City-folk might consider Griswold, Iowa (pop. 1,089) a bit too country. After all, this town 40 miles east of the Missouri River has a business district two blocks long. Corn and soybeans stretch for miles on either side. Farmers park combines in driveways. But if you take a right turn at Dusty’s restaurant, you’ll find a welding operation considered world-class by its OEM customers. In fact, this small company has the most controllable ¾ yet operator friendly and affordable ¾ GMAW welding systems in the state.
Yellow Jacket Mfg., Inc. designs and manufactures exhaust components and systems for agricultural and construction equipment, trucks, all terrain vehicles and performance and racing vehicles. President John Marshall purchased Yellow Jacket in 1992 when it made glasspack mufflers for the automotive aftermarket. The company soon expanded into the agricultural aftermarket, and in 1996 began serving a skid steer manufacturer. Based on the success of the products developed for OEMs, Marshall decided to focus on small- to mid-sized OEMs…and one of the world’s leading ATV manufacturers.
While the ATV manufacturer liked Yellow Jacket’s muffler design capabilities, the customer’s welding engineer wanted to know how Yellow Jacket planned to ensure weld consistency in a hand-held welding application.
“You can’t control a welding operator, but you can control his welding parameters,” states Steve Smith, branch manager for Linweld’s Atlantic, Iowa welding supply store and Marshall’s good friend. “That’s why Miller Electric’s new S-74DX wire feeder provided the perfect solution for helping to guarantee weld consistency.”
Smith and Marshall came to this conclusion after meeting with the customer twice. They decided that a basic wire feeder such as Miller’s S-22A could not guarantee customer satisfaction because operators can set voltage and wire feed speed to meet their personal tastes, not customer specifications. On the other end of the spectrum, “a sophisticated programmable feeder such as Miller’s 60M seemed like overkill,” says Marshall. “We didn’t need to pulse weld and didn’t want to spend that much for a feeder. What we needed was control over the weld parameters and the ability to remote the feeders from the power sources.”
Keeping Control
The S-74DX provides a happy medium between the S-22A and 60M because it cost one-third less than a 60M, yet provides the benefits of a full-featured wire feeder with microprocessor capabilities. This includes an adjustable weld sequence control, four weld programs to store and recall customized weld parameters, and weld parameter range limiting.
“Range limiting allows a welding engineer or supervisor to set voltage and wire feed speed to specific values, which are accurately displayed on the feeder’s digital meters,” says Smith. “Then, using DIP switches inside the feeder, he can lock in those values to ± 5, 10 or 20 percent of nominal. This ensures that operators consistently weld within specifications, yet it still gives them limited freedom to fine tune the arc to suit their personal tastes.’
For instance, Yellow Jacket’s Tony McCullough and Tony Stender work at finish welding stations welding mounting brackets, the outlet tube and spark arrestor coupler to the 16 ga. aluminized steel outer tube. McCullough welds at 24 volts and 270 IPM ¾ the established values for program 2 ¾ while Stender uses slightly different values. However, the S-74DX locks Stender into a voltage and wire feed speed that is within ± 10 percent of McCullough’s.
The welding operators securing the baffles to the mufflers inner core also use the S-74DX, but with a different program ¾ the feeder can store four programs ¾ and different values locked in. For example, operator Harry Roller welds this 18 ga. material at 19.5 volts and 280 IPM, ± 10 percent.
Other valued features of the feeder include its Posifeed™ four-drive-roll system. Four all-gear-driven-drive-roll carriers grip the wire more positively than a single-driven wheel/idler wheel arrangement. The wire drive system is designed for easy loading and threading of welding wire, while an independent jog speed control allows Yellow Jacket’s operators to set jog wire feed speeds independently of welding speeds. This alleviates bird’s nesting when feeding wire into the gun. A solid state speed control and brake circuit provide excellent speed control and wire regulation and increase service life over systems with electrical/mechanical relays.
Gearing Up
Before March 2001, Yellow Jacket had five employees, miscellaneous Miller power sources and an extensive knowledge of how to design mufflers and bend and shape tubing. The ability to outsource both design and manufacturing attracts customers, especially those that find it difficult to get muffler configurations that meet their needs or those without in-house capabilities.
“The ATV customer gave us the muffler’s length, diameter, inlet tube diameter and location of outlet tube. How the muffler met noise abatement, back pressure and emissions requirements depended entirely on our design skill,” says Marshall.
After winning the ATV contract, Yellow Jacket added 16 more employees and two buildings full of new fabricating equipment. For muffler components where the customer demanded control of weld parameters, Yellow Jacket purchased five S-74DX feeders. For components with less critical tolerances and for an automated rotational welding station, it purchased four S-22A feeders with digital displays and the optional presettable voltage and wire feed speed control. It paired all of these feeders with Miller’s Deltaweld® 302 GMAW power sources and OXO APX450 guns.
“We recommended the Deltaweld because of its remote amperage and voltage control capabilities,” says Smith. “This let us stack all the Deltawelds against the wall and place the feeders at or underneath the weld stations.”
Marshall explains that “the muffler is a small, lightweight item. We wanted to position our work cells as close together as possible so people could literally hand the product from one station to the next. Having only the wire feeder in the cell saves us at least three feet of floor space per cell. It also lets us easily reconfigure the line to improve parts flow. We did that once, and it doubled capacity compared to our original estimate. During peak production season, we can make and ship 350 parts per day.”
Yellow Jacket uses .035 in. diameter ER70S-6 wire and 92 percent argon/8 percent CO2 (or “C8”) shielding for all its welding applications. For short circuit MIG welding, this combination provides good wet-out, keeps the spatter down to eliminate grinding and minimizes smoke. Yellow Jacket tested .023 in. diameter wire for appearance and to prevent burn-through, but it reduced productivity too much.
Fabricating the Muffler
The ATV mufflers start out as steel tubing, stamped parts and two welded subassemblies (the baffle tubes and one end-cap/outlet valve). The outer shell of the muffler is 5 in. diameter tubing and the inlet is 1-1/4 in. diameter tubing, both .065 in. wall thickness (16 ga.). They arrive at Yellow Jacket’s raw materials warehouse in 10 to 21 ft. lengths. An HE&M Sidewinder saw cuts the outer shell tubing into 15-3/4 in. lengths. Using a small press, an operator punches holes for the inlet tube and a threaded coupler for the spark arrestor. Before cutting the 20-in sections for inlet tubing, an operator welds 20 tubes together and cuts them as a bundle to improve throughput.
Wire baskets of subcomponents are then brought over to the main manufacturing building. Here, an Eaton Leonard NC bender puts two 90 bends in the inlet tube. An operator then takes the tube and cuts it in half with a vertical saw. He then fixes those halves in a jig and cuts them in half again. This creates four inlet tubes from the original 20-in. length, which minimizes tube waste. A hydraulic swedging machine then swedges one end of the tube, shrinking its outside diameter to its inside diameter. This enables an operator to hand-fit the inlet tube into the muffler.
To form the inner core of the muffler, an operator takes a 13-3/4 in. long sheet of 18 ga. aluminized steel and shapes it into a tube using a hand-powered three-roll roller (a new Arcotech Urethane roller, which is more precise, will be installed shortly). At the next station, an operator lays the core inside a jig and, inside the core, sandwiches a spark arrestor between two baffles. The spark arrestor is a stamped plate that looks like a fan blade. It creates a vortex that directs particles into a collection chamber. The baffles consistent of two end plates, an inner tube extending from the front plate and three outer tubes, centered around the inner tube, extending from the back plate. The baffles redirect exhaust flow to control sound.
After clamping the jig, the operator makes three plug welds to hold the spark arrestor and baffles in place and six tack welds to close the tube seam. To finish the core, the next operator makes plug welds to secure the baffles and spark arrestor to the core; the aluminized sheet has 15 dime-sized holes for this purpose. This same operator further secures one of the baffles to the inside of the tube with four 1/2 in. long skip welds. The other baffle will ultimately rest against the end cap and does not need securing.
At this point, the core is complete. So that the 4-3/8 in. diameter inner core can easily slide inside the 5 in. diameter outer tube, a hydraulic press flares one end of the outside tube. An operator then wraps a sheet of ceramic fiber insulation around the core, aligns the holes for outlet tube and spark arrestor coupler (the core also has holes punched into it for this purpose), and slides the two tubes together. The next operator tack welds the end caps in place and stacks them next to the rotational welding machine, which Yellow Jacket designed itself.
“Common wisdom calls for using a horizontal weave to catch both sides of the joint. However,” says Marshall, “we found that a horizontal weave blows through the 18. ga. end cap. By using a vertical weave, we can cool the puddle enough to prevent burn through, yet still create a puddle that’s wide enough to catch both sides of the joint and hot enough to ensure good penetration.
“This is where we really start controlling our weld parameters tightly,” he continues. The vertical weave is so finicky that there’s no room to adjust parameters. Parameter control is also critical for the final welds on the muffler, which are the two mounting brackets, outlet valve and spark arrestor coupler. These welds must endure severe vibration. We’re confident that they’ll hold up because of the control we get with the S-74DX feeder.”
Six months after installing its new welding systems, Yellow Jacket Product Manager Rob Brosan states that “Our operators don’t mind S-74DX’s range control, and they enjoy using the feeder. In fact, most of them used the 60M feeders at their previous employer. They report that the S-74DX is more user friendly. The controls on the S-74DX are clearly defined and straight-forward when you want to change parameters or programs. You hit a button and you’re ready to weld.”
For more information on Yellow Jacket Mfg., call 778-4492 or fax (712) 778-4493.