My good friend Brent Williams recently left Miller Electric where he was Marketing Manager of The Tig Division.
You might be asking...Why would anyone in their right mind leave Miller?
I am guessing the same reason I left Delta TechOps. When its time to go, you just know.
Oh well. Miller's loss, our gain...because today... I am interviewing Brent Williams with some Tig Welding questions.
So why should you even care what Brent has to say?
Here is why....
Brent is one of the sharpest guys I know.
His unique perspective is built on
years of communicating with Millers Tig customers on all kinds of applications. Everything from a guy who stick welded
stainless drip pans with a foot pedal...to tig welding gold jewelry
where most people would use a laser welder.
And...A few years ago, Brent went on an extensive tour of the aerospace industry in order to learn how to make a better Tig welding machine.
Why aerospace welding? Because in aerospace welding, virtually all metals are used. i.e., Low alloy steel, Stainless steels, Nickel alloys, Aluminum, Magnesium, Titanium, cobalt and more....
Not only is there a tremendous variety of alloys, but some of the welding applications are razor blade type thickness.
So read on...and learn from Brent Williams as I ask him some Tig Welding Questions.
Jody: You were deep in Millers
Tig business for several years and you have even been
responsible for Design and rollout of several Miller Tig machines. I
know what I look for in a Tig welder. e.g., low amp start, sure
start, smooth DC arc, smooth AC arc, good duty cycle, are some of the
main things for me.
There are more settings and features on Todays Tig welders than ever before. Not all of them are equally important. , In your opinion, What are the main factors that make for a good all around Tig welder?
BRENT: There certainly has been a major advancement in TIG welder technology in recent years. The advanced inverter-based power sources of today have come a long way from the traditional equipment that I started welding with. While conventional equipment “did the job,” inverters offer much better arc control & form factor – making them my preferred choice, especially for a TIG welder.
I look for the same things you mentioned – good arc starts, smooth output, adequate power & duty cycle. In addition, I like to have a few extra adjustments for more control – like pulse, AC Balance & AC Frequency. These features help adjust the output for more control – making welding easier & faster while improving quality & reducing rejects.
With all the models & features available, choosing the best TIG welder can seem overwhelming. However, the process doesn’t need to be difficult – just stick to the basics:
Now, there’s a growing concern in the market that involves repair after warranty. Qualified repair stations are becoming more difficult to find & welders are becoming more expensive to repair. So, after the warranty is expired – it’s not uncommon for a major repair to cost nearly the same as a new machine. So, consider the warranty period & parts cost after warranty when pricing your TIG welder machine.
Jody: There are still a lot of folks out there with questions on AC waveshapes.
Not only were you involved with design and selection of waveshapes in Miller Tig units, But you also have quite a bit of experience with High Tech companies like Boeing, Delta TechOps, etc along with plenty end users ( like John Marcella of Marcella Manifolds) that utilize AC waveshaping extensively. What has the end users feedback taught you concerning how different AC waveshapes are applied.
BRENT: AC waveforms have recently become commonplace in high-end TIG machines for industry leaders. With equipment advancements & nearly limitless combinations, the industry is still learning every day. Much of the information we have today is a direct result of working with end-users. My work with end-users taught me a lot about how waveforms affect the arc & the weld. You can only observe & learn so much in a lab environment – conditions are just too ideal & consistent. So, we worked with lead users that wanted to understand how to fully optimize their welds using advanced waveforms. In some cases, they may have been developing a new procedure or experiencing an issue with a particular weld or part & changing the waveform was the answer.
The topic of AC waveforms is being discussed on many different levels – as the industry looks to create standards for consistency. Here are some interesting things that AC waveforms can influence:
Advanced Square wave
BRENT: I’ll never forget my 1st encounter with advanced square wave – it was quite a difference from the conventional equipment I was familiar with. A very square wave produces a smooth, stable arc with great directional control. However aggressive & loud it may be. But, as my first experience with an inverter-style AC arc – it was a significant improvement to the welding arc.
End-users were amazed too. They were able to produce smaller, more precise welds than ever before in AC because of the added arc precision. In most applications, advanced square did a great job – although it was overkill for some. And, in others it actually caused problems. A common issue is porosity – especially on thick aluminum parts. If the puddle forms & solidifies too quickly, porosity can be more prevalent. Typically slowing the process & allowing the puddle to fully develop before adding filler metal will resolve the issue – as it slows down solidification by creating a more fluid puddle & wider heat-affected zone. Aluminum is an interesting material – it’s thermal conductivity is always sinking or removing heat … unlike steel or stainless, that actually hold heat around the HAZ & have a more controlled cooling rate.
Soft Square Wave
with end-users really illustrated the benefits of a soft AC
squarewave. The waveform maintains the benefits of true squarewave –
but the corners are rounded. End-users noticed quickly that the arc
noise was reduced & later, that they had better puddle control.
For most applications, soft-square is ideal. End-users reported a
smooth, stable arc that allowed them to get the work done
Sine or "Sinusoidal"
BRENT: the benefits of sine wave are not so readily apparent, especially as the industry has talked down about it as an inferior option. But, new technology allows the arc to quickly change polarities like a square wave – then return to its classic, rounded shape. The benefit? I nice soft arc that still welds like an inverter. If you just like the feel & sound of a sine wave, or you want that arc characteristic for a certain application – sine is the way to go.
Many end-users that weld anodized aluminum still prefer a sine wave – especially those that use a bump technique. I worked with end-users to develop & refine the AC output so it affected the puddle like an old sine wave machine.
As indicated above, there is quite a bit of science to the AC waveform. As you can imagine, it took many years to discover the benefits of certain waveforms & combinations. The slightest change in an AC waveform can cause instability – so much of my insight was gained from learning what “not to do.”
BRENT: this waveform was included in equipment before anyone really understood the effects, let along any benefits. However, working with leading end-users it was discovered that triangle had some cool benefits.
Jody: Sometimes a 200 amp Tig welder
barely has enough juice for a certain job. In that type of
situation, which waveshape seems to gets the most out of the
BRENT: If you run completely out of power & need to get the most out of your machine – I have a few suggestions for you.
Jody: There is an
ongoing discussion on tungsten electrodes. Back in the days
when all tig welders were conventional transformers, Pure tungsten
was recommended for AC welding of aluminum.
then Zirconiated was said to ball just as well but carries more amperage than pure tungsten and was recommended for X ray quality aluminum tig welding.
BRENT: Yes, the best tungsten is often debated. My short answer is – use what works. But, diving deeper into the subject of tungsten can make a big difference.
Back in the day, using AC to weld aluminum caused the tungsten electrode to ball up or erode. This was primarily due to the heat of the arc. Very quickly it became standard to use pure or zirconiated tungsten because they would form a uniform ball that produced a smooth arc. This ball had a larger mass, so it could carry the heat caused by the electrode positive (EP) portion of the AC wave with limited erosion. Every tungsten does have an operating range – which must be considered … but welding aluminum with a ball produced the most consistent results & was accepted as the proper technique. Zirconium adds to the current carrying capacity of the tungsten, so it was generally preferred for x-ray or high amperage welding because it would hold up better than a pure electrode.
That rule was pretty much true until AC inverters became mainstream. Sine wave & the conventional square wave produced by transformer-based products had very similar balling characteristics in most applications. The introduction of balance helped to extend electrode life over a balanced arc by directing more of the heat into the work, but except for special applications – aluminum was still welded with a balled, pure or zirconiated tungsten.
Does that mean other tungsten electrodes aren’t used with transformer-based units that produce traditional sine or conventional squarewave units? Of course not. Thorium will make an acceptable aluminum weld – but it can form an irregular ball that causes general instability & can be more susceptible to erosion & weld inclusion. More recently, rare earth electrodes like ceriated & lanthanated electrodes improve welding with conventional AC equipment. I’ve actually seen ceriated electrodes take nearly double the amperage of a pure electrode – so think beyond red & green.
Jody:Now we have inverters that allow for welding aluminum using a tapered electrode. Along with AC frequency control, AC balance, and waveshape selection.
really challenged what people knew about aluminum welding. In
reality, inverters changed AC TIG welding dramatically when they made
it possible to weld aluminum with a sharp tungsten. Well, nearly
sharp … as a proper tungsten may have a slight ball at the very
Jody:In your opinion, what is the best all around electrode for use with Tig Inverters?
BRENT: If I had
to choose a single electrode – it would be ceriated. I’ve had
great luck with cerium on all vintages of equipment, in all
applications … it holds up well – resists erosion & resists
frosting that can hinder arc starts. Lanthanum is probably my 2nd
Jody:and if you had to select only 2 types ...one for DC and one for AC, what would they be and why?
BRENT: Now I can truly get the best of both worlds .. and my choice would be 2% lanthanated for DCEN & 2% ceriated for AC. Lanthanum is great on DCEN – especially at extremely low amperages. Not only does it provide a stable arc, but it keeps starting consistently over a long period of time. That means better results in high quality & purity applications.
I have to stick
with Ceriated on AC because I really like its performance. It erodes
just slightly & then holds that same geometry for a long time.
Other electrodes will erode slightly & can then become unstable –
as the geometry changes or forms nodules.
Jody: We had numerous discussions about low amp crisp arc starts when I was in the aerospace industry and you were with Miller Tig Solutions. What did you learn during that time about how does tungsten selection affect arc starts?
BRENT: I learned pretty quickly that arc starts are critical. In fact, if a machine won’t light the arc consistently – expensive parts & components can be damaged beyond repair. An erratic or misplaced arc strike is not allowed in critical applications. Now, consider the inconsistency of high frequency used to start the arc & you have a sense for how un-reliable starting can really be. For those that don’t know, high frequency or HF is used to establish the arc by “jumping the gap” between the electrode & work. HF can leak to ground as it searches for the “path of least resistance” & have negative effects on starts.
Proper tungsten selection is critical to repeatable arc starts. Now, I have a favorite “general” setting for most applications. But, for precision work where quality counts – I match the tungsten to the amperage I’m welding at. I would say that 3/32” diameter electrodes cover a large range of applications in the industry, but they have limitations. On low amp work, a smaller tungsten not only starts more consistently & with less energy – it produces a smaller arc cone for a smaller bead & heat affected zone.
entire welding circuit is a giant resistor. Current flow through the
completed circuit & generates heat where the resistance is the
highest. Every part of the circuit has some resistance – but the
tungsten is a major resistor that inhibits arc starts. The larger
the tungsten, the more energy it takes to reduce its resistance. So,
smaller tungsten electrodes have less resistance & result in
better arc starts.
Jody: You mentioned to me once that when putting a scope on Tig welders during testing, often swapping to a new tig torch made a big difference in the performance of the machine.
can you elaborate on that?
BRENT: TIG torches have a huge impact on the arc & weld quality. The primary concern is regular maintenance & replacement of old, corroded cables. As cables & components become overheated they can breakdown.
On top of normal wear & tear, I’ve also seen torches with issues that hindered equipment performance. TIG is an interesting process that requires some special considerations because of the purity requirements of the welds & the use of high frequency. Torches made with inferior materials can leak high frequency along the entire length. If the HF leaks away to ground before it reaches the electrode, it can’t start the arc & makes the machine appear to have an issue. In reality, it has nothing to do with the machine & everything to do with the torch. These same inferior materials can have a negative impact on weld quality as well.
Jody: Its a shame about the current helium shortage because I think there is tremendous potential for improvements to most AC tig welders with nothing more than mixing some helium with argon. Also cup size and gas flow rates are 2 often overlooked details that can make a big difference for Tig Welding Aluminum.
BRENT: Yes, the shortage has caused the entire industry to look for alternatives. Helium can really help with penetration & issues like porosity. It’s a quick fix when you need it & don’t have time to run a complete design of experiments to find the magic waveform.
Cup size has
always fascinated me. I was taught to use the largest possible cup
available that still allowed you access the joint. If you do that,
you can cut back the flow rate & use less gas. This can also
improve arc starts & improve low-end stability – so wasting gas
should be avoided. To further improve shielding at low flow rates,
use a gas lens. These devices break up the gas flow so it’s less
turbulent for more even coverage. The biggest benefit to a gas lens
is being able to increase your tungsten stickout without
Jody: I often talk about
the benefits of high speed pulse tig welding.
and...I have been pretty vocal about not liking pulse rates from 2 to around 30 pps. I either like 0.5 to 1 pps, or over 30 pps. pretty much nothing in between for manual pulse tig on DC.
BRENT: I share your dislike of low pulse rates. Although, you can really stack some dimes on aluminum with a low pulse frequency if you just add filler rod during the high pulse. And, I’ve gotten some pretty nice ripple patterns at 10 pps on stainless steel. But, weld with those settings all day? No thanks!
Not only does a low-frequency pulse arc look like a strobe light, it tends to slow down the process. Now, if you’re objective is to increase puddle control – it may help you accomplish your goals. But, to really achieve the benefits of pulsing – you have to go above the visible spectrum. 30-40 pps is above the threshold for human perception – relatively speaking. So, the arc looks normal with perhaps little flutter.
As you increase pulse frequency, you have multiple benefits. Let’s talk productivity first. The arc becomes more constricted – as it’s constantly pulsing between a high peak & low background setting. That means the current density is higher, even though the average amperage is lower. Laymans terms? Better directional control, increased penetration & reduced distortion ….
Better control: as frequency increases, the arc becomes stiff & resists wander.
Increased penetration: higher current density & a smaller arc cone help to concentrate the heat – for faster travel speeds & consistent penetration. I have seen frequencies of 400 hz actually double travel speeds in some applications, without sacrificing travel speeds.
Jody: I have seen real benefits with using high speed pulse with rates of 30 and higher.
BRENT: Faster travel speeds, increased weld penetration, improved weld quality & reduced distortion.
distortion? Absolutely! Especially on stainless steel which is
prone to distortion. The science behind it involves 2 critical
aspects: average weld width & heat input – which both directly
affect the amount & degree of distortion. A concentrated arc
produces a narrower weld & pulsing also lowers heat input – so
there’s a compound benefit.
Jody: What are some real applications you have seen where high speed pulse tig shined over non pulse tig.
absolute favorite high speed pulsing story involves welding beer
kegs. The end-user changed grades of stainless to help correct a
forming issue – which seriously impacted weldability. We worked to
develop a pulsing condition that actually exceeded their travel speed
& weld quality before the material change! We were faced with a
50% reduction in travel speed due to reduced sulfur content in the
material & ended up traveling 15% faster. To top it off, we
added a 2% hydrogen mixture to the argon for even faster travel
Jody: What do you see as changes coming to
power sources in the next 5-10 years?
BRENT: The future of power sources will be determined by a few big influencers:
Well, thats a lot of helpful info from an expert.