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Inverter/Wire Feeder Package Provides Simplicity, Portability and Multi-Process Benefits to Equipment Repair Outfit

Executive Summary

JR’s Welding relies on the extreme portability and ease-of-use of Miller Electric Mfg. Co.’s XMT® 350 VS inverter and SuitCase® X-TREME 12VS wire feeder to perform field repairs on heavy equipment.

The compact package provides the following benefits:

JR's Welding Relies on Unique Wire Feeder/Inverter Package From Miller

"When it comes to repairing heavy equipment, we have time to do it right, but we don't have time to do it over," says Jeremy Bohm, owner of JR's Welding, Pulaski, Wis. In theory, doing it right the first time is a desirable goal for most. In practice, however, getting it right the first time is mandatory for Bohm. At JR's Welding, where Bohm and only one employee specialize in heavy equipment repair, quality work is done in a timely manner-but quality always comes first.

To put theory into practice, Bohm must simplify by using the "least" equipment possible to get the most work accomplished without undermining quality. The company rebuilds heavy equipment, such as buckets, booms, blades, or a variety of heavy equipment that has been worn by excavation or abrasive applications (roadwork, mining, farming). Bohm and his employee, Rick Naparalla, regularly perform on-site repairs in their shop but are often called on to do repair work on-site in situations where customers can't bring their equipment to the shop. As a result, Bohm prefers welding equipment from Miller Electric, which provides him with the required benefits of portability, simplicity and multi-process flexibility while not compromising on performance. For these reasons, Bohm's favorite welding system combines the lightweight yet powerful XMT® 350 VS inverter paired with a SuitCase™ X-TREME™ 12VS portable wire feeder.

Whether your company makes heavy equipment repairs in-house or subcontracts repair work, advice from industry expert Bohm can help improve your operations.

Build-up Repair

Because many of JR's customers specialize in re-building roads, they often do the repair work on large excavation buckets used to unearth pavement and other abrasive materials. In these cases, buckets are being used to move concrete, rock and dirt, an abrasion-resistant application versus a more impact-resistant process (such as a hammer mill used to pound concrete). The bucket effectively "scratches" the earth (low-stress abrasion) but also receives prominent gouges from its impact against concrete and rock (gouging abrasion), causing significant wear to the bucket. The surface of the bucket develops cracks, which are repaired by air carbon arc gouging out the material surrounding the fractures and filling them in with new metal (see photo).

When a bucket develops a crack, the area must undergo a process of gouging and grinding. But even before gouging takes place, the crack must be analyzed to determine the appropriate method for repair. If Bohm can see a fatigue crack on the bucket (or on any thicker material), he typically sends it out for stress relieving, a process of bringing the steel to a higher temperature and slowly cooling it in a controlled manner. The controlled heating and cooling process restores the metal to its proper temper, where simple air-cooling will cause the steel to become brittle.

JRs Welding prefers the XMT 350 VS/SuitCase 12VS wire feeder/welder combination for its unbeatable combination of portability, simplicity, multi-process flexibility and arc performance

A fatigue crack looks different than a tear; it may have a jagged break to indicate that the area has been under consistent pressure or experienced significant movement. Bohm and Naparalla must gouge out the fatigued material and grind the surface so that the "non-fatigued," clean area can be filled in with new metal. A tear, or catastrophic failure of a part, happens suddenly and doesn't require stress relieving because the temper of the metal surrounding the tear remains intact.

Beyond the cracks that occur are areas that simply wear away to the point of needing repair or replacement. For worn parts, such as the seams and teeth of a bucket, Bohm must grind the surface clean and build the area back up. The wear on only one seam of a bucket may require seven or eight weld passes to repair (see photo). Where extreme abrasion occurs, Bohm flame cuts a pattern that matches the worn out area and welds it back in (see photo). Depending on the severity of the damage, a large bucket used for removing concrete pavement may take 24 to 30 hours to repair.

Because the base metal of the excavation equipment, typically low-to-medium alloy carbon steel, is being "pulled apart" or adjusted by the abrasive impact, the application requires a filler metal with high tensile strength. As a standard, Bohm uses gas-shielded (100 percent CO2) .045 tubular flux cored wire (classified as E71T-1 or E71T-9 by AWS), designed to produce high deposition rates for the all-position welding required to repair the heavy equipment. The fast-freezing slag, while it's dirty, actually provides Bohm with a better weld; post-weld removal of slag isn't necessary.

Extreme Portability

In order to get it right the first time, Bohm must choose his equipment wisely. With only one employee, often traveling to job sites, he needs equipment that offers portability, as well as multiprocess flexibility. Further, because Bohm needs to travel between sites, he doesn't want "more" equipment, just equipment that provides him with the features he needs to make quality repairs in a timely manner. For these purposes, Bohm pairs Miller's XMT 350 VS inverter with the Miller SuitCase X-TREME 12VS wire feeder.

The X-TREME suitcase-style" feeder allows Bohm to easily travel from the shop to the field because it weighs just 35 lbs. It is a "voltage sensing" model that requires only one cable between the feeder and the welder (e.g., no need for a remote supply cord, which is just one more item to carry and connect). When a customer needs something fixed in the field, Bohm must act quickly.

"It's always a breakdown, and the customer needs it repaired immediately," says Bohm. "They call you today, but they want it done yesterday, so I need to be able to pick up and go. This feeder makes it easy for me to travel around."

In the field, Bohm can leave the XMT on his truck and carry the X-TREME to the repair site, providing the portability he needs to respond to varying conditions. "Our work here varies drastically," says Bohm. "You might be doing one thing in the shop in the morning, but in the afternoon you might have the X-TREME in the truck out in the field working. And if it's difficult to maneuver your truck so that your power source is close to the repair, you just have to carry the feeder a hundred feet or so, not the whole works."

For loading 25- or 33-lb. spools of wire, Bohm appreciates the feeder's new easy-open case and drive-roll operation. "I like the way it opens up," says Bohm. "You don't have to pick it up or tip it over to change the wire spool. You can leave it upright and just flip the lid open. The drive rolls are very easy to adjust, so the process of changing spools is much faster with the X-TREME than with other feeders I've used."

A Perfect Match

In the past, contractors often adapted CC power sources, designed for Stick/TIG welding, for spray transfer MIG and flux cored welding by adding a voltage sensing wire feeder. Today, many engineering firms, construction companies and building codes no longer allow flux cored welding with a CC power source. It does not provide adequate assurance that the weld is being made with the proper voltage because operators must hunt for a voltage off a volt/amp curve. With the XMT 350 VS inverter, Bohm has the benefit of both constant voltage and constant current for flux cored welding and gouging, because this inverter is a true CC/CV power source.

When the XMT VS is paired with the X-TREME, the job becomes even easier. "These machines make it easy to switch from Stick application mode, where we do our gouging, back to the voltage sensing feeder mode for welding," says Bohm. "For our repairs, the XMT and X-TREME offer the features we need."

The digital meters on the SuitCase X-TREME 12 VS feeder and XMT 350 VS inverter enable operator Rick Naparalla to easily set and confirm welding paramters.

The panel of the XMT provides a simple set-up procedure with a four-position process switch and easy-to-read digital meters. Bohm selects the welding process and sets his voltage (typically at 28.5 volts) on the XMT, then he sets his wire feed speed (375 IPM in this case) at theX-TREME feeder which also displays wire feed speed and voltage while welding on its digital meters. In addition, the XMT's single arc control knob allows Bohm to customize the arc characteristics. When carbon arc gouging (with the machine set in the Stick mode) he sets the arc control knob for maximum dig to produce the best gouging performance. When wire welding, the arc control knob adjusts inductance, and Bohm is able to fine tune the arc for proper wetting and minimum spatter.

To further enhance the duo's performance, Bohm uses a Bernard Q-Gun with Centerfire consumables. With the gun's rotating nozzle, built-in spatter shield and quick-change tip, Bohm recognizes increased productivity by avoiding common problems. "The rotating nozzle allows me to get into places where I normally wouldn't be able to get at, and the quick-change tip is a big plus," says Bohm. "The 'drop-in' design makes it simple to change tips, and we eliminated any problems with BBs (spatter) in the threads-not that much spatter gets in there because of the spatter shield. Now, we spend a lot less time changing tips."

Twice as Nice

Together, the XMT and X-TREME make an extremely durable, portable package for quickly moving to the field. "The 350 is nice and light, so we can slide it into our trailer, grab the feeder and get on the road real fast," says Bohm. "And that SuitCase has an extremely tough case. The case on my other feeder wasn't as tough, plus it was very big and bulky."

Occasionally, Bohm leaves his trailer in the field, but he doesn't worry. A couple of months ago, he took his equipment on the road, left the trailer at the jobsite and came home only to realize that tornadoes were ripping through the area. "I came home, looked at the T.V. and saw right where we parked the trailer," says Bohm. "Then I saw the tornado, right there, coming through on the highway. I thought the equipment was gone. I got there the next morning, and there was a tree across the road, but the equipment was fine."

Additionally, when coupled with the X-TREME, the superior arc characteristics of the XMT make bucket repair a simpler task than with systems Bohm has used in the past. "The XMT runs a lot smoother than other machines I've used," says Bohm. "I've got more arc control, and it makes a world of difference. And with the X-TREME's start control (Soft Start), I get a much smoother arc start without popping or flaring."

Although the XMT 350 VS weighs just 80 lbs., it provides enough power for operator Rick Naparalla to air carbon arc gouge at 425 amps to remove bad (fatigued) metal from this excavator bucket.

When it comes to his welding equipment, Bohm knows what he needs-and what he doesn't need. When it comes to repairing heavy equipment, Bohm knows what he needs to do. "We strive for quality first, that's what we do," says Bohm. "Our customers like that, and they keep coming back."

Welding Systems Made Easy

For heavy equipment repair, Bohm needs simple, portable, multi-process welding equipment, but he doesn't want to sacrifice important features for simplicity. With the XMT 350 VS and 12VS-now offered as a package from Miller-he has found the perfect welding system. For carbon arc gouging and welding heavy equipment, Bohm needs multi-process flexibility but doesn't need the remote control capabilities found on most CC/CV inverters. The XMT 350 VS offers a simple solution and, along with the X-TREME, provides the portability and flexibility Bohm needs to move from the shop to the field without compromising on quality and performance.[ENDPARA}

XMT 350 VS

* Single process selector switch with only four options: Stick, MIG, Lift-Arc™ DC TIG and scratch start TIG

* Simpler control panel (no 14-pin remote control connection and corresponding operating modes as on the full featured model)

* Auto-Line™ primary power management technology, which provides the following benefits: lowest amp (17.8) draw of any inverter in its class(a benefit for construction sites starved for power), the ability to connect to virtually any primary power (190 to 630 VAC) and the ability to maintain a steady arc despite primary power fluctuations. On 460 VAC the line voltage compensation is an amazing +37%, -59%.

* Wind Tunnel Technology™, Fan-on-Demand® and Miller's industry-leading reliability

SUITCASE X-TREME 12VS

* Short circuit or spray transfer MIG with CC or CV power source

* Most durable case design available in the Industry

* Enhanced duty cycle of 425 amps at 60 percent

* Digital meters, trigger hold, gas solenoid and contactor standard

* Advanced electronics for superior arc starts and overall weld quality

* Potted and trayed main board for the harshest enviroments<-->

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