Dies for high pressure die casting are normally manufactured by machining of slabs of tool steel to the required dimensions. This manufacturing requires several steps such as rough machining, heat-treatment, EDM (electro discharge machining) and polishing. With the AM (additive manufacturing) method SLM (Selective Laser Melting) it has become possible to print the dies fully or in part. Several advantages are expected, such as a better thermal distribution in the die in service and thereby extended die life and better component quality. This is due to the possibility of making the cooling channels conformal. There are also expectations of reduced time and cost in the manufacturing process due to fewer manufacturing steps and better material utilisation. Hopes are to print a net shape or near net shape that can be used directly as a die component. In this paper it is investigated to what extent this can be fulfilled by printing two die inserts to be used for casting fatigue test samples of aluminium. They were printed on a 3D Systems ProX DMP 300 in maraging steel powder. The result is that it is possible to obtain a sufficiently smooth surface die surface. However, the current design with an SLM insert fitted in a machined die makes extensive post printing manufacturing necessary.
Maraging steels are good candidates for the laser powder bed fusion process (L-PBF), also known as Selective Laser Melting, due to excellent weldability and resistance to quench cracking. Powders physical and chemical characteristics dominate the final microstructure and properties of the printed parts, that are also heavily influenced by the process parameters. In this study, the effects of the scanning strategies on dimensions, average surface roughness, density and material hardness were evaluated, keeping the powder type and the volumetric energy density (Andrew number) constant. The effects of the scanning strategy on these properties are far less understood than on other important ones, like residual stresses and distortion, strongly affected by the scanning strategy. In this study, parallel stripes, chessboard and hexagonal pattern strategies were studied, keeping the Andrew number constant but varying the interlayer rotation. In general, the hexagonal strategy underperformed compared to the chessboard and the stripes ones.
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