High-Performance Composites

MAR 2013

High-Performance Composites is read by qualified composites industry professionals in the fields of continuous carbon fiber and other high-performance composites as well as the associated end-markets of aerospace, military, and automotive.

Issue link: https://hpc.epubxp.com/i/110847

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Page 37 of 67

WORK IN PROGRESS Autoclave 35 45 3 8.5 4.25 4.25 Energy Usage (kWh) 77 54 <1 Consumable cost (relative ratio) source: Vistex TPC Curing time (hours) Documented parameters measured during the comparative study of curing methods. note the extremely low energy usage of tpc. Quickstep Preparation time (min) By the numbers 100% 96% 11% Tooling Costs (relative ratio) 72% 72% 100% Capital Equipment ($) 125K 550K 2K There are many CMMs. One software makes them more powerful. Whether you have an existing CMM device or about to purchase one, Verisurf-X is the only software you need. With its 3D CAD-based architecture, flexible reporting options, and ease of use, Verisurf-X will reduce training time and increase productivity, right out of the box. No matter what you are making or measuring, Verisurf-X provides the power to drive your devices, reduce cost, improve quality, and streamline data management – all while maintaining CAD-based digital workflow. 36 | high-performance composites Learn more about the power of Verisurf-X by visiting our Website, or call for an onsite demo. www.verisurf.com • 866-340-5551 gap between the wooden female base mold and the machined curing mold. Kuppers explains that, for the thinner four- to eight-ply demonstration parts, the rubber mask trapped sufficient heat and insulated the layup so that no heat elements were needed in the base mold. But he admits, "For thicker parts — say, 32 plies or more — we would likely need to heat the base mold as well, to ensure rapid ramp-up and uniform temperature." The demonstration involved fourply prepreg blanks, made with Hexcel's (Stamford, Conn.) HexPly 6K carbon/epoxy material and preformed to part shape in a diaphragm forming process. The preforms then were placed on the curing mold and covered with a release film and a breather cloth. Thermocouples were inserted between the film and the breather to monitor the temperature during cure, and pressure uniformity was measured via FlexiForce sensors (from Tekscan, S. Boston, Mass.) placed between the layup and the base mold. A pressure plate was added to a simple 10-ton, single-ram hydraulic press for better performance. Walczyk reports that sensors showed uniform temperatures over the part, and pressure measurements showed that the greatest pressure disparity across the tool was approximately 12 percent. For a prospective production part, the desired pressure was 100 psi/6.89 bar, so the actual pressure at the part surface varied from 90 to 110 psi across the part. This was better than predicted by the simulation, notes Kuppers. At this point, the process was proven further through actual production of composite kayak paddles. For this mold set, the FEA model predicted less than a 10 percent disparity in pressure across the paddle, a result of significant advances in the optimization algorithm. Again, an aluminum tool mold was designed with CAD and machined. It was polished, sealed with Frekote mold release from Henkel Corp. (Rocky Hill, Conn.) and then fitted with two 100W flexible heaters. The base mold was machined from Modulan epoxy tooling board supplied by McCausey Lumber Co. (Roseville, Mich.), and the silicone rubber mask was designed via the iterative modeling process previously described. The paddle comprised eight plies of woven 3K carbon/epoxy prepreg, supplied by Gurit (USA) Inc. (Bristol, R.I.). When the pressure distribution was measured during cure by sensors distributed across the paddle, a mere 5.5

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