NEW TIG TECHNOLOGY: THE RIGHT CHOICE

Are you a ?Don?t fix it if ain?t broke? person? Or does the phrase ?Change or die!? best describe your attitude?

Professional TIG welders tend to identify themselves as either traditionalists or innovators. There?s room for all types, which is why manufacturers offer a variety of welders. However, fans of conventional TIG welders should consider that switching to advanced TIG will be like going from a plain screwdriver to an 18-volt lithium ion hammer drill/driver: you?ll complete jobs faster, expend less effort and tackle bigger projects without adding manpower. Sure the tool costs more up front ? but you can pay for it with just one job.

The internal operating principles of advanced welders aren?t really important to most welders. However, understanding the capabilities they provide and how to apply them may directly affect your bottom line, as has been the case with the seven companies profiled in this story. These companies report that the core benefits of advanced TIG welders are:
? Superior arc and weld puddle control in both DC and AC applications, which leads to . . .
? Faster travel speeds and greater productivity
? Improved weld quality and better bead appearance
? Optimized bead profile, which reduces over-welding and the need for post-weld grinding
? Easier to learn to weld, simplifying the training of new welders
? Smaller heat-affected zone, reduced warping and better part fit-up
? Lower installation and operating costs
? Precise low-end arc starting, which improves weld quality and consistency

UNDERSTANDING PAYBACK AND ROI
We?ll expand on advanced TIG benefits shortly. But first, it?s important to discuss financial implications. An advanced TIG system costs about 20 percent more than a conventional TIG system. If you?re comparing 350-amp water-cooled torch systems, the street prices will be around $7,700 and $6,300, respectively.

The $1,400 difference might seem like a lot . . . until you consider the value of productivity and quality improvements. For example, A1A Dock Products (Hollywood, FL), a small manufacturer of aluminum ladders, justified a TIG equipment upgrade because the advanced TIG technology increased productivity by 18 percent. ?I didn?t want to change in the beginning,? says A1A president Helmut Grundler, who did not see the value of new TIG welders when his old ones still ran well. ?Then I found out how much better the [advanced machines] welded.?

The economic evaluation shown in Table 1 provides payback and ROI calculations based on actual results from AIA. It adheres to good accounting principles, so it?s literally something you can take to the bank. From A1A?s non-banking perspective, output increased and labor costs stayed the same. Their advanced TIG welder ?bought itself in the first two weeks of operating.?

While A1A derived its savings from labor costs, other savings could come through reduced post-weld grinding, the elimination of rework/rejects, reduced filler metal and gas use, primary power flexibility and energy efficiency. The following sections explain how advanced TIG technology creates these benefits.

SUPERIOR ARC AND WELD PUDDLE CONTROL: DC TIG
A newer technology, high speed pulsed TIG welding involves pulsing at frequencies up to 500 pulses per second (PPS) for manual applications and up to 5,000 PPS for automated applications. Increasing the number of pulses per second:
? Constricts and focuses arc cone, which increases arc stability, penetration and travel speeds, as well as narrows the weld bead
? Reduces heat input for less warping and better part fit-up, as well as minimizes the heat-affected zone
? Produces a smoother the ripple effect in the weld bead, enhancing weld cosmetics
? Increases puddle agitation, producing a better grain molecular structure within the weld

Stainless steel, which is particularly prone to problems related to excessive heat input, is a primary candidate for pulsed TIG. Take the results form H.L. Lyons (Louisville, KY), a manufacturer of stainless steel refrigerator doors that switched from conventional to high-speed pulsed DC TIG. Today, operators no longer need to grind away excess weld bead material because high speed pulsed TIG (specifically, 175 pps) enables them to maintain an optimum balance between bead width and penetration (which also ensures optimum weld appearance and strength).

?It?s a significant reduction in my production costs,? says Keith Lyons, co-owner. ?We?ve reduced the welding time by half and reduced the finishing time by a third. We?re actually assembling now, on one shift, about 30 percent more than we did on three shifts last year.?

CARBON COPY
The potential for general productivity improvements in carbon steel applications means that others should explore the potential of pulsing, as did Barrett Firearms (Murfreesboro, TN), the nation?s leading manufacturer of .50 caliber rifles.

?We set pulsing parameters that enabled me to run faster yet drop the temperature of each welded part by 75 degrees,? says welder Joey Cannon. ?With standard technology, going ?faster? meant putting more heat into the part or using less heat but sacrificing penetration. This new technology allows me to focus the arc, increase amperage, run faster, shrink our heat-affected zone ? all while maintaining excellent penetration.?

Cannon estimates that reducing heat input by 75 deg eliminates about .025 in of warping over the rifle receiver?s 36 in length. While Barrett, like other quality-oriented manufacturers, straightens all components to maintain consistently tight tolerances, this activity takes time. Thus, pulsed TIG not only reduced welding time by two-and-a-half minutes per receiver, it further lowered cycle time because Barrett spends less time compensating for warping. ?When you figure the total cost of everything ? from power savings, to reduced warping to a 45 percent production increase ? the [advanced TIG welder] paid for itself within the first week,? states Cannon.

FANTASTIC FOR NON-FERROUS: MORE CONTROLS FOR AC TIG
The vast majority of aluminum and magnesium applications benefit from advanced AC TIG technology because the new controls now available (see Figure 1) give welders far more tools to tailor the arc to the application at hand.

The technical reason behind these improvements is enough subject matter for a separate article. The important point here is that, ?The difference between inverter and conventional TIG technology is like night and day,? according to A1A?s production manager, Derek Grundler. It ?creates a much narrower weld bead than a conventional TIG,? he says.

?It allows us to direct the arc ? which really helps when welding in corners ? where conventional machines spread out the arc. The technology also lets us sharpen the tungsten like a pencil point and maintain a point, so the arc comes off of the tip? instead of dancing around a balled tungsten and creating a wide bead.

The ability to tailor the weld bead profile, making it only as wide as necessary, eliminated the over-welding typical with conventional TIG technology in fillet weld applications. Joints require less filler metal, so travel speed and production naturally increase ? 18 percent in the case of A1A.

In the case of Vesco Metal Craft (Chula Vista, CA), a fabricator of rugby wheel chairs, advanced TIG technology increased productivity by 30 to 50 percent while improving quality and appearance. ?The [advanced TIG machine] welds phenomenally,? says co-owner Neil Vesco. ?The diversity of the different waveforms ? from welding thick aluminum with a regular advanced squarewave to welding thin aluminum with the triangular wave ? is what makes it ideal as far as we?re concerned. Then add in the ability to set EN and EP current independently, along with the ability to vary the AC frequency between 20 to 400 Hz, and we get better looking, deeper penetrating welds than ever before. Regardless of how we set it up, it welds just phenomenally.?

Tom Vesco, Neil?s father and co-owner, likes the increased productivity and the five-month payback associated with it, but he loves what advanced TIG technology does to VMC?s future. ?Now we have time to do other things,? he says. ?If we?re constantly trying to keep up with orders, we really can?t grow and expand. Now we can devote some time to R&D for other products.?

For growing shops, the ability to train new welders can be a significant roadblock. Fortunately, advanced TIG technology is significantly easier to use. For example, Engineered Metals & Composites, Inc. (EM&C; West Columbia, SC), an OEM manufacturer of aluminum towers and small components for the marine industry, only uses advanced TIG welders for areas where new welding operators work.

?Inverter technology makes the [machine] more user-friendly to a less-skilled welder,? says Ed Forbes, vice president of manufacturing. ?I constantly harp on this fact because it lets us bring in people with almost no experience and make them instant welders. If you take a new person off [an advanced TIG machine] and put that person on a machine with conventional technology, it?s like he?s never welded before.?

LESS TO INSTALL AND OPERATE
In addition to creating productivity and training benefits, advanced TIG technology also lowers installation and operating costs. Conventional welders, especially older ones, are primary power hogs. For example, Barrett Firearms? old welders drew 126 amps on 230 V, single phase power when welding at 300 amps. Conversely, a 350-amp advanced TIG welder only draws 34 amps when welding at 350 amps. Welder Joey Cannon notes, ?I usually run the machine at an average of 120 amps, so we?re probably pulling 5 or 6 amps of primary.?

By switching to advanced TIG technology, Barrett now runs three welders off of the power it previously took to run one welder, which frees power for adding other fabricating equipment. Advanced TIG welders also run off of any type of primary power available (single- or three-phase, from 190 to 630V). This flexibility led to a savings of C$160,000 at the Northern Alberta Institute of Technology (NAIT) in Edmonton, Alberta.

Because conventional TIG welders can only use single-phase power, NAIT would have had to convert 575 VAC three-phase into single-phase power when it wanted to install new welders at 132 stations. Instead, NAIT waited until a new 350-amp welder with primary power flexibility became available. ?Rather than spend C$160,000 on outlets and switching boxes, we felt it was more feasible to spend that money on new machinery [that] eliminated the need to make major electrical upgrades to accommodate the GTAW equipment,? says Bob Clark, associate chair of the welding program at NAIT.

In addition to lowering installation costs, advanced TIG welders reduce operating costs by reducing energy use. In fact, these welders are so energy efficient that they may qualify purchasers for utility rebates. For example, Bellingham Technical College (BTC; Bellingham, WA) received a $1,000 per machine rebate for its 200 amp TIG/stick inverters. These new welders draw one-sixth less amperage and reduce utility bills by an estimated $200 per year per welder.

As attractive as lower utility bills are, the potential for reduced filler metal use could be even more attractive. Miller welding engineers have calculated that advanced TIG technology reduces filler metal use by 13 percent by eliminating over-welding ? which leads to a savings of about $1,400 for a welding station that currently consumes 2,000 lb of aluminum filler rod annually. Note that reduced filler metal use, coupled with increased travel speeds (generally by at least 15 percent) naturally reduces shielding gas use, too.

IMPROVED ARC STARTS
In critical applications, the cost of a quality TIG arc start is almost priceless. For this reason, welders often use a ?run-on tab? (a small block of brass or other metal) on which to start the arc and then carry it over to the workpiece. While solving problems, a run-on tab doesn?t eliminate the root cause of rejected welds, nor can it be used in all situations.

Traditional TIG machines feature a set of high frequency (HF) arc starting points that function in a manner similar to a spark plug gap. Any variability (such as grinding dust, dirt or high humidity) changes the amount of resistance required to bridge the gap, producing arc start variability.

Advanced TIG welders designed for aerospace welding, tool/die welding and other low amperage TIG applications now feature solid-state circuitry and hardware that functions much like a capacitor with an output controlled by a high-speed power switching transistor. This circuit provides more consistent HF arc starts because it eliminates sources of variability. New technology also prevents the current over-shoots that cause burn-through, eliminating the root cause of many rejected welds while positively and consistently starting a DC TIG arc at 1 amp.

Given the price of alloy metals and cost of aerospace components and delicate tooling, an advanced TIG welder could pay for itself by preventing just one or two burn-through incidents ? that?s a fast return on investment. Manufacturers and fabricators interested in experiencing advanced AC and DC TIG technology firsthand should contact their local welding supply distributor and ask for a demonstration in their specific application. Test the unit, experiment with some of the advanced functions and see if they solve problems or improve productivity.

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John Luck is a product manager at Miller Electric Mfg. Co., 1635 West Spencer Street, P.O. Box 1079, Appleton, WI 54912-1079, 800-426-4553, www.millerwelds.com.