Pulse MIG welding vs stitch welding…a few details
A lot of articles and videos have been made about pulse TIG welding, but few exist on Pulse MIG welding. One of the reasons, is that Pulse MIG welding hasn’t been officially recognized as a welding process by the American Welding Society.
The reason is that the process is so difficult to set correctly and takes a lot of skill to make things work correctly. But that does not mean it is not a worthwhile process to use. It simply means that there are many variables that are hard to define and control. MIG pulse is not like TIG pulse. The amperage does not pulse. Rather, the Voltage does, at least in a single, simple pulse MIG.
The voltage alternates between a high and low voltage level. Stitch welding involves a pulsing of the voltage and wire on and off. The voltage is set, and a timer sets the off/on phase of the wire feed and voltage. This On/Off pulsing is simply an automatic bumping of the weld, where the weld is allowed to completely cool while welding.
During true Pulse MIG welding the arc never extinguishes and the pulsing up and down action can be as low as 1 hz on double pulse MIGs up to 500 hz on single pulse MIGs. This creates vastly different weld appearances. One issue with the stitch welding process is that it can create porosity where the weld is. But if done right, it yields an beautiful bead and a very well defined ripple.
Pulse MIG is capable of this as well, but it yields stronger welds and is usually porosity free. Pulse MIG welding isn’t for everyone, but a lot of people that have never had a spot/stitch feature on their welder really could benefit from having one, especially on light materials.