Transferability of Process Parameters in Laser Powder Bed Fusion Processes for an Energy and Cost Efficient Manufacturing

Abstract

In the past decade, the sales of metal additive manufacturing systems have increased intensely. In particular, PBF-LB/M systems (powder bed fusion of metals using a laser-based system) represent a technology of great industrial interest, in which metallic powders are molten and solidified layer upon layer by a focused laser beam. This leads to a simultaneous increase in demand for metallic powder materials. Due to adjusted process parameters of PBF-LB/M systems, the powder is usually procured by the system's manufacturer. The requirement and freedom to process different feedstocks in a reproducible quality and the economic and ecological factors involved are reasons to have a closer look at the differences between the quality of the provided metallic powders. Besides, different feedstock materials require different energy inputs, allowing a sustainable process control to be established. In this work, powder quality of stainless steel 1.4404 and the effects during the processing of metallic powders that are nominally the same were analyzed and the influence on the build process followed by the final part quality was investigated. Thus, a correlation between morphology, particle size distribution, absorptivity, flowability, and densification depending on process parameters was demonstrated. Optimized exposure parameters to ensure a more sustainable and energy and cost-efficient manufacturing process were determined.Sustainability 2020, 12, 1565 2 of 14 useful for medical devices, e.g., surgical devices with thin-walled structures and, alongside Ti and Co-Cr alloys, for medical implants [4,5]. The ability to create complex lattice structures has resulted in a redesign of existing stainless steel components and lightweight structures in the automotive and aerospace industry to ensure more efficient and sustainable components [5].However, in order to ensure sustainable production, the entire process chain must be taken into consideration. Starting with powder production, through transportation and processing of the powder in the PBF-LB/M system, up to the use of a durable component and recycling of the nonfused metal powder. Kellens et al. [6] emphasize that energy consumption during the PBF-LB/M process is dominated by laser exposure. This was confirmed by Liu et al. [7], who state that energy consumption depends on exposure parameters such as laser power, scanning speed, layer thickness, etc. on the process level. Thus, the correlation between powder characteristics, the PBF-LB/M-process itself, and the final part quality represent a significant area of focus for sustainable process management.Great research efforts in the scientific community concerning stainless steel 1.4404 have addressed the correlation between input parameters (e.g., particle size distribution, chemical composition, process parameters, etc.) and output parameters (e.g., mechanical properties, relative density, microstructure, etc.). Process parameters consist of a large number of variables, including laser power, scanning speed, layer thickness...

Nanoparticle Additivation Effects on Laser Powder Bed Fusion of Metals and Polymers—A Theoretical Concept for an Inter-Laboratory Study Design All Along the Process Chain, Including Research Data Management

“…Following sample preparation, testing the effect of NPs on the as-built part properties of each participant's build job will be carried out in the fifth step (Figure 2). Both powder properties and process parameter sets affect the microstructural formations, porosity, and mechanical properties of as-built metal and polymer parts [2,3,13,17,18,30,34,36]. Therefore, the effect of NPs on microstructural and mechanical properties has to be investigated with the test methods shown in Figure 6.…”

“…Matrix grain size and crystal orientation will be measured separately for metal parts; molecular weight and crystallinity will be separately measured for polymer parts to assess the parts' microstructural formations. mechanical properties of as-built metal and polymer parts [2,3,13,17,18,30,34,36]. Therefore, the effect of NPs on microstructural and mechanical properties has to be investigated with the test methods shown in Figure 6.…”

A Critical Review on Effect of Process Parameters on Mechanical and Microstructural Properties of Powder-Bed Fusion Additive Manufacturing of SS316L

“…Chen et al [9] found that for finer particles, the hardness in the XY cross-section (276 HV) is lower than the hardness in the YZ (286 HV) and XZ (291 HV) cross-sections. Pannitz et al [24] performed a comprehensive study on five different powders available of SS316L at standard process parameters and found that the achieved average hardness is 195.4 HV. The hardness value is strongly correlated with the porosity.…”

“…The observation from the collated data is plotted concerning different parameters, such as hatch spacing, layer thickness, and energy density. The overall effect of hatch spacing on hardness from the collected literature data is shown in Figure 5 [24]. The lower hatch spacing contains more overlap in between laser scan tracks that helps to achieve complete fusion between tracks, whereas higher hatch spacing involves more porosity defects.…”

Reliability-Based Evaluation of the Suitability of Polymers for Additive Manufacturing Intended for Extreme Operating Conditions

“…Additionally, in recent years, customers have been paying more and more attention to the green level of a product and incorporating green factors into their choice of living products [ 5 ]. In order to ensure sustainable production, the entire process chain must be taken into consideration [ 6 ].…”