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A novel process for tailored stiffness and strength in extrusion based additive manufacturing

Abstract

Extrusion based additive manufacturing (AM) techniques have gained interest and were continuously developed during the last quarter-century. However, the currently integrated processes have their limitations in different aspects. When compared to injection moulded parts, additively produced parts often suffer from limited mechanical properties, uncontrollable anisotropy, higher surface roughness, the need for support structures during production, limited process speed, etc. In this research, a novel (AM) process to reduce the aforementioned limitations is proposed. Therefore, an additive manufacturing platform with two additional degrees of freedom compared to conventional AM machines and with custom-made software was developed. This system enables Curved Layer Additive Manufacturing (CLAM). This process allows for the development of innovative build schemes, which result in a severe reduction of required support material. Another advantage of this extra flexibility is the possibility to tailor the part’s strength and stiffness according to the loads it will be subjected to. This characteristic is promising since the machine is able to process both thermoplastic and continuous fibre reinforced thermoplastics. Such an engineering solution allows for weight reduction and reduced material consumption. Furthermore, the manufactured part‘s surface roughness can be reduced by adding a finishing layer. Finally, this technology allows automated filament placement on curved layers, non-geodesic filament winding of complex shapes, the creation of continuous fibre reinforced metamaterials, etc. This study compares and assesses build time, surface roughness, mechanical properties such as flexural strength and modulus, impact strength, etc. of samples produced with both regular extrusion based AM and with the own CLAM technique

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