Carbon Fiber 2013 Conference Report
Opportunities knock in Knoxville: CF 2013 featured nearly 30 speakers and almost 300 attendees, representing a wide range of participating industry, government and academic organizations.
#cuttingtools #precursor #sheetmoldingcompound
At CompositesWorld’s Carbon Fiber 2013 conference, held Dec. 9-12 in Knoxville, Tenn., CW’s conference director Scott Stephenson capped 16 years of experience in conference organization on this subject with his best attended and most informative event yet. The 2013 edition featured nearly 30 speakers and almost 300 attendees, representing a wide range of participating industry, government and academic organizations. HPC staffers were on hand and identified the following highlights (for more, see "Automotive CFRP: The shape fo thigns to come," under “Editor's Picks,” at top right).
Carbon fiber in transportation
A highlight in recent years has been Chris Red’s Market Outlooks. This year, Red’s three-hour pre-conference presentation, “Emerging Opportunities and Challenges for Carbon Fiber in Passenger Automobiles: Is the CFRP industry ready for mass production?” asked and answered questions that were top-of-mind for many attendees. Red, who heads market research firm Composites Forecasts and Consulting LLC (Mesa, Ariz.), said the automotive industry today accounts for about 6 percent of the world’s total carbon fiber demand. He identified 104 car models that now feature OEM-specified carbon fiber composites to some degree despite the current cost of raw fiber. However, he warned that the continuing raw material cost disparity, carbon fiber vs. aluminum and steel, and even more importantly, processing challenges, will likely stall progress. “We can’t get into mid- and high-volume model production scenarios within the next 10 years,” he pointed out, but allowed that legislation that mandates reductions in greenhouse gas emissions will be a powerful driver for OEMs, who must dramatically improve auto efficiency and meet end-of-life recycling goals in the coming decade. Given these competing forces, Red believes that mid- to full-size luxury cars, luxury sports cars and some SUVs and CUVs hold the most promise for carbon composites adoption.
Red asserted that there are good opportunities beyond exterior body panels for carbon fiber composites, particularly in suspension components, such as chassis frames, powertrain elements, brakes and wheels. Of the OEMs examined in his research, BMW (Munich, Germany) and the Volkswagen Group (Wolfsburg, Germany) are the biggest users of carbon fiber at present. A joint venture between Brembo SpA (Curno, Italy) and SGL Carbon SE (Wiesbaden, Germany) is one of the largest single users of carbon fiber materials, with a dominant market share. Not surprisingly, 70 percent of carbon fiber composite part suppliers are located in Europe. Among the largest are ITCA Colonnella SpA (Colonnella, Italy), Sotira (Meslay du Maine, France) and Mubea Carbo Tech Composites GmbH (Salzburg, Germany). Some North American firms made his “biggest” composites supplier list, including Morrison Molded Fiber Glass Companies (Ashtabula, Ohio), Multimatic Inc. (Markham, Ontario, Canada) and Plasan Carbon Composites (Bennington, Vt. and Walker, Mich.). Red concluded that, despite a drop in carbon fiber usage in automotive of nearly 50 percent between 2005 and 2010, the identified vehicle population in his research will, over the next 10 years — and without a speculative demand add-on — consume more than 173 million lb/78.6 million kg of carbon fiber. “Outside of wind energy,” he concluded, “the automobile represents the biggest growth opportunity for carbon fiber market growth and penetration.” (For a more in-depth look at Red’s findings, see “Learn More,” p. XX)
In addition to Red’s preconference observations, conference attendees were offered a mixed menu of auto-related presentations. Plasan’s chief technology officer Gary Lownsdale updated attendees on his company’s work in developing equipment and processes for medium-volume manufacture of composite parts and structures for automobiles. The company’s 200,000-ft2/18,580m2 plant in Warren is producing 30,000 to 50,000 vehicle sets per year, Lownsdale reported, with new equipment on the way that will boost capacity to 100,000 vehicles sets annually. Most of the facility’s carbon fiber work is focused on General Motors Co,’s (Detroit, Mich.) Chevrolet Corvette ZR1 and Corvette Stingray and Chrysler Goup LLC’s (Auburn Hills, Mich.) SRT Viper. Parts for these programs are manufactured using Plasan’s RapidClave system, developed in partnership with Globe Machine Manufacturing Co. (Tacoma, Wash.). The RapidClave acts as a high-speed autoclave, reducing cycle times from 90 to 17 minutes by use of a ram-actuated air column inside a sealed chamber. Lownsdale said the RapicClave produces parts with Class A surfaces and has been a significant technology upgrade for the processor. “We’re moving from hours per part to parts per hour,” he quipped.
As work at the Warren facility evolves, Lownsdale said Plasan is looking to increase layup automation, reduce RapidClave cycle time to 7 minutes and develop RTM capability — the latter coming by way of a recently announced investment in Plasan by carbon fiber source Toray Industries Inc. (Tokyo, Japan). Plasan also is looking at increased thermoplastics use by way of a combined pultrusion/compression molding process that might offer cycle times as short as two minutes.
The transportation market will continue to be Plasan’s major focus for the next several years, Lownsdale said, adding that the company is considering establishment of miniature plants globally to serve a variety of geographies.
Volkswagen AG’s Hendrik Mainka, part of the company’s materials and processes group, confirmed that the company is building a carbon fiber production facility in Germany, and is also involved with Oak Ridge National Laboratory (ORNL, Oak Ridge, Tenn.) lignin precursor production facility to evaluate that material’s possible application to automotive parts. Despite lignin’s shortcomings, such as greater brittleness than polyacrylonitrile (PAN) precursor, use of a lignin precursor could save 40 percent in production costs compared to PAN-based fiber, he predicts.
Mike Siwajek, director of research at Continental Structural Plastics (CSP, Auburn Hills, Mich.) described his company’s work on producing carbon fiber sheet molding compound (SMC), a material that is 45 percent lighter than glass SMC and up to 72 percent lighter than steel. The company has produced and tested demonstration parts, and is currently fine-tuning forms and fibers. The company’s Pouance, France plant, formerly a Sotira Automotive facility, is the location for trials of resin transfer molding (RTM) processing of carbon parts, at very fast cycle times with highly reactive resin systems.
Sigmatex (UK) Ltd. (Runcorn, U.K.) technical manager Chris McHugh spoke about his company’s efforts is to improve the “attractiveness” of carbon fiber for high-volume automotive applications. The key, he said, is multifunctionality, combining different fibers to create hybrids, making lighter-weight fabrics with spread tows, or weaving preforms in a high-speed process. For example, Sigmatex has developed a “scaffolding” method to minimize crimp in 2-D woven fabrics, with no surface resin treatment needed. The company also has developed a high-speed spread-tow weaving technology with reduced crimp. He also described how the company’s waste fibers are reused, by combining and consolidating the dry fibers into a mat or “sliver” (pronounced sly-ver) and commingling them with a thermoplastic matrix, forming a product called sigmaRF. The product offers automotive parts producers a lower-cost and environmentally sustainable carbon material option, says McHugh.
Many eyebrows were raised at the conference by Patrick Blanchard, technical leader, Composites Group at Ford Motor Co. Research & Advanced Engineering (Dearborn, Mich.), who addressed emerging CAFE standards and Ford’s lightweighting efforts. He reminded the audience that CAFE targets progress annually and require 3.5 percent fuel-efficiency improvements, year over year, through 2025. He also noted that Ford research shows that consumers are not concerned about vehicle weight. They are most concerned with vehicle handling and braking and safety. Although vehicle weight affects these things, he said, weight by itself is unimportant. Finally, he claimed that powertrain advances that involve hybrid electric and plug-in electric technologies alone will enable Ford and other OEMs to meet CAFE targets. Reductions in vehicle weight, he argued, will extend the range of high-efficiency cars, but weight elimination is not necessary to increase efficiency. That said, he did note that weight is an issue, because new customer features in cars and trucks, since 1998, have added 17 lb/year to each new car model and 43 lb/year to each new truck model. Ford, Blanchard noted, is looking at aluminum and lightweight steel to help trim mass (Ford subsequently announced that its newest Ford F-150 pickup truck would use an aluminum frame). These "legacy" materials, he explained, fit best with Ford's manufacturing systems, which of course favor metals. By comparison, carbon fiber composites, he noted, are lacking in several respects: Their production processes are not scalable to auto OEM volumes. Design and CAE tools need improvement. Robust repair technologies are not yet available. An adequate fiber supply is not yet in evidence. And carbon composite are not yet proven to be compatible with vehicle painting processes. Notably, Blanchard’s objections did not include the high cost of raw fiber, but in a subsequent Q&A session, he said he left price out of his presentation because Ford’s infrastructure requirements present the bigger hurdles to the material. Blanchard noted that Ford has 39 assembly plants, globally, which produce 7 million vehicles per year. Reconfiguring those plants to accommodate carbon fiber manufacture, he clamed, would be prohibitively expensive. Nevertheless, he did say that he thinks composites usage in automotive has a future, particularly in multimaterial applications, but he made clear that carbon fiber use at Ford is not a forgone conclusion.
Mark Campbell of MW Industries Inc.’s (Rosemont, Ill.) Hyperco division offered an example of how elegant and simple a composites solution can be. Despite his position as the leader of new product development at the world’s largest supplier of suspension components and springs to the racing industry, company management made the decision to explore carbon fiber composites for racing springs. Initial helical designs were complete failures, because they lacked sufficient strength in torsion. While the company looked at other ways to use carbon fiber, including in “bump stops” (cushioning devices that limits the upward movement of the wheel suspension to prevent damage from metal-to-metal contact) on NASCAR race cars (which were ultimately banned by NASCAR racing officials), Campbell said an “a-ha” moment resulted when several thin “Belleville washers” (saucer-like carbon/epoxy discs) were stacked — back to front to back, etc. — atop each other (see photo, p. XX). The MW team found that by molding in lip/flange details, the discs could interlock when stacked, and could be flipped over and restacked in different configurations to achieve different spring rates. Hyperco is able to achieve very high spring rates when the discs are compressed, without any internal side loading friction on the spring shaft that is typical of conventional coil springs, because the discs remain parallel in compression. A&P Technology supplied the fiber forms, which were prepregged by TCR Composites Inc. (Ogden, Utah). The spring design, which Campbell calls “game-changing,” goes by the name of Carbon Composite Bellow Springs and is reportedly “revolutionizing” the sports car racing industry. Other sporting goods applications are on the horizon, says Campbell.
Although much attention was focused on forms of motorized transport, Lance Criscuolo, president of Zyvex Technologies Inc. (Columbus, Ohio), provided an update on his company’s efforts to bring carbon nanotubes (CNTs) to composite structures in the world of bycycling. Zyvex sells resin systems and prepregs that feature carbon nanotubes integrated within the resin matrix and functionalized to enhance product performance. Noted advantages included intermediate-fiber performance from standard carbon fibers, good abrasion resistance, high fracture toughness, good crack resistance and better transfer of mechanical loads to the carbon fiber, — and a minimal cost premium (+3 to +6 percent). Criscuolo pointed in particular to Zyvex’ work with Enve Composites (Ogden, Utah), which manufactures carbon fiber mountain bike racing wheels. Typical mountain bike wheels, Criscuolo said, fail after only one race, necessitating expensive and frequent replacement. Enve developed the Arove 250, made with Zyvex’ Arovex prepreg with CNTs, and demonstrated substantial improvement: One wheel now lasts more than 125 races before failure.
Carbon fiber in commercial aerospace
Mark Rigalski, a senior technical fellow at The Boeing Co.’s (Chicago Ill.) operations in Seattle, Wash.), discussed in broad terms his company’s current and future plans to incorporate carbon fiber into large aerostructures. He reported that Boeing is bullish about commercial air travel globally in the next 20 years, anticipating annual growth of 4.1 percent in airline passengers, 5 percent in total air traffic and 5.1 percent in cargo traffic. Boeing, he noted, is focused primarily on 787 Dreamliner production ramp-up, 777X material and manufacturing decisions, and material selection for a 737 replacement. He reported that the economics that drove composites use on the 787 are not yet as good on a 737 replacement, but said that a switch to carbon fiber wings for the 777X will make that plane 35 percent composite, by weight — second only to its 787 in terms of composites content on Boeing aircraft. Expanding on Boeing’s recyclability and sustainability goals, Rigalski said that material choice in aircraft is becoming increasingly important, but must always be balanced against efficiency. He commented that aluminum’s easy recyclability still makes it attractive, but admitted, “you wouldn’t want to use a heavier material on a plane just because it’s recyclable.”
In what the CompositesWorld staff believes was the first public disclosure of this work, Dave Kehrl of A&P Technology Inc. (Cincinnati, Ohio) described his company’s support of Boeing’s 787 Dreamliner program. It began in 2003, during initial trade studies, at a time when Boeing thought that 787 fuselage frames would be titanium. According to Kehrl, a Boeing employee at the time, composites were ultimately selected, but a different solution was needed — one that could conform to the curved fuselage shape. A&P developed a braid architecture and the equipment necessary to align the central, axial fibers with the tangent of the frame curvature. Defined by the braiding mandrels, the part curvature can be varied to form overbraided, multi-ply curved preforms that can meet the many load cases at each skin/stringer/frame intersection, as defined by the finite element model. According to Kehrl, The frames were the first braided, resin-infused primary structure for an aircraft. Begun in 2005, production is now ramping up to meet the 787’s production schedule. Infusion is done by C&D Zodiac - Advanced Composites Div. (Huntington Beach, Calif.) in North America, and by Alenia Aermacchi (Venegono Superiori, Italy).
Gary Roberts, a research materials engineer with NASA Glenn Research Center (Cleveland, Ohio), discussed work in collaboration with A&P Technology (Cincinnati, Ohio), Drexel University (Philadelphia, Pa.) and the Army Research Laboratory (ARL, Adelphi, Md.) on a hybrid composite/metal gear concept for rotorcraft drive systems. A helicopter’s drive system constitutes up to 15 percent of the craft’s empty dry weight, and OEMs and operators have long wished for ways to reduce system weight. Using composites with steel, Roberts pointed out, shifts the gear dynamics to a higher frequency, which could help control vibration and noise at critical frequencies. Replacing the central web of a small, round toothed steel “spur” gear with carbon composite, in a sandwich design that maintained the outer steel teeth and inner steel hub, brought a 20 percent weight reduction. Moreover, no damage or degradation was sustained during a stringent endurance test. Although static testing showed some slight delaminations at loads far beyond design loads, there was no crushing of the composite, despite myriad load cases that included radial, torque and vibration loads. Roberts says the team is scaling up to a full-size helical bull gear, and looking at ways to emulate the dynamic loads at realistic hot-oil temperatures and strains. Three major U.S. OEMs are reportedly interested in the research results.
One of the most anticipated presentations detailed use of carbon fiber in the forthcoming CFM International LEAP aircraft engine, which will be used on the Airbus A320neo and the Boeing 737 MAX narrow-body commercial jets. Presenters Bruno Dambrine, a composite expert at Safran-Snecma (Paris, France) and Jon Goering, a divisional chief technology officer with Albany Engineered Composites (AEC, Rochester, N.H.) supplying carbon fiber preforms and other components to SNECMA for the manufacture of fan module and low-pressure turbine structures in AEC’s expertise is in weaving preforms to be used in resin transfer molding (RTM) of LEAP engine blades, fan case and other smaller parts. Dambrine said material development for the engine focused primarily on finding the best combination of weaving method and resin toughness, settling in the end on the jacquard weaving method. The concern, he said, was how the composite would perform when damaged. Jacquard, he said, offered the composite structures the ability to sustain loads throughout damage development, giving the pilot time to put the aircraft on the ground without catastrophic failure in the air. Blade tests of proved this out, he reported, showing that microcracks were readily arrested by the material and design combination. The use of composites in the engine is expected to save about 1,000 lb/454 kg per aircraft. Because the A320neo and 737 MAX programs are progressing rapidly, Dambrine noted, “the greatest challenge we have is to make sure we can do the ramp-up.” SNECMA will manufacture 1,800 shipsets per year by 2020, with preforms coming from AEC’s U.S. facility and a similar plant in Commercy, France. Dambrine acknowledged that much work remains to meet production goals, but said that process development work done so far has proven that “we know exactly how many fibers we have in each preform. The closed mold, fixed resin quantity and process repeatability will help us meet weight specifications.” (Read about HPC’s recent tour of AEC’s New Hampshire facilities on p. XX.)
Carbon fiber in alternative energy
In this category, the wind industry has long been forecast as a major consumer of carbon fiber, particularly in wind blade spar caps. Projections offered at the conference indicated that the aerospace and wind energy are and will be for several years to come the two largest markets for the material. Two presentations, however, cast some doubt on carbon fiber's future in wind turbine blade applications. Although he was overall positive about the wind energy market in North America — wind, at $0.06/kWh is reportedly competitive with natural gas in electric power generation — Steve Johnson, manufacturing engineering manager at GE Wind Energy (Fairfield, Conn.), noted that manufacturing costs must be kept in check if wind is to remain competitive . "Cost is king in the wind industry," he said. Although low blade weight is important, it's not critical, he says. For that reason, carbon fiber is not considered by GE as an essential manufacturing material, particularly given its relatively high cost. A carbon fiber spar cap, Johnson said, weighs 80 percent less than one reinforced with glass fiber, but it costs five times more. "We love carbon fiber, but we hate the cost associated with it," he concluded.
Like Johnson, presenter Aaron Barr was optimistic about global wind energy production. The technical advisor at MAKE Consulting (Chicago, Ill.) said 2013 would be a "down" year but would be followed by several years of anticipated expansion. He claimed that only two blade manufacturers, Vestas Wind Systems A/S (Aarhus, Denmark) and Gamesa (Madrid, Spain), are now using carbon fiber in spar caps, with Vestas accounting for the vast majority of the total. However, Barr reported that Vestas, is struggling financially and faces an uncertain future, one reason why carbon fiber's penetration as a percentage of installed wind blades is expected to drop from a high of 23 percent in 2012 to 19 percent in 2013, and to 18 percent by 2016. "There's no magic number for when you need carbon fiber," he said, and he projected "flat" carbon fiber use in wind blades through 2020. "All of this, however," he said, "is underpinned by just a few OEMs using carbon fiber." The tipping point for carbon fiber might come in the form of a cheaper precursor, which would be expected to reduce the cost of carbon fiber to $5/lb, which MAKE anticipates will occur by 2018.
Meanwhile, Neel Sirosh, vice president and general manager of LightSail Energy (Berkeley, Calif.), highlighted carbon fiber’s role in emerging energy storage and natural-gas storage technologies for alternative energy scenarios. He highlighted LightSail’s storage solution that uses electricity to drive a small, proprietary compressor; a water spray absorbs the heat of compression. Energy is thus stored in the form of compressed air and warm water, to help even out transmission grid spikes. To make the technology work, large 12m/29.4-ft long, 2m/6.6-ft diameter ASME-standard tanks are required, for which Sirosh (formerly with Quantum Technologies (Lake Forest, Calif.) is pursuing carbon outer wraps with a polymer liner. He believes the shift to renewable energy and the shale gas boom will drive a big demand for carbon for storage tanks.
Carbon fiber in construction
That was the subject of John Carson’s presentation. Carson is the executive director of AltusGroup Inc. (Bethlehem, Pa.), a consortium of precast concrete producers that use “C-GRID” carbon grids, pioneered by Chomarat North America(Anderson, S.C.), to replace traditional welded steel-wire mesh for concrete reinforcement. The group’s CarbonCast precast concrete solutions have grown steadily over the past 10 years and are replacing heavier and thicker steel grid-reinforced precast elements. According to Carson, carbon fiber reinforcement lends “pseudo-ductile” behavior to the precast concrete and improves its fatigue performance, corrosion resistance, crack control and insulation properties, and allows the use of castings with thinner profiles and less mass. CarbonCast has been used in more than 125 parking garage structures to date, and is growing in architectural cladding — 50 to 65 percent lighter building façades are possible. “The cost of the carbon is insignificant compared to the crane cost,” noted Carson, referring to the installation of façade panels during skyscraper construction, and added that the energy savings are significant as well.
Carbon fiber out of the autoclave
The push to reduce carbon composite molding cycle times drew many attendees to presentations about out-of-autoclave (OOA) manufacturing systems. Dale Brosius, president of Quickstep Composites (Dayton, Ohio) reported on application of his company’s fluid-based pressure/heating/cooling technology, called Quickstep, to a SBIR research project with Dayton-based Vector Composites Inc. Conducted with U.S. Air Force cooperation, it assessed quality in the manufacture of 72-inch/1,829-mm tapered spars made with a prepreg of Cytec Aerospace Materials’ (Tempe, Ariz.) Cycom 977-3 OOA epoxy and IM7 carbon fiber from Hexcel (Stamford, Conn.). The goal, said Brosius, was to reduce dwell time of the spars from six to three hours but still meet all mechanical and aesthetic requirements. Flat-panel tests using the process proved the viability of the shorter dwell time; this was followed by tapered spar production and evaluation. After 50 cures of 3-inch and 5-inch 76 mm and 127 mm) wide C-channels and full length spars, the process demonstrated the ability to make “zero-void” laminates with 4-ply and 8-ply debulks up to 32 plies thick. Radius thinning was 0 to 6 percent and total cycle time was just over four hours.
In line with the OOA theme, Mathieu Boulanger, business development director at Roctool Inc. (Charlotte, N.C.; Le Bourget du Lac, France), summarized his firm’s work in technology for high-speed compression molding. The company’s emphasis has always been on rapid heating and cooling, and its applying that technology in a variety of processes. RocTool’s 3iTech molding system uses a steel tool and an inductor coil or braid to provide close-to-the surface heating in specific, prescribed areas of a tool so as to maximize heating efficiency. Cooling is provided by water. Boulanger reported on a compression molding process that used this technology to manufacture a carbon fiber composite electronics housing that is less than 1.1 mm/0.04 inch thick. Heating and cooling for the part, he said, cycles from 80°C to 260°C to 80°C (176°F to 500°F to 176°F) in 2.5 minutes. Finished parts, he reported, offer a high-quality resin-rich surface. On the horizon is an RTM/3iTech process that uses polyurethane and reduces cycle time from 60 to 5 minutes.
Notably, Jim Martin, who is responsible for composite process and business development at Globe Machine Mfg. Co. described the RapidClave machine technology used by customer Plasan Carbon Composites. It works by enclosing a thin tool and layup in an air-tight chamber, applying vacuum and heat and filling the chamber with compressed air, producing autoclave-like consolidation pressure for a very fast cure, without the energy, nitrogen or consumables required with an autoclave. Quickly engaged smart connectors and mold shuttles help accelerate part processing times. Martin discussed recent tests that show that out-of-autoclave chemistry is not required — standard autoclave-cure prepregs can be used in a RapidClave with good Class A results, he claimed, even with very short ramps and an accelerated cure. For example, a Hexcel epoxy prepreg cured in the RapidClave still fell within the supplier’s autoclave-cure specifications, and Globe is continuing tests with other prepregs as well. The equipment promises cure in mere minutes, particularly with improvements under development, such as infrared heating and more automation.
Also part of the out-of-autoclave discussion were reports exciting developments at ORNL by Chad Duty, group leader of lab’s manufacturing demonstration facility. He and his group are demonstrating new ways of additive manufacturing, or 3D printing, using new materials, better polymers and better, faster systems. A big focus is the use of continuous carbon nanofibers as a reinforcement in fused deposition modeling (FDM) to improve z-directional strength of printed parts. Duty says that strength can be improved three-fold, based on his group’s tests. Another focus is “big-area additive manufacturing,” or BAAM, which uses thermoplastic pellets with short fibers; build rates can reach 20 lbs per hour. GE is reportedly interested in Duty’s group’s work, as are other firms anxious to push this technology.
Carbon fiber in thermoplastics
Carbon-fiber reinforced thermoplastics were a strong subtheme at the conference. Jason Carling, Toho Tenax America Inc. (Rockwood, Tenn.) global research and development manager, focused here, with predictions about where carbon fiber will be adopted and used in the next decade. Although more than 90 percent of today’s carbon fiber goes to continuous filament applications in thermoset resin, he said he believes that will change: “The future is continuous carbon fiber in thermoplastic resins.” Aerospace, automotive and durable goods will be the primary market sectors that adopt carbon/thermoplastic forms, he claimed. If the right surface treatments and sizings are used on the fiber to help tailor strength and modulus, he contended, then continuous carbon fiber will be successfully combined with commodity resins like polyolefin for high-production automotive parts.
Addressing a not often visited corner of the carbon fiber market, Randal Spencer, president and CEO of Concordia Manufacturing Co. Inc. (Coventry, R.I.), explored his firm’s work in development of commingled yarns with thermoplastic prepreg. In commingling, a carbon fiber yarn is woven together with a thermoplastic, also in fiber form, to create a fabric material (2-D or 3-D) in which the thermoplastic is integral with the carbon fiber. Spencer noted that a carbon fiber commingled with polyetheretherketone (PEEK) fiber was first developed in the late 1980s for the F-22 fighter jet. Although it was not ultimately specified for the plane, commingled carbon and thermoplastic fibers found application later in the 1990s, in the Prince Vortex tennis racquet. This time, carbon fiber yarn was commingled with a nylon fiber in a prepreg. Today, said Spencer, commingled carbon fiber/thermoplastic materials are being considered particularly for tubing applications, using carbon fiber and polyphenylene sulfide (PPS). Voids, reported Spencer, are less than 1 percent.
Carbon fiber design tools
A key enabler in the effort to make composites more economically competitive is found in the virtual world of design and simulation software. Brett Chouinard, the chief operating officer of Altair Engineering Inc. (Troy, N.Y.), described how far simulation of composite materials has come during the past decade. He and his company are proponents of virtual testing because it offers “infinite exploration” of a process thanks to the huge numbers of model nodes that can be quickly built in Altair’s software, as well as the ability to rapidly modify a design, based on the simulation, to meet performance requirements. Despite this progress, however, and the software’s ability to provide micromechanical solutions, Chouinard says the huge complexity of composite part data, due to the multiple plies and orientations, means that physical testing will continue to be necessary, but he added, “Larger computers, the integration of micromechanics and integrated math engines are coming in the future.”
Robert Judd, chair of the Russ College of Engineering and Technology and the director of the Center for Advanced Software Systems Integration (CASSI), both at Ohio State University (Columbus, Ohio), discussed a spreadsheet-based cost modeling software program trademarked Gcalc/Compeat$, that he, his students and staff from GE (Schenectady, N.Y.) developed to more accurately estimate, upfront, the cost of composite material and manufacturing costs. “Cost estimating needs to be done early in the design cycle,” he explained, noting that estimtes must lifecycle costs if composites are to gain market share. He and his team believe that up to 75 percent of the opportunities for cost savings occur in the conceptual and preliminary design phases of a project — thus, it is absolutely critical to have a good handle on costs during these early stages. The software reportedly delivers “bottoms-up” detail and functionality with parametric estimating ease of use. It allows users to enter many detailed levels of material and process information, including fiber type, scrap rates, autoclave energy useage, ply buildups, trimming time and much more. And the spreadsheet can be integrated with a part’s CAD program. Although currently not commercially available — it is an in-house tool for GE engineers — Judd claims the software enables cost estimates for composite parts as accurate as those available for metal parts.
Carbon fiber from alternative precursors
Much has been written about the potential for lignin precursors, (the subject of research at nearby ORNL, which conference attendees had the opportunity to visit while in Knoxville). But Anthony Vicari, research associate at Lux Research Inc. (Boston, Mass.), revisited one of the hotter topics in the carbon fiber of late: The prospect of developing a non-polyacrylonitrile (PAN) precursor for the manufacture of commercial (heavy-tow) carbon fiber. He reported that more efficient and alternative heating systems, combined with a polyolefin-based precursor, likely will help produce carbon fiber of about $10.50/kg, down from an average of about $19/kg today. Looking more broadly, Vicari said Lux Research has been evaluating material development trends over the last few decades, trying to determine what they say about the future. In particular, Vicari said Lux correlated key material patent years with significant commercial adoption milestones (called inflections), such as the first use of a given material in an aircraft, car or medical device, for example. Lux applied this assessment to glass fiber in an attempt to predict carbon fiber’s future in the automotive industry. The result: Lux found two patent inflections, one in 1996 and another in 2006. The first heralded the introduction of the BMW i3 in 2011, which features a passenger cell made entirely of carbon fiber. The 2006 inflection, in turn, predicts the introduction in 2016 of the first mainstream car made “largely of CFRP,” said Vicari.
In a key presentation, however, Tracy Albers of GrafTech International (Parma, Ohio) the company’s research and development manager, described how GrafTech has actually incorporated ORNL’s lignin-based carbon fiber into a commercial product. Despite concerns about nonuniform characteristics of lignin, which include a branching, relatively amorphous structure that varies from tree to tree, GrafTech has created a GRAFSHIELD heat management product for casting furnaces that incorporates the lignin carbon in a composite facing. “Lignin is a drop-in replacement for our GRAFSHIELD GRI product,” Albers claims. “And it performs as well as a pitch-based carbon fiber we used previously.” Albers argued that lignin-based carbon is a “promising technology” and urged attendees to consider working with ORNL’s carbon fiber consortium.
Carbon fiber marketplace
Steve Carmichael, director of sales at Mitsubishi Chemical Carbon Fiber & Composites Inc. (Sacramento, Calif.) offered a high-level view of the carbon fiber marketplace, and a sense for where it might be headed in terms of supply and demand. He reported first that global nameplate capacity for all carbon fiber types (actual output is lower, due to knockdown effects) is about 99,000 metric tonnes (218.26 million lb). Demand, he said, is expected to reach 80,000 metric tonnes (176.37 million lb) by 2020. Looking at emerging markets for carbon fiber (beyond aerospace), Carmichael referenced recreation, transportation, infrastructure and natural gas pressure vessels. He also walked attendees through one of the paradoxes of the carbon fiber market: Carbon fiber manufacturing is capital-intensive — new capacity is added in large chunks that take much time to develop. Growth of carbon fiber consumption, on the other hand, tends to be more sporadic and, thus, out of sync with manufacturing cycles. He also commented on demands from some composites industry customers for more standardization and less complexity in the product offerings of carbon fiber suppliers. But Carmichael argued that carbon fiber’s complexity is, in fact, one of its greatest virtues in that it enables its users meet a variety of end-market needs. That complexity, he said, needs to be “sold” to customers, not minimized.
Carbon fiber and export control
John Larkin, president of LTI Assoc. (Alpharetta, Ga.), led attendees through one of the more complex aspects of manufacturing carbon fiber composite structures: U.S. export control. He noted that such controls, which are used by China, the U.K., the U.S., Germany, Switzerland, France, Japan, Korea and others, are designed primarily to prevent the spread of weapons and related sensitive technologies. He then walked the crowd through some critical concepts and definitions, including defense article (something specifically designed, developed, configured, adapted, or modified for a military application), dual-use products (those designed primarily for commercial use, but could have military applications, and deemed export (any communication of controlled information or technology to a foreign national within the U.S.). This was followed by an exploration of export law too complex to summarize, but Larkin did finish with some basic advice. He said an exporter must obtain an export license when 1) the product in question is on an export control list or 2), is not listed but one of the parties in the transaction is on the exporting country’s blacklist, or 3) the product’s end-use is controlled. Last but not least, he pointed out that noncompliance with export control laws can be expensive (up to $1 million in penalties) and could result in imprisonment. Contact Larkin for more information about export control: firstname.lastname@example.org.
The matrix binds the fiber reinforcement, gives the composite component its shape and determines its surface quality. A composite matrix may be a polymer, ceramic, metal or carbon. Here’s a guide to selection.
Compared to legacy materials like steel, aluminum, iron and titanium, composites are still coming of age, and only just now are being better understood by design and manufacturing engineers. However, composites’ physical properties — combined with unbeatable light weight — make them undeniably attractive.
Fast-reacting resins and speedier processes are making economical volume manufacturing possible.