Höfflin Dennis, Rosilius Maximilian, Seitz Philipp, Schiffler Andreas, Hartmann Jürgen
Institute of Digital Engineering, University of Applied Sciences Würzburg Schweinfurt, 97070 Würzburg, Germany.
Bavarian Center of Applied Energy Research e.V., 97074 Würzburg, Germany.
Sensors (Basel). 2021 Dec 22;22(1):46. doi: 10.3390/s22010046.
Nowadays, additive manufacturing processes are becoming more and more appealing due to their production-oriented design guidelines, especially with regard to topology optimisation and minimal downstream production depth in contrast to conventional technologies. However, a scientific path in the areas of quality assurance, material and microstructural properties, intrinsic thermal permeability and dependent stress parameters inhibits enthusiasm for the potential degrees of freedom of the direct metal laser melting process (DMLS). Especially in quality assurance, post-processing destructive measuring methods are still predominantly necessary in order to evaluate the components adequately. The overall objective of these investigations is to gain process knowledge make reliable in situ statements about component quality and material properties based on the process parameters used and emission values measured. The knowledge will then be used to develop non-destructive tools for the quality management of additively manufactured components. To assess the effectiveness of the research design in relation to the objectives for further investigations, this pre-study evaluates the dependencies between the process parameters, process emission during manufacturing and resulting thermal diffusivity and the relative density of samples fabricated by DMLS. Therefore, the approach deals with additively built metal samples made on an EOS M290 apparatus with varying hatch distances while simultaneously detecting the process emission. Afterwards, the relative density of the samples is determined optically, and thermal diffusivity is measured using the laser flash method. As a result of this pre-study, all interactions of the within factors are presented. The process variable hatch distance indicates a strong influence on the resulting material properties, as an increase in the hatch distance from 0.11 mm to 1 mm leads to a drop in relative density of 57.4%. The associated thermal diffusivity also reveals a sharp decrease from 5.3 mm/s to 1.3 mm/s with growing hatch distances. The variability of the material properties can also be observed in the measured process emissions. However, as various factors overlap in the thermal radiation signal, no clear assignment is possible within the scope of this work.
如今，增材制造工艺因其以生产为导向的设计准则而越来越有吸引力，特别是在拓扑优化和与传统技术相比最小的下游生产深度方面。然而，在质量保证、材料和微观结构特性、固有热导率和相关应力参数等领域的科学研究进展阻碍了人们对直接金属激光熔化工艺（DMLS）潜在自由度的热情。特别是在质量保证方面，为了充分评估部件，后处理破坏性测量方法仍然是主要必需的。这些研究的总体目标是基于所使用的工艺参数和测量的发射值，获得工艺知识，对部件质量和材料性能做出可靠的原位陈述。然后，这些知识将用于开发用于增材制造部件质量管理的无损检测工具。为了评估与进一步研究目标相关的研究设计的有效性，本预研究评估了工艺参数、制造过程中的工艺排放与所得热扩散率以及通过DMLS制造的样品的相对密度之间的相关性。因此，该方法涉及在EOS M290设备上制造的具有不同扫描间距的增材制造金属样品，同时检测工艺排放。之后，通过光学方法确定样品的相对密度，并使用激光闪光法测量热扩散率。作为本预研究的结果，展示了内部因素的所有相互作用。工艺变量扫描间距对所得材料性能有很大影响，因为扫描间距从0.11毫米增加到1毫米会导致相对密度下降57.4%。随着扫描间距的增加，相关的热扩散率也从5.3毫米/秒急剧下降到1.3毫米/秒。在测量的工艺排放中也可以观察到材料性能的变化。然而，由于各种因素在热辐射信号中相互重叠，在本工作范围内无法进行明确的关联。
