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What is additive manufacturing?
Additive manufacturing is a process applied by the industry to produce parts. The special characteristic of this process is that material is added layer by layer until the desired part is produced. In contrast, subtractive manufacturing (e.g. milling, turning, drilling, etc.) removes material from a big block of material until the desired part is produced. Additive and subtractive manufacturing, as well as casting or molding are complementary processes, and it is important to understand the differences, in order to exploit the benefits of the corresponding process. One of the biggest benefits of additive manufacturing is that parts can be produced with inner structures, reducing the required amount of material and the weight of the part; furthermore, it also facilitates the production of complex parts or of big assemblies. Nevertheless, additive manufacturing is currently not able to achieve the surface finishing quality of subtractive manufacturing processes; thus, when needed, additive-manufactured parts are commonly machined with subtractive technologies.
What are the additive manufacturing technologies?
There are different additive manufacturing technologies, depending on the material that are used for the production process. The main types of technologies are: a) extrusion, b) light polymerized, c) powder bed, and d) powder fed. Extrusion-based technologies are usually applied to soft materials (e.g. thermoplastics, rubbers, some metal alloys, and some ceramics) and the most common technologies are: fused deposition modeling (FMD), fused filament fabrication (FFF), or robocasting. Light polymerized-based technologies require photopolymer materials (a polymer that changes its properties when exposed to light) and the leading technologies are: stereolithography (SLA) and continuous liquid interface production (CLIP). Powder-bed-based technologies use powder material (e.g. powdered metal alloys, powdered polymers, ceramic powders) regardless of its hardness and the principal technologies are: electron-beam melting (EBM), selective laser melting (SLM), selective laser sintering (SLS), and direct metal laser sintering (DMLS). The powder-fed-based technologies are also used for metal alloys, and its main technology is direct energy deposition (DED). For each technology, there are different considerations regarding accuracy (fulfillment of dimensional tolerances), repeatability (reproduction of the same output for the same input), and resolution (dimension of the smallest reproduced features).
What does design for additive manufacturing involve?
Additive manufacturing needs a different thinking from the point of view of design. It is not only about selecting the material and the proper technology, but also about understanding how it works and then transforming those characteristics into design requirements. For instance, metal additive manufacturing based on direct metal laser sintering (DMLS) uses a high-power laser beam to melt layer by layer the metal powder according to the path of the laser beam. In this case, it is important to understand the path of the laser beam to avoid that some spots of the part receive more energy that other spots, creating different material properties across the part. In a similar way, the thermal dissipation also plays an important role to produce a homogeneous part. The orientation of the part also needs to be considered, because the orientation affects the paths for the laser and also because according to the orientation different support structures are needed. The behavior of the material itself also plays an important role, since it might shrink and it will affect the dimensional tolerances of the part and thus its proper utilization.
Is there additive manufacturing software support for the design?
A proper design is essential for achieving good results for additive manufacturing. Fortunately, new software tools are emerging to support the additive manufacturing process and the design in particular. There are tools in the context of analysis-based design that support the creation of inner structures, while simulating the thermal and structural behavior of the new design, aiming to reduce the weight of the part and the needed amount of material without affecting its functionality. There are also tools dealing with the process planning for additive manufacturing; this involves the orientation of the part, the generation of support structures, the slicing process, and the generation of the required files to feed the additive manufacturing machine. The simulation of the additive manufacturing process itself is also supported by software tools, in this case each layer is simulated considering the material and the type of technology, ensuring that the properties of the resulting part are adequate and that the part does not collapse by its own weight. PULSATE offers such solutions to transform the functional requirements into an optimal 3D representation that can directly be used for production. In this way, additive manufacturing adopters will gain a higher confidence in planning and calculating the process, leading to better results without the need for a trial and error phase.
Insight related to Model-based product & process optimisation, Path planning & CAM, Product design in the context of Aerospace (Aeronautics), Automotive, Industrial Machinery
