Evaluation of the Stability and Precision of Powder Delivery during Laser Additive Manufacturing

2013 ◽  
Vol 380-384 ◽  
pp. 4348-4352
Author(s):  
Kai Zhang ◽  
Lei Wang ◽  
Xiao Feng Shang
Keyword(s):  
Laser Beam ◽  
Molten Pool ◽  
Gas Flow ◽  
Feeding Rate ◽  
Shielding Gas ◽  
Metal Parts ◽  
Deposited Metal ◽  
Computer Aided ◽  
The Stability ◽  
Powder Feeding

The fabrication of metal parts is the backbone of the modern manufacturing industry. Laser forming is 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 work piece 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. In the LMDS process, the powder delivery system is an important component to perform the powder transport from powder storage box to powder nozzle, which supplies the raw material for the as-deposited metal parts. Consequently, the stability and precision of powder delivery during LMDS is essential to achieve the metal parts with high quality, so it is critical to evaluate the main factors closely related to the stability and precision of powder delivery. The shielding gas flow and the powder feeding rate were ascertained through experimental measure and formula calculation. The results prove that the suitable shielding gas flow and powder feeding rate can promote the stability and precision of powder delivery, which is the basis for the fabrication of as-deposited metal parts with flying colors.

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.

scholarly journals Numerical Simulation of the Behavior of Hydrogen Source in a Novel Welding Process to Reduce Diffusible Hydrogen

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1619 ◽  
Author(s):  
Shinichi Tashiro ◽  
Naoki Mukai ◽  
Yoshihide Inoue ◽  
Anthony B. Murphy ◽  
Tetsuo Suga ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Arc Welding ◽  
Gas Flow ◽  
Operating Conditions ◽  
Shielding Gas ◽  
Diffusible Hydrogen ◽  
Welding Torch ◽  
Deposited Metal ◽  
Suction Nozzle ◽  
Gas Nozzle

This study aims to reduce the diffusible hydrogen content in deposited metal during gas metal arc welding (GMAW) and flux-cored arc welding (FCAW) which induces cold cracking. To achieve this, a novel welding torch with a dual gas nozzle has been developed. This special welding torch decreases the hydrogen source gas evaporated from a welding wire by the suction from the inner gas nozzle. In order to improve the suction efficiency of this evaporated gas, precise control of the suction gas flow is indispensable. In this paper, a simplified numerical simulation model of this process has been described. This model can take account of the evaporation of the hydrogen source gas from the wire while simulating the behavior of the shielding gas and the arc. Using this model, the effect of suction nozzle structure and torch operating conditions on suction gas flow pattern and suction efficiency was also investigated to understand the process mechanism. Furthermore, the diffusible hydrogen content in deposited metal was measured by chromatography as a validation step. Results show that some of the shielding gas introduced from a shielding nozzle was drawn inward and also branched into an upward flow that was sucked into the suction nozzle and a downward flow to a base metal. This branching height was defined as the suction limit height, which decisively governed the suction efficiency. As a result, in order to reduce the diffusible hydrogen, it was suggested that the suction limit height should be controlled towards below the wire position, where the evaporation rate of the hydrogen source gas peaks through optimization of the suction nozzle design and the torch operating conditions.

Effects of Processing Parameters on Powder Utilization Ratio during Laser Metal Deposition Shaping

2012 ◽  
Vol 549 ◽  
pp. 790-794 ◽  
Author(s):  
Kai Zhang ◽  
Xin Min Zhang ◽  
Wei Jun Liu
Keyword(s):  
Laser Power ◽  
Gas Flow ◽  
Feeding Rate ◽  
Processing Parameters ◽  
Metal Deposition ◽  
Layer By Layer ◽  
Laser Metal Deposition ◽  
Forming Efficiency ◽  
Utilization Ratio ◽  
Powder Feeding

The Laser Metal Deposition Shaping (LMDS) process involves injecting metallic powder into a molten pool created by a high power industrial laser. As the laser traverses across the substrate in a layer-by-layer fashion, a fully dense metal is left in its path. A few processing parameters involved with the LMDS include the laser power, traverse speed, powder feeding rate, and gas flow rate, etc, which affect many factors of LMDS technology. Among them, the powder utilization ratio is an important one because it directly determines the build rate and build height per layer. Due to some objective reasons, the powder utilization ratio is far less than 100%. In order to ensure the stability of LMDS technology, it is necessary to investigate the match between powder utilization ratio and build rate and forming efficiency, and grasp the influence rules of processing parameters on powder utilization ratio. Accordingly, the related experiments were performed with the varied laser power, scanning speed and powder feeding rate. The results prove that the powder utilization ratio is a varied value, and affected by the processing parameters. Consequently, the relative ideal parameter match should be chosen in accordance with the specific circumstances during the LMDS technology, thus ensuring the better powder utilization ratio and promoting the forming efficiency and economic benefit.

Numerical Simulation and Analysis of Coaxial Powder Feeding Flow during Laser Direct Deposition

2011 ◽  
Vol 88-89 ◽  
pp. 38-41
Author(s):  
Wei Zhang ◽  
Shu Qin Shi
Keyword(s):  
Flow Field ◽  
Molten Pool ◽  
Gas Flow ◽  
Calculation Model ◽  
Powder Flow ◽  
Flow Process ◽  
Forming Efficiency ◽  
And Performance ◽  
Powder Flow Field ◽  
Powder Feeding

Coaxial powder feeding with carrier gas is the key part of laser direct metal deposition (DMD) rapid prototyping system. The convergence of powder flow would greatly affect forming efficiency, precision and performance. Numerical calculation model of flow field was built and simulated in this paper. The results of simulation and analysis had shown that powder flow field was very complex. The flow process could be divided into two parts, converging process and dispersing process. The main influencing factors of convergence included powder feeding rate, carrier gas flow rate, and the distance from nozzle to molten pool. There was a convergent focus where utilization ratio of powder was maximum. So the distance from nozzle to molten pool must be adjusted to equal to convergent focus (1.5cm) during DMD.

The influence of the Stokes and Archimedes forces on the stability of a two-phase flow

2003 ◽  
Vol 3 ◽  
pp. 266-270
Author(s):  
B.H. Khudjuyerov ◽  
I.A. Chuliev
Keyword(s):  
Spectral Method ◽  
Stability Region ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Stability Characteristic ◽  
Phase Flow ◽  
Two Phase ◽  
The Stability

The problem of the stability of a two-phase flow is considered. The solution of the stability equations is performed by the spectral method using polynomials of Chebyshev. A decrease in the stability region gas flow with the addition of particles of the solid phase. The analysis influence on the stability characteristic of Stokes and Archimedes forces.

Limitations of the Schlieren technique for shielding gas flow visualization in arc welding processes

2021 ◽  
Author(s):  
Mateus Barancelli Schwedersky ◽  
Álisson Fernandes da Rosa ◽  
Marcelo Pompermaier Okuyama ◽  
Régis Henrique Gonçalves e Silva
Keyword(s):  
Flow Visualization ◽  
Arc Welding ◽  
Gas Flow ◽  
Shielding Gas ◽  
Schlieren Technique ◽  
Welding Processes
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