SEP 2018


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SEPTEMBER 2018 32 CompositesWorld WORK IN PROGRESS » Injection overmolding has been much in the composites industry news lately, but primarily in the realm of creating hybrid composites. Shaped continuous fiber-reinforced prepregs or pre- cured composite shapes are positioned within the mold cavity and then encapsulated within a larger short-fiber-reinforced injection- molded part in such a way as to provide extra reinforcement only where needed to avoid overdesigned parts and control production costs. Almost unnoticed in this flurry of publicity is news around plastic/ metal hybrid (PMH) structures — those that combine sheet-metal substructures injection overmolded with a thermoplastic composite. e PMH category was recently expanded thanks to a new development first announced in Europe in March. Called hollow-profile hybrid (HPH) technology, the development enables the effi- cient use of extruded or welded tubular metal substructures in place of stamped or stamped-plus-welded sheet metal to achieve higher mechanical performance for PMH components subject to high loads. HPH technology made its North American debut April 30-May 1 at the 13 th annual Automotive Engineering Plastics Conference (AutoEPCON) organized by the Society of Plastics Engineers (SPE, Bethel, CT, US) and held in the Detroit suburbs. LANXESS extends plastic/metal hybrids to tubular structures. Composite + metal: Hollow-profile hybrid technology Hollow-profile hybrid (HPH) technology This advanced version of conventional PMH technology uses injection molded, glass- reinforced PA 6 "structural elements" that are inserted into a steel or aluminum tube that, in turn, is inserted into an injection molding tool and overmolded with more PA 6 composite to form external bracketry or functional components (for example, the black structures with red handles, pictured left). Source | LANXESS Corp. By Peggy Malnati / Contributing Writer "Traditional" plastic-metal hybrid structures PMH technology was initially developed around 1995 by Bayer AG (Leverkusen, Germany). e composites team and PMH tech- nology were spun off as part of Bayer's Chemicals and Polymers businesses in 2004 to become LANXESS Corp. (Pittsburgh, PA, US). PMH uses a selectively perforated stamped steel or aluminum sheet-metal substructure that is placed into an injection molding tool that is, typically, selectively over- molded (that is, the metal substrate is not entirely encapsulated) with fiber- glass-reinforced polyamide 6 (GR-PA 6). e resulting hybrid structure features the part designer's choice of functional parts, including brackets, ribs, bosses and other geometries in composite on the outside. e perforations, which allow the thermoplastic composite to flow through and around the metal substructure, encourage a strong bond between both materials and enable the resulting structure to offer the best of both worlds. at is, the part benefits from the high stiffness and strength of thin-wall sheet metal, but it is stiffened and stabi- lized by, for example, composite ribs that prevent the metal from buckling. Additionally, the composite contributes corrosion HPH enables the use of tubular metal substructures to achieve higher perform- ance in PMH components.

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