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Selecting Portable Welding and Cutting Equipment for Maintenance and Repair

Executive Summary

Maintenance manager discusses how a fleet of Miller Electric Mfg. Co’s engine-driven welding generators, wire feeders and plasma cutters create the ultimate maintenance fleet.

Steven Young, Sr. of Murphy Concrete & Construction Company says the following:

Selecting Portable Equipment for Maintenance and Repair

A veteran shares advice, puts new equipment to the test

Steven Young, Sr., uses the Bobcat’s generator power to run a Spectrum 375 plasma cutter.

“Having the right equipment for the job saves you more time than you can imagine, and that’s a fact,” says Steven Young, Sr. This supervisor and maintenance manager for the asphalt division of Murphy Concrete & Construction Company, Inc. (MCC), has more than 30 years of welding experience to back his claim. “Good equipment pays for itself again and again. That’s why I feel a Bobcat™ 250 welding generator, SuitCase 8VS™ wire feeder and Spectrum® 375 plasma cutter from Miller Electric Mfg. Co. are worth every penny. These three pieces of equipment are definitely a no-hesitation investment for plant and equipment maintenance.”

Headquartered in Appleton, Wis., MCC operates Readi-Mix plants, asphalt plants and is a major regional supplier of aggregates and agricultural lime. These highly abrasive substances quickly wear any steel surface they touch during processing and transportation. Young and his crew keep busy cutting out worn sections and welding on new ones. In addition, other divisions tap Young’s welding skill for new construction.

Mobile Equipment

With large, multiple plants, “We need portable and lightweight welding and cutting equipment because we never know where we’re going to be needed from one hour to the next,” says Young. For welding, cutting and auxiliary power in the field, this expert’s “must have” list includes a:

Previously, Young and his crew would cram all this equipment into the back of their service trucks to move it between job sites. Using the acquisition of the new Miller equipment as an excuse to tinker, he custom built a trailer to organize and transport all of his tools (see Fig. 1).

Figure 1.

With the Bobcat, a SuitCase 8VS and Spectrum plasma cutter on a trailer, Young is ready to tackle any welding challenge, such as helping build this new concrete facility.

“I think rigging up a service trailer was the best move we ever made. I recommend it for anyone that needs mobility,” states Young. The trailer saves time because it can be dropped at the job site, which keeps men working when the truck needs to move to another location. There is no need to coil up cables and pick up the tools when making a lunch run, either.

The Bobcat and the compressor ride in the bed of the trailer with plenty of room for storage buckets and materials. Three reels with 100 ft. of welding cable each mount on top of side storage boxes. The plasma cutter, wire feeder and assorted tools go in the storage boxes. Shielding gas tanks and oxy-fuel tanks go in a rack in the front. Near that, a reel holds 50 ft. of hose for oxy-fuel; a PVC tube holds the oxy-fuel torch.

Equipment Specs

When considering an engine-driven welding generator for general maintenance and fabrication, professionals look for one with the following features:

At least 9,500 continuous watts of Accu-Rated® generator power for plasma cutters, tools, lights, etc. Look for a machine with good simultaneous welding and auxiliary power (see Fig. 2), which will improve productivity when you need to run tools while welding (see Fig. 3 for typical tool power requirements).

These engine drive specs are largely predicated on the fact that Young prefers to flux cored weld whenever possible because it provides excellent penetration, works well on dirty and rusty material and works, within limits, in windy conditions.

* The number of minutes out of a 10-minute period a machine produce an arc at maximum rated output. At 100% duty cycle, a machine can operate non-stop

FIG. 2


FIG. 3


When choosing an engine drive for flux cored welding with larger diameter wires or 200 ft. or more of cable, look for one with a strong voltage rating. The 1/16-in. diameter, gas-shielded E71T-9 wire Young prefers calls for welding at 210 to 250 amps and 23 to 26 volts. Long cable lengths also affect CV welding performance because voltage at the arc drops with cable length. For example, a 2/0 AWG cable loses about 4 volts over 200 ft. with a 250 amp DC welding current.

Since the Bobcat welding generator has a maximum output of 28 volts, it “has plenty of juice to spare,” says Young. “The Bobcat is a great general-purpose flux cored machine. Its arc is as good as anything out there,” according to Young.

Process Payback

Many welding operators prefer traditional repair tools: a Stick rod and an oxy-fuel torch. Young believes much more in productivity, especially when his crew gets stretched thin by peak season work. That’s why Young has been a long-time fan of flux cored welding and a new fan of portable plasma cutters.

“I get more work done by far with flux cored welding. It out-produces Stick by a 3:1 ratio,” he states.

The smaller versions of portable or “suitcase” feeders weigh less than 25 lb. (empty), hold an 8-in. diameter spool of wire and run wire sizes up to .052 in. Larger suitcase feeders weigh about 30 lb., hold a 12-in wire spool and run wires up to 5/64-in. A portable feeder costs $900 to $1,500, depending on size and options. With a modest arc-on time of 25 percent, or 10 hours out of a 40-hour week, it can pay for itself through increased productivity in just one month of welding (assuming an average labor rate of $35/hour).

“Portable feeders are good for mobility. For example, a cement plant needs welds made 80 ft. off the ground,” Young says. “I’ve got 100 ft. of cable on a spool, so I can park the engine drive and weld all day without moving it.”

Small plasma cutters don’t weigh much more than suitcase feeders. Young’s Spectrum 375 weighs 49 lb., but its 27-amp output can cut 3/8-in. steel at 10 IPM..

“If you can incorporate a plasma cutter into your operation, it will save you half the repair time. That’s worth a lot to a contractor, a farmer or anybody,” he says.

Young uses the Spectrum 375 to cut everything on the job site under 3/8-in. thick, such as installing a new bed liner. He notes that thin (1/8 in. or less) and hardened steels don’t warp. For example, the paddles in an asphalt drier are made from a “tri-braze” steel with a 400 Brinnel hardness. They need to be cut to specific sizes and have slots cut in them for mounting.

“When we cut the paddles with a torch, we noticed warping. We wanted a flat surface for easy fit-up and bolting, so we shifted to plasma cutting and got away from warping,” Young says. “We also get a cleaner cut with less grinding, and we can cut holes or slots with square corners. There are a lot of advantages to running a plasma cutter instead of an oxy-fuel torch.”

The Ultimate Test

Young did not initially consider an engine drive from Miller. Like many people of the Ford/Chevy truck mind-set, he never seriously contemplated another brand. Then his neighbor convinced him to try the a Bobcat welding generator instead of his old brand when one if his six engine drives needed replacing.

The first day Young had the Miller equipment, he set it up in his driveway to test it out. He connected the Spectrum 375 to the Bobcat’s 240V receptacle and three grinders to the 120 V receptacles. Then he invited the neighbors over, turned on the Bobcat and started the equipment—and ran it all simultaneously.

While an extreme test, Young proves a final point when selecting an engine drive: check its generator power capabilities, as machines vary greatly, especially with regards to motor-starting capabilities. Further, some machines provide no useful power when welding, some provide good power with the voltage control set near maximum, and a third class provides the best results because the auxiliary power is independent of the voltage setting. The Bobcat 250 falls in the second category, and its performance more than satisfies Young.

“I don’t know what kind of welding and generator power testing they do at Miller, but I thought we gave the Bobcat welding generator the ultimate test,” Young states. “The guy running the plasma cutter didn’t notice any erratic performance and the grinders ran fine. The Bobcat’s a heck of an engine drive, and I think anyone using a different brand of machine should look at Miller. In fact, I wish I had 100 Bobcats out there with men to run them.”

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