The markets: Automotive (2018)

As the global auto industry hurtles toward its confrontation with US fuel economy and European Union (EU) emissions standards in 2017, the pressure built to find more radical solutions to lightweighting.

As the global auto industry hurtles toward its confrontation with US fuel economy and European Union (EU) emissions standards in 2017, the pressure built to find more radical solutions to lightweighting. Corporate average fuel economy (CAFE) standards in the US will soar to 54.5 mpg by 2025. In the European Union (EU), CO2 emissions restrictions will reduce passenger cars emission limits difficult-to-achieve 95g of CO2/km in 2020. Automakers are less than two model development cycles from the compliance due dates. 

In terms of materials, reinforced thermoplastics continue to make gains in areas once thought to be the province of thermoset composites. A case in point: A European transportation-composites consortium, led by OEM Renault Trucks (Saint-Priest, France) and materials supplier Solvay (Brussels, Belgium), designed, produced and validated a thermoplastic composite engine-compartment bulkhead. It replaces a multi-piece stamped-steel assembly on a mid-size commercial truck. The project was noteworthy because bulkheads separate the engine compartment, with its heat and aggressive chemicals, from the passenger compartment and provide occupant protection. Further, the structural assembly is mounted to the body-in-white (BIW) and plays a safety role during crashes, making its performance both critical and challenging, given the vehicle’s size and weight. Ultimately, the program replaced a 21-piece stamped-steel assembly (including multiple spot welds and fasteners) with a 3-mm-thick composite assembly that halves part count, reduces mass by 25%, improves performance and did so at acceptable part cost via a compression molding process easily capable of the 20,000 units/yr requirement.

 The bulkhead also plays roles in vehicle durability and in damping noise/vibration/harshness (NVH). The four-year program involved significant use of virtual prototyping, plus materials and process development. Molded parts passed a battery of rigorous physical tests.

Market penetration? Composites are well-entrenched in the automotive world, and that includes carbon composites, but there is still much to be done. Dr. Sanjay Mazumdar, CEO of Lucintel (Irving, TX, US), a global market research and management consulting firm, told CW that the total worldwide demand for carbon composite products in the automotive industry could be expected to double to US$6.3 billion in 2021, with a high compound average growth rate (CAGR) of 17%. He noted that this is because the need is critical to reduce vehicle weight toward the end goal of increasing fuel economy and emissions reduction. Behind the industry’s multi-material mantra, Muzamdar noted, Lucintel’s interviews with automaker execs in 2016 revealed they believe they must develop automotive structural parts with 50% weight-savings potential. Although they are looking into lightweight materials that include advanced high-strength steel (AHSS, steel with tensile strength that exceeds 780 MPa), aluminum, magnesium and CFRP, only the latter offers the potential for weight savings greater than that 50% threshold. For that reason, CFRP is receiving attention. Currently, most major automakers, such as BMW, Mercedes, Ford and GM, he says, are focusing on developing what he calls “transformational technologies” able to incorporate CFRP in mass-volume cars as a means to meet the stringent government guidelines. That said, auto OEM execs were clear that barriers remain to the achievement of that goal, not the least of which is carbon fiber’s current cost. Other issues include the lack of proven automated production technologies, mature recycling pathways and established repair strategies and practices.

All that said, were the auto industry to suddenly convert whole to composites (carbon fiber, in particular), could the current supply chain support it? Most observers answer, No. (Those with longer memories will recall that a similar situation existed around the turn of the century in the aircraft market). IACMI’s Dale Brosius sees this situation, in context, as entirely positive for the composites industry.

Indeed, as 2017 began, Chris Red of Composites Forecasts and Consulting LLC (Mesa, AZ, US) estimated at CW’s Carbon Fiber Conference that commercial aircraft structures consumed 7,500 MT of carbon fiber in 2016 and said this will grow to slightly more than 10,100 MT in 2025, an increase of about 35%. This represents maturation of widebody aircraft programs and organic market growth. Should Boeing and Airbus elect to put carbon fiber wings on every narrowbody aircraft built, (admittedly, a very optimistic scenario) this would add 7,000 MT to this forecast, at 5 MT per aircraft, assuming growth to 1,400 aircraft per year. For OEM automotive, Red’s numbers go from just under 12,000 MT to almost 33,000 MT in the same period, nearly tripling that market. And his numbers, Brosius believes, might be low. At the same conference. Andreas Wuellner of SGL Carbon Fibers (Wiesbaden, Germany) envisioned 20% of the world’s 100 million vehicles built in 2025 using a mere 2 kg each, but that adds up to an annual market of 40,000 MT — a sizable piece of today’s overall market. Keying on the recent trend toward CFRP use just in B-pillars (e.g., BMW 7 Series, Audi R8 and Lamborghini Huracán, Brosius believes the B-pillar not only potentially represents the automotive industry’s easily applied “killer app” but more to the point, at ~2 kg of carbon fiber per pillar (~4 kg per vehicle) on only 20% of the world’s vehicles, would represent 80,000 MT of carbon fiber — equal to the entire current market for all applications! 

Automaker Volvo Car Group (Gothenberg, Sweden) made news in summer 2017 when it announced that by 2019 all of its vehicles would be hybrids or powered solely by electric motor. Polestar, Volvo’s performance brand, has confirmed plans for its first three models. The first model, the 600-hp Polestar 1, is set to roll out in mid-2019 with a carbon fiber composite body to lower its center of gravity, improve torsional stiffness by 45%, and unweight it to help achieve its predicted 150 km-per-charge range. Notably, Volvo, now owned by Geely Automobile Holdings of China (Hangzhou, China) will build the car in a production facility in China.

Suffice it to say, the automotive market isn’t likely to disappoint the composites industry. The tale might be the other way around. If automakers get serious about the use of composites, even on a limited sale, can the composites industry keep up with the demand? 

Elsewhere, although additive manufacturing came rather spectacularly to the automotive world’s attention in the 2014-2015 timeframe with the world’s first 3D-printed composite body for an automobile, the excitement has been tempered a bit by the technology’s realities. But that takes nothing away from its promise in some key areas. 

Conceived as a showcase for large-scale 3D printing capabilities developed through a public/private partnership anchored by Oak Ridge National Laboratory (ORNL, Oak Ridge, TN, US), the passenger cell or tub (seat frames, cockpit, hood and tail) and four fenders — five pieces total — for the 680-kg, battery-powered two-seater Strati roadster were printed on a large-format Big Area Additive Manufacturing (BAAM) printer built by Cincinnati Inc. (Harrison, OH, US) in 44 hours at the 2014 IMTS show (Sept. 8-13, Chicago, IL, US). Since then, serious inquiries into the utility of 3D printing in the composites realm revealed early size and material limitations. Most commercial 3D printers (BAAM was an exceptional case) were small-format and, while a few could build milled-fiber-reinforced polymer parts, they were unable to print composites with continuous-fiber reinforcement. By 2017, however, things had changed. Large-format 3D printers have been added to the product lines of several CNC machinery manufacturers. Among them are Thermwood’s (Dale, IN, US) trademarked Large-Scale Additive Manufacturing (LSAM) system, a large, extruder-based polymer additive machine able to print parts more than 6m long. Ingersoll Machine Tools (Rockford, IL, US) is developing a similar system targeted at parts up to five times this size. That said, Brosius doesn’t foresee 3D printing achieving the structural efficiency (strength-to-weight ratio) necessary to replace today’s continuous fiber-reinforced composites on any mass scale. Likewise, in high volume applications, it will be difficult for 3D printing to displace discontinuously reinforced materials, such as SMC or long fiber thermoplastics, especially given the short cycle times achieved using compression and injection molding today. 

Where 3D printing is most likely to make its mark, Brosius argues, is in the realm of toolmaking. Software suppliers have been active, with slicing programs that create print paths and applications that can perform topology optimization and predict polymer crystallization, cooling rates, residual stress and part warpage. One result is 3D printing’s utility in prototyping. Given that development of conventional machined patterns and layup tooling processes can take 6 to 12 months, 3D printing them compares favorably because it can be done in less than half the time and at lower cost. And the tools can be printed with integrated hot-air heating/cooling channels, thereby saving steps. But what about high pressure processes? Brosius notes that Purdue University has printed small compression molding tools using thermoplastics that are able to withstand 500-psi and 175°C, and exploration is underway to design tools able to make 10-50 prototype parts via compression molding, RTM and injection molding. If successful, this will dramatically reduce the cost of prototype molding for automotive and other industrial applications. 

But this unique ability to cost-effectively realize one-off, accurate custom designs suggests, says Brosius, “that this market’s killer application will be tooling for making composite parts.” Series production demands tools that can print many thousands of parts. A new project, initiated by the in conjunction with ORNL, seeks to leverage a Wolf Robotics LLC (Ft. Collins, CO, US) additive manufacturing process to develop metal tooling for high-rate processes, with stated goals of similar longevity to conventional tool steels, and more than 50% reduction in fabrication time and cost. “With the potential to incorporate conformal heating and cooling channels, and to modify the tool quickly, this technology could be truly transformative if it can be scaled to make production tooling in the size needed for automotive parts like body panels and floor pans,” says Brosius. “It’s not a question of if, but when.” 

 

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