In simple terms, pulsed MIG is a non-contact transfer method between the electrode and the weld puddle. This means that at no time does the electrode ever touch the puddle. This is accomplished through high-speed manipulation of the electrical output of the welding machine. It is designed to be a spatterless process that will run at a lower heat input than spray or globular transfer methods.
The pulsed MIG process works by forming one droplet of molten metal at the end of the electrode per pulse. Then, just the right amount of current is added to push that one droplet across the arc and into the puddle. The transfer of these droplets occurs through the arc, one droplet per pulse.
During the process, the current rises to a peak when the droplet is formed. Then, in the background current phase, the current is lowered to reduce the overall heat input. It is the height and the width of the peak that is important for proper transfer.
Pulsed MIG Compared to Other Transfer Methods
How does pulsed MIG compare to other welding transfer modes?
In short circuit, the wire touches the work piece and shorts to itself. This is the coldest form of welding that still offers good fusion. Short circuit allows operators to weld on both thick and thin material in all positions. It also has the benefit of a small, quickly solidifying puddle. Its disadvantages include limited wire feed speed, and deposition rates. There is also a danger of “cold lapping” on thicker metals. This is where there is not enough energy in the puddle to fuse properly. Short circuit also produces an increased amount of spatter over the other transfer methods.
Pulsed MIG is an advanced form of welding that takes the best of all the other forms of transfer while minimizing or eliminating their disadvantages. Unlike short circuit, pulsed MIG does not create spatter or run the risk of cold lapping. The welding positions in pulsed MIG are not limited as they are with globular or spray and its wire use is definitely more efficient. By cooling off the spray arc process, pulsed MIG is able to expand its welding range and its lower heat input does not make burnthrough on thin metals a problem. Pulsed MIG is one of the best welding processes for a wide variety of applications and metal types.