CompositesWorld

MAR 2017

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NEWS 31 CompositesWorld.com Class A Body Panels But thermoplastics might be developing new support with carbon fiber. Gary Lownsdale, president of Trans Tech Intl. (Loudon, TN, US) and a 50-year veteran of the automotive and composites industries, sees the trajectory of carbon compos- ites in automotive moving toward thermoplastic resins for two main reasons: fast processing for <2-minute cycle times and the ease of injection molding compared to resin transfer molding (RTM). "Injection molding is now a very well-understood and well-controlled process," he explains. "It is easy to model the parts and simulate the process with readily available software. It is also a high-pressure process, which helps with complex shapes and consistent quality." What about high-pressure RTM (HP-RTM) using thermoset resins? "HP-RTM is reaching toward injection molding," says Lownsdale, "but there are still many unknowns." Lownsdale rebuffs the issue of print-through in thermoplas- tics, noting that it remains a concern for SMC as well. "ere are techniques to overcome this, like using a thin veil against the tool," he acknowledges. "Another solution is gap molding, where they bring the press down and then back it off just enough to allow a resin-rich surface before closing the press to finish molding." Lownsdale also sees some molding limitations. For example, he believes fenders are not as well-suited to SMC, "because they are much more complex in shape." He also points out that some SMC molders still struggle with paint defects. CSP and Menzolit say they have overcome these problems, adopting Industry 4.0 data analysis to drive part defect and scrap rates close to zero (see Side Story, "SMC 4.0," on p. 30). Polotzki says the "paint pop" issue is well known with SMC (see Learn More). "We advise the molder to use in-mold coating (IMC) technology and avoid these problems." He says IMC closes the material surface, eliminating pinholes. "It costs a little bit more, but the result is much better. It enables electrical conductivity in the surface so that these parts can go through inline painting." Siwajek says European OEMs have continued to have some issues with painted SMC, but notes they also have taken different approaches. Some OEMs have brought parts molding in-house, while others have used hybrid systems that feature a thermoplastic outer with an SMC inner. "e problem is such parts have to be painted outside of the factory, handled carefully as they are shipped into the assembly line and then attached after the E-coat process, which adds complexity, cost and risk." Siwajek notes that one of his company's highest volume jobs currently is the Jeep Wrangler roof (see the opening photo on p. 28) for Fiat Chrysler America (FCA, London, UK). "It is a unique application because it has a Class A surface on both the inside and outside of the part. We make up to 900 of these per day." Carbon fiber SMC Looking ahead, the demand for lightweighting will prompt serious efforts to incorporate carbon fiber reinforcement into SMC. "We are working on several projects looking at carbon fiber in SMC for serial applications," says Polotzki. "However, at the current price of carbon fiber, this will only be used in niche products, such as high-end and premium cars." What price would enable use of carbon fiber SMC in mass production vehicles? "Below €11/ kg [US$5.3/lb]," Polotzki replies. "en it makes more sense as a means to reduce density, wall thickness and, thus, weight." Menzolit's partner in applications for automaker Daimler AG (Stuttgart, Germany), Aliancys (Schaffhausen, Switzerland), also has moved forward with carbon fiber, installing a new SMC line at its R&D; facilities in Zwolle, e Netherlands, for trialing a full range of SMC products with customers. "We have made the devel- opment of carbon fiber-based solutions a key priority in our long- term strategy," says Aliancys CTO Paul Vercoulen. Magna Exteriors (Concord, ON, Canada) was recognized by the Society of Plastics Engineers (SPE, Bethel, CT, US) this past FIG. 2 Less weight and lower cost Plastic Omnium's carbon fiber-reinforced tailgate prototype (left) offers a 10% weight reduction compared to an all-aluminum design, while its Higate hybrid tailgate (right), with molded in color for the Citroën C4 Picasso integrates a Class A LGF PP outer, an SMC inner, lights, antennae, motorization and crash protection at less weight than steel and at low cost. Source | Plastic Omnium

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