Aerospace Fabricator Reduces Power Draw, Improves Weld Performance with New Fleet of AC/DC TIG Welding Inverters
It’s a big jump from coffee pots and bike frames to flight-critical components for airplanes and missiles, but that’s the exact evolution that has driven Ace Clearwater Enterprises to the forefront as a leading aerospace and power generation fabricator in Southern California. The company specializes in complex formed and welded assemblies. It grew from its beginnings as Ace Welding in the 1940s, expanded with the purchases of tube bending and metal forming facilities, and is now a complete turnkey operation.
Ace Clearwater has experienced consistent growth and is currently at a stage where it is investing money back into its technology to remain ahead of customers’ needs and the pace of innovation. This includes working with The Defense Advance Research Projects Agency (DARPA) and The University of Southern California (USC) on a super computing project that will bring weld stress simulation to the shop floor, purchasing new forming and testing equipment, and updating almost an entire fleet of arc welding equipment with new inverters.
The transition from old transformer-based welding equipment to smaller, more energy-efficient inverters has yielded two specific benefits: reduced power draw (which has helped stabilize power consumption even as the company adds new fabricating equipment in other parts of the shop) and improved w eld quality through advanced AC TIG welding controls.
“It is certainly more efficient in terms of the use of electricity,” says Gary Johnson, vice president, Ace Clearwater Enterprises. “Once the welders got a hold of the inverters and got over the intimidation factor (of new technology), it’s made welding more efficient. It’s much quicker, much cleaner, and the welders would never go back to the old machines.”
Lead Welder Hieu Tran welds a .03-in.-wall 5052 aluminum air duct with Miller’s Dynasty® 350 AC/DC TIG inverter.
All welds are important, but some applications are more hard-core than others. Ace Clearwater specializes in high-end, extreme quality fabrications for power generation and aerospace. This includes hot section ducting, exhaust systems and hydraulic reservoirs—even parts for an unmanned combat aerial system. Customers include Honywell, General Electric, Lockhead Martin, Cessna, Airbus and Boeing.
“If it flies, we’ve got parts on it,” says Johnson.
With the exception of painting, Ace Clearwater takes each part from blueprint to completion. It works with a variety of materials, including aluminum, Inconel, titanium, magnesium, stainless steel and nickel alloys. The company has added tube bending, forming, foundry, machining and hydroforming capabilities over the years to make the company entirely self-sufficient. Complex welding is still the company’s core competency.
“Everything goes to our NDT (non-destructive testing) department where it gets X-rayed or dye-penetrant tested,” says Jose Saenz, welding engineer, Ace Clearwater. “Our welders have to be very, very careful as to how a part is prepared, how it is fit up, and make sure the parts are cleaned. Many people don’t understand that it’s not just welding, but it takes years and years of experience for these guys to get that proficient that, when they weld a part, it’s a good part.”
|New welding inverters have reduced power draw and increased weld performance over old transformer-based machines. The company has replaced 23 units with new inverters.|
The need for new welding equipment at Ace Clearwater was two-pronged: The company needed to replace aging transformer-based units in its fleet that had become too much of a maintenance drag, thus affecting uptime and weld quality; and how to reduce cost associated with electricity usage in the welding application.
Kevin Blankenship of Sims Welding (Long Beach, Ca.), brought in a Dynasty® 350 AC/DC TIG welding inverter from Miller Electric Mfg. Co. to first determine if the machine would meet Ace Cleawater’s strict welding criteria. Lead Welder Hieu Tran worked with Blankenship to test the machine on a variety of materials to ensure it could meet specifications required by Ace Clearwater’s customers. The inverter did everything that a standard TIG machine could do with the added benefit of advanced AC TIG controls (adjustable frequency, extended balance controls and the ability to independently set electrode negative (EN) and electrode positive (EP)—see next section). The economic benefit, however, came in the form of reduced amperage draw.
Casey Breeden, district manager for Miller, tested the inverter head-to-head with the older transformer-based machine at Ace Clearwater’s Torrance, California facility. Both machines were tested on 480 V single-phase power.
Welding at 100 Amps
Welding at 150 Amps
The old TIG machines drew 29.5 amps at idle compared to .4 amps with the new inverter. Sitting at idle is common in shops as a welder won’t turn off the machine during breaks or in-between fixtures. The savings continued when an arc was struck: 4.5 amps vs. 16 amps while welding at 100 amps, and 6.9 amps vs. 17.1 amps while welding at 150 amps. Taking into account that Ace Clearwater runs two shifts each day, rough calculations estimate that annual electricity savings, combined with productivity efficiencies and quality improvements (reduced rework), allow for a three-year payback* on the new machines—still within the fleet’s original warranty.
Ace Clearwater now runs 23 new TIG inverters off 480 V three-phase power, which reduces the power draw even further. Old TIG machines typically only run off single-phase power whereas new inverters offer fabricators the ability to run off either single- or three-phase. Having the ability to run off three-phase power also increases the duty cycle (time a machine can run at a rated output in a 10-minute period ) of the machine.
There is also a substantial size and weight difference between inverters and old transformers. The old machines, often weighing 400 lb. or more, anchored the entire welding cell and limited the placement and movement of fixtures. The new inverters take up considerably less space, are positioned on a wheeled cart, and are much easier to move around.
“If you look at the older machines, they are two-, three-feet wide by about four-feet long,” says Saenz. “Now, it doesn’t sound like much, but when you think about that in a welder’s booth where he has to have his machine, his toolbox, a workbench and then the tooling that is being used at the time, if you can save a little bit of space to make it easier for that welder to get around and weld the setup, it’s important.”
Advance Controls Simplify Welding on Difficult Alloys
Switching to an inverter with advanced AC TIG controls gives Ace Clearwater the power to finely tune the weld profile and appearance to its application. The biggest benefit to the welding staff is the ability to adjust the AC frequency on the new inverters. The AC output of conventional TIG welders is fixed at 60 Hz (the frequency of the primary power). Conversely, new inverters give the welder the power to adjust frequency between 20 and 400 Hz. The arc becomes more focused as frequency increases, improving penetration, reducing arc wander and creating a smaller heat affected zone.
This adjustability is particularly helpful on thin aluminum components where varying degrees of aesthetics and penetration are important. Jeffrey Berg, welder, Ace Clearwater, regularly welds a 6061 T-6 aluminum air-cooled fuel cooler for jet fighters. The thicknesses he encounters range from .006 to .250 in. Certain gaps between super thin aluminum components require a deep penetrating pass and then a wider cover pass without blowing through the piece, something that has been made substantially easier with the adjustable frequency and the ability to focus the arc.
“With the other machines, you really didn’t have control over the way a weld looked other than to adjust your speed,” says Berg. “I can move the frequency up high enough (400 Hz) to get the penetration that I want for the first pass, and then turn the frequency back down (120-140 Hz) for the cover pass.”
New inverters feature additional adjustment options that are beneficial to thin aluminum applications. Independent AC amperage control allows Ace Clearwater to independently set the electrode negative (EN) and electrode positive (EP) amperage values. More current in EN than in EP produces deeper penetration and faster travel speeds with minimal cleaning action and less heat on the tungsten. This allows for a smaller tungsten and narrower bead profiles.
Inverters also have a 30- to 99-percent electrode negative balance capability, while most conventional TIG machines have approximately 45 to 68-percent electrode negative balance. Berg and Tran prefer to keep their electrode negative balance set at 75. The higher balance on the electrode negative side offers more penetration and maximizes electrode life. The overall quality benefits are obvious to Saenz, who measures overall success by the quality of the final product:
“When the guy has better control over the bead than with the older machine, we’ve been seeing the quality of the weld go up and we’ve had fewer rejections compared to what we had before.”
“The control of the inverters is much better than on a regular transformer with 60 Hz,” says Saenz. “They’re physically smaller, so they’re easier to move around the shop. Once they learned how to adjust it with the new controls they could easily relate it back to what they did with the old machines. And, of course, the added benefit was that they were drawing a lot less electricity, which makes them more economical.”
* Takes into account dealer pricing and trade-in value of old equipment