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Originally Posted by About.com: Composites / Plastics
Hexcel Thermoplastic TowFlex Featured in BMW M3 Bumber
BMW M3 bumpers molded from Hexcel Composites' TowFlex®& continuous fiber reinforced thermoplastic materials (CFRTP) have won three industry awards. The front and rear bumpers, molded by Jacob Composites of Wilhelmsdorf, Germany, won the "Best Use of Composites for Market Expansion" award at the Composite Fabricators Association "Composites 2001" show and the "Automotive Multipart Assembly" award at the Society of Plastics Engineers annual thermoforming conference. Most recently, the German Plastics Industry Congregation (GKV) presented Jacob Composites with the "Innovation Award" for Technical Parts at the opening session of K2001 in Dusseldorf.
The new CFRTP bumpers were developed to increase energy absorption and reduce weight for the M3 sports coupe. The bumper systems had to fit within the same space and have the same attachment points as previous metal bumpers. A group of three companies based in Wilhelmsdorf, Germany - Jacob Composites GmbH, Advanced Composite Systems GmbH (AC.S), and composite consultants – worked with BMW M designers to develop a bumper system using CFRTP materials. Hexcel Composites' TowFlex E-glass/nylon 6 fabrics were selected to meet the demanding performance, manufacturing cost, and recycling requirements. The resulting bumper system demonstrated improved crash performance with a 60% weight saving.
The manufacturing advantages of high speed CFRTP molding and thermoplastic welding were a key factor enabling mass production of the bumpers. AC.S produces flat sheet stock from multiple layers of TowFlex fabric in their unique continuous compression molding process. Continuous tubular profiles for the bumper crush columns are produced using the same process. The flat sheets are supplied to Jacob Composites for forming bumper beams and crush column boxes in a high-speed matched-mold thermoforming process. The bumper beams, crush columns, and crush column boxes are assembled using high frequency welding. Complete bumper assemblies are supplied directly to the BMW plant in Regensburg, Germany.
Hexcel worked closely with AC.S to develop specific TowFlex products for the bumper system. "We are very pleased with the success of our combined efforts on this project," said Tim Greene, Marketing Manager, Hexcel Composites- Applied Fiber Systems. "This is a strong example of our focus on customer responsiveness and technical support to develop new applications for our thermoplastic materials."
TowFlex CFRTP materials are used to produce a wide range of products. Applications include recreational equipment, industrial pump components, orthopedic braces, medical devices, and aerospace/military parts. Benefits of available TowFlex products include rapid processing, high impact resistance, low thermal expansion, good vibration damping, and resistance to harsh high temperature or corrosive environments.
TowFlex materials are produced by spreading and powder coating continuous glass, carbon, or aramid reinforcement fibers with thermoplastic particles. The uniformly distributed resin particles are melt-fused to the reinforcement fibers. This process results in a flexible, drapeable material that can be produced with a variety of thermoplastic resins including polypropylene, nylon 6, PPS, PEI, and PEEK. Hexcel provides TowFlex materials in a variety of product forms including drapeable fabrics, braided sleeving, unidirectional tape, and continuous towpreg. TowFlex products offer performance, processing, and cost advantages compared with other material forms or metal.
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