What’s New In TIG Welding?

February 2012

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The benefits of inverter technology and wireless TIG remote foot controls

TIG inverter technology helps companies with better part quality, increased productivity, space savings and reduced power draw. Additionally, wireless remote TIG foot controls can provide numerous benefits in productivity and reliability.

TIG welding inverter technology isn’t new—inverters have been available for years. The welding industry, however, is a major proponent of the “if it’s not broke, don’t fix it” philosophy. As such, the old transformer-style machines of the past are still used extensively in manufacturing and fabrication facilities around the world. While these machines are reliable, they are energy hogs that don’t feature the latest TIG welding advancements, and if that weren’t enough, they take up valuable space on the shop floor.

The case for TIG inverters

We hear it all the time: “My Syncrowave has run for 20 years.” Those machines are built like tanks, and we’re extremely proud of them. However, TIG technology has evolved (and continues to evolve) to a point where the ROI and long-term savings (i.e. profit) with inverters make solid business sense. Key features include the ability to independently set electrode positive (EP) and electrode negative (EN) amperages, expanded AC balance and frequency controls, and DC-pulsed TIG controls that far surpass old technology at up to 5,000 pulses per second. They also draw substantially less power and take up a considerably smaller footprint on the shop floor.

The key benefits of an inverter-based power source:

·    Improved productivity: faster travel speeds, improved deposition, and less rework and clean-up

·    Improved quality: superior arc control (AC), expanded pulsing rates (DC), better control over heat input into the piece, less distortion, better preservation of base metal    microstructure, narrowed weld bead and heat affected zone, and more accurate weld placement through directional control

·    Energy savings: reduces your energy draw (possibly lower bills) and allows for more units to run off existing power (expanded production)

·    Space savings: smaller, compact machines help with the flow and layout of production  

As an example, today’s TIG inverters — such as the 350-amp Dynasty 350 specified by Aluwind, a leading green industry manufacturer based out of Castle Rock, Colo. — give the operator the ability to adjust AC balance and frequency beyond the limits of older technology. This proves extremely helpful in aluminum welding applications where cleaning action (removing oxides) and penetration are equally important, but where a different balance of each might be required from joint to joint.

“Allowing you to independently set your balance and frequency gets you the best weld you can get,” says Nathan Smith, shop foreman, Aluwind. “With balance, you’re either going to get better penetration or better cleaning. Since we weld on thicker materials, we tend to go with quite a bit of penetration, upwards of 75 or 80 percent electrode negative or (EN).”

Today’s inverters allow operators to set the EN portion of the cycle up to 99 percent. This extended balance range allows for the arc to be fine-tuned according to base metal conditions in each application. If there is a heavy-oxide layer that requires more cleaning, that EN portion of the cycle can be lowered for more cleaning action (65 percent is a good starting point). If the bead is too wide and etching is seen at the sides of the weld, it allows the operator to turn the balance up to narrow the bead, direct more heat into the part for better penetration and increase travel speeds. Also, EN and electrode positive (EP) cycles can be set independently to further fine-tune the arc and extend tungsten performance.  

Another benefit is the ability to change AC frequency. Older TIG technology is typically locked in at the line frequency: 60 hertz in North America and 50 hertz in other locations around the globe. New inverter technology gives operators the ability to dial that in between 20 and 400 hertz. Higher frequencies limit the time that the arc expands on each half cycle, creating a narrow, focused arc with significantly better directional control, ideal for welding in corners, on root passes and fillet welds. Lowering the frequency creates a softer arc with a wider puddle, ideal for gaps and build-up.

“The frequency is going to let you go from a larger wide arc to a narrow arc to focus your heat more in one spot and to get better penetration,” says Smith.   

The ability to exert that greater control over the arc shape and the heat being put into the weld arguably provides its greatest benefit at the start of the weld. Advanced AC controls make it easier than ever to get the puddle started and moving along — a regular challenge with aluminum.

“The biggest thing I’ve noticed is the heating of the material,” says Tina Madrigal, a welder with Aluwind. “With older machines you would either have to preheat the thicker stuff or just pass your torch over it until it got warm enough that you could start your puddle. With this new technology, it’s pretty much just hit and go. It starts the puddle right away.”

Inverters provide power, space savings

Modern TIG inverters are extremely efficient compared to older transformer-based machines. OMF Performance Products’ owner, Tim Orchard, previously ran a 350-amp squarewave TIG machine that would draw 110 amps off the shop’s 208-volt input power. Orchard reports that the previous machine maxed out at about 25 percent less power than he needed. Switching to the 700-amp Dynasty TIG welder actually reduced the amp draw down to 70 amps max and allowed OMF to increase amperage (up to 500 amps) and switch to a smaller filler rod (1/8 in.).

“As far as inches per minute (IPM) of weld,” claims Orchard, “we probably went up a minimum of 20 percent.”

The inverters have also helped in terms of power infrastructure. In Southern California, where industrial space doesn’t allow a lot of room for expansion, extra space and resources are at a minimum. In addition to the increases in production, OMF has seen a reduction in its power bills and has been able to set aside two separate work areas (one for MIG, one for TIG), whereas the company was previously limited to one work area for welding that was taken up by a much larger, less-mobile transformer-based welder.

“We rent space, we don’t own. Every square foot costs X amount of dollars,” explains Orchard. “We also—because we rent—have to deal with the electricity that is in these buildings. Bringing in more electricity is out of the question because we don’t own them. So we just can’t afford to spend a lot of money. With our other machines, at one point when we were in heavy production (seven to eight welders at a time), we rented a whole extra building just to get the electricity. When we started going with the inverter machines, we didn’t have that problem. I would say, conservatively, we’re seeing 25 to 30 percent less power draw.”

   
Wireless remote foot controls provide productivity, reliability

Welders are often restricted by the length and cumbersome nature of cords, wires and lead required to lay a weld. These elements slow movement around weld cells, clutter the floor, and create impediments to safety and productivity. A new advancement, however, is eliminating one point of hassle, hazard and cost: wireless TIG foot controls.

Foot pedals are the most common method of controlling amperage. A major limitation to mobility and common source of failure is the remote control cord that connects the remote to the power source. While remote controls offer an advantage by allowing welders to make on-the-fly adjustments, the cord itself gets tangled around weld tables, chairs and fixtures, making it difficult for the welder to reposition around the workpiece.

Three fabricators were among the first to operate wireless remote controls: RAFAB Specialty Fabrication and Big Cat Human Powered Vehicles of Orlando, Fla., and Chart Industries of La Crosse, Wis. While each company presented unique challenges, all three experienced similar benefits from working with wireless TIG remote controls:

* Repositioning the remote quickly and easily around the weld without having to untangle cords improved productivity.

* Whether an extension or the original, remote control cords presented a regular point of wear and failure. Going wireless eliminated these failures and the associated downtime.

* Weld cell safety was improved by reducing clutter and potential tripping hazards.

* They received the same performance, responsiveness and effectiveness as a corded TIG control model.

“We looked at the welding process and for ways we could save time and cost,” says Paulo Camasmie, owner of Big Cat Human Powered Vehicles. “A lot of time is wasted moving around the fixture and, maybe surprisingly, moving the pedal around because of the cord. It’s an afterthought for most people, but if you really clock it, you’ll see that it takes up time. My initial observations showed that moving the pedal around was two minutes within a cycle time of 39 minutes.”

Corded foot controls notoriously become tangled with other cables, table legs, positioners and stands. Welders reposition quite often and must put down their torch and filler metal to untangle and move the remote foot control. Switching to a wireless remote eliminated the unproductive segment of the welding cycle.

“After switching to a wireless remote control we concluded that we were shaving three minutes off the cycle time. If you’re making 10 trikes each day, now you’re saving 30 minutes – that’s one more trike I can build each day.”

Rick Arnold, owner, RAFAB Specialty Fabrication, similarly sees the wireless remote as a method to incrementally increase productivity  and help stay competitive in a challenging marketplace.  

“I have three jobs going at the same time, and I’ll bounce back and forth between three work areas,” says Arnold. “They’re all within 20 feet of each other but there are all kinds of legs and obstructions in the way. Eliminating that is huge. With the economy the way it is, I have to make up 12 to 15 percent somewhere. If I can help do it with this [wireless remote], that’s great.”

RAFAB’s overall savings come from more easily repositioning around the welding benches and the cost savings in not having to consistently replace or repair broken remote-control cords. Many fabricators, like Arnold, find the cost of repairing the cord alone to be too high and simply replace the whole ensemble.

“If I have a choice between putting $180 into fixing a cord and pedal or spending $240 on a new one, I’ll just get a new one and be done with it,” says Arnold. “We’ve always kept two spares, but there were times when we’d go through both of them and damage a third within a couple of days.

 

Overall lifespan of a pedal in my shop is four months (because of the damage done to the cord). If we went through three a year, that’s $720 in pedals per machine, and I have five machines.”

Switching to wireless has eliminated that failure point and extended the life of his pedals. That comes out to a potential annual savings of $3,600 in reduced repair/replacement costs if Arnold has a wireless TIG foot pedal on each machine (he currently only has it on three) and he gets at least one year of service out of it before replacing, and the wireless pedal could last even longer.
 
The savings could be even larger for Chart Industries, the world’s leading supplier of brazed aluminum heat exchangers for air separation and hydrocarbon plants around the world. The massive heat exchangers are as long as 28 ft. and can weigh in excess of 60,000 pounds. Chart has anywhere from 50 to 100 TIG welders working at a time depending on workflow. That level of production chews through one or two remote control cords each week.   

“With the wireless remote, we’re not fighting to get around things anymore,” says Kevin Bigley, weld tech engineer, Chart Industries. “We just pick it up, carry it along with our torch, and we’re right where we need to be.”

Miller Electric Mfg. Co.

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