By switching to a Millermatic 350P pulsed MIG welder, Iron Grip’s welder operators can maintain a cleaner, more accessible work area. The need to apply anti-spatter has been eliminated and barbells require very little post-weld clean up.

Not all weight sets are created equal, and when top health clubs, professional sports teams, corporate fitness centers, U.S. Armed Forces and other institutions need free weights, the majority turn to Iron Grip Barbell Company.

Scott Frasco and Michael Rojas founded Iron Grip in 1993, introducing weight plates that featured integrated handgrips and a special design that represented a significant improvement to one of the oldest pieces of fitness equipment.

Now, with a workforce of 65 people and annual sales in excess of $14 million, Iron Grip offers more than 10 product lines with more than 1,000 different items. Iron Grip is the largest provider of commercial freeweight equipment worldwide, and the only manufacturer with a line of exclusively American-made freeweight equipment.

The company recently reexamined its manufacturing processes and increased production by 16 percent, reduced scrap and removed a potential source of weld defects by upgrading from conventional MIG welders to Millermatic 350P pulsed MIG welders.

Iron Grip’s dumbbells and fixed barbells are assembled from precision-machined steel bars and drilled, chamfered and precision-machined heads that are welded together for durability and safety. They are available in painted steel and steel encapsulated in urethane.

Why Weld?
“We elected not to go with bolting because bolts eventually will come loose. A properly designed weld joint is going to be stronger than a bolt,” Winter Douglas, manufacturing engineer for Iron Grip, said.

The result is maintenance-free equipment that has a much lower failure rate.

Iron Grip’s dumbbells range from 5 lbs to 150 lbs, and its dumbbells go to 200 lbs.

Iron Grip uses high-quality steel throughout to achieve the best welding results, and it has a patented design for attaching bars to heads.

Handles are pressed with a 30-ton hydraulic press into a flat ring around the base of the dumbbell. That moves the weld away from the handle and the greatest stress point, eliminating a potential source of failure.

A 45-degree fillet weld from head to handle has the potential to create a heat-affected zone at the top of the weld, which is the greatest stress point in a dumbbell and could be a source of failure under high stress.

The Millermatic 350P pulsed MIG welder offers a choice of built-in programs and the ability to fine tune parameters. Iron Grip achieved top quality welds within their first two hours with a 350P and rarely needs to change settings.

Iron Grip’s welded design eliminates bolts and minimizes stress points that can lead to failure. An aesthetically pleasing, sound weld does not allow a point for stress to focus. The Millermatic 350P has made this easier to achieve than ever before.

Once the handle is pressed into the weight, the assembly is placed on a turntable to allow welders to make a continuous weld around the circumference while maintaining the same gun angle. The operator controls rotation with a foot pedal.

Douglas designed the turntable and procedure after he saw another company use multiple welds to get around a circumference – the part stayed stationary while the welder moved. One of Douglas’s goals is to remove guesswork and variability that can lead to imperfect welds, both for aesthetic and reliability reasons.

But the importance of a solid, smooth weld goes beyond cosmetic perfection. Dumbbells are subject to repeated stress and an improper weld could lead to a spot where stress can focus and start to crack.

“It is critical to make sure that we have a nice, smooth transition where we aren’t going to have a problem in cracks developing around a certain spot,” Douglas said.

“Any time you have a flaw or an area where the stress has the ability to focus, that’s going to cause a stress riser,” according to Mike Cunningham of Cameron Welding Supply, Iron Grip’s welding distributor. “It can be as simple as a nick in a part where the stress can accumulate or a weld without a smooth transition where the stress forces can gather at that one crevice or point. Having a smooth transition allows the stress to move completely through the entire dumbbell and not focus in one part.”

“What we’re looking for is a nice flat, even, smooth weld that grabs to both sides and looks seamless,” Douglas said. Anything less will lead to the part being scrapped.

Short circuit’s limitations
Until recently, Iron Grip welders used a shortcircuit welding process that allowed them to produce the high-quality, aesthetically pleasing welds for which Iron Grip is known. However, it requires the application of anti-spatter material, and parts were scrapped occasionally because of weld flaws.

“The short circuit process held several disadvantages for Iron Grip. During the short-circuit transfer process, the weld wire shorts to the base material 60 to 120 times a second. Each time the wire shorts to the work, excess wire burns off, and particles are blown away from the welding arc. These particles are not part of the final weld and are known as spatter,” Cunningham said.

To control spatter, Iron Grip welders taped the handles and applied anti-spatter material with a brush or a rag. Operators welded the part and, because it was too hot too handle, they would set it aside until it was cool enough to remove the anti-spatter and tape.

These pre- and post-weld steps added four minutes or more to the production of each dumbbell. In addition, Douglas estimated that when using the short circuit process at least two parts would be scrapped each day due to an imperfect weld.

“The difficult part is if you scrap one half, you’ve scrapped the part, so one bad weld would cause us to scrap the entire dumbbell. I’m not going to try to salvage it to sell to a customer. A good part requires two flawless welds, and there’s really no in-between,” Douglas said.

Douglas continued to explore alternatives to improve the process, and his research led him to pulsed MIG, a modified spray transfer method that pulses current between peak and low background levels.

During the high peak current, metal is sprayed across the arc. During the background level of the cycle, the puddle is allowed to cool. It eliminates the continual shorting of the wire and associated spatter that occurs in short-circuit transfer. Instead, pulsed MIG promised to give a very flat, smooth appearance, exactly what Douglas was looking for.

“A good part is a good part, and there’s really no in-between,” says Winter Douglas, Iron Grip manufacturing engineer.

Unfortunately, Douglas’ first foray into pulsed MIG welding didn’t produce the desired results. The machine was complicated, and experts he turned to couldn’t get the pulse program to work to Iron Grip standards. Until recently, this was typical of pulsed MIG power sources.

“When the first pulsed MIG machines came out, they were so complicated that a lot of welders shied away from using them. You had to set the pulse width, the frequency, and the background current, and the average welder really couldn’t use it,” Cunningham said.

Pulsed MIG Grows Up
“Everyone told me how good pulse was, yet I spent a lot of money to get a machine, and we couldn’t get it to work,” Douglas said. Undaunted, he turned to the Internet for his research and found a possible solution: Miller Electric’s Millermatic 350P.

With this unit, pulsed MIG welding seemed to have come of age.

The unit provides 300 amps with a 60-percent duty cycle. It looked easy to use: two control knobs give complete access to built-in pulsed MIG programs, it has the flexibility to fine tune parameters, and two large digital displays relay information in an easyto- read format. In addition, case studies on Miller- Welds.com said the unit was operator friendly and gave consistently high-quality welds.

However, Douglas still was leery after his first foray into pulsed MIG welding and asked Cunningham and Ed Bogner, the district manager for Miller Electric, for a demonstration. Douglas brought dumbbell components to the demonstration.

Within two hours, they were making productionquality welds that met Iron Grip’s standards.

“I’m glad we produced acceptable parts quickly because we started out with the ten-pound weights, by the time we got the thing dialed in, we were up to 25-pounders,” Cunningham said.

“One of the key things we were able to do the first time we tried the 350P was to produce a beautiful, flat, smooth weld without stress risers in it. We didn’t improve the quality, because we always had very high standards, but production and efficiency is completely different. It’s much easier and quicker to achieve the same result,” Douglas said.

Peace of Mind
Douglas bought two of the machines and overnight eliminated the need for anti-spatter, along with it the associated application time and clean-up and cool down times. Plus, the machines eliminated the variable of whether there was too much or too little of the antispatter material being applied.

“Previously, we averaged 168 dumbbells per shift. At our best, we hit 180 a day,” Douglas said.

“Now we average 206 per shift. The actual increase in productivity is 16.5 percent, and we reduced the scrap rate by 20 percent. The people and material were the same. Only the welding units are different,” he added.

Assuming an hourly rate of $20, saving 16.5 percent on 16 hours of machine time per day translates into a savings of $52.80 per day. At that rate, each Millermatic 350P paid for itself in 77 work days, or about 4 months. This does not take into consideration the 20 percent savings in scrap, or Douglas’ increased peace-of-mind.

“There are a lot of elements involved in achieving a good weld,” Douglas said.

“Defects can come from a weld that’s too hot or too cold or from welding two dissimilar metals that flex at different rates, or by joining a large head to a small diameter handle. Our design minimizes those possibilities, but still the weld was a potential problem spot. With the previous machines, the operator needed to be more trained and more cautious when they welded.

In addition, while steel prices are volatile, Iron Grip strives to maintain its prices, and the Millermatic 350P helps them accomplish that.

“The only way to maintain prices and not pass every price increase to our customers is to make production as efficient as I can,” Douglas said.

“We have to use equipment that we can rely on, and that I think is fool-proof. The Millermatic 350P is the do-all easy guy. It really does it all well, and if we had a need for more welders, it would be the machine I would buy again.”