CompositesWorld
Issue link: https://cw.epubxp.com/i/866813
NEWS CompositesWorld.com 89 Fiber-metal Laminates surface for bonding. (e company notes that it is working on next-generation "greener" chemical options for anodizing.) Next, the treated sheets are transferred to an area where auto- mated equipment sprays them with primer, a step called bond priming. Primed, cut sheets are re-rolled, with a protective paper layer preventing metal-to-metal contact, and covered in protec- tive black plastic for storage until needed in fabrication. Panel layup occurs by hand in aluminum female panel molds (for large, relatively flat panels) or on jigs for smaller, more complex parts with cutouts. Laser projection systems, sourced from Virtek Vision International (Waterloo, ON, Canada), guide layup by indicating exactly where sheet overlaps will occur, in coordination with registration pins on the jigs and molds. A prepared aluminum sheet is first down in the mold and, depending on the size of the final panel, is overlapped with an additional sheet or sheets by approximately 25 mm. Epoxy film adhesive (the same epoxy as employed in the glass fiber prepreg) in the overlap holds the splices together. is allows consider- ably larger panels than standard aluminum plate aircraft builds, explains van Mourik. "Splicing joins the sheets together for much larger panels, which helps simplify aircraft manufacture since fewer panels are needed. We can produce panels up to 44m 2 ," he says, "and are really limited only by the size of the autoclave." Fig. 2 (p. 87) shows how panel designs can be built up by splicing the FML lami- nates with additional epoxy film adhesive, to create larger and/or complexly curved parts, and, he adds, to optimize panel weight distribution. 5 Completed layups are autoclave-cured for 3.5 hours. Cure temperature depends on the laminate type in production. 7 Completed panels are milled to ensure a smooth surface. 6 A completed cured panel undergoes C-scan inspection. 8 A completed panel with stringers attached undergoes final inspection.