Molten Pool Tracking Using a Superpixel-Based Approach in a Laser Metal Deposition Process

2021 ◽  
Vol 143 (10) ◽  
Author(s):  
Angel-Iván García-Moreno ◽  
Juan-Manuel Alvarado-Orozco ◽  
Juansethi Ibarra-Medina ◽  
Enrique Martínez-Franco
Keyword(s):  
Molten Pool ◽  
Infrared Camera ◽  
Ground Truth ◽  
Deposition Process ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Detector Resolution ◽  
Direct Laser ◽  
Color Similarity ◽  
Manufacturing Technologies

Abstract Nowadays, additive manufacturing technologies (AM) suffer from insufficient or lacking methodologies/techniques for quality control. This fact represents a key technological barrier preventing broader industrial adoption of AM, particularly in high-value applications where component failure cannot be accepted. This article presents a real-time melt pool segmentation and monitoring technique applicable to the direct laser metal deposition (LMD) process. An infrared camera with an InSb detector (resolution of 640 × 480, spectral range between 3 and 5 μm) was used. An algorithm, called gravitational superpixels, is presented. This algorithm can group pixels and generate superpixels based on a block generation technique that compares color similarity and temperature in infrared images. Besides, a color similarity correction is applied to reduce uncertainty in segmentation, as well as for eliminating the image background. The task of extracting edges is based on the law of universal gravitation. A quantitative and qualitative algorithm performance analysis, which uses standard metrics, is presented. The analysis demonstrates better versatility than reduction/feature extraction or image segmentation approaches by high-/low-pass filtering. The experimental validation was carried out, extracting and measuring the molten pool geometry and its thermal signature. Then, measures were compared against ground truth and against results obtained by other similar methods. The proposed gravitational superpixel method has higher precision and performance. Our proposal has a significant potential for monitoring industrial AM processes since it requires minimal modifications of commercially available industrial machines.

2D longitudinal modeling of heat transfer and fluid flow during multilayered direct laser metal deposition process

2012 ◽  
Vol 24 (3) ◽  
pp. 032008 ◽  
Author(s):  
Simon Morville ◽  
Muriel Carin ◽  
Patrice Peyre ◽  
Myriam Gharbi ◽  
Denis Carron ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Deposition Process ◽  
Metal Deposition ◽  
Longitudinal Modeling ◽  
Laser Metal Deposition ◽  
Direct Laser ◽  
Direct Laser Metal Deposition

scholarly journals Ultrasonic Characterization of Components Manufactured by Direct Laser Metal Deposition

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2658
Author(s):  
Anna Castellano ◽  
Marco Mazzarisi ◽  
Sabina Luisa Campanelli ◽  
Andrea Angelastro ◽  
Aguinaldo Fraddosio ◽  
...  
Keyword(s):  
Microstructural Analysis ◽  
Deposition Process ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Nickel Based Superalloy ◽  
Ultrasonic Characterization ◽  
Direct Laser ◽  
New Material ◽  
Direct Laser Metal Deposition

Direct laser metal deposition (DLMD) is an innovative additive technology becoming of key importance in the field of repairing applications for industrial and aeronautical components. The performance of the repaired components is highly related to the intrinsic presence of defects, such as cracks, porosity, excess of dilution or debonding between clad and substrate. Usually, the quality of depositions is evaluated through destructive tests and microstructural analysis. Clearly, such methodologies are inapplicable in-process or on repaired components. The proposed work aims to evaluate the capability of ultrasonic techniques to perform the mechanical characterization of additive manufactured (AM) components. The tested specimens were manufactured by DLMD using a nickel-based superalloy deposited on an AISI 304 substrate. Ultrasonic goniometric immersion tests were performed in order to mechanical characterize the substrate and the new material obtained by AM process, consisting of the substrate and the deposition. Furthermore, the relationship was evaluated between the acoustic and the mechanical properties of the AM components and the deposition process parameters and the geometrical characteristics of multiclad depositions, respectively. Finally, the effectiveness of the proposed non-destructive experimental approach for the characterization of the created deposition anomalies has been investigated.

A Methodology for Optimization of the Direct Laser Metal Deposition Process

2011 ◽  
Vol 473 ◽  
pp. 75-82 ◽  
Author(s):  
Andrea Angelastro ◽  
Sabina L. Campanelli ◽  
Giuseppe Casalino ◽  
Antonio D. Ludovico ◽  
Simone Ferrara
Keyword(s):  
Optimization Procedure ◽  
Deposition Process ◽  
Metal Deposition ◽  
Hard Coatings ◽  
Full Density ◽  
Laser Metal Deposition ◽  
Scanning Velocity ◽  
3D Cad ◽  
Direct Laser ◽  
Direct Laser Metal Deposition

Direct Laser Metal Deposition (DLMD) is actually one of the most attractive techniques in the group of Material Accretion Manufacturing (MAM) processes. In fact, the DLMD technology is able to realize, to repair and restore, objects, moulds and tools, directly from the 3D CAD model in a rapid and economic way. A great variety of metals, including those very difficult to work with the conventional techniques, can be shaped in a large number of complex geometries. This technique is also well suited to produce very hard coatings. The metallic parts, which are obtained through melting coaxially fed powders with a laser, present very good mechanical properties, with minimum porosity and good adhesion to the substrate. The objective of this work was to optimise the scanning velocity of the laser beam in order to maximize the density of DLMD parts. The optimization procedure was worked out with a mathematical model together with an experimental analysis to study the shape of the track clad generated melting coaxially fed powders with a laser. The material tested was Colmonoy 227-F, a nickel alloy specially designed for manufacturing moulds. The presented methodology has permitted to select the better combination of parameters that produce almost full density parts, free of cracks and well bonded to the substrate sintered parts.

scholarly journals Influence of Process Parameters and Deposition Strategy on Laser Metal Deposition of 316L Powder

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1160 ◽  
Author(s):  
Federico Mazzucato ◽  
Alberta Aversa ◽  
Roberto Doglione ◽  
Sara Biamino ◽  
Anna Valente ◽  
...  
Keyword(s):  
Deposition Process ◽  
Metal Deposition ◽  
Process Window ◽  
Laser Metal Deposition ◽  
Scanning Strategy ◽  
Influence Of Process Parameters ◽  
Melt Pool ◽  
Manufacturing Technologies ◽  
Blown Powder ◽  
Building Parameters

In blown powder additive manufacturing technologies the geometrical stability of the built parts is more complex with respect to more conventional powder bed processes. Because of this reason, in order to select the most suitable building parameters, it is important to investigate the shape and the properties of the single metal bead formation and the effect that a scan track has on the nearby ones. In the present study, a methodology to identify an appropriate laser metal deposition process window was introduced, and the effect of the building parameters on the geometry of circular steel samples was investigated. The effect of the scanning strategy on the deposited part was also investigated. This work draws the attention to the importance of the obtainment of the most suitable melt pool shape, demonstrating that the laser power and the scanning strategy have a strong influence not only on the shape but also on the mechanical properties of the final component.

Numerical Simulation of Temperature Field of Direct Laser Metal Deposition Shaping Process of Titanium Alloys

2011 ◽  
Vol 295-297 ◽  
pp. 2112-2119
Author(s):  
Yuan Kong ◽  
Wei Jun Liu ◽  
Yue Chao Wang
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Thermal Stress ◽  
Stress Field ◽  
Molten Pool ◽  
Three Dimensional ◽  
Metal Deposition ◽  
Laser Metal Deposition ◽  
Forming Process ◽  
Direct Laser

In order to control the thermal stress of forming process, based on “element birth and death” technology of finite element method, a numerical simulation of three-dimensional temperature field and stress field during multi-track & multi-layer laser metal deposition shaping(LMDS) process is developed with ANSYS parametric design language (APDL). The dynamic variances of temperature field and stress field of forming process are calculated with the energy compensation of interaction between molten pool-powder and laser-powder. The temperature field, temperature gradient, thermal stress field and distribution of residual stress are obtained. The results indicate that although the nodes on different layers are activated at different time, their temperature variations are similar. The temperature gradients of samples are larger near the molten pool area and mainly along z-direction. Finally, it’s verified that the analysis results are consistent with actual situation by the experiments with same process parameters.

scholarly journals Simulation of thermal behaviours and powder flow for direct laser metal deposition process

2018 ◽  
Vol 190 ◽  
pp. 02001
Author(s):  
Quanren Zeng ◽  
Yankang Tian ◽  
Zhenhai Xu ◽  
Yi Qin
Keyword(s):  
Cfd Simulation ◽  
Effective Means ◽  
Flow Distribution ◽  
Fem Analysis ◽  
Deposition Process ◽  
Metal Deposition ◽  
Powder Flow ◽  
Laser Metal Deposition ◽  
Melt Pool ◽  
Direct Laser

Laser engineering net-shaping (LENS), based on directed energy deposition (DED), is one of the popular AM technologies for producing fully dense complex metal structural components directly from laser metal deposition without using dies or tooling and hence greatly reduces the lead-time and production cost. However, many factors, such as powder-related and laser-related manufacturing parameters, will affect the final quality of components produced by LENS process, especially the powder flow distribution and thermal history at the substrate. The powder concentration normally determines the density and strength of deposited components; while the thermal behaviours of melt pool mainly determines the cooling rate, residual stress and consequent cracks in deposited components. Trial and errors method is obviously too expensive to afford for diverse applications of different metal materials and various manufacturing input parameters. Numerical simulation of the LENS process will be an effective means to identify reasonable manufacturing parameter sets for producing high quality crack-free components. In this paper, the laser metal powder deposition process of LENS is reported. The gas-powder flow distribution below the deposition nozzle is obtained via CFD simulation. The thermal behaviours of substrate and as-deposited layer/track during the LENS process are investigated by using FEM analysis. Temperature field distributions caused by the moving laser beam and the resultant melt pool on the substrate, are simulated and compared. The research offers a more accurate and practical thermal behaviour model for LENS process, which could be applied to further investigation of the interactions between laser, melt pool and powder particles; it will be particularly useful for manufacturing key components which has more demanding requirement on the components’ functional performance.

Laser Metal Deposition Shaping System for Direct Fabrication of Parts

2011 ◽  
Vol 66-68 ◽  
pp. 2202-2207 ◽  
Author(s):  
Kai Zhang ◽  
Xiao Feng Shang ◽  
Wei Jun Liu
Keyword(s):  
Control System ◽  
Laser Beam ◽  
Molten Pool ◽  
Metal Deposition ◽  
Laser Forming ◽  
Laser Metal Deposition ◽  
Small Stream ◽  
Metal Parts ◽  
Direct Laser ◽  
Computer Aided

The fabrication of metal parts is the backbone of the modern manufacturing industry. Laser forming is the combination of five common technologies: lasers, rapid prototyping (RP), computer-aided design (CAD), computer-aided manufacturing (CAM), and powder metallurgy. The resulting process creates part by focusing an industrial laser beam on the surface of processing workpiece to create a molten pool of metal. A small stream of powdered alloy is then injected into the molten pool to build up the part gradually. By moving the laser beam back and forth and tracing out a pattern determined by a CAD, the solid metal part is fabricated line by line, one layer at a time. By this method, a material having a very fine microstructure due to rapid solidification process can be produced. In the present work, a type of direct laser deposition process, called Laser Metal Deposition Shaping (LMDS), has been employed and developed to fabricate metal parts. The LMDS apparatus consists of four primary components: energy supply system, motion control system, powder delivery system, and computer control system. These components have their specified functions, but work in association with each other.

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