CompositesWorld

JAN 2016

CompositesWorld

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CompositesWorld.com 31 NEWS N E W S N S N E W S E N W S W Turnkey Composites Manufacturing SIDE STORY Diefenbacher (Eppingen, Germany) began ofering turnkey systems for composites in the 1990s, spanning multiple technologies, including sheet molding compound (SMC), long fber thermoplastic (LFT) and glass mat thermoplastic (GMT). The company has now developed automated systems for high-pressure resin transfer molding (HP-RTM, see "Learn More, ") and wet compression molding (see "Learn More," p. 37). "The functions of a fully automated HP-RTM system are similar to that for SMC, although more chal- lenging," says Diefenbacher technology and business development director Matthias Graf, "including unwinding and cutting fabric, stacking, preforming and loading the preform in and out of the press." Diefenbacher has collaborated with KraussMafei (Munich, Germany) since 2009, and also developed its alternating "driving tables" (shuttle tables) with BMW (Munich, Germany). "This was the most economical way to press structural CFRP parts," says Graf. One was out of the press for demolding of the CFRP part and placing the next preform in the bottom mold while the other table was inside the press for resin injection and curing. Changeover time was only 15 seconds. Graf says the twin tables also enabled management of the myriad unknowns in the development of automated HP-RTM systems: cycle time, how to clean the molds, time required to load the preforms and whether online measurement was needed prior to mold close to ensure positional accuracy. "All of the early HP-RTM lines looked like this," says Graf, "and enabled robotic mold-cleaning, of line." Two tables, however, required two bottom mold sections for every top mold section. "The mold sections are actually moved in and out of the press," Graf explains, "with the heating and electrical staying connected, such that all functions stay operational for the mold." Today, many of the original uncertainties are understood. "Automated HP-RTM systems are now a proven technology, just like SMC," says Graf. "We don't have to clean every cycle. The internal mold release systems have developed sufciently to enable continued cycling with occasional mold cleaning. There is also no need for QA checks after loading the preforms into the press, and demolding is not a big issue." Graf says Diefenbacher still ofers twin-shuttle table systems, but this means 50% greater investment in the molds. "So now we ofer a simple press with an automated mold- changing system and a mold set with one top and one bottom for each part." Touted as capable of 120,000 parts/yr, based on three shifts/day, it can achieve 2-3-minute cycle times, depending on part dimensions. "We can preform in 90 seconds," Graf says, noting that progress made here includes reducing material waste, "which is a large gain for our customers." Simplifying automated HP-RTM Single-shuttle system This Diefenbacher PreformCenter (top) is using a shuttle conveyor to place stacks of carbon fber fabric on the mold, forming a near-net shape preform (bottom) like that shown here for a car trunk lid inner shell. The preform will then be placed into an RTM mold where resin is injected and the part is cured, yielding the fnal part. Source | Diefenbacher systems requires an investment on the integrator's part but in the end will save the customer time. "In a turnkey system, this project engineering must also be done, so you will pay for it either way. Te issue is whether you know what this investment will be or are you guessing and assuming risk." "Te customer knows the total investment up front only if working with one turnkey supplier," asserts Graf. "And that supplier must fulfll the performance requirements and schedule according to the contract. I think this takes risk away from the customer and provides a labor savings because it is easy to lose 10% over the system price in months of trying to get the line producing parts well." Egger adds that purchasing a turnkey solution doesn't mean customers are settling for less production fexibility than they would get sourcing individual units separately. "Tese systems can be for one style of part or for many diferent types of parts, with the system cost varying accordingly," he says. "Tat is a decision the customer has to make up front." Chantal Wierckx, business development director for turnkey systems provider Composite Alliance Corp. (Dallas, TX, US), goes back to fabricator risk: "If there is a problem in making a part, who accepts the responsi- bility? Does the moldmaker help or does he say that the press system is the problem?" Turnkey systems eliminate the fngerpointing. "We ofer one point of responsibility." Sven Torstrick, net-shape RTM team manager at Germany's national aeronautics and space research agency, DLR (Stade, Germany), and a system user, also sees a trend toward turnkey solutions, noting that equipment suppliers have made a lot of progress, with more such options available. "For example, at the time we began EVo [2009, see the Side Story on p. 32], Fill [Gurten, Austria] said that a line like ours would require a lot of development, but now they have most of the technology on ofer." However, he also points out that "since we did not rely on one supplier, we know every screw in the system and have a very good understanding of every subcomponent, how the line works, and where issues are likely to arise. With a turnkey system, that would be diferent." Egger acknowledges the user's need for this level of knowl- edge: "We have customers who want to buy each piece separate because they want to keep their know-how in-house, but we also have customers who want to have a complete cell without spending too much efort. We must be ready for both." For Erich Fries, head of KraussMafei's (Munich, Germany) composites business unit, there is no real trend. "You either present a simple solution or a turnkey solution," he says. "We will have a mix of both in the future, based on the customer's Integrated manufacturing systems System integrators emphasize that assembly of production machinery into automated systems does not necessarily limit a customer's production fexibility. Also available for parts trialing in KraussMafei's Composites Technical Center, this system at a Korean customer's facility ofers multiple process options: wet pressing, HP-RTM, C-RTM and thermoplastic RTM. Source | KraussMafei

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