. Instead of each component being individually assembled, sometimes in several steps, all the components can be injection molded from plastic onto a metal baseplate in one shot. In the sunroof system fitted on the Opel Astra Caravan, for example, ArvinMeritor uses two Ticona polymers for so-called kinematic components.
Clever roof systems
While metal provides the high stiffness required for sunroof constructions, the advantages of Hostaform® POM in this composite are outstanding sliding properties and low wear. The polyoxymethylene copolymer (POM) also makes it possible to integrate additional functions on a metal frame. To ensure easy opening and positioning of the sunroof, the molded-on sliding tracks have to meet specified tolerances of 0.05 mm, despite different sliders. Tests confirm that the Hostaform grade C 9021MN ensures smooth sunroof operation, even at temperatures of -40 to +120 °C.
Just a light breeze
40 percent of all cars in Europe are now fitted with sunroof systems, which indicates their growing popularity. A similar proportion is installed on cars in the United States. When it comes to top-priced vehicles imported from Europe into the United States, the figure even rises to nearly 100 percent. Optimum air circulation through suitable sunroof systems has a positive effect on passenger perceptions of comfort and the reaction speed of the driver. To reduce drafts and noise level, the engineers at Herborn have for the first time succeeded in producing air deflectors with an integrated net by outsert molding. In this process, depending on the model, suitably shaped metal profiles are inserted into the injection mold and then overmolded together with nets also placed in the mold. The process saves costly operations such as post-trimming and deflashing and means that the air deflectors are ready for installation immediately on ejection from the mold. This development has also been facilitated by the excellent properties of Celstran® LFT. The high heat distorsion temperature of this long-fiber-reinforced thermoplastic makes it particularly suitable for combined processing with metal. This successful composite construction achieves savings in the number of components, further processing steps and assembly operations. In this way, outsert molding can help leverage material and cost-saving potentials.
Outsert molding
is one of two different processes for manufacturing composite parts from metal and plastic. In the more common insert molding process, metal parts – e.g. contacts – are inserted into an injection mold and overmolded with plastic. This method is employed to produce many different components in everyday use today: from electrical connectors to car keys. In all these cases, plastic is the carrier of the so-called “inserts”. In outsert molding, by contrast, plastic functional elements such as expanding pins, centering domes, guide elements and even moving levers are injection molded onto a metal baseplate, where they are anchored using holes and undercuts.
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