Analysis and development of additive manufacturing processes
With the development of rapid prototyping and rapid manufacturing technol- ogies the shape restrictions of manufactured parts have decreased gradually. One of the most promising near net shaping technologies is metal-based additive manufacturing by Selective Laser Melting (SLM), where functional metal parts with high accuracy can be obtained without any specific tooling. Topology optimisation by machine learning offers new possibilities for produc- ing components with lower weight together with lower amount of engineering hours spent for designing. Additive manufacturing enables manufacturing of these, usually organic shapes, for which traditional, subtractive methods cannot be used. An example of topology optimised part, used in formula racing car is shown in Fig.1.
Fig. 1. Example of topology optimised and metal 3D printed part where both, weight at similar maximum stresses and man hours for designing could be drastically decreased.
The present research attempts to advance further in manufacturing of near net shaped parts by enabling tailoring material properties at selected areas of the part. This is realised through producing multimaterials. First, a porous preform is 3D printed which is followed by embedding with ceramic, metal or polymer through post treatments – infiltration or pressure assisted sin- tering. When combined with finite element analysis (FEA), the material in the part can be tailored to have specific properties in specific areas of the body (e.g. increased strength, hardness, wear resistance, chemical inertness etc.). Our investigations have shown that damage tolerance of highly brittle ceramics can be dramatically increased. For example, functional grading of ceramics – metal printed parts have high perspectives in orthopaedic appli- cations, where biocompatibility from ceramic and strength from metal can be adjusted in one part (see Fig.2).
Fig. 2. Schematic of functionally graded metal-ceramic composite produced by SLM followed by hot isostatic pressing