Determination of Equilibrium Wire Feed Speeds for a Stable GMAW Process

2008 ◽  
Author(s):  
Z. H. Rao ◽  
J. Hu ◽  
S. M. Liao ◽  
H. L. Tsai
Keyword(s):  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Published Data ◽  
Trial And Error ◽  
Electrode Diameter ◽  
Current Electrode ◽  
Electrode Wire ◽  
Metal Arc Welding ◽  
Wire Feed

In gas metal arc welding (GMAW), for given welding conditions (e.g., current, electrode diameter, electrode material, etc.), the consumable electrode wire must be fed in such a speed that it dynamically balances the electrode melting speed in order to achieve a stable welding. In this article, a comprehensive model for GMAW was developed to study the interplay between the transport phenomena including the electrode melting and plasma arc, and the dynamically equilibrium wire feed speeds (WFSs) under different welding conditions. The predicted WFSs are in excellent agreement with published data that were obtained through the trial-and-error procedure.

Instability phenomena in the gas—metal arc welding self-regulation process

2002 ◽  
Vol 216 (6) ◽  
pp. 899-910 ◽  
Author(s):  
Z Bingül
Keyword(s):  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Self Regulation ◽  
Thermal Inertia ◽  
Theoretical Explanation ◽  
Normal Extension ◽  
Current Electrode ◽  
Arc Voltage ◽  
Regulation Process ◽  
Metal Arc Welding

Arc instability is a very important determinant of weld quality. The instability behaviour of the gas-metal arc welding (GMAW) process is characterized by strong oscillations in arc length and current. This phenomenon was reported by Halmoy [1] for the short electrode extension and by Lebedev [2] for the long electrode extension, particularly as related to the arc voltage-current characteristics and the thermal inertia of the electrode wire respectively. However, with these studies, a complete theoretical explanation of the instability phenomena is lacking since the process is not modelled dynamically. In the present work, a model of the GMAW process is developed using an exact arc voltage characteristic. This model is used to study stability of the self-regulation process and to develop a simulation program that helps to understand the transient or dynamic nature of the GMAW process and relationships among current, electrode extension and contact tube-work distance (CTWD). The process is shown to exhibit instabilities at both long electrode extension and normal extension. The experimental results agree closely with both Lebedev's and Halmoy's results. Results obtained from simulation runs of the model were also experimentally confirmed by the present author, as reported in this study. In order to explain the concept of the instability phenomena, the metal transfer mode and the arc voltage-current characteristic were examined. Based on this examination, the conclusion of this study is that their combined effects lead to the oscillations in arc current and length.

Analysis and Improvement of Metal Transfer Behaviors in Consumable Double-Electrode GMAW Process

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Ming Zhu ◽  
Yu Shi ◽  
Ding Fan
Keyword(s):  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Metal Transfer ◽  
Force Balance ◽  
Current Electrode ◽  
Main Metal ◽  
Metal Arc Welding ◽  
Weld Appearance ◽  
Double Electrode ◽  
Welding Consumable

Consumable double-electrode gas metal arc welding (consumable DE-GMAW) is the efficient improvement of DE-GMAW. Due to the variety of coupled arc and metal transfer behaviors, this paper applies static force balance theory to analyze the changes in the forces acting on the main and bypass droplets separately. For main torch, the bypass arc changes the forces affecting on the main droplet, and the main metal transfer becomes more desirable. For bypass torch, with direct current electrode negative (DCEN) polarity, the volume of droplet is big and not easily transfers to the weld pool. In order to improve the bypass metal transfer, a method has been proposed which adds CO2 to pure argon shielding gas to change the forces affecting on the bypass droplet. Then, the welding experiment is carried out to test the effectiveness of this method. It is found that bypass droplet transfers easily and the diameter of bypass droplet is decreased significantly. Also a good weld appearance is acquired.

Modeling of Weld Dilution in Gas Metal Arc Welding Process Using Taguchi's Design of Experiments

2011 ◽  
Vol 110-116 ◽  
pp. 2963-2968 ◽  
Author(s):  
Masood Aghakhani ◽  
Ehsan Mehrdad ◽  
Ehsan Hayati ◽  
Maziar Mahdipour Jalilian ◽  
Arash Karbasian
Keyword(s):  
Mathematical Model ◽  
Arc Welding ◽  
Gas Flow ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Welding Parameters ◽  
Gas Flow Rate ◽  
Metal Arc Welding ◽  
Wire Feed ◽  
Plate Distance

Gas metal arc welding is a fusion welding process which has got wide applications in industry. In order to obtain a good quality weld, it is therefore, necessary to control the input welding parameters. In other words proper selection of input welding parameters in this process contribute to weld productivity. One of the important welding output parameters in this process is weld dilution affecting the quality and productivity of weldment. In this research paper using Taguchi method of design of experiments a mathematical model was developed using parameters such as, wire feed rate (W), welding voltage (V), nozzle-to-plate distance (N), welding speed (S) and gas flow rate (G) on weld dilution. After collecting data, signal-to-noise ratios (S/N) were calculated and used in order to obtain the optimum levels for every input parameter. Subsequently, using analysis of variance the significant coefficients for each input factor on the weld dilution were determined and validated. Finally a mathematical model based on regression analysis for predicting the weld dilution was obtained. Results show that wire feed rate (W),arc voltage (V) have increasing effect while Nozzle-to-plate distance (N) and welding speed (S) have decreasing effect on the dilution whereas gas Flow rate alone has almost no effect on dilution but its interaction with other parameters makes it quite significant in increasing the weld dilution

Static Tensile Strength and Process Optimization of Gas Metal Arc Welding (GMAW) for 1.5 mm Electro-Galvanized Transformation Induced Plasticity 780 (TRIP780) Steel Joint for Automotive Body Structural Applications

2009 ◽  
Author(s):  
Ramakrishna Koganti ◽  
Cindy Jiang ◽  
Chris Karas
Keyword(s):  
Tensile Strength ◽  
Feed Rate ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Lap Joint ◽  
Transformation Induced Plasticity ◽  
Metal Arc Welding ◽  
Static Tensile ◽  
The Wire ◽  
Wire Feed

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to Heat affected Zones (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.5 mm Electro Galvanized (EG) Transformation Induced Plasticity 780 (TRIP780) to itself was investigated. The objective of the study was to understand the wire feed rate and torch speed influence on lap joint strength. Design of Experiments (DOE) was conducted to understand the wire feed and torch speed influence on tensile strength. Based on the statistical analysis, wire feed rate and torch speed were significant factors on static tensile strength. Two way interaction effect between wire feed and torch speed was significant. Metallurgical properties of the lap joints were evaluated using optical microscopy. No significant drop in hardness at HAZ, however, significant hardening was observed at the base metal and weld fillet interface.

Gas Metal Arc Welding (GMAW) Process Optimization of a 1.4 mm Uncoated Dual Phase 980 (DP980) Joint for Automotive Body Structural Applications

2010 ◽  
Author(s):  
Ramakrishna Koganti ◽  
Adrian Elliott ◽  
Cindy Jiang
Keyword(s):  
Tensile Strength ◽  
Feed Rate ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Lap Joints ◽  
Lap Joint ◽  
Metal Arc Welding ◽  
Static Tensile ◽  
The Wire ◽  
Wire Feed

With the increasing demand for safety, energy saving and emission reduction, Advanced High Strength Steels (AHSS) have become very attractive steels for automobile makers. The usage of AHSS steels is projected to grow significantly in the next 5–10 years with new safety and fuel economy regulations. These new steels have significant manufacturing challenges, particularly for welding and stamping. Welding of AHSS remains one of the technical challenges in the successful application of AHSS in automobile structures due to heat-affected zone (HAZ) at the weld joint. In this study Gas Metal Arc Welding (GMAW) of a lap joint configuration consisting of 1.4 mm uncoated DP980 to itself was investigated. The objective of the study was to understand the wire feed rate and torch speed influence on lap joint tensile strength (static and fatigue). A two factor, two level, full factorial design of experiment (DOE) was conducted to understand the wire feed and torch speed influence on tensile and fatigue strength of the welded joints. In order to understand the curvature effect, a center point was also included in the experiment. Based on the statistical analysis, neither factor was significant on static tensile strength, however, a two way interaction between wire feed rate and torch speed was significant on static tensile strength. Metallurgical properties of the lap joints were evaluated using optical microscopy. A significant hardness drop of 40% was observed at the HAZ.

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