Secondary finishing is dramatically reduced in an interesting new injection molding process out of Germany called “DirectSkinning”.
The new technology combines injection molding of thermoplastics with the reaction injection molding (RIM) process used for polyurethane processing. A coated component is produced directly on an injection-molding machine in a single mold in a process that can be compared to multi-component injection molding. After a thermoplastic substrate such as ABS is molded, the polyurethane system is injected into the closed mold via a polyurethane mixing head, coating the thermoplastic. “When a rotary table or swivel platen mold is used, the two production steps can be performed in parallel, for example, thus ensuring short cycle times and high productivity,” says Andreas Bürkle, who is in charge of a DirectSkinning project at fischer automotive in Horb, Germany.
The thickness and color of the polyurethane layer can be varied over a broad range. A separate coating system is eliminated, reducing investment cost and saving space. Transportation and interim storage of the injection moldings are eliminated. The polyurethane coating provides a soft feel for automotive interior parts, and also provides a cosmetic surface, such as a leather grain appearance. Scratch resistance is also improved.
It was recently announced by the developer of the technology, Bayer MaterialScience, that DirectSkinning is now being used for a production model in a component that seals off a drawer located on the dashboard of the BMW 5 Gran Turismo.