Welding on DC, ceriated / thoriated tungsten keeps "balling up"

[RobK]

Hi all,

I have been testing the "steep" part of the learning curve for my new TIG welder. I have sharpened a couple of tungstens and been practicing on some scrap mild steel of various thicknesses from 1mm to 3mm.

I have set up like this:-

1.6mm ceriated tungsten, no. 6 ceramic and about 6 lpm argon, 45 to 50 amps DCEN for the thicker stuff, and

1.0mm thoriated tungsten, no 5 ceramic, and 6 lpm argon, 30 - 45 amps DCEN for the thinner stuff.

The tungstens were sharpened to about two and a half "diameters" on the cone angle. Tungsten tip projection was almost as large as the size of the outlet hole of the ceramic nozzle (about 6 to 8 mm).

The problem is that I keep getting the tips of the tungsten "balled up". The ground points don't seem to last more than 15 minutes before turning into a lollipop, and needing re-grinding.

Am I missing some important point in setting up my machine? I have it on DC, and have tried the "pulse" function, but I am still doing a lot of grinding.

How long would you normally expect a tungsten to remain pointed if you were DC welding with one? Is there any rule-of-thumb technique for keeping the point on a tungsten?

Any advice welcomed...

Cheers,

Rob

 

[Drains]

Is there any rule-of-thumb technique for keeping the point on a tungsten?

Only, make sure you've enough gas, keep the job clean, and don't touch down!

Other than that, can't help, sorry.

Edit, are you sharpening in line with the tungsten? Keeps the arc focussed. Sharpen across the way and you're in the doo doo.

 

[Wedg1e]

Try going up a tungsten size? Use the 1.6 where you were using the 1mm, then up to a 2.4 or whatever instead of the 1.6...

Stickout should generally be as short as you can get away with, I think.

 

[Seano]

Your stickout depends on what you are doing Rob, ie outside corner,butt,lap the way I work it is I only generally have as much stickout as the length of the ground tip on the tungsten back to the shoulder where the angle changes back to horizontal, if that makes sense to you.....

a gas pressure of 8-10 lpm (for ally) depending on conditions (around 12 lpm for steel) for something like inside corners I would set my torch so that I could touch both sided of the joint with ceramic, then extend your tungsten into the angle of the joint, that should give you just about the right amount of stickout, always make sure that when you up your ceramic dia you also increase your gas pressure by a little to ensure that you get good even gas coverage, also as stated before always grind your tungsten's axially and not radially on the wheel, a good tight arc while welding should not see any balling up of your tip, hope this helps Rob.

Just a thought and please excuse me if I have this wrong, but you ARE using DC[ELECTRODE]N and not DC[EARTH]N I have seen a few guy's at work accidently make that mistake, also you may want to try a 1.5% Lanthanated (gold tip) tungsten to counter act your balling up problem, also 1.6 for 1mm is ok but for 3mm I would move up to 2.4dia tungsten allowing you to put more juice through it if you need to.


Sean.

 

[RobK]

Additional info...

Hi, again,

Thanks for the info so far. Just to clarify the polarity thing; I have the torch set up as DC electrode negative. This is the default setting on my machine, as the gas connection is right next to the negative electrode connection, and I don't think it would reach if I plugged the torch into the positive socket (though I have not tried!). I think I may be using too little gas (6 lpm ) and might have had the tungsten sticking out too far on butt welds. I was using a 1.6 mm tungsten, ground to a point over about 5mm from it's pointed end to the "un-ground" full diameter shoulder, but I had it sticking out about 8mm to get a better view of the joint and the arc. This may be too much by the sounds of what you (Sean) have written. I will try increasing the gas flow rate and having less tungsten sticking out and see if that works better today.

I have been grinding them so that the grind mark run "along" the length of the tungsten (shank to tip, in straight lines), not "around" it.

I have also been doing a bit more browsing and found some info on the Miller web site. They mention a "rule-of-thumb" for setting the current, saying you should use one amp of current for every thou of steel thickness, so a 2mm plate (80 thou) would be 80 amps, and so on... If this is right, I have had the current a bit low for what I was attempting. Anyone got any opinions on this 1amp-per-thou rule?

Just to make things more interesting, I was attempting to butt-weld a very thin steel strip onto thicker metal, to see how difficult it would be to cope with dis-similar thicknesses, and get both sides to melt and fuse without burning the thin stuff away. That was proving challenging.

Any other advice on this welcomed...

Cheers,

Rob

 

[Seano]

Hi, again,

I have also been doing a bit more browsing and found some info on the Miller web site. They mention a "rule-of-thumb" for setting the current, saying you should use one amp of current for every thou of steel thickness, so a 2mm plate (80 thou) would be 80 amps, and so on... If this is right, I have had the current a bit low for what I was attempting. Anyone got any opinions on this 1amp-per-thou rule?

Just to make things more interesting, I was attempting to butt-weld a very thin steel strip onto thicker metal, to see how difficult it would be to cope with dis-similar thicknesses, and get both sides to melt and fuse without burning the thin stuff away. That was proving challenging.

Any other advice on this welcomed...

Cheers,Rob

Hi Rob, the miller rule is a pretty good guide, you won't go far wrong following their advice in the beginning, and of course as you do more welding you will gain more knowledge through experience.

As for the dissimilar thickness, it is very tricky I agree, what you need to be looking at it concentrating your heat onto the thickest material, this will reduce the chance of the thin edge burning away, and the only other bit of advice I can give you is.....Practice........Practice........Practice...

Sean.

 

[hotrodder]

How about a pic of a used tungsten? The settings you've posted are all fine (at the amperages you're using i typically run 5lpm through # 5 - 7 ceramics), a 1.6mm tungsten should be good for 120A DCEN without problems.

If polarity is definatly correct the only other causes that come to mind are wrong gas and/or leaks in the system resulting an oxidised tungsten or that you've stuck the filler in the arc/dipped the tungsten and the 'balling' is base metal stuck to it- both of which would wreck the tungsten pretty quickly!

First thing i'd do is test for leaks

 

[Drains]

Rob, don't forget to knock off any contaminated tungsten. Don't regrind a contaminated tip, as it'll just go again. It's got to be clean material. It might seem a waste of "good" electrode, but it's necessary. As your technique improves you'll not need to re-grind so often and your tungstens will last longer.

 

[RobK]

Hi,

Slightly off topic, but how do I insert an image into this thread? I have always typed, and never posted photos. When I click on the icon for adding an image, it is prompting me for a URL, and not allowing me to browse to my hard drive. Do I have to post the images via a different method to a web site somewhere first?

Cheers,

Rob

 

[Drains]

Rob, all is revealed...

 

[RobK]

Tungstens - before, and after a few minutes...

Hi again,

This is how I have had the torch set up. A no. 6 ceramic and a 1.6mm tungsten, 2% ceriated. DC electrode negative, various current settings from 50 to 90, depending on metal thickness. These tungstens were used at about 80 amps, if I recall correctly. This is what they looked like after a few minutes of use.

The tungsten did not touch the steel. On one test, I did not even weld anything. (I just set the tungsten out a LITTLE BIT further out than the torch shown in this photo). I struck the arc (HF start) and watched the tungsten start to erode! I have tried using a little less of the tungsten sticking out of the ceramic, as shown in this photo, and that seemed to help, but the point still eroded. I have read on the Miller site about the point angle, weld penetration and arc focus. I was getting an arc that was too broad, with not enough penetration, and ugly wide weld beads, so I have tried to grind this tungsten to a blunter tip angle (see photo), as that apparently helps to focus the arc in a narrower beam.

Is this due to an air leak in my argon? I have the gauge set to approx 8 lpm.

I would like to be able to use the tungsten sticking out further to get into tight corners. I have read (in various places) about "gas lenses" to enable me to do this. Any suggestions on a suitable "gas-lens" set up for this WP17 torch? Parts description/order nos. supplier, prices etc...?

Any ideas?

Cheers,

Rob

 

[Hitch]

They look like touchdowns/rod touching contamination.
Best thing to do with them is snap em off, and re grind.
Practice, practice, practice. Keep the tungsten away from theweld pool and rod.

 

[irondarren]

rob slag sounds like your problem or should i say mill scale, to ge the electrodes to last any length of time the welded area needs to be clean, so clean you can eat your diner of it. mill scale or the grey blue coating loves nothing better than jump on the electrode. make the welding area s clean as possible by grinding the surface back.

 

[Paul.]

I agree with Hitch, they look like touchdowns, a sure way to tell is to spark test them on a grindstone, tungsten will give a brighter spark than steel, so if the blob on the end gives a dull spark, its contamination from the parent material or the filler rod, and as Darren says clean the metal before you start to weld.

 

[Drains]

Hold on a minute.... What gas are you using? It is pure argon I assume - like BOC pureshield for instance? If it is, i'd think about taking it back and getting another bottle, for free too...

 

[RobK]

Gas usage...

Hi,

I am using pure argon. At least, thats what is says on the bottle...

I got it from Energas, in a half-size cylinder.

Cheers,

Rob

 

[Drains]

Hi,

I am using pure argon. At least, thats what is says on the bottle...

I got it from Energas, in a half-size cylinder.

Cheers,

Rob

Well if you can swear you've not been touching down, not had the amps too high for the tungsten, had it DCEN, and had the gas turned on, and coming out at the torch... then it's the gas....

 

[RobK]

Tests...

I am going to run a test either today or tomorrow to check this out. I will cut back a tungsten to be SURE it has no tip contamination, grind it, and clamp the torch over a polished piece of steel, and strike the arc at a reasonable current (65 amps for 1.6mm tungsten?), and let it run for a few minutes. This should eliminate any issues relating to dirty steel, tip contamination, or touching down. If it still erodes, it may be the gas.

Got to sort my tax return today. Bummer...

 

[irondarren]

Are you using filler rods? if so they are A18 and not ccms type ones. filler rods need to be the triple deoxidized ones other wise they can blow back on the tip. (very slim chance)

 

[Seano]

Certainly has all the appearances of touchdown to me also by the looks of those tips, just a thought also Rob, that clean tip angle looks a might shallow imo....2 / 2.5 times 1.6 = 3.2 / 4 a steeper angle will give you a more defined arc and better control....remember the 3 P's Rob.....the usual 2p's worth.....

Sean.