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74 Show report | Commercial UAV Expo 2019 Forecast3D attended the expo to showcase its additive manufacturing (AM) capabilities, and in particular the production services it can provide for UAS developers. As Chris Boensel told us, “Many UAS manufacturers aren’t large companies with vertically integrated supply chains, so their UAVs are developed with small- scale production in mind. It’s therefore not cost-effective for many of them to make the considerable investments in time and cost needed for injection moulding, compression moulding and so on.” Boensel also noted that many end- users in the UAV market often want customised versions of airframes, so small design changes will inevitably be needed at various points throughout an aircraft’s design. That would mean having to make new (and expensive) moulds if it were not for AM. “Because of these specific market conditions, AM is increasingly the most cost-effective option to realise, test and iterate new designs before putting them into production,” Boensel said. “The nimbleness of it – being able to design and print slight geometric and density- related changes on the fly – makes it more advantageous than traditional injection moulding, and even better than CNC machining in some respects.” The company provides a range of AM processes and materials, including multi-jet fusion (MJF) with nylon-based materials such as PA12, PA11 and some TPUs, as well as fused deposition modelling (FDM) of a range of production plastics and nylons. “FDM uses extrusion, where a spooled material is heated and layered out, melting out from the nozzle,” Boensel explained. “MJF uses a Hewlett-Packard printer to emit droplets of reagent and colour, which drop onto a powder bed, layer by layer at high speed. SLS [selective laser sintering] also works on a powder bed, but melts the powder into shape using a laser. “Each method has its uses and weaknesses. MJF tends to give better material properties than SLS, which is why the former is becoming so popular among AM companies and customers, and why we have 26 MJF machines for series production lines.” Minco showcased its range of flat, flexible circuits, which it develops as an alternative for conventional wiring harnesses to provide a number of key advantages for unmanned vehicle developers. “The materials in our flex circuits lend themselves to lower mass, easier installation and higher reliability than traditional wire harnesses,” said Chris Clark. “More and more, engineers find themselves having to stuff a great many wires into an enclosure, and often they have to worry about wearing, pinching or one of them snapping loose. “Troubleshooting therefore becomes difficult as well, because it’s time- consuming to figure out which wire is broken. Our flex circuits wrap around device edges and corners similarly to tape; you can also add stiffeners in specific areas to drive bends and provide wear resistance around rough points, say around engines or avionics bays.” Three main components comprise the material responsible for the flex circuits’ mechanical versatility, reliability, thinness and low mass. Copper is used as the conductor, polyimide for the insulator, and acrylic adhesives for laminating the manufactured materials together while everything is in sheet form. Depending on the amount of February/March 2020 | Unmanned Systems Technology Additive manufacturing from Forecast3D One of Minco’s flexible circuits