Tig Welding Expert Brent Williams sits down with Jody for an interview

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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.

What to look for in a Tig Welding Machine

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:

  1. Application: Selecting the proper TIG welder begins with the application. Specifically, you need to choose a machine that is capable of welding the material & thickness you plan to be working with. Materials: DC machines can most metals – including steel & stainless steels. However, if you plan to TIG weld aluminum – you need AC. Select an AC/DC TIG machine for the ability to weld all metals. A square-wave AC unit will give you better arc stability & puddle control over other AC units. You may also be able to adjust the AC Balance for oxide cleaning or etching control. Higher settings also preserve your tungsten by reducing erosion. Thickness: As a rule of thumb, you need about 1 amp for every 0.001” of material thickness. So, for 1/8” material that is 0.125” you will need approximately 125 amps. Duty Cycle: I’m glad you brought this up – because understanding duty cycle can help you make the right choice when selecting any type of welder. You have to look beyond the model name & number to the rated output of the machine. Don’t be fooled by a unit that boasts 200A of output on the top end, but can only sustain that level for a very short time without causing thermal overload. Traditionally the name of a welder had something to do with the duty cycle – but that isn’t always the case anymore. The duty cycle should be printed on the rating card of the machine – indicating the power level it can sustain for a % of 10 minutes. You should clearly see the rated output volts & amps, which should align with the type of welding you plan to do. Every welder is 100% duty cycle – somewhere on its power output curve. Pay close attention to rated output & check the duty cycle near or at the maximum output of the machine. Duty cycle is relative – so you use it compare models to make sure you get what you pay for & don’t over-buy when you don’t need to.
  2. Location: Consider where you’ll be welding & how often you’ll need to move your welder. For those that weld mostly in the shop & bring the work in, portability may not be an issue. For others who work in a shop & in the field – portability is a major consideration. It’s often difficult to find a machine that’s ideally suited for the shop & the field. But, if you’re doing about the same type of work in both settings, there’s no reason a single welder or system won’t work. Shop Welding: Consider a package that has wheels – even if you don’t plan to carry your welder to the track or a friend’s house, being able to easily move & reposition it around the shop is very handy. Field Welding: When you have to carry the welder to the work, many factors need to be considered. Now, portability is a relative term – but for our discussion, portability means the welder can be carried. Weight: primarily we want to make sure the welder is light-weight & can be easily carried around a jobsite. A good rule of thumb is less than 50 lbs. for a single person, single handle lift. In my opinion, the lighter – the better. Power: if you weld in the shop, chances are you’ll have a dedicated power receptacle to plug into. However, field applications bring the question of uncertain power … so a multi-voltage unit is a good idea. A 110/220V unit is good for most household & workshop requirements … with the most power delivered on the 220V side for the shop. If you’re welding in an industrial setting – you may need to consider a 208V or 460V. Some units automatically switch to the voltage while others have a special adapter cord or require manual linking. Power Draw: Everyone should be concerned with power draw. Many people purchase equipment only to find out they don’t have enough power to operate it. Manufacturers rate their equipment at a given duty cycle, but you also want to look at the Maximum Amp Draw – which you may occasionally reach when welding thicker material. I personally prefer an inverter power source because they draw less power than a conventional machine. That means they are cheaper to install & operate. Generator Power Options: If you plan to run your TIG welder using a generator, make sure it has the capability of operating on one … specifically, the one you plan to use most often. Both Locations: Well, if you need to weld in both the shop & the field with the same unit – it might be a good idea to choose a system that can be configured for the shop or the field. Make sure the welder can be easily removed from where it’s mounted – whether on a cart, cooler or table.
  3. Reputation, Warranty & Customer Support: I’ve had a chance to weld with a lot of TIG welders. At the end of the day – many brands do a good job when they are working properly. In today’s age of technology, welders have become seriously sophisticated – using high-end electronics for various benefits – so they all need to be maintained & repaired occasionally. Whether you buy a light-duty TIG welder for occasional use or an industrial TIG welder for every-day fabrication – you need to select a welder intended for your application & know that the manufacturer stands behind the product – replacing or repairing any defects or failures.

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.

  1. Budget: As you consider all of the above items, budget comes into play. In a perfect world – we’d have the right welder for every job. But – we live in reality & have to make the best decision for our immediate need. After thinking about what, how often & where you’ll be welding, think about the unit that fits your budget & does the job Be realistic – don’t be oversold on features you don’t already intend on using, do some research ahead of time & buy what you want. Now, if you’re fortunate enough to have an unlimited budget – carefully consider the upgrade. Remember that “features” add complexity to equipment, although having options is a nice luxury if you can afford it. Don’t be cheap – buy the right welder for the job. Like any tool, your welding equipment was designed for an intended application or job. Using your machine for something it wasn’t intended for can cause problems. If welding is your livelihood, consider the value of equipment designed for your intention.
  2. Call me spoiled – but after having my pick of the market, I’ve got an ideal setup for just about every situation! As a rule, I like water-cooled options in the shop. My ideal machine can be easily disconnecting from the rest of the system for field deployment. I keep a field kit that’s ready to go at a moment’s notice. Inside are the essentials I need for welding with my air-cooled rig wherever I need to go – that way I don’t forget anything!!!

AC Waveshape Questions

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:

  1. Sound: Arc “noise” is generated by alternating current. The waveform (including frequency & balance) determine the sound emitted by the arc. Early in my career I noticed a distinct difference in the sound of AC TIG machines. The difference between traditional AC & an inverter is “night & day,” very explainable & not a difficult comparison. But, I focused on the subtleties between inverter models & found that sound was only an indicator of many differences. Early on, some equipment provided similar benefits to others, but delivered a more smooth & quiet arc.
  2. Meters: All welding equipment typically lists digital meters as “reference only.” But waveforms can influence the values displayed on the meters. Some welding codes have considered including AC TIG waveform in complex waveform standards.
  3. Heat distribution: Waveforms can also impact the penetration profile, distortion & tungsten erosion.

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

BRENT: Working 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 easily.

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.”

Triangle Waveform

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.

  1. Greater punching & penetration power: The saw-tooth waveform hits a higher peak amperage at the same output level. Now, it only remains that higher amperage for a brief time – but it does affect the weld.
  2. Less distortion: One particular industry leader found that triangle resulted in less distortion than any other wave form – so they standardized on it for that job. The puddle formed quickly so the weld could be made with the lowest possible heat input & distortion.
  3. Anodized: Those anodized aluminum welders that have taken the time to explore triangle have found some serious benefits. Using the bump technique – triangle helps but through the coating & maintain a puddle throughout the weld.

How to get the most out of a small inverter

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 power source

BRENT: If you run completely out of power & need to get the most out of your machine – I have a few suggestions for you.

  1. Use TRIANGLE … you’ll get a little more top end in the waveform.
  2. AC Balance … turn your balance DOWN. That’s right, decrease your AC balance within reason & certainly not enough to cause tungsten erosion. But, studies have shown that decreasing AC balance can actually increase penetration when compared to higher levels at the same amperage levels.
  3. Try a little preheat – and I mean just a little! Depending on the material, you should always know the proper preheat for welding. But, with aluminum it’s especially important. Many welded alloys are heat-treatable & can be severely affected by improper preheat temps. As a rule, keep your preheat well below 300 degrees F – you’ll still be able to remove any surface moisture & slow the cooling rate of the aluminum so you can form a puddle more easily.
  4. Add some helium – but only as a last resort. In case you don’t know, helium is expensive! But, it does improve penetration by driving a higher arc voltage. It does this because of ionization potential.

Tungsten Electrodes Selection

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.

BRENT: Inverters 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 tip.

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 choice.

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.

Arc Starts

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.

Technically, the 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.

Tig Torch issues

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.

Helium shortage

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 contamination.

Pulse Tig Welding

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.

Reduced 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.

BRENT: my 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 speeds.

Industry trends in Tig Welding

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:

  1. Technology: the welding industry typically lags other markets when it comes to applying new technology. That’s driven by an expectation of reliability & up-time along with the difference in application. Most electronic devices are developed for high voltage applications – which translates to low current or heat. Welding is exactly the opposite – high current applications that place unique heat stresses on internal components, so it typically take longer for new technology to be hardened to the application & environment.
  2. User Interfaces: with the dominance of LCD displays in the market on devices with seemingly limitless capabilities, expect to see the adoption of more network or mobile controlled systems. Some companies are already advertising apps for android & iOS devices that monitor & control key welding details. Let’s face it, why would a company invest in creating an internal LCD when devices exist that can connect & run your app? Pushing the envelope a bit, look for an innovative approach that completely redefines the user interface. Wireless remote controls have only just been made commercial available in recent years – but other industries are light-years ahead. This will actually help advance welding – providing potential learning & information sources.
  3. End-Users: ultimately the needs & demands of the market will drive power source changes. As technology advances, units will be optimized for the market & application. A few years ago I visited the Essen Welding Fair in Germany & was intrigued to find a small stick welder shaped like a hand-held drill. The concept was a little heavy for me, but imagine the technology that would allow a portable welding tool that weighed no more than a 12 or 18V cordless drill?
  4. Regulations: standards are becoming more global every day. Europe & the IEC standard (CE) are leading the way with their directive … which is actually a good thing for the industry. Today there are individual standards & design regulations for almost every country. Most are adopting some version of the IEC standards. Having multiple requirements simply adds complexity & cost to equipment. But, look for regulations on power consumption, noise emission levels & safety to impact designs. In some cases, sacrifices will need to be made in order to comply. However, until thresholds are established – the impact is unknown.

Well, thats a lot of helpful info from an expert.

Exit Tig Welding interview and Learn more about Brent Williams Welding Consulting Services

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