Gas Metal Arc Welding (GMAW): The "Preferred Option" for High-Quality Welding
Gas Metal Arc Welding (GMAW): The "Preferred Option" for High-Quality Welding
Gas metal arc welding (GMAW) uses inert gas or active gas as the protective medium to isolate the impact of air on the molten pool. It features high welding quality and beautiful weld formation. It is divided into two mainstream types: tungsten inert gas welding (TIG) and CO₂ gas shielded welding (MIG/MAG), which are suitable for different materials and scenarios, respectively.
1. Tungsten Inert Gas Welding (TIG Welding): The "Expert" in Precision Welding
TIG welding uses argon gas (purity ≥99.99%) as the protective gas. It heats the workpiece through the arc between the tungsten electrode and the workpiece, and can be performed with or without filler wire (autogenous welding). It is suitable for precision welding of easily oxidized materials such as stainless steel, aluminum alloys, and titanium alloys, such as aerospace components, pressure vessels, and medical equipment.
Key Operational Points:
Tungsten Electrode Selection: Use ceriated tungsten electrodes for welding stainless steel and pure tungsten electrodes for welding aluminum alloys. Adjust the tungsten electrode diameter according to the current (e.g., 2.4mm tungsten electrode for 100-150A current). Control the extension length of the tungsten electrode at 2-5mm to avoid contact with the filler wire, which may cause tungsten electrode burnout.
Gas Control: Adjust the argon flow according to the workpiece thickness: 8-10L/min for thin plates (≤3mm) and 12-15L/min for thick plates (>5mm). Extend the argon protection time by 3-5 seconds when terminating the arc to prevent high-temperature oxidation of the weld.
Filler Wire Technique: Add the filler wire from the front of the molten pool, avoiding direct contact with the arc. Control the welding speed at 5-10cm/min to ensure full fusion of the molten pool and avoid lack of fusion defects.
2. CO₂ Gas Shielded Welding (MIG/MAG Welding): The "High-Efficiency Expert" for Mass Production
CO₂ gas shielded welding uses CO₂ or a mixed gas of CO₂ and argon as the protective medium, with automatic wire feeding. It has high welding efficiency (2-3 times that of SMAW) and low cost, making it suitable for mass production of low-carbon steel and low-alloy steel, such as automotive bodies, home appliance casings, and container manufacturing.
Key Operational Points:
Parameter Matching: Strictly match the current and voltage (e.g., 22-24V for 150A current). Control the wire extension length at 10-15mm (approximately 5-10 times the wire diameter); an excessively long extension may cause excessive spatter, while an excessively short one may burn the nozzle.
Welding Angle: Adopt the leftward welding method (moving the welding torch from right to left). Maintain an angle of 15-25° between the welding torch and the workpiece to ensure full coverage of the molten pool by the gas. Use a wind shield when the wind speed exceeds 2m/s to prevent the protective gas from being blown away, which may cause porosity.
Spatter Control: Apply anti-spatter agent to the workpiece surface before welding. Regularly clean the spatter inside the nozzle (every 30-50 minutes of welding). If there is excessive spatter, adjust the current-voltage matching or replace the wire (e.g., use low-spatter wire).
