Pulsed Productivity

10 ways pulsed MIG welding leads to increased productivity

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Selecting the optimal MIG welding process requires balancing multiple factors. For many applications on materials 1/16 in. thick and up, the pulsed MIG welding process offers an optimal combination of benefits that improves productivity, including:

  • The ability to minimize spatter
  • Reduce heat input to prevent burnthrough and minimize or reduce distortion
  • Enable all-position welding
  • Preserve mechanical properties

A new generation of welding systems make these benefits more accessible than ever because they provide pulsed MIG capabilities without complexity. As a result, many more operators can achieve success.

For example, “quick job” buttons on a front panel can recall a synergic line with preprogrammed weld parameters with the push of one button. This directly addresses the industry’s need for skilled operators and faster training. Functions such as an RFID reader can scan operator badges. This allows locking parameter limits for quick jobs, improving repeatability and adherence to weld procedure specifications (WPSs). Operators can adjust wire feed speed and trim (arc length) up or down within a range, but they can’t stray outside of the WPS.

Finally, the newest pulsed MIG welding power sources on the market, such as ESAB’s Warrior Edge, feature next-generation current control modules using field programmable gate array (FPGA) technology. An FPGA can clear a short circuit or manage current transients 10 to 20 times faster than the microprocessor controls found in typical inverter welding machines. As a result, the system minimizes spatter and creates a stable, more controllable weld pool.

With improvements such as these, it is worth reviewing the fundamentals of the pulsed MIG process and how they can help more companies improve welding productivity.

Process fundamentals

Pulsed MIG welding is a modified spray transfer process where the power source pulses the welding output between a high and low output up to several hundred times per second. The pulse of peak current and voltage pinches off a droplet of molten metal that is slightly smaller than the wire diameter and propels it across the arc. As with spray transfer, the wire never touches the weld puddle. However, during the background portion of the pulse, the current and voltage are too low for metal transfer but sufficient to keep the arc established. It is this drop in current that minimizes heat input for many of the pulsed MIG advantages.

The nature of pulsed MIG welding means it combines the best characteristics of spray transfer and short-circuit MIG without any of their drawbacks, and it completely avoids the issues associated with globular transfer.

Top 10

Here are 10 ways pulsed MIG welding can increase productivity:

  1. Minimized spatter. Pulsed MIG minimizes the spatter associated with short-circuit MIG because controlled transfer of fine metal droplets across the arc doesn’t disrupt the weld puddle. With little to no spatter, operators spend less time on post-weld cleanup and more time welding.
  2. Minimized distortion. Pulsed MIG extends its reduced heat benefits into a mean current range associated with short-circuit MIG. As a result, the process can reduce or eliminate the production delays or post-weld re-work associated with combating distortion.
  3. Minimized burnthrough. With pulsed MIG, operators can weld material as thin as 1/16 in. without burnthrough or degrading mechanical or metallurgical properties.
  4. Reliable fusion. The peak pulsed current provides consistent reliable fusion and achieves the desired penetration profile on sections up to 3/8 in. thick. Increasing penetration or travel speed is as easy as increasing wire feed speed. Pulsed MIG avoids the cold lap issue associated with short-circuit MIG and is permitted for use in prequalified WPSs for structural steel, pressure vessels, pipe and other critical applications according to AWS, ASME, ISO and other standards.
  5. All-position welding. The background portion of the pulsed waveform gives the weld puddle a chance to slightly solidify. As a result, pulsed MIG enables welding in all positions with reasonably high travel speeds and deposition rates. When moving large weldments becomes time consuming or hazardous, pulsed MIG provides a good solution for welding with solid wire.
  6. Excellent directional control. Pulsed MIG enables operators, including those with less experience, to make more precise and consistent welds. Pulsed MIG provides greater directional control over the weld pool because it focuses the arc cone, slightly freezes the puddle and avoids the turbulence associated with short-circuit MIG or globular transfer.
  7. Tailored bead profile. The ability to adjust the width of the arc cone by adjusting wire feed speed and trim (arc length) helps operators tailor the bead profile to the application. Wider weld beads can improve the profile on both sides of a joint, while a narrower bead helps provide good fusion at the root of a joint.
  8. Lower filler metal costs. Because of the ability to control heat input, pulsed MIG typically enables using the next size larger wire diameter (e.g., moving from 0.035 to 0.045). This can reduce filler metal costs because larger diameter wire cost less per pound. In addition, using a single wire for more applications potentially lowers stocking costs.
  9. Softer arc starts and stops. As noted, FPGAs regulate current at a much faster rate than conventional welding inverters. A hot start routine provides a high level of energy to ensure positive arc starts and good fusion (e.g., prevents cold lap). Then, the power source tightly regulates current and voltage, eliminating overshoot and undershoot to prevent popping and spatter. At weld termination, it ramps down to a cooler welding parameter to fill in the crater and reduce or eliminate the potential for crater cracking.
  10. Futureproof. FPGA technology enables continuous process improvement and development without the need for hardware updates, giving users the confidence of buying a future-proof system. For example, users may initially purchase a system optimized for pulsed MIG welding with carbon steel. If their needs grow, a simple software update can add synergic lines for aluminum, stainless and alloys, as well as lines for specialty applications.

Given the continuous labor scarcity and increasing need to manage costs, pulsed MIG welding deserves a renewed examination for many industry applications. By asking their welding representative for the opportunity to test a new system, any shop or facility will be pleasantly surprised with the new capabilities of pulsed MIG welding.

ESAB

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