November 1, 2008
by Jeff Herb
High volume manufacturers and fabricators applying lean principles to reduce waste should consider new pulsed MIG welding technology. Is it the right process for your application? Here are eight points to consider:
1. Reduced spatter. Do you pay people to chip spatter or apply and remove anti-spatter compound? Just add up the labour costs. Chances are a new pulsed MIG system could pay for itself in a matter of months. New welding systems monitor arc conditions thousands of times per second. With such a fast response rate, they detect and clear a short before it becomes a major problem or causes spatter. Pulsing technology also adjusts the current to a pre-determined level at the beginning of each peak at the background phase, but it also adjusts the current up or down to generate optimum arc conditions for a specific wire diameter and type, wire-feed speed and gas combination.
2. No slag to chip. If you use flux-cored wire because its deoxidizers compensate for mill scale, or for high deposition rates, consider pulsed MIG welding with metal-cored wire.
3. Lower fume emissions. Many manufacturers of construction and agricultural equipment have switched from flux cored welding to the pulsed MIG process to reduce fume emissions. Pulsed MIG helps with regulatory compliance and it creates a more comfortable atmosphere for the operator.
4. Less burn-through and distortion. If you staff a welding repair station to deal with burn-through, or if distortion causes part fit-up or other tolerance issues, you’re a good candidate for pulsed MIG. The power source switches output from high peak current to low background current several hundred times per second. The peak current pinches off a spray-transfer droplet, while the background current is set at a level that maintains the arc but is too low for metal transfer to occur. The background current lowers overall heat input, addressing the burn-through and warping issues commonly associated with spray transfer MIG. Note that pulse of peak current helps ensure good fusion, overcoming concerns related to cold lap. It also provides faster travel speeds, which improves productivity.