Resource: CompositesWorld
The CompositesWorld 2012 conference, Materials, Markets and Manufacturing, colocated with the Society for the Advancement of Material and Process Engineering (SAMPE) Fall Technical Conference in Charleston, S.C., USA, Oct. 22-23, gathered together a strong slate of speakers and some very interesting presentations. CW was there and offers this review of some of the presentations.
Leading off was Ross Kozarsky, analyst for advanced materials at Lux Research Inc. (Boston, Mass., USA). He focused on the prospect of carbon fiber adoption in automotive platforms, compared to the likelihood of advanced metals. Carbon must decrease significantly in price, to about $5/lb by 2017, in his view, for widespread adoption, and he discussed briefly the work being done at Oak Ridge National Laboratory (ORNL) on alternative precursors and carbonization technologies as enabling a lower price. He cautioned, “The metals guys aren’t going to just step aside — they’re innovating too.” Kozarsky used as an example magnesium, which is now available in a nanocrystalline sheet form that is easier to form. His prediction is a $2.7 billion market for automotive carbon fiber composites in 2020.

Sanjay Mazumdar, the CEO of Lucintel (Irving, Texas, USA), give his view of the composites market, including automotive composites, and stressed that “There is a huge opportunity in automotive because the penetration of composites so far into the sector has been small.” In his view, the lack of more robust composites manufacturing methods is a barrier to entry for carbon composites, but usage will increase as price of the composite (through better manufacturing) goes down. Mazumdar also challenged attendees to look at the performance to price ratio, as a guide to predicting which composites, like natural fiber composites in auto interiors, might be good targets for growth.

Charles Rowe, technical director, Composites Manufacturing Technology Center, SCRA Applied R&D (Anderson, S.C., USA), discussed applicaiton of composites in U.S. Navy craft and structures. In particular, he emphasized work the Navy has done on the DDG-1000 deckhouse and hangar, which Rowe says is the largest naval structure made with composites, plus the composite sail cusp on the Virginia Class submarine. Emerging technologies Rowe said the Navy is interested in include stitched preforms, "smart" vacuum-assisted resin transfer molding (VARTM), prepregs and steel-to-composite joints. Further down the road, he said to expect increased interest as well in closed molding, out-of-autoclave epoxy, hybrid fibers and application of aerospace composites to naval craft. Rowe also added that the DDG-51, which has been in service for many years, is being considered for redesign and might make increased use of composites.

Gordon Shank, Canadian branch director, Enigneered Natural Composites (ENC), presented information about BioMid, his company's new 100 percent cellulose fiber. Sourced from wood and refined for use in composites manufacturing, Shank says BioMid, at 1650 denier and 900 filaments, has a volume similar to 3K carbon fiber and is heat resistant up to 360°C/680°F. Shank says moisture absorption has been a challenge with this fiber, but that this can be mitigated with pre-manufacturing drying. ENC, he noted, is seaking a prepreg partner as well. For a fuller report on BioMid.

David Maass, principal at Danobat FIBRA (Elgoibar, Spain), presented information on Danobat's development of a machine designed for the rapid placement of dry, woven, multiaxial, glass, non-crimp fabric (NCF) in a wind blade manufacturing application. The system consists of two blade molds under two gantry-mounted placement head. Each head unrolls and places fabric in the mold in widths up to 40 inches/1,016 mm. Maass said each 200-ft/61m blade mold consumes 40 rolls, and each head can place about 2.4 million lb of fabric per day. Other features include 30-second automated roll changes, programmable tackifier application, on-the-fly fabric cutting, automated wrinkle inspection, layup time of about 4,000 lb/1,814 kg per hour, and physical properties of finished product similar to toughened prepregs. Maass noted that the system offers speed, efficiency and consistency that is rare in blade manufacturing, and that the device has potential for use in aerospace manufacturing.

Tommy Fristedt, president of LayStitch Technologies (Highland, Mich., USA), reviewed the advantages offered by tailored fiber placement (TFP) technology of the type offered by his firm. TFP technology stitches carbon fiber onto a carrier fabric in prescribed shapes that can then be used as preforms in composites molding processes. The system uses a stationary stitching head over a horizontally oriented backing material that is moved relative to the head. Fristedt says the machine applies 1,000 stitches/min, offers full orientation freedom, allows the user to mix material types, can stitch dry fiber or towpreg and is compatible with RTM, compression molding or injection molding. Notable applications include a mountain bike frame booster, a robot arm, Airbus A350 XWB window frame, boat propeller and helicopter longerons.

Bob Skillen, CEO and chief engineer at VX Aerospace (Melbourne, Fla., USA), discussed his company's manufacturing experience using a relatively new material type called C-PLY, developed by Stephen Tsai at Stanford University (Palo Alto, Calif., USA) and offered by Chomarat (Anderson, S.C., USA). Skillen compared his experience working with traditional quasi-isotropic layups vs. the off-angle (e.g., 0°/20°) C-PLY multiaxials. Skillen said the shallow angle orientations offered by C-PLY allow highly customized stacks that take advantage of good shear coupling and push first ply failure and last ply failure closer together, thus strengthening the finished product on the whole. Skillen said fiber fraction volume is 60-63 percent, with minimal voids and without crimp. High-Performance Composites will explore this material and applications in depth in an upcoming issue.

Alex Grous, composite applications chemist, Dixie Chemical Co. (Pasadena, Texas, USA) discussed is firm's methacrylated fatty acid (MFA) reactive diluent, a partial styrene replacement derived from palm kernel and coconut oil for use with polyester and vinyl ester in pultrusion, sheet molding compound (SMC), bulk molding compound (BMC), casting and RTM processes. Applied in loadings of 15-18 percent, the MFA offers styrene emissions reduction of up to 27 percent, good toughness, good elongation, low/no odor and 60 percent bio content. Grous walked attendees through several case histories where Dixie worked with partners (Ashland, Premix, Maine Compostie Alliance) to develop parts and structures made with resins comprised, in part, of MFA. The most data came from the Maine Composite Alliance, which assessed MFA loadings of 15 percent in vinyl ester in a construction application, and 18.6 percent in polyester in a marine application. Infusion times were unchanged, Grous said, or slightly improved. Toughness, flex strength and other properties were basically unchanged. Vinyl ester/MFA showed an increase in elongation. Polyester/MFA showed higher viscosity. Grous presented his data with Eric Koettker, director of composite material sales at Dixie Chemical, and Daniel Walcyzk, prorfessor at Rensselaer Polytechnic Institute. 

Jaron Kuppers, design and process engineer at Vistex Composites (Howes Cave, N.Y., USA), introduced a new thermal press curing (TPC) system, a novel out-of-autoclave method for curing of composite parts. The system uses a matched metal mold with a rubber mask (also matched) over the part to provide uniform hydrostatic pressure during cure. The bottom of the tool, he said, is usually aluminum, with heaters. Rubber thickness can be varied to meet specific pressure requirements. Kuppers offered data comparing TPC to autoclave cure and the Quickstep process molding the same part. The TPC process cured in 4.25 hours, compared to 8.5 hours in the autoclave and 4.25 hours in the Quickstep mold (although Kuppers said the Quickstep mold was unable to provide adequate pressure for the part). Fiber fraction volume of the finished part — a canoe paddle — had a fiber fraction volume of 59 percent via the TPC process. The process also consumed less than 1 kWh of energy and had 11 percent of the consumables cost compared to the other two processes. The company also tested ram vs. platen press design and found the former's pressure "wandered" more easily. He said the company is starting to test thermoplastics and noted that the process is limited to relatively small parts.

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