Gas metal arc welding

About: Gas metal arc welding is a research topic. Over the lifetime, 11706 publications have been published within this topic receiving 109555 citations. The topic is also known as: metal active gas welding & GMAW.

Arc sensing for defects in constant-voltage gas metal arc welding

Abstract: A method for detecting flaws in automatic, constant-voltage gas metal arc welding using the process current and voltage signals was developed. Seven algorithms process the current and voltage signals to give quality parameters. A defect-detection algorithm processes the quality parameters and flags welds that are different from a baseline. The baseline is constructed from the recorded quality parameters of previously made, defect-free welds. Two series of tests were conducted to test the sensitivity of the algorithms for defects and to test the entire sensor system in production. In the first series, on a 3-mm lap joint, the algorithms detected a lack of shielding gas, oily parts and melt-through from inadequate part cross section, but could not detect off-joint welding. The algorithms showed a mixed sensitivity to melt-through from large root openings. In production tests, 520 welds were monitored. The defect detection algorithm was tuned on data from the first 82 welds. The sensot flagged five of the six defects monitored and did not flag any defect-free welds The defect not detected was a small pore, < 3 mm diameter.

Fume emissions during gas metal arc welding

Abstract: The control of exposure to welding fumes is of increasing importance in promoting a healthy, safe and productive work environment. This article describes the effects of shielding gas composition on the amount and composition of welding fumes produced during gas metal arc welding (GMAW). The amount of fumes generated during welding was measured for steady current over a range of wire-feed speeds and arc voltages using the standard procedures contained in ANSI/AWS F1.2 [American Welding Society. ANSI/AWS F1.2. Laboratory method for measuring fume generation rates and total fume emission of welding and allied processes. Miami, Florida; 1992]. Results of these measurements show that the fume formation rates (FFRs) increase with CO2 and O2 in the shielding gas mixture. The lowest FFRs were obtained with the mixtures of Ar + 2%CO2 and Ar + 3%CO2 + 1%O2. The highest FFRs were obtained with the mixtures of Ar + 18%CO2 and Ar + 5%CO2 + 4%O2. The welding fumes contains mainly iron, manganese, silicon, titanium and ...

Gas metal arc welding system

Abstract: Power delivered to the welding arc from a constant current rapid response power supply is controllable to maximize arc stability particularly in out-of-position welding operations. A first control modulates the output current from the power supply between a high value close to the maximum output value and a minimum value just sufficient to maintain the welding arc. The modulation is effected at a given frequency appropriately adjusted in accordance with the electrode material and diameter to maintain optimum spray metal transfer in the welding arc. A further control is effected by pulse width modulating the output from the power supply in accord with a set-in current programmed signal which is compared with a current feedback signal or, alternatively, a set in voltage programmed signal which is compared with a voltage feedback signal. This latter control provides for operation of the power supply in a constant current control mode or alternatively, a constant voltage control mode. Still further control of the power in the welding arc is effected by pulsing the current between base and peak levels at a relatively low frequency which enables control of the weld puddle in out-of-weld positions.

Effect of oxide fluxes on activation mechanisms of tungsten inert gas process

Abstract: Activated tungsten inert gas (TIG) welding, which involves the deposition of an inorganic powder on the metal surface prior welding, improves TIG welding performances in terms of weld bead penetration. Most common commercial fluxes contain halides and oxides. The present paper focuses on fluxes made of oxides. It appears that oxides have two different effects: one on the fusion zone chemistry and the other on the electric arc behaviour. First, oxygen reverses the Marangoni convection movements that become centripetal, contributing thus to increase 'D' penetration. On the other hand, oxides may cause an increase in the energy flux density transferred by the arc to the metal. The characterisation of the arc plasma by optical emission spectroscopy suggests that oxides do not increase the arc temperature. It is established that the oxide effects by Marangoni convection appear for a critical value of the welding energy, whereas the oxide effects on the electrical arc exist irrespective of the welding e...