Welding transfer modes are the ways that the filler metal moves from the electrode to the workpiece during welding. Different transfer modes have different characteristics, advantages, and disadvantages, depending on the welding process, parameters, and application. Knowing how to select and control the transfer mode can help you improve the quality, productivity, and efficiency of your welding operation.
In this article, we will explain the four main transfer modes for MIG welding (GMAW) — short circuit, globular, spray, and pulsed spray — and provide some tips for achieving the best results with each of them.
I. Short Circuit Transfer Mode
Short circuit transfer mode is when the electrode touches the weld pool and creates a short circuit, which transfers the filler metal to the joint. This mode operates at low currents and voltages, and produces a small, fast-freezing weld pool. It is suitable for welding thin materials, out-of-position welding, and filling large gaps.
1) Some of the benefits of short circuit transfer mode are:
Low heat input, which reduces distortion and warping
Low spatter, which reduces post-weld cleanup
Good weld appearance and penetration
Easy to use and control
2) Some of the drawbacks of short circuit transfer mode are:
Low deposition rate, which reduces productivity
Prone to lack of fusion and porosity, especially on thicker materials
Requires a consistent contact tip to work distance (CTWD) to maintain a stable arc
3) Some of the tips for achieving the best results with short circuit transfer mode are:
Use a constant voltage (CV) power source with adjustable inductance to control the arc stability and spatter
Use a shielding gas mixture of 75% argon and 25% CO2 for solid wires, or 100% CO2 for metal-cored wires
Use a small electrode diameter (0.023 to 0.035 inch) to increase the current density and penetration
Use a short CTWD (1/4 to 3/8 inch) to reduce the arc length and heat loss
Use a moderate travel speed (10 to 20 inches per minute) to avoid undercutting and cold lap
II. Globular Transfer Mode
Globular transfer mode is when large, irregular drops of filler metal transfer across the arc gap under the influence of gravity or electromagnetic forces. This mode operates at higher currents and voltages than short circuit transfer, and produces a large, fluid weld pool. It is suitable for welding thick materials, flat or horizontal positions, and high deposition applications.
1) Some of the benefits of globular transfer mode are:
High deposition rate, which increases productivity
High penetration, which improves weld strength
Low electrode wear, which reduces downtime and cost
2) Some of the drawbacks of globular transfer mode are:
High heat input, which increases distortion and warping
High spatter, which increases post-weld cleanup
Poor weld appearance and consistency
Difficult to use and control
3) Some of the tips for achieving the best results with globular transfer mode are:
Use a CV power source with high inductance to control the arc stability and spatter
Use a shielding gas mixture of 80% argon and 20% CO2 for solid wires, or 100% CO2 for metal-cored wires
Use a large electrode diameter (0.045 to 1/16 inch) to reduce the current density and heat input
Use a long CTWD (1/2 to 3/4 inch) to increase the arc length and droplet detachment
Use a slow travel speed (5 to 10 inches per minute) to avoid lack of fusion and porosity
III. Spray Transfer Mode
Spray transfer mode is when small, fine drops of filler metal transfer across the arc gap in a spray-like pattern. This mode operates at high currents and voltages, and produces a narrow, deep weld pool. It is suitable for welding thin to thick materials, flat or horizontal positions, and high-quality applications.
1) Some of the benefits of spray transfer mode are:
Low heat input, which reduces distortion and warping
Low spatter, which reduces post-weld cleanup
Excellent weld appearance and consistency
Easy to use and control
2) Some of the drawbacks of spray transfer mode are:
High penetration, which can cause burn-through on thin materials
Limited to flat or horizontal positions, due to the fluidity of the weld pool
Requires a high shielding gas flow rate, which increases the cost
3) Some of the tips for achieving the best results with spray transfer mode are:
Use a CV power source with low inductance to control the arc stability and spatter
Use a shielding gas mixture of 85% to 98% argon and 2% to 15% CO2 for solid wires, or 75% to 80% argon and 20% to 25% CO2 for metal-cored wires
Use a small to medium electrode diameter (0.035 to 0.052 inch) to increase the current density and penetration
Use a short to medium CTWD (3/8 to 1/2 inch) to reduce the arc length and heat loss
Use a moderate to fast travel speed (15 to 30 inches per minute) to avoid undercutting and sagging
IV. Pulsed Spray Transfer Mode
Pulsed spray transfer mode is when small, fine drops of filler metal transfer across the arc gap in a spray-like pattern, but with a pulsing current that alternates between a high peak current and a low background current. This mode operates at lower average currents and voltages than spray transfer, and produces a controlled, stable weld pool. It is suitable for welding thin to thick materials, all positions, and high-quality applications.
1) Some of the benefits of pulsed spray transfer mode are:
Low heat input, which reduces distortion and warping
Low spatter, which reduces post-weld cleanup
Excellent weld appearance and consistency
Easy to use and control
Versatile for all positions and materials
2) Some of the drawbacks of pulsed spray transfer mode are:
Requires a more advanced power source with specific pulsed waveforms, which increases cost and complexity
Requires a higher level of skill and experience to optimize the welding parameters
May produce more fumes and noise than other modes
3) Some of the tips for achieving the best results with pulsed spray transfer mode are:
Use a pulsed power source with adjustable peak current, background current, frequency, and arc length control to control the arc stability and spatter
Use a shielding gas mixture of 90% to 95% argon and 5% to 10% CO2 for solid wires, or 75% to 80% argon and 20% to 25% CO2 for metal-cored wires
Use a small to medium electrode diameter (0.035 to 0.052 inch) to increase the current density and penetration
Use a medium to long CTWD (1/2 to 3/4 inch) to increase the arc length and droplet detachment
Use a moderate to fast travel speed (15 to 30 inches per minute) to avoid undercutting and sagging
V. Conclusion
Welding transfer modes are the ways that the filler metal moves from the electrode to the workpiece during welding. Different transfer modes have different characteristics, advantages, and disadvantages, depending on the welding process, parameters, and application. In this article, we explained the four main transfer modes for MIG welding (GMAW) — short circuit, globular, spray, and pulsed spray — and provided some tips for achieving the best results with each of them.
Knowing how to select and control the transfer mode can help you improve the quality, productivity, and efficiency of your welding operation. You should consider factors such as the material type and thickness, the welding position, the desired weld appearance and penetration, and the available equipment and settings when choosing the transfer mode. You should also experiment with different welding variables and observe the effects on the transfer mode and the weld outcome.
Related articles:
1. Advantages of Pulse Spray Transfer in GMAW Welding
2. Mig Welding – Short Arc and Spray Transfer
3. Cold Metal Transfer (CMT) Welding VS. Retract Droplet Transfer (RDT) Welding
4. Megmeet RDT (Retract Droplet Transfer) Cold Metal Transfer Zero-Spatter High-speed Servo Arc Welding Technology Makes Its Debut at the Exhibition
5. Shielding Gases for TIG & MIG Welding: which gas is best?
