TIG welding is often considered the hardest manual welding process to learn. It is a slower process than MIG or stick welding and it requires more patience, coordination and practice. Not
only does TIG welding require a steadier hand, it also involves using two hands. The welder controls the travel speed and maintains a good arc length with one hand while feeding the tungsten electrode with the other hand. Oh, and let’s not forget that there can be a foot pedal involved.
“The user skill, hand-eye coordination and training needed to be good at TIG welding can take months to develop,” says Sean McKeen, application engineer, Perfect Welding, Fronius USA LLC. “It takes muscle memory and coordination to make quality welds consistently. Control of the weld pool is both easy and hard; easy in the sense that the pool and arc go exactly where the welder points the tungsten, but hard in the sense that every little movement will show up in the finished weld, so the welder can’t be too shaky.”
TIG welding is a useful skill to master as the process is considered necessary for many applications. It is often used when a high quality of weld is required but production time isn’t the main concern, such as in the aerospace industry and for pressure vessel and pipe fabrication and high-end automotive work.
In today’s world, one of the ways to improve the TIG welding process is with a better power source. Features such as targeted heat input and improved ignition offer maximum control. Although many welders might not need to invest in advanced equipment – some of the technology benefits really only come into play in certain applications – it’s still prudent for those that perform welding to be aware of what’s available in the latest welding technology.
A good start
The scratch start TIG welding arc is initiated by scratching the sharpened tungsten electrode against the workpiece being welded. The scratch start method is a basic process, usually found on low-cost machines. It is not considered user friendly and tends to take out the very tip of the tungsten, leading to a tungsten inclusion.
Two other types of arc starts for TIG welding are considered to work more efficiently. Some power sources have a lift arc start, in which the welder just touches the tungsten electrode to the workpiece and then lifts up to initiate the arc. This is similar to the scratch start method, but it is a little easier for the welder to get the hang of without degrading the tungsten too much.
The most desirable TIG welding arc is the high-frequency start. On newer and higher end TIG power sources, a foot pedal or a switch on the actual torch is used to control the amperage while welding. With a high-frequency start, the welder holds the torch above the weld seam with a proper distance from the workpiece. Once this is done, the welder pushes the foot pedal or switch to initiate the arc. The high-voltage burst initiates the arc without the welder touching the tungsten to the workpiece at all. This makes it less likely to contaminate the tungsten.
The new Fronius iWave TIG power source takes the high-frequency ignition process to a new level. With its RPI Auto intelligent ignition function, the welding system automatically accepts the changes to the ignition settings, including when the ignition worsens, without the need for manual intervention.
“RPI ignition stands for reverse polarity ignition and it allows for more consistent arc starts that are less aggressive and require less energy to strip an electron from the tungsten to initiate the arc,” McKeen says. “The polarity is reversed for the ignition of the arc and immediately switches back to polarity once the arc is established. That provides a more consistent and gentler arc start than the typical DC negative start.”
Further advances
The new iWave comes with a multitude of innovations and also possesses multi-process capability.
For maximum control over the arc and targeted heat input, the CycleTIG feature allows the welder to reliably maintain control of the weld pool and weld even the thinnest material with ease. It’s also helpful for repair welding, such as edge repairs.
“CycleTIG is a new feature offered for precise heat control when TIG welding,” McKeen says. “This feature makes pulse parameters a bit more user friendly because they can be set using a standalone value instead of being based off a percentage of the main welding current. This means the pulsing parameters do not change when the main welding current is changed like it is for the regular pulse parameters, allowing the welder to dial in their weld more easily.”
Traditionally, when the welder changes the main welding current, all the pulsing parameters change, meaning they have to figure out the new pulse parameter based on the new welding current.
“CycleTIG also allows the arc to extinguish between pulses to further remove unnecessary heat input,” he adds.
iWave offers the option of selecting the waveform during AC welding. If required, waveforms can be combined.
“We have the ability to customize both the top and bottom half of the waveforms,” McKeen says. “Everyone offers a variation of a square wave, soft square wave, triangle wave and sine wave. But on some competitive machines, the welder can only set the waveform as a whole. With ours, adjustments can be made to both the top and bottom halves of the waveform. This allows for better arc control in certain applications like edge buildup. We also have an advantage on aluminum because of the number of waveforms we have.”
McKeen adds that on the TIG welding side, Fronius offers a higher duty cycle for the same amperage classes that competitors offer. The iWave, for example, provides 100 percent duty cycle at 400 amps versus a competitive machine that provides 30 percent duty cycle at 400 amps.
In addition to TIG welding, the iWave Multi-process Pro provides access to all MIG/MAG process variants. Starting with standard TIG or standard MIG/MAG applications, the iWave enables upgrades to the full function range, including cold metal transfer (CMT), pulse multi control (PMC) and low spatter control (LSC).
“Most competitors that offer a MIG, stick and TIG machine have to make compromises, McKeen says. “This means the machines might not have high-frequency start or are not AC/DC. Or, the AC/DC machine doesn’t have advanced MIG processes available or the pulse feature is a simplified pulse.”
Another benefit of the high-end power source is welding with cellulose electrodes. Cellulose rods are typically used in the pipe industry when making root passes. A multi-process power source needs to have the power capabilities to keep the cellulose rod lit. These rods are usually run with a longer arc length and manipulated in a way that requires a high, constant power output that most machines can’t offer.
Welder friendly
Today’s power sources feature some type of Industry 4.0 benefits. The iWave supports the main communication standards and is ready for WLAN, Bluetooth and NFC for optimum use.
WLAN enables communication with other devices in the same network with a host of digital advantages, such as central user management, real-time data transfer and rapid updates. The welding system integrates directly into a network via WLAN so firmware updates can be carried out easily.
“Industry 4.0 features include the constant updates to keep up with technology and the ability to hook up and monitor equipment remotely using ethernet or our WeldCube product,” McKeen says. “We’re constantly updating our firmware to stay up to date so the equipment can be integrated easily and to address bugs to prevent stops in production.
“Updating the equipment is simple,” he continues. “A computer with internet connection downloads the most recent firmware, and an ethernet cord connects to the power source for the firmware to be installed in the power source via the smart manager. Our data monitoring options allow users to customize what data is monitored and track parts or defects through the production process, allowing higher quality control and quicker diagnosis of weld equipment or setup issues.”
Peripheral devices, such as remote control or the Fronius Vizor Connect welding helmet, can be wirelessly connected via Bluetooth.
With the NFC card or fob, individual authorizations for each user can be assigned via the integrated authorization system. The system immediately detects what that user may or may not do when they log in with a key card or key fob. For instance, the welder may be allowed to change processes or job numbers, but not change settings.
Additional features are included to protect the power source from damage such as sensing when the equipment is shorted or letting the user know when incoming power from the wall is outside the operating range.
“Typically, incoming wall power isn’t consistent and the stability of the arc has a lot to do with the consistency of the power,” McKeen says. “We use digital high-pass filters and capacitors to clean up the incoming wall power before being rectified to DC to maximize efficiency. So, we need less amperage than other power sources, which allows for less power consumption.”
Sustainability is also a focus. The iWave operating concept, technologies for noise reduction during welding and ergonomic aspects, such as the working height of the systems or the design of the welding torch, all help to improve the welder’s experience. A recyclable plastic housing and components that can be individually serviced and replaced also help protect the environment.
