Spark control

(Photo: WikiCommons)

Your shop might not have a new welding power supply in its arsenal but you do need one - you might not just know it yet.

There is a welding skill shortage in the labour market that might never be fixed, so by steadily evolving their power supplies welding companies are confident their machines can bridge the gap in skilled labour.

"One of the things that is happening with welding technology today, is that we are developing processes that make it easier for the welder to be good," said Greg Stauffer Vice President for Sales Support and Standard Equipment at ESAB.

"We make a new welder productive and a skilled welder even better. That is where the technology is taking you - how do you take something you are doing today and make it better tomorrow?"

Matthew Albright, Product Manager, Welding Equipment for Lincoln Electric said, "Instead of having to train 50 or 100 experts you can train one. A shop should have one person responsible for the welding process, and that person would be there to set the welding equipment."

In essence, the individual operators of the welding power sources do not need to know as much about welding because the machine is compensating.

RELATED: Is welding experiencing a green revolution?

In order for a welder to change operations from one joint to another, or from one thickness to another, they have to understand the intricacies of welding. They need to know about wire feed speed and voltage effect spatter, penetration, deposition, and other factors.

Microprocessor controlled power sources can be set-up so that the procedures are stored in the machine and the operator just has to punch the correct code to access the parameters for the job that is at hand.

"If I can take someone who knows how to weld but does not know how to set the machines, that many not know the relationship between penetration and deposition rate and all those other complex issues and how it effects the process, I can get someone into the shop faster and compensate for the lack of skilled labour that I have funnelling through my environment," said Albright.

"You need someone trained to set the machine. I can take all that knowledge that takes time to train somebody to have them become the decision maker."

Manipulation and control:

Whereas the sparks used to literally fly off the end of a melding gun or rod, power source manufactures want to control the spark. By controlling the spark they can then manipulate it to do what it is meant to do - weld metal more efficiently.

Variables commonly manipulated include voltage, amperage, the relationship between them (volt/amp curve) frequency, amplitude and time, such as the rate of change (current ramp) or duration of a steady state (pulse width).

"There is manipulation of the frequency and amplitude with Pulsed MIG but there is more to it," said Ken Stanzel, Product Manager for Miller Electric.

"The wire comes down and touches a work piece. Once it breaks a power peak occurs. A ball pinches off of the wire and accelerates across the arc column into the puddle. Then you drop down into a background level. What it's doing is conditioning the end of the wire and getting it ready for the next ball at a high rate of speed. The power source is applying and creating heat that is helping maintain the puddle on the work piece and preparing for the next pulse. Another ball shoots across the column as the process continues."

How a power source controls the arc depends on the welding process selected and the condition at hand. The variables being manipulated, and the manner of manipulation, depend on the process, situation and power source at hand.

"Manufacturers such as Victor Technologies incorporate microprocessors and microcontrollers into welding power sources so that they can create the most predictable welding arc possible, as well as controlling the power source's response to unpredictable events," said Tom Wermert, Senior Brand Manager for Victor Technologies.

"Among other factors, superior control improves arc starts, a common point of weld failure, accommodates variations in arc length - whether that's human hand shake, poor fit-up or running over a tack weld, minimizes or eliminates wasteful spatter and helps reduce over-welding."

Wermert states that their Thermal Arc Fabricator 252i samples the welding voltage and current four times every 50 microseconds. "The system brings reference signals into the microcontroller, applies the appropriate algorithms and adjusts the welding output current once every 50 microseconds," he adds. Updating the welding output 20,000 times per second it can detect, react to and control an unpredictable welding event.

It is worth noting that all arcs can be modified. Stick electrodes, sub-arc, MIG, flux core wired and metalcore wire and even TIG arcs can be manipulated to get the perfect arc. "You are talking about DC currents and you are changing the response times of the machine, you are changing waveforms, you can get them to pulse, you can get slow the current rise and you can speed up the current rise. There is really a lot of things you can do to change the arc," said ESAB's Stauffer.

"Some of our advanced systems have 200 pre-programmed welding conditions for different filler materials different wire diameter and shielding gases. So instead of you sitting down and trying to figure out how to make the machine do what you want we have taken the work out of it for you."

By setting up different arc profiles in the machine, a weld operator can move from material to material, from job to job, quickly and with less errors. If you want to short arc stainless steel for a specific job after completing a different job, the weld operator would have to punch in the correct code to reset the arc to be ideal for stainless steel.

Since stainless steel does not like to melt, the proper arcs characteristics would be to slow down the current rise so that you can get a little more arc time before it short arcs so that you can wet the puddle out and get less spatter.

Manipulating and controlling the welding arc is a fine line between art and science according to Lincoln's Albright. "We have very comprehensive programs and engineers who spend their entire day and careers manipulating the arc. We have proprietary technology to control the arc in our machines."

Manufacturers can do things with waveforms that they were not able to do five years ago primarily because of all the welding data that has been collected and analysed over the past many years.

"Now we have access to the data pertaining to welding which was typically hard to get," he said.

"Due to the fact that power supplies can now generate and send data packets to collection systems in order to help companies a comprehensive view of what is happening in their system from a welding standpoint."

Efficiency and savings:

At the end of the day, the manufacturer must see positives to its business in any new technology that is introduced to the shop floor. All industry is concerned with quality and productivity. Large conglomerates and small fabrication shops all need to be as efficient as possible to compete with not just the shop next door but with the one half way around the world.

The benefits from this advanced technology means that set-up time is reduced, the welding process is quicker and fewer parts end up in the scrap heap.

"It allows us to have higher travel speeds, and reduce spatter and secondary cleanup operations without reducing function and weld soundness," said Miller's Stanzel.

"It helps ensure that the work is done right the first time. Aesthetically you find better bead appearance, and a nice looking weld is important in a number of industries."

"Advanced technology power sources increase welding speed and precision while helping compensate for human limitations," said Victor Technologies' Wermert.

"They enable people to 'weld it right the first time' while eliminating activities that compensate for a less-than-ideal weld, noticeably grinding and rework."

Although welding will never shed its image as a power-hungry manufacturing activity, the new power sources are more efficient. Using advanced inverter technology these machines are putting more energy into the arc while drawing less at the plug.

"New modern machines are more power efficient," according to Stanzel.

"Manufacturers have found $100-200 per machine savings per year in electrical use when converting form an older phase control machine to a new inverter."

Inverter-based technology generally offers a 10 to 25 per cent energy efficiency advantage.

"Inverters can also lower primary amperage draw. Circuit breakers are sized to match equipment requirements," said Wermert.

"Using an inverter can enable connecting more pieces of equipment to the same size breaker, eliminate or reduce nuisance trips and reduce the size and cost electrical system upgrades."

The future is better:

While welding is an extremely complex process and a necessary process in manufacturing, welding manufacturers can provide power supplies to industry segments that can compensate or control the behavioural habits of the operator. Besides helping streamline production, "It gets someone proficient faster," said Lincoln's Albright.

"They streamline production by allowing the Quality and Assurance department to verify procedure and follow through faster. They often times increase productivity because of travel speeds, depositions rates. The new power sources reduce spatter so post weld cleaning is reduced. After weld visual inspections can be reduced."

When looking to the future the one main element is the skilled labour shortage that exists and will be continue to get worse. "I think the number one question to ask as we develop machines into the future is how can we make it so the operators can be less skilled but still receive a high quality weld?" asks Miller's Stanzel.

"What we will see is a trend to take and make the arc welding process more user friendly. More and more robust algorithms built into the machines to overcome operator deficiencies. The user-friendly machine will compensate more, acting for the operator and protecting the finished weld. When an operator doesn't have the skills for optimum welding the machine will compensate and the machine will help him complete the job at a high level."