In medium- and heavy-duty industrial welding applications, enhanced weld quality, reduced operating costs and welding productivity reign supreme. Manufacturers in heavy equipment (farm, construction, aggregate and mining), power generation, transportation, railcar, shipbuilding, offshore, structural steel and wind tower industries are seeking every welding advantage they can find. Compounding that factor is the chronic shortage of skilled welders. That said, even the most skilled workforces benefit from the functionalities incorporated into today’s advanced welding systems.
As an example, take the new Aristo Mig 4004i Pulse power source from Esab, which pairs with the Aristo Feed 3004 wire feeder and the user-friendly U6 or more advanced U82 control panel to form a complete welding system, together with the correct filler metal.
The inverter advantage
The Aristo Mig 4004i Pulse is an inverter-based, multi-process welding power source that can be used for various processes. Those can include gas metal arc welding (GMAW), pulsed spray transfer (including modified pulsed spray processes such as Esab’s SuperPulse process), gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW).
In addition to its versatility, users will immediately notice that the Aristo Mig has a footprint that is 80 percent smaller and weighs 70 percent less – almost 100 pounds – than conventional technology power sources with a similar output. The Aristo Mig has an output range of 4 to 400 amps, a 60 percent duty cycle at 400 A/36 V and a 100 percent duty cycle at 300 A/32 V; the machine operates from a 380 to 460 V (+/-10 percent), three-phase supply at 50/60 Hz.
The compact size (17.5 in. high by 24 in. long by 9.8 in. wide) and light weight especially help fabricators that want to move their welding system around a large weldment, have limited space in their welding cells or want to mount the power sources on a mezzanine or pedestal to get it off the factory floor. Inverter technology also means that the Aristo Mig can help lower utility bills, as it has energy efficiency of 88 percent and a power factor rating of 0.94 (with a 1.0 power factor being perfect).
While mobility and power savings are attractive, the real benefits come from the system’s advanced capabilities, many of which are controlled from the U6 or U82 panel. For example, they offer up to 250 pre-programmed synergic lines. Operators start by selecting the welding process (GMAW short arc/spray transfer, pulsed spray or SuperPulse), followed with the wire type by AWS classification, shielding gas type and wire diameter.
Once those selections are made, the system sets the optimum welding parameters for those variables using its synergic lines. It then displays the data on the panel interface. The Esab-designed synergic lines also help the operator avoid globular regions between short arc and spray arc where the arc becomes unstable and generates excess spatter.
With each synergic line, there is a start and stop data set as default. Some of those functions (creep start, hot start and crater fill) can be activated by using the keys on the interface. To further fine-tune the weld settings, the start and stop data can be customized and subsequently stored (the U6 has a memory to store up to 10 welding schedules; the U82 can store up to 255). In addition, the U82 enables users to create customized synergic lines specific to their application, further optimizing performance. Activating the trigger switch enables users to switch between preset weld data during welding by quickly double clicking the torch trigger.
With the U82 panel, users can set limits on voltage and amperage, ensuring that operators can’t step outside of a set welding procedure. Further, once the weld data has been set, the control box can be locked, preventing unauthorized personnel from changing the data. Additional quality functions include storing data on the last 99 welds; monitoring production statistics, such as arc-on time and quantity of wire consumed; and exporting statistics and procedures using a USB connection.
Some of these functions are mandatory for users of this type of equipment, including Väderstad-Verken in Sweden, one of Europe’s biggest manufacturers of farm machinery for soil preparation and seeding. Recently, the company expanded its welding equipment with 10 new Aristo Mig 4004i Pulse systems, which also run such Esab filler metals as metal powder core Filarc PZ 6105R and OK AristoRod 12.50 solid wire. Väderstad has worked with Esab for more than 15 years and together they have written a specification regarding how a welding machine for Väderstad should be set up.
“As an example, a welding machine must have programmable presets,” says welding manager Johan Andersson. “The welder should not have to waste time on settings between jobs; he should be able to do it from the welding torch.”
In a fabrication facility with 10 operators all using the short-circuit GMAW process on the same component, there’s a reasonable chance you’ll find 10 different opinions on the settings that constitute a perfect arc. On top of that, operators new to the production line might have trouble consistently setting parameters.
To harmonize parameters between workstations, using one of the provided synergic lines in combination with the limit and lock functions is a good place to start. But, there’s another way that might have more operator appeal: QSet.
QSet artificial intelligence is an innovation that improves the efficiency of short arc welding. To use QSet, operators push a single button and then weld for eight seconds on a sample of the actual joint they plan to weld. QSet then automatically selects the optimal short-circuit frequency for the gas/wire combination installed.
By varying the number of short circuits per second and the duration of the short, along with other variables, the machine provides ideal weld pool conditions and consistent weld quality. It can also lower spatter levels for reduced post-weld cleaning. QSet even adjusts for variations in electrode stick-out, such as when operators are welding in a deep corner or groove.
QSet, as well as all of the Aristo Mig’s synergic lines, provides for easy weld pool heat adjustment. To weld “hotter and faster” or “colder and slower” when shifting from the flat to vertical position, for example, operators simply adjust wire feed speed up or down. The system automatically adjusts all other welding parameters to maintain optimum performance. By eliminating the technical adjustments, QSet frees newer operators to focus on gun manipulation and technique.
Pulsed spray and SuperPulse
Traditionally, manufacturers and fabricators selected the short arc process for reduced heat input, especially on thinner sections of stainless steel and aluminum (from 0.187 in. to 5/8 in. thick). With stainless steel, thermal conductivity is poor, which means that it’s highly prone to warping. Excess heat also “burns out” the alloying elements, which can severely degrade mechanical properties and reduce the material’s ability to inhibit corrosion.
Conversely, aluminum, because of its excellent conductivity, is highly prone to burn through and – in what may seem a contradiction – incomplete fusion. The potential for poor fusion occurs because the weld pool solidifies too quickly and because the short arc process doesn’t have sufficient heat to penetrate through the root of the weld. This is especially notable on square butt joints and fillet welds.
Pulsed spray and SuperPulse (technically a modified pulsed spray transfer process) overcome the limitations inherent in both the short-circuit GMAW and conventional spray transfer processes. With the pulsing processes, the Aristo Mig pulses the arc between a high peak current that promotes metal transfer and a low background current where no metal transfer occurs but the arc does not become extinguished. By varying the amplitude, duration and frequency of the peak and background current, the system can more efficiently control heat input while ensuring excellent fusion.
Not only does the process reduce spatter with little to no post-weld cleanup required, it also promotes faster travel speeds and enables all-position welding and using larger diameter wires across a broad range of metal thicknesses. When using SuperPulse, a GTAW-like bead appearance is produced. In short, the process can increase productivity and quality while reducing weld costs in many operations.
When first introduced, pulsed spray systems offered a handful of canned programs. If one of those programs didn’t work well, it took an expert to modify them. Today, the Aristo Mig system with the U82 control panel features 18 synergic lines dedicated to pulsed spray, including those for carbon steel, duplex steel, GMAW brazing, nickel-chromium-molybdenum and five each for stainless steel and aluminum.
These synergic lines provide out-of-the-box functionality for about 95 percent of all stainless and aluminum applications. And, the system enables experts to program and store custom synergic lines, such as for welding other alloys.
As previously mentioned, SuperPulse provides a GTAW-like bead appearance. Traditionally, many operators enhanced this appearance by manipulating the gun with a whipping motion, directing the wire from the leading edge of the puddle back to the middle of the puddle and back again to the leading edge. It’s important to know, though, that this type of manipulation can add unintended variables.
To produce the classic “stacked dime” bead appearance without any gun manipulation, Esab developed the SuperPulse process. Even better, SuperPulse enables operators to easily adjust the distance between “stacks.” By combining excellent, customizable bead aesthetics with a consistent travel speed, the Aristo Mig satisfies the needs of welding operators, supervisors and quality control personnel alike. Coupled with other features that appeal to operators, supervisors and owners, Esab believes that more fabricators and manufacturers should examine the benefits of advanced systems such as the Aristo Mig.