Pulsed MIG Welding Increases Productivity, Reduces Distortion and Cleanup for Specialty Sports Equipment

As fabricators, we may be the only group of people on earth who look at an NFL goalpost and wonder about the fabrication techniques and welding methods that go into its construction. Naturally, the goal must be strong enough to withstand weather and the occasional group of fans determined to tear it down after a big win. But what’s it made of? How do they weld it? What welding and fabrication challenges do they face?

Sportsfield Specialties of Delhi, N.Y., manufactures athletic field equipment for a wide range of sports at all levels, from youth sports up to the pros. Its products include goalposts, soccer goals, sandpit jumps, hurdles, high jumps and batting cages. The company also specializes in modular products such as press boxes and dugouts. The majority of these products are fabricated out of aluminum and stainless steel for function, appearance and formability.

Aluminum, specifically, poses a unique set of challenges—especially when it comes to welding. It has a lower relative melting point than other metals yet requires heat to ensure proper puddle formation, cleanliness is critical, and it is more sensitive to heat input and distortion.

TIG welding has been used in most aluminum applications because MIG welding was traditionally thought to put too much heat into the part. Aluminum wire is also softer and more difficult to feed through a wire feeder and gun than other metals. Sportsfield Specialties found solutions to these challenges, and others, when it implemented a Pulsed MIG welding process. Those capabilities have been taken to the next level with the introduction of the new Millermatic® 350P Aluminum All-in-One MIG system from Miller Electric Mfg. Co. This dedicated aluminum system features new technology designed to provide smooth and consistent feeding of aluminum wire for greater quality and reduced downtime. It also features synergic “one knob” control in both MIG and Pulsed MIG settings, which automatically matches welding parameters to wire feed speed adjusted at the gun, eliminating trips back-and-forth to the machine.

Pulsed MIG versus TIG and Conventional MIG

According to Robert Barriger, production supervisor at Sportsfield Specialties, aluminum makes up the bulk of the company’s work. Goalposts, for instance, are constructed mostly of 11 ga. 6063. The crossbar and vertical posts are schedule 40 aluminum pipe.

“The gooseneck on the posts are 6061, so we can roll it. The wall thickness is roughly 5/16-inch,” he said. “The sheet is one-eighth inch or 11 gauge aluminum.”

Welding aluminum has historically been a TIG application for its ability to weld different thicknesses, and it’s easier for operators to control the heat input. The downside is that TIG welding is a substantially more complicated process. It’s also a slower process, which isn’t ideal in a manufacturing environment. Conventional MIG works well on thicker material, but the process can be too hot on thinner gauge aluminum and cause burn through and distortion.

Pulsed MIG welding provides the best of both processes by putting less heat into the weld to control distortion but still providing the good fusion and high deposition rate of regular MIG welding. The welding power source rapidly and automatically switches between a high peak current (ensuring good fusion) and a low background current (lowers heat input and reduces distortion). Because of the pulsing of the current, the operator can vary the heat input into the parts and weld thinner gauge material without burning through or warping the part.

“Personally I think Pulsed MIG is much faster,” said Barriger. “TIG welding gives you a neater bead, but it creates more heat than most people realize. TIG has its place, but Pulsed MIG is much quicker and you don’t get distortion from it (as you do with conventional MIG).”

Another major factor for aluminum fabricators is appearance. In addition to the reduced distortion, Pulsed MIG lays down a bead superior in aesthetics to conventional MIG welding. Barriger estimates that his welders might save as much as 15-20 minutes per part in cleanup thanks to reduced spatter.

“It gives you good appearance, and you don’t have the spatter all over it,” he continued. “That is one of the biggest benefits to the Pulsed MIG process. With aluminum a lot of it is not painted, so you need to clean or grind off the spatter, which will leave marks. With Pulsed MIG you can just wipe it down if needed and palletize it.”