Active Monitoring of the Selective Laser Melting Process Using an Artificial Neural Net Classifier on Layer-by-Layer Surface Profile Data

2019 ◽  
Author(s):  
B. Baucher ◽  
S. Chakraborty ◽  
A. Chaudhury ◽  
B. Terry
Keyword(s):  
Selective Laser Melting ◽  
Surface Profile ◽  
Melting Process ◽  
Layer By Layer ◽  
Neural Net ◽  
Layer Surface ◽  
Profile Data ◽  
Laser Melting ◽  
Active Monitoring ◽  
Artificial Neural Net

scholarly journals Active Monitoring of Selective Laser Melting Process by Training an Artificial Neural Net Classifier on Layer-By-Layer Surface Laser Profilometry Data

2021 ◽  
Author(s):  
Benjamin S. Terry ◽  
Brandon Baucher ◽  
Anil Chaudhary ◽  
Subhadeep Chakraborty
Keyword(s):  
Selective Laser Melting ◽  
Layer By Layer ◽  
Neural Net ◽  
Layer Surface ◽  
Laser Melting ◽  
Active Monitoring ◽  
Powder Bed ◽  
Artificial Neural Net ◽  
Artificial Neural ◽  
Height Data

Abstract This paper reports some recent results related to active monitoring of Selective Laser Melting (SLM) processes through analysis of layer-by-layer surface profile data. Estimation of fault probability was carried out experimentally in a Renishaw AM250 machine, by collecting Fe3Si powder bed height data, in-situ, during the metal additive manufacturing of a Heat Exchanger section, comprised of a series of conformal channels. Specifically, high-resolution powder bed surface height data from a laser profilometer was linked to post-print ground-truth labels (faulty or nominal) for each site from CT scans, by training a shallow artificial neural net (ANN). The ANN demonstrated interesting capabilities for discovering correlations between surface roughness characteristics and the presence and size of faults. Strong performance was achieved with respect to several standard metrics for classifying faulty and nominal sites. These developments can potentially enable active monitoring processes to become a future component of a layer-by-layer feedback system for better control of SLM processes.

Inverse Thermal Analysis of Melting Pool in Selective Laser Melting Process

2015 ◽  
Vol 651-653 ◽  
pp. 1519-1524 ◽  
Author(s):  
Laurent van Belle ◽  
Alban Agazzi
Keyword(s):  
Heat Source ◽  
Residual Stresses ◽  
Selective Laser Melting ◽  
Selective Laser Sintering ◽  
Solid Material ◽  
Melting Process ◽  
Layer By Layer ◽  
Laser Melting ◽  
Mechanical Modelling ◽  
Melting Pool

The Selective Laser Melting (SLM) process of metallic powder is an additive technology. It allows the production of complex-shaped parts which are difficult to obtain by conventional methods. The principle is similar to Selective Laser Sintering (SLS) process: it consists, from an initial CAD model, to create the desired part layer by layer. The laser scans a powder bed of 40 μm thick. The irradiated powder is instantly melted and becomes a solid material when the laser moves away. A new layer of powder is left and the laser starts a new cycle of scanning. The sudden and intense phase changing involves high thermal gradients which induce contraction and expansion cycles in the part. These cycles results in irreversible plastic strains. The presence of residual stresses in the manufactured part can damage the mechanical properties, such as the fatigue life. This study focuses on the thermal and mechanical modelling of the SLM process. One of the key points of the mechanical modelling is the determination of the heat source generated by the laser in order to predict residual stresses. This work is divided in three parts. In a first part, an experimental protocol is established in order to measure the temperature variation during the process. In the second part, a thermal model of the process is proposed. Finally, an inverse method to determine the power and the shape of the heat source is developed. Experimental and computational results are fitted. The influence of several geometries of the heat source is investigated.

Three-Dimensional Temperature Gradient Mechanism in Selective Laser Melting of Ti-6Al-4V

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
C. H. Fu ◽  
Y. B. Guo
Keyword(s):  
Temperature Gradient ◽  
Selective Laser Melting ◽  
Molten Pool ◽  
Three Dimensional ◽  
Melting Process ◽  
Layer By Layer ◽  
Laser Melting ◽  
Transient Nature ◽  
Melting Pool ◽  
Three Dimensional Finite Element

Selective laser melting (SLM) is widely used in making three-dimensional functional parts layer by layer. Temperature magnitude and history during SLM directly determine the molten pool dimensions and surface integrity. However, due to the transient nature and small size of the molten pool, the temperature gradient and the molten pool size are challenging to measure and control. A three-dimensional finite element (FE) simulation model has been developed to simulate multilayer deposition of Ti-6Al-4 V in SLM. A physics-based layer buildup approach coupled with a surface moving heat flux was incorporated into the modeling process. The melting pool shape and dimensions were predicted and experimentally validated. Temperature gradient and thermal history in the multilayer buildup process was also obtained. Furthermore, the influences of process parameters and materials on the melting process were evaluated.

scholarly journals Modelling of Selective Laser Melting Process of Quartz Glass at Elevated Temperatures

2021 ◽  
Vol 248 ◽  
pp. 01001
Author(s):  
M.A. Gridnev ◽  
R.S. Khmyrov ◽  
A.V. Gusarov
Keyword(s):  
Selective Laser Melting ◽  
Quartz Glass ◽  
Elevated Temperatures ◽  
Melting Process ◽  
Coupled Processes ◽  
Powder Layer ◽  
Layer By Layer ◽  
Laser Melting ◽  
Material Quality ◽  
Powder Consolidation

Selective laser melting (SLM) to date is the method of additive manufacturing allowing fabricating products from powder layer-by-layer according to a 3D model. However, when applying this method to fragile materials, parts crack while fabricating due to high temperatures. Quartz glass is a promising material for fabricating products by SLM without cracks due to a low thermal expansion. However, quality of fabricated material differs from the fused cast ones. This article aims to test the method of SLM with preheating to improve the material quality. Experiments on single track formation in SLM are analysed by modelling the coupled processes of heat transfer and powder consolidation in the laser-interaction zone. The mathematical model is validated by the experiments. It is shown that the preheating can improve the material quality and increase the process productivity but overheating may result in undesirable crystallization.

scholarly journals Improving surface quality in selective laser melting based tool making

2021 ◽  
Author(s):  
Filippo Simoni ◽  
Andrea Huxol ◽  
Franz-Josef Villmer
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Melting Process ◽  
Laser Remelting ◽  
Laser Melting ◽  
Great Cost ◽  
Starting Point ◽  
Processing Techniques

AbstractIn the last years, Additive Manufacturing, thanks to its capability of continuous improvements in performance and cost-efficiency, was able to partly replace and redefine well-established manufacturing processes. This research is based on the idea to achieve great cost and operational benefits especially in the field of tool making for injection molding by combining traditional and additive manufacturing in one process chain. Special attention is given to the surface quality in terms of surface roughness and its optimization directly in the Selective Laser Melting process. This article presents the possibility for a remelting process of the SLM parts as a way to optimize the surfaces of the produced parts. The influence of laser remelting on the surface roughness of the parts is analyzed while varying machine parameters like laser power and scan settings. Laser remelting with optimized parameter settings considerably improves the surface quality of SLM parts and is a great starting point for further post-processing techniques, which require a low initial value of surface roughness.

scholarly journals Fabrication of Mesh Patterns Using a Selective Laser-Melting Process

2019 ◽  
Vol 9 (9) ◽  
pp. 1922 ◽  
Author(s):  
Tae Woo Hwang ◽  
Young Yun Woo ◽  
Sang Wook Han ◽  
Young Hoon Moon
Keyword(s):  
Selective Laser Melting ◽  
Laser Scanning ◽  
Dimensional Accuracy ◽  
Base Plate ◽  
Steel Powder ◽  
Melting Process ◽  
304 Stainless Steel ◽  
Process Conditions ◽  
Laser Melting ◽  
Metal Mesh

The selective laser-melting (SLM) process can be applied to the additive building of complex metal parts using melting metal powder with laser scanning. A metal mesh is a common type of metal screen consisting of parallel rows and intersecting columns. It is widely used in the agricultural, industrial, transportation, and machine protection sectors. This study investigated the fabrication of parts containing a mesh pattern from the SLM of AISI 304 stainless steel powder. The formation of a mesh pattern has a strong potential to increase the functionality and cost-effectiveness of the SLM process. To fabricate a single-layered thin mesh pattern, laser layering has been conducted on a copper base plate. The high thermal conductivity of copper allows heat to pass through it quickly, and prevents the adhesion of a thin laser-melted layer. The effects of the process conditions such as the laser scan speed and scanning path on the size and dimensional accuracy of the fabricated mesh patterns were characterized. As the analysis results indicate, a part with a mesh pattern was successfully obtained, and the application of the proposed method was shown to be feasible with a high degree of reliability.

scholarly journals Selective Laser Melting Process of Al–Based Pyramidal Horns for the W-Band: Fabrication and Testing

2021 ◽  
Author(s):  
L. Lamagna ◽  
A. Paiella ◽  
S. Masi ◽  
L. Bottini ◽  
A. Boschetto ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
High Surface ◽  
Melting Process ◽  
Horn Antenna ◽  
Post Processing ◽  
Laser Melting ◽  
Performance Impact ◽  
Horn Antennas ◽  
Sand Blasting ◽  
W Band

AbstractIn the context of exploring the possibility of using Al-powder Selective Laser Melting to fabricate horn antennas for astronomical applications at millimeter wavelengths, we describe the design, the fabrication, the mechanical characterization, and the electromagnetic performance of additive manufactured horn antennas for the W-band. Our aim, in particular, is to evaluate the performance impact of two basic kinds of surface post-processing (manual grinding and sand-blasting) to deal with the well-known issue of high surface roughness in 3D printed devices. We performed comparative tests of co-polar and cross-polar angular response across the whole W-band, assuming a commercially available rectangular horn antenna as a reference. Based on gain and directivity measurements of the manufactured samples, we find decibel-level detectable deviations from the behavior of the reference horn antenna, and marginal evidence of performance degradation at the top edge of the W-band. We conclude that both kinds of post-processing allow achieving good performance for the W-band, but the higher reliability and uniformity of the sand-blasting post-process encourage exploring similar techniques for further development of aluminum devices at these frequencies.

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