Investigation of Sectoral Scanning in Selective Laser Melting

2010 ◽  
Author(s):  
Evren Yasa ◽  
Jan Deckers ◽  
Jean-Pierre Kruth ◽  
Marleen Rombouts ◽  
Jan Luyten
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Laser Beam ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Random Order ◽  
Laser Source ◽  
Metal Powders ◽  
Laser Melting ◽  
Powder Bed

Selective laser melting (SLM), a powder metallurgical (PM) additive manufacturing (AM) technology, is able to produce fully functional parts directly from standard metal powders without using any intermediate binders or any additional post-processing steps. During the process, a laser beam selectively scans a powder bed according to the CAD data of the part to be produced and completely melts the powder particles together. Stacking and bonding two-dimensional powder layers in this way, allows production of fully dense parts with any geometrical complexity. The scanning of the powder bed by the laser beam can be achieved in several different ways, one of which is island or sectoral scanning. In this way, the area to be scanned is divided in small square areas (‘sectors’) which are scanned in a random order. This study is carried out to explore the influence of sectoral scanning on density, surface quality, mechanical properties and residual stresses formed during SLM. The experiments are carried out on a machine with an Nd:YAG laser source using AISI 316L stainless steel powder. As a result of this experimental study, it is concluded that sectoral scanning has some advantages such as lower residual stresses and better surface quality. However, the selection of parameters related to sectoral scanning is a critical task since it may cause aligned porosity at the edges between sectors or scanned tracks, which is very undesired in terms of mechanical properties.

Modeling, Simulation and Experimental Validation of Heat Transfer During Selective Laser Melting

2015 ◽  
Author(s):  
Mohammad Masoomi ◽  
Xiang Gao ◽  
Scott M. Thompson ◽  
Nima Shamsaei ◽  
Linkan Bian ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mechanical Properties ◽  
Selective Laser Melting ◽  
Heat Fluxes ◽  
Transient Temperature ◽  
Thermal Gradients ◽  
Layer By Layer ◽  
Metal Powders ◽  
Laser Melting ◽  
Powder Bed

Selective Laser Melting (SLM), a laser powder-bed fusion (PBF-L) additive manufacturing method, utilizes a laser to selectively fuse adjacent metal powders. The powders are aligned in a bed that moves vertically to allow for layer-by-layer part construction-Process-related heat transfer and thermal gradients have a strong influence on the microstructural features, and subsequent mechanical properties, of the parts fabricated via SLM. In order to understand and control the heat transfer inherent to SLM, and to ensure high quality parts with targeted microstructures and mechanical properties, comprehensive knowledge of the related energy and mass transport during manufacturing is required. In this study, the transient temperature distribution within and around parts being fabricated via SLM is numerically simulated and the results are provided to aid in quantify the SLM heat transfer. In order to verify simulation output, and to estimate actual thermal gradients and heat transfer, experiments were separately conducted within a SLM machine using a substrate with embedded thermocouples. The experiments focused on characterizing heat fluxes during initial deposition on an initially-cold substrate and during the fabrication of a thin-walled structure built via stainless steel 17-4 powders. Results indicate that it is important to model heat transfer thorough powder bed as well as substrate.

scholarly journals Performance Consistency of AlSi10Mg Alloy Manufactured by Simulating Multi Laser Beam Selective Laser Melting (SLM): Microstructures and Mechanical Properties

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2354 ◽  
Author(s):  
Bin Liu ◽  
Zezhou Kuai ◽  
Zhonghua Li ◽  
Jianbin Tong ◽  
Peikang Bai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Powder Bed ◽  
Research Material ◽  
Significant Difference ◽  
Microstructures And Mechanical Properties ◽  
Overlap Area

Multi-laser beam selective laser melting (SLM) technology based on a powder bed has been used to manufacture AlSi10Mg samples. The AlSi10Mg alloy was used as research material to systematically study the performance consistency of both the laser overlap areas and the isolated areas of the multi-laser beam SLM manufactured parts. The microstructures and mechanical properties of all isolated and overlap processing areas were compared under optimized process parameters. It was discovered that there is a raised platform at the junction of the overlap areas and the isolated areas of the multi-laser SLM samples. The roughness is significantly reduced after two scans. However, the surface roughness of the samples is highest after four scans. As the number of laser scans increases, the relative density of the overlap areas of the samples improves, and there is no significant change in hardness. The tensile properties of the tensile samples are poor when the overlap area width is 0, 0.1, or 0.2 mm. When the widths of the overlap areas are equal to or greater than 0.3 mm, there is no significant difference in the tensile strength between the overlap and the isolated areas.

Review on Powder-Bed Laser Additive Manufacturing of Inconel 718 Parts

2015 ◽  
Author(s):  
Xiaoqing Wang ◽  
Xibing Gong ◽  
Kevin Chou
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Literature Review ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Manufacturing Processes ◽  
Laser Melting ◽  
Laser Additive Manufacturing ◽  
Powder Bed ◽  
General Aspects

This study presents a thorough literature review on the powder-bed laser additive manufacturing processes such as selective laser melting (SLM) of Inconel 718 parts. The paper first introduces the general aspects of powder-bed laser additive manufacturing and then discusses the unique characteristics and advantages of SLM. Moreover, the bulk of this study includes extensive discussions of microstructures and mechanical properties, together with the application ranges, of Inconel 718 parts fabricated by SLM.

Quasicrystalline Composites by Additive Manufacturing

2019 ◽  
Vol 818 ◽  
pp. 72-76 ◽  
Author(s):  
Konda Gokuldoss Prashanth ◽  
Sergio Scudino
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Complex Shape ◽  
Powder Bed Fusion ◽  
Laser Melting ◽  
Powder Bed ◽  
Novel Materials ◽  
Tunable Properties

Laser based powder bed fusion (LBPF) or selective laser melting (SLM) is making a leap march towards fabricating novel materials with improved functionalities. An attempt has been made here to fabricate hard quasicrystalline composites via SLM, which demonstrates that the process parameters can be used to vary the phases in the composites. The mechanical properties of the composite depend on their constituents and hence can be varied by varying the process parameters. The results show that SLM not only produces parts with improved functionalities and complex shape but also leads to defined phases and tunable properties.

Selective laser melting (SLM) of pure gold for manufacturing dental crowns

2014 ◽  
Vol 20 (6) ◽  
pp. 471-479 ◽  
Author(s):  
Mushtaq Khan ◽  
Phill Dickens
Keyword(s):  
Mechanical Properties ◽  
Layer Thickness ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Processing Parameters ◽  
Pure Gold ◽  
Laser Melting ◽  
Content Type ◽  
Dental Crowns ◽  
Suitable Processing

Purpose – This paper aims to present the application aspect of the work to manufacturing premolar and molar dental crowns by selective laser melting (SLM) of pure gold. Over the years different metals have been processed using laser-based Additive Manufacturing processes, but very little work has been published on the SLM of gold (Au). Previously published work presented suitable processing parameters for SLM of pure gold. Design/methodology/approach – Suitable processing parameters were used to manufacture premolar and molar dental crowns using SLM system. Different layer thickness was used to analyse the effect on surface quality of crowns. Mechanical properties are checked using nanoindentation and micro Computerized Tomography scanning. Findings – Dental crowns were successfully manufacturing using new build platform and suitable processing parameters. Parts were manufacturing using minimal supports which prevented parts from damaging during removal. A bed temperature of 100°C was found suitable for reducing warpage in the layers. Layer thickness of 50μm was found to have better surface quality and structural integrity as compared to 75μm. Porosity was found to be predominantly inter-layer. Small difference in mechanical properties of dental crowns is associated with the laser processing. Originality/value – This research is the first of its kind which presents dental crown manufacturing using SLM of pure gold.

Stress and Deformation Evaluations of Scanning Strategy Effect in Selective Laser Melting

2016 ◽  
Author(s):  
Bo Cheng ◽  
Subin Shrestha ◽  
Y. Kevin Chou
Keyword(s):  
Residual Stresses ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
High Energy ◽  
Powder Layer ◽  
Stress Difference ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Scanning Pattern ◽  
Stress And Deformation

Selective laser melting (SLM) is one of the Additive manufacturing (AM) processes that can build physical part in an added material method from digital data. In such a process, computer designed part model will be decomposed into hundreds of thousands of layers. The layered information is then transferred to SLM equipment and the part is built in a layer by layer fashion. Each powder layer will be scanned and melted in the required region by a high energy laser beam in a given scanning pattern so as to form a desired geometry. Finally, fully functional parts can be produced by repeatedly powder deposition, melting and solidification process. This process offers numerous advantages such as tooling-free productions and design freedom in geometry. In addition, SLM process is quite suitable for complicated parts such as customer designed medical implants and internal channels which are difficult to manufacture by conventional methods such as casting and machining. However, the localized heating and cooling process can lead to defects such as high residual stress, part distortion or delamination failure in SLM fabricated parts. These potential defects may impede the wide application of this technology. It is known that the laser beam scanning path will affect the thermomechanical behaviors of the build part, and thus, altering the scanning pattern may be a feasible strategy to reduce residual stresses and deformations by influencing the heat intensity input distribution. In this study, a 3D sequentially coupled finite element method (FEM) model, incorporating a volumetric moving Gaussian heat source, powder as well as solid material temperature dependent properties and layer addition features, was developed to study the complex thermomechanical process of SLM. The model was applied to evaluate six different scanning strategies effect on part temperature, stress and deformation. The major results have been summarized as follows. (1) Among all cases tested, the out-in scanning pattern has the maximum stresses along the X and Y directions; while the 45 degree inclined scanning may reduce residual stresses in both directions. (2) Large directional stress difference can be caused by back and forth line scanning strategy while minor directional stress difference is observed for other tested cases. (3) X and Y directional stress concentration is shown around the edge of deposited layers and the interface between deposited layers and substrate for all cases. (4) The 45 degree inclined scanning case has the smallest build direction deformation while the in-out scanning case has the largest deformation among the tested cases.

scholarly journals Effect of build orientation on the surface quality, microstructure and mechanical properties of selective laser melting 316L stainless steel

2018 ◽  
Vol 24 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Hamza Hassn Alsalla ◽  
Christopher Smith ◽  
Liang Hao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Mechanical Performance ◽  
Laser Melting ◽  
Content Type ◽  
Microstructure And Mechanical Properties ◽  
Conventional Material

Purpose The purpose of this paper is to investigate the density, surface quality, microstructure and mechanical properties of the components of the selective laser melting (SLM) parts made at different building orientations. SLM is an additive manufacturing technique for three-dimensional parts. The process parameters are known to affect the properties of the eventual part. In this study, process parameters were investigated in the building of 316L structures at a variety of building orientations and for which the fracture toughness was measured. Design/methodology/approach Hardness and tensile tests were carried out to evaluate the effect of consolidation on the mechanical performance of specimens. Optical and electron microscopy were used to characterise the microstructure of the SLM specimens and their effects on properties relating to fracture and the mechanics. It was found that the density of built samples is 96 per cent, and the hardness is similar in comparison to conventional material. Findings The highest fracture toughness value was found to be 176 MPa m^(1/2) in the oz. building direction, and the lowest value was 145 MPa m^(1/2) in the z building direction. This was due to pores and some cracks at the edge, which are slightly lower in comparison to a conventional product. The build direction does have an effect on the microstructure of parts, which subsequently has an effect upon their mechanical properties and surface quality. Dendritic grain structures were found in oz. samples due to the high temperature gradient, fast cooling rate and reduced porosity. The tensile properties of such parts were found to be better than those made from conventional material. Originality/value The relationship between the process parameters, microstructure, surface quality and toughness has not previously been reported.

Review on powder-bed laser additive manufacturing of Inconel 718 parts

2016 ◽  
Vol 231 (11) ◽  
pp. 1890-1903 ◽  
Author(s):  
Xiaoqing Wang ◽  
Xibing Gong ◽  
Kevin Chou
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Literature Review ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Manufacturing Processes ◽  
Laser Melting ◽  
Laser Additive Manufacturing ◽  
Powder Bed ◽  
General Aspects

This study presents a thorough literature review on the powder-bed laser additive manufacturing processes such as selective laser melting of Inconel 718 parts. This article first introduces the general aspects of powder-bed laser additive manufacturing and then discusses the unique characteristics and advantages of selective laser melting. The bulk of this study includes extensive discussions of microstructures and mechanical properties, together with the application ranges of Inconel 718 parts fabricated by selective laser melting.

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