1. GAS METAL ARC WELDING MODES OF METAL TRANSFER

2. Short Circuit Transfer
Rational:
Knowing and understanding the modes of metal transfer (arc type) and how to change/control them is an essential skill for a well trained welder.
Listed below are the three common GMAW arc types.
Short Circuit Transfer
Closed arc type
Electrode contacts grounded base metal
Welding circuit is short circuited and re-fires automatically
Self regulating arc
Lowest amount of delivered voltage and amperage
Works well for thin material (up to 3/16”)
Weld spatter can be a problem
Creates the smallest heat affective zone

3. Globular Transfer Open arc type
Electrode does not contact grounded base metal
Electrode melts in globs larger then the electrode diameter
Gravity separates filler metal from electrode
Filler metal may occasionally contact base metal (short circuit)
Largely uncontrollable
High amount of weld spatter (Requires the most post-weld clean up)
Little commercial application

4. Axial Spray Transfer/Pulse Spray Transfer
Open arc type
Electrode does not contact grounded base metal
Electrode melts in droplets smaller than the electrode diameter
Filler metal propelled across arc gap at high velocity
Highest amount of delivered voltage and amperage
High amount of control
Used mainly on thick material (3/16” +)
Requires the use of a minimum 80% inert shielding gas
Requires a amperage setting above the transition current level
Can be pulsed (GMAW-P) to reduce heat input
Pulsed spray transfer requires the use of two distinctly different sets of welding parameters
Power source toggles between the two sets of parameters at a prescribed rate (pulse per second)
Produces the greatest amount of base metal penetration