Mechanical Properties of Laser Beam Melting Components Depending on Various Process Errors
Additive Manufacturing processes are constantly gaining more influence. The layer-wise creation of solid components by joining formless materials allows tool-free generation of parts with very complex geometries. Laser Beam Melting is one possible Additive Manufacturing process which allows the production of metal components with very good mechanical properties suitable for industrial applications. These are for example located in the field of medical technologies or aerospace. Despite this potential a breakthrough of the technology has not occurred yet. One of the main reasons for this issue is the lack of process stability and quality management. Due to the principle of this process, mechanical properties of the components are strongly depending on the process parameters being used for production. As a consequence incorrect parameters or process errors will influence part properties. For that reason possible process errors were identified and documented using high resolution imaging. In a next step tensile test specimens with pre-defined process errors were produced. The influence of these defects on mechanical properties were examined by determining the tensile strength and the elongation at break. The results from mechanical testing are validated with microscopy studies on error samples and tensile specimens. Finally this paper will give a summary of the impact of process errors on mechanical part quality. As an outlook the suitability of high resolution imaging for error detection is discussed. Based on these results a future contribution to quality management is aspired.
Additive manufacturing of soft magnetic permalloy from Fe and Ni powders: Control of magnetic anisotropy
Abstract The influence of the process parameters in Laser Beam Melting (LBM) on the element distribution and magnetic properties of permalloy ( Ni 78.5 Fe 21.5 ) is studied. Iron and nickel powders are mixed in the respective proportions to build twenty-five permalloy samples. The process parameters for each sample are varied to achieve different volume energy densities. An increase of the saturation magnetization MS up to 14% of the samples with respect to the initial powder blend is found. For a volume energy density of 428  J mm 3 we detect a stripe-like segregation of iron and nickel in the uppermost layer. In the volume a homogeneous element distribution is found. The segregation at the surface leads to a sizable uniaxial magnetic anisotropy. When using parameter combinations resulting in similar volume energy densities, we observe different surface morphologies depending on scan speed and laser power. The implications for creating tailored magnetic anisotropy directions in Fe-Ni soft magnets are discussed.
Quality control of laser- and powder bed-based Additive Manufacturing (AM) technologies
Abstract The quality of metal components manufactured by laser- and powder bed-based additive manufacturing technologies has continuously been improved over the last years. However, to establish this production technology in industries with very high quality standards the accessibility of prevalent quality management methods to all steps of the process chain needs still to be enhanced. This publication describes which tools are and will be available to fulfil those requirements from the perspective of a laser machine manufacturer. Generally five aspects of the part building process are covered by separate Quality Management (QM) modules: the powder quality, the temperature management, the process gas atmosphere, the melt pool behaviour and the documentation module. This paper sets the focus on melt pool analysis and control.