Aerospace-grade Compression Molding

Composites World (Gardiner) - Continuous Compression Molding process produces structures 30 percent lighter than aluminum at costs that have both Airbus and Boeing sold. In the drive to lightweight commercial aircraft, a recently opened frontier is the production of interior aircraft brackets, many in the form of lengthy formed profiles. These critical but often unseen aircraft assembly components — C-channels, H-beams, U-sections, L- and T-stringers and hollow trapezoidal/hat stringers — have long been produced in aluminum. Compression molding, a process more commonly associated with automotive and industrial composites, is changing that. Continuous Compression Molding (CCM), an automated, semicontinuous manufacturing process, has the capacity to take reinforced thermoformable input (for input types, click on the sidebar link at the end of this article) and produce highly shaped profiles or flat panels of effectively unlimited length. Operable by one person, the computer-controlled process yields product at speeds approaching those quoted for pultrusion — as high as 40m/hr (131 ft/hr) for shaped profiles and up to 91m/hr (300 ft/hr) for flat panels.

Spelz and Carson agree that the next step is to combine the high mechanical properties (traditionally achievable only with thermoset composites) with the high speed, high quality and low cost of CCM to produce, first, stringers and stiffeners for aircraft ceilings and structural components, and, eventually, skin-stringer assemblies, well-aimed at applications such as flooring. CCM profiles and CCM flat sheets can be fusion-bonded to produce very long assemblies, quickly and cost-effectively. Here, Carson sees a whole new world open to Xperion/CDI. “Based on CDI’s long history as a supplier, we know the material and labor costs of aerospace parts,” he notes. “We now have a process which is easily adapted to take advantage of the opportunities we see, We can replace aluminum and other metal structures with composites that are at least 30 percent lighter but at a cost previously unattainable, and we can readily recycle.”