July/August 2020

| 12 | July/August 2020 www.smartmachinesandfactories.com | FEATURES |  Production: fully integrated in-line production cells. According to 3D Systems’ benchmark tests, within 11 days, a Figure4 array with eight modules can turn out 10,000 units of a textured automotive vent, while the injection moulding process was still in the design stage. By the time 10,000 units of the automotive vent could be produced using traditional injection moulding, a manufacturer using Figure4 could have produced nearly 14,000 units. Accelerating adoption Also moving towards digitalised additive manufacturing is Siemens Digital Industries Software. The Siemens Additive Manufacturing (AM) Network is designed to accelerate the adoption of AM for industrial processes and applications. Partners include Decathlon, HP and Materialise. The network is designed to provide an end-to-end digital process that connects the demand for parts with a supplier network and provides a cloud- based environment to foster collaboration. The order-to-delivery process is also digitalised. Siemens is engaging the network to validate a new process called the AM Path Optimizer a beta technology integrated in the NX software. It is designed to help solve process overheating, reduce scrap and increase production yield, this time in parts manufactured in metal powder. AM Path Optimizer complements a digital twin manufacturing strategy and addresses errors originated from suboptimal scan profiles and process parameters. The technology combines physics-based simulation with machine learning to analyse a full job file in a few minutes before execution on the machine. Metal powder 3D printing is not only feasible with polymers, but also with metal powders. Selective LED-based melting (SLEDM) – the targeted melting of metal powder using high-power LED light sources – is a patent-applied technology developed by a team led by Franz Haas, head of the Institute of Production Engineering at Graz Technical University (TU Graz) in Austria. The technology is similar to selective laser melting (SLM) and electron beam melting (EBM), in which metal powder is melted by means of a laser or electron beam and built up into a component layer-by-layer. However, SLEDM solves two time- consuming problems of these powder bed-based manufacturing processes: the ability to produce large parts and avoiding manual post-processing. The LEDs are equipped with a complex lens system in which the diameter of the LED focus can be easily changed between 0.05 and 20mm during the melting process. This enables larger volumes to be melted without having to dispense with filigree internal structures, reducing the average production time of components by a factor of 20. A demonstrator of the process is already being constructed at the Medical University of Graz, where the first laboratory for medical 3D printing was opened in October 2019. The process will be used to produce bioresorbable metal implants. These are screws made of magnesium alloys used for bone fractures and which dissolve in the body after the fracture has mended. A second operation, which is often stressful, is therefore no longer necessary. Thanks to SLEDM, the production of such implants is now possible in the operating theatre itself, because “an LED light is naturally less dangerous for the operation than a powerful laser source,” says Haas. A second line of exploration is producing bipolar plates for fuel cells, or components for battery systems. Table 1 Factors pushing breakeven point of 3D printing towards higher production numbers  Process Speed: shortens the time of liquid material in the vat, enabling a wider range of hybrid materials that mirror those used in traditional moulding processes  Improved dimensional accuracy  Design needs to address functionality only, not the draft angles, undercuts, side inserts and other features required for injection moulding.  Development of CAD/CAM software that enables design for the unique capabilities of 3D printing, including organic and complex designs, consolidation of parts within an assembly, and use of lighter-weight materials with greater strength.  Advanced robotics systems that enable fast connections between modular operations and a high level of scalability. Robotic arms take the parts through each step of the primary and secondary processes, including the washing, drying and curing operations.  Being able to move continuously (and autonomously) among manufacturing steps.  Digital inspection involving the sensor and data capture practices of Industry 4.0.  Real-time communication using industry standard protocols both locally on the factory floor and remotely via web and cloud connectivity.  Operation within automated production lines, allowing fast and flexible switching of production between different parts and long and short-run batches.