scholarly journals Quality over Quantity: How Different Dispersion Qualities of Minute Amounts of Nano-Additives Affect Material Properties in Powder Bed Fusion of Polyamide 12

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5322
Author(s):  
Alexander Sommereyns ◽  
Stan Gann ◽  
Jochen Schmidt ◽  
Abootorab Baqerzadeh Chehreh ◽  
Arne Lüddecke ◽  
...  
Keyword(s):  
Material Properties ◽  
Carbon Nanoparticles ◽  
Material Behavior ◽  
Process Conditions ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Polyamide 12 ◽  
Nano Additives ◽  
Dispersion Quality

The great interest, within the fields of research and industry, in enhancing the range and functionality of polymer powders for laser powder bed fusion (LB-PBF-P) increases the need for material modifications. To exploit the full potential of the additivation method of feedstock powders with nanoparticles, the influence of nanoparticles on the LB-PBF process and the material behavior must be understood. In this study, the impact of the quantity and dispersion quality of carbon nanoparticles deposited on polyamide 12 particles is investigated using tensile and cubic specimens manufactured under the same process conditions. The nano-additives are added through dry coating and colloidal deposition. The specimens are analyzed by tensile testing, differential scanning calorimetry, polarized light and electron microscopy, X-ray diffraction, infrared spectroscopy, and micro-computed tomography. The results show that minute amounts (0.005 vol%) of highly dispersed carbon nanoparticles shift the mechanical properties to higher ductility at the expense of tensile strength. Despite changes in crystallinity due to nano-additives, the crystalline phases of polyamide 12 are retained. Layer bonding and part densities strongly depend on the quantity and dispersion quality of the nanoparticles. Nanoparticle loadings for CO2 laser-operated PBF show only minor changes in material properties, while the potential is greater at lower laser wavelengths.

Improvement of Build Speed and Quality of H13 Tool Steel Processed by Laser-Beam Powder Bed Fusion with a High-Power Laser

2021 ◽  
Vol 68 (10) ◽  
pp. 415-421
Author(s):  
Takashi MIZOGUCHI ◽  
Takaya NAGAHAMA ◽  
Makoto TANO ◽  
Shigeru MATSUNAGA ◽  
Takayuki YOSHIMI ◽  
...  
Keyword(s):  
Laser Beam ◽  
Tool Steel ◽  
High Power ◽  
Powder Bed Fusion ◽  
High Power Laser ◽  
Power Laser ◽  
Powder Bed ◽  
H13 Tool Steel

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

Study of High Temperature Properties of AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion

2021 ◽  
Vol 1016 ◽  
pp. 1485-1491
Author(s):  
Marialaura Tocci ◽  
Alessandra Varone ◽  
Roberto Montanari ◽  
Annalisa Pola
Keyword(s):  
High Temperature ◽  
Additive Manufacturing ◽  
Test Temperature ◽  
Vertical Direction ◽  
Material Behavior ◽  
High Temperature Strength ◽  
Powder Bed Fusion ◽  
Mechanical Spectroscopy ◽  
Powder Bed ◽  
Good Thermal Stability

Additive manufacturing of Al alloys can represent an interesting solution for high-performance components in various industrial fields, as for instance the automotive and aerospace industry. Often, for these applications, the alloys are required to withstand exposure to high temperatures. Therefore, the investigation of the evolution of material properties with increasing temperature is of utmost importance in order to assess their suitability for this kind of applications. In the present study, tensile properties at high temperature were investigated for an AlSi10Mg alloy. Samples were manufactured by laser-based powder bed fusion in horizontal and vertical direction in order to examine the influence of building direction on material behavior. The samples were tested in as-built condition and after exposure to high temperature. Tensile tests were performed up to 150 °C and the effect of holding time at the test temperature was evaluated. Furthermore, the alloy was characterized by mechanical spectroscopy in order to evaluate the behavior of dynamic modulus with temperature and, thus, to provide a comprehensive characterization of the material behavior. It was found that the peculiar microstructure of the alloy produced by additive manufacturing is responsible for good high-temperature strength of the material up to 150 °C. The material also exhibits a good thermal stability even after holding at test temperature for 10 h.

scholarly journals Improving the quality of up-facing inclined surfaces in laser powder bed fusion of metals using a dual laser setup

Procedia CIRP ◽  
2020 ◽  
Vol 94 ◽  
pp. 266-269 ◽  
Author(s):  
Jitka Metelkova ◽  
Daniel Ordnung ◽  
Yannis Kinds ◽  
Ann Witvrouw ◽  
Brecht Van Hooreweder
Keyword(s):  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Inclined Surfaces ◽  
Dual Laser ◽  
Laser Setup

Towards Thermal Simulation of Powder Bed Fusion on Path Level

2019 ◽  
Author(s):  
Yaqi Zhang ◽  
Vadim Shapiro ◽  
Paul Witherell
Keyword(s):  
Manufacturing Process ◽  
Thermal Simulation ◽  
Experimental Results ◽  
Intermediate Step ◽  
Valuable Insight ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Thermal Simulations ◽  
Element Method

Abstract Powder bed fusion (PBF) is a widely used additive manufacturing (AM) technology to produce metallic parts. Understanding the relationships between process parameter settings and the quality of finished parts remains a critical research question. Developing this understating involves an intermediate step: Process parameters, such as laser power and scan speed, influence the ongoing process characteristics, which then affect the final quality of the finished parts. Conventional approaches to addressing those challenges such as powder-based simulations (e.g., discrete element method (DEM)) and voxel-based simulations (e.g., finite element method (FEM)) can provide valuable insight into process physics. Those types of simulations, however, are not well-suited to handle realistic manufacturing plans due to their high computational complexity. Thermal simulations of the PBF process have the potential to implement that intermediate step. Developing accurate thermal simulations, however, is difficult due to the physical and geometric complexities of the manufacturing process. We propose a new, meso-scale, thermal-simulation, which is built on the path-level interactions described by a typical process plan. Since our model is rooted in manufactured geometry, it has the ability to produce scalable, thermal simulations for evaluating realistic process plans. The proof-of-concept simulation result is validated against experimental results in the literature and experimental results from National Institute of Standards and Technology (NIST). In our model, the laser-scan path is discretized into elements, and each element represents the newly melted material. An element-growth mechanism is introduced to simulate the evolution of the melt pool and its thermal characteristics during the manufacturing process. The proposed simulation reduces computational demands by attempting to capture the most important thermal effects developed during the manufacturing process. Those effects include laser-energy absorption, thermal interaction between adjacent elements and elements within the underneath substrate, thermal convection and radiation, and powder melting.

Design Rules and In-Situ Quality Monitoring of Thin-Wall Features Made Using Laser Powder Bed Fusion

2019 ◽  
Author(s):  
Aniruddha Gaikwad ◽  
Farhad Imani ◽  
Prahalad Rao ◽  
Hui Yang ◽  
Edward Reutzel
Keyword(s):  
Neural Network ◽  
Aspect Ratio ◽  
Convolutional Neural Network ◽  
Thin Wall ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Design Rules ◽  
Powder Bed

Abstract The goal of this work is to quantify the link between the design features (geometry), in-situ process sensor signatures, and build quality of parts made using laser powder bed fusion (LPBF) additive manufacturing (AM) process. This knowledge is critical for establishing design rules for AM parts, and to detecting impending build failures using in-process sensor data. As a step towards this goal, the objectives of this work are two-fold: 1) Quantify the effect of the geometry and orientation on the build quality of thin-wall features. To explain further, the geometry-related factor is the ratio of the length of a thin-wall (l) to its thickness (t) defined as the aspect ratio (length-to-thickness ratio, l/t), and the angular orientation (θ) of the part, which is defined as the angle of the part in the X-Y plane relative to the re-coater blade of the LPBF machine. 2) Assess the thin-wall build quality by analyzing images of the part obtained at each layer from an in-situ optical camera using a convolutional neural network. To realize these objectives, we designed a test part with a set of thin-wall features (fins) with varying aspect ratio from Titanium alloy (Ti-6Al-4V) material — the aspect ratio l/t of the thin-walls ranges from 36 to 183 (11 mm long (constant), and 0.06 mm to 0.3 mm in thickness). These thin-wall test parts were built under three angular orientations of 0°, 60°, and 90°. Further, the parts were examined offline using X-ray computed tomography (XCT). Through the offline XCT data, the build quality of the thin-wall features in terms of their geometric integrity is quantified as a function of the aspect ratio and orientation angle, which suggests a set of design guidelines for building thin-wall structures with LPBF. To monitor the quality of the thin-wall, in-process images of the top surface of the powder bed were acquired at each layer during the build process. The optical images are correlated with the post build quantitative measurements of the thin-wall through a deep learning convolutional neural network (CNN). The statistical correlation (Pearson coefficient, ρ) between the offline XCT measured thin-wall quality, and CNN predicted measurement ranges from 80% to 98%. Consequently, the impending poor quality of a thin-wall is captured from in-situ process data.

scholarly journals The Influence of Printing Orientation on Surface Texture Parameters in Powder Bed Fusion Technology with 316L Steel

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 639 ◽  
Author(s):  
Tomasz Kozior ◽  
Jerzy Bochnia
Keyword(s):  
Surface Texture ◽  
Microelectromechanical Systems ◽  
Powder Bed Fusion ◽  
Additive Technology ◽  
Powder Bed ◽  
Texture Parameters ◽  
316L Steel ◽  
Spatial Parameters ◽  
The Impact

Laser technologies for fast prototyping using metal powder-based materials allow for faster production of prototype constructions actually used in the tooling industry. This paper presents the results of measurements on the surface texture of flat samples and the surface texture of a prototype of a reduced-mass lathe chuck, made with the additive technology—powder bed fusion. The paper presents an analysis of the impact of samples’ orientation on the building platform on the surface geometrical texture parameters (two-dimensional roughness profile parameters (Ra, Rz, Rv, and so on) and spatial parameters (Sa, Sz, and so on). The research results showed that the printing orientation has a very large impact on the quality of the surface texture and that it is possible to set digital models on the building platform (parallel—0° to the building platform plane), allowing for manufacturing models with low roughness parameters. This investigation is especially important for the design and 3D printing of microelectromechanical systems (MEMS) models, where surface texture quality and printable resolution are still a large problem.

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