Choosing the Correct Welding Technique for GMAW-P

Tips and Techniques for Welding GMAW-P 

Manufacturing sectors use pulsed gas metal arc welding (GMAW-P) to weld most of the work in flat and horizontal positions. But occasionally they must weld certain work vertically. When welding vertical-up, flux-cored arc welding (FCAW) is used. Here is one of the questions that most often comes up - Is this necessary, or is there a solution to get away from having to use multiple processes? Most of the manufacturing sectors look for a single process and wire to get the work done. There are a few guidelines to follow that will assist you in choosing the best option for your manufacturing needs.

The Major Advantage of GMAW-P

Let us start with some background information. GMAW-P is a robust process that has many advantages. With proper setup and weld technique, this process can practically eliminate weld spatter and minimize distortion because of the lower weld heat input. Less distortion can be especially advantageous on thin materials and stainless steel.

GMAW-P is remarkably like the spray-transfer mode in that the arc melts the welding electrode before it crosses the joint gap. With GMAW-P, this can be accomplished with much lower arc energy than with GMAW (Gas Metal Arc Welding) spray arc. Additionally, the droplets of molten metal are uniform in size and frequency compared with those generated with spray transfer, which is of random size and frequently leads to the potential for weld spatter.

Choosing the Correct Welding Technique for GMAW-P

When it comes to welding position and technique, welding vertical-up always produces a weld that is structurally superior to vertical-down regardless of the process. Welding vertical-down with GMAW in either short-circuiting or spray-transfer modes is advantageous for sheet metal to minimize burn-through and distortion because of the higher travel speed, which lowers the weld's heat input.

GMAW-P, on the other hand, is not ideal for vertical-down welding. With GMAW-P a continuous loop of information is being sent back to the arc controller, which is monitoring the arc and adjusting maintain a constant or steady arc. One thing that will negatively affect this is frequent or rapid changes in arc length, which occur in vertical-down welding. Since gravity pulls on the weld puddle, it is difficult for the welder to maintain a constant pace in front of the weld puddle, and this causes changes in the arc characteristics, typically resulting in an inconsistent arc and weld spatter.

With GMAW-P there is reduced background current or arc energy between pulses, allowing the weld puddle to solidify quickly. This makes it quite suitable for welding vertical-up even with 0.045- or 0.052-in. wire diameters. Rapid weld solidification is more forgiving for the welding operator as compared to FCAW or other processes.

Which Welding Technique You Should Go for?

To answer your original question, there is no reason to resort to FCAW for a stronger high-quality weld when welding vertical-up. If the filler metals are from equivalent AWS (American Welding Society) classifications, both welding processes will deliver similar mechanical properties.