arcing from gas lens parts, not tungsten

Date 09-02-2009 02:30

I have heard of humidity causing condensation in water cooled torches when the cooling water is rather cold, and particularly if it flows continuously.

By Steve.E (**)

Date 09-02-2009 09:59

Hi Stringer, Is your post purge time set sufficiently to prevent tip oxidation? Also if ignition is a problem a quick rub of the electrode on the job before you hit the trigger will usually help.

By SWP

Date 09-02-2009 13:07

I've seen this problem with pure tungsten on an inverter power supply. I wonder if your 2% thoriated is sub-grade, maybe not a good quality. Other than that, I would ensure the work connection was good.

By Lawrence (*****)

Date 09-02-2009 14:42 Edited 09-02-2009 14:45

Miller Synchrowaves from the Late 1990s (they were triangular boxes) were notorious for poor arc starting at low currents (less than 60a)

There are some internal potentiometers (pots) under the hood that can make adjustments. Our Synchrowave 350's required adjustment of these pots about every 6 months. I don't recommend going under the hood of one of these things unless you have training to do so. If you local welding supply knows about this issue they may be able to identify the pot # and help you to do this. There are a number of pots under the hood so it's riskey to do this without knowing exactly whats going on. Owners manuals are online at the Miller website. Be sure you get the exact part number for your unit when accessing manuals.

In the meantime... here are selveral things that may help.

Tungsten prep must be perfect.. any oxide on the tip will reduce performance.

Like the Aerowave, this power supply does not like you to "sneek up" on the foot pedal... A good hard stomp on the pedal will get the best arc starting... This is common on many capacitor discharge type arc starting units. So set the current only high enough to do the job so that you can go down on the pedal with some authority.

Also, the smallest dia. electrode that can get the job done will be a help.

Hope this helps a bit.

By Stringer (***)

Date 09-10-2009 05:10

I won't be tinkering with the machine, so we can all put that to rest. My side of the blue box is the outside of the box. I've worked on 'em but I just don't enjoy it.

By Stephan (***)

Date 09-02-2009 14:58

Stringer,

as a humble addendum to what the others said.

This phenomenon you describe is rather well-known, what can be recognised by the already given replies.

Often it may be found that the electrode composition plays a major part with this. This again is a variable dealing with the electrode materials' work function.

Professor John Norrish of the University of Wollongong in Australia - one of the most outstanding welding experts in the world - has conducted some examinations comparing the power supply's open circuit voltage vs. the HF arc start rate at relatively low currents.

At an OCV of 30 V and a current of 20... 30 A (electrode vertex angle was 45°) he tested thoriated, lanthanated, ceriated and Ytterbium-oxide (Y2O3) doped tungsten electrodes and achieved relatively similar arc start rates.

At 22 V and 24 V OCV however, the lanthanum-oxide doped electrodes (1% La2O3) showed definitely the best results in arc start induced by HF.

Anyway, often the arc start induced by HF becomes unstable due to both a combination of electrode material and an "...adverse phase relationship..:" (John Norrish, 1992) what means that a lack of synchronisation between the power supply and the arc starting device does occur.

Of course also the work function of the base material can play a part with an improper arc ignition. Often it's rather a tricky combination of all the little peripheral factors (electrode condition, variations in the vertex angle, surface contaminations,...,...) what leads to inconsistent HF arc ignitions.

We have helped ourselves in semi-automatic GTAW applications e.g. when welding thin stainless steel sheets at low current values, by wrapping the ceramic gas nozzle into a conductive foil (aluminium foil). The physical effect is to create a negative space charge, and to hereby improve the ignition. It worked quite well!

Perhaps it's worth a try for you.

Stephan

By Lawrence (*****)

Date 09-02-2009 17:13 Edited 09-02-2009 17:16

Stephen,

We found similar results during production trials of tungsten electrodes a few years ago at United Airlines when we were doing semi-auto repairs on rotating airseals. Because of HF/EMF interferance we used capacitor discharge for arc starting rather than High Frequency however.

At lower current settings we found that lanthanum 1.5 (at that time EWG) to have the best arc starting for low current welding with both GTAW and Microplasma.. But that brand and manufacturing of the electrodes (powder mettalurgy) played a very big part as well.. Various electrodes produced by different vendors of the same tungsten designation would have wildly different performance values both in arc starting and in effective length of work function (how many hours or arc starts an indivudual tungsten electrode tip prep would continue to provide good/satisfactory emmissions)

However, with the case of a Synchrowave that produces in the neighborhood of 70 open circuit volts for a GTAW arc start I would think that work function of the electrodes (assuming anything other than EWP) would be negligable. I just don't think the fine differences between Thorium, Lanthanum and Cerium electrodes under the condition described are going to be the cause of this kind of problem.

I think the designers of the Synchrowave 350 "over-thought" the product and created various levels of outputs so that operators could custom taylor arc starting charicteristics for various electrode diameters and current settings.. Doing this created a pandoras box of instability that our origninal poster must now deal with :) But we won't know if this theory applies until we find out the vintage of his power supply.

I believe the newer Synchrowaves moved away from this design concept.

By ssbn727 (*****)

Date 09-02-2009 18:32 Edited 09-02-2009 18:34

And suffice to say, it may, or may not even be the power supply or the electrode either so, without any more details than what we presently have to work with, I believe that it is ill advised to speculate any further without a h&ll of a lot more data revealed to us by Stringer!!!

Also, it's never a good idea to advise owners, or even operators of this type of equipment to even think of fooling around with those
"Teeny-weeny-eety-beety, tiny" little pots located in the "guts" (various circuit boards) of the power source especially if they have no training on diagnosing, or troubleshooting electrical, electronic, or even solid-state electronic components on a power supply even if one warns them of the consequences because, there's always one that will try to do it on their own in spite of what one may have said with respect to what the consequences may be as a result, and no matter how well intended one's advice might have been, the advice may end up becoming an indirect cause as to why the power source no longer works, or it's performance has worsened substantially so, that now the owner has to foot a repair bill that could have been avoided all together and resulting in animosity amongst the parties - at the very least!!! ;)

SO DON'T EVEN THINK ABOUT IT!!! In other words: "FUGGEDABOUDIT, Bad-a-Bing, Bad-a-Boom, Bad-a-BANG!!!" :) :) :) Everything else that Lawrence mentioned are very good suggestions!!! ;)

Hey Stringer, is there anymore information that you can share with us which may, or may not be relevant regarding the primary input power, whether or not the power source has power factor correction, the serial # of this model Synchrowave, the way the work lead is set up, the type of torch you have, the gas type, the exact percentage of thorium you're using, environmental conditions in the workplace, etc...

In other words, anything that better describes the actual working conditions, the actual equipment conditions, the actual accessories, anything at all that may even sound totally irrelevant because, attempting to help diagnose a condition that causes erratic arc energy transfer, or anything close to that vague description can originate form a multitude of sources and even more than one at times! ;)

It's not unlike navigating a vintage submarine through some very tricky hostile inland waters which can result in an accident or worse, revealing it's presence because for the most part, the boat is being navigated blindly with the exception of some very limited passive sonar if indeed the boat even has such a capability, and maybe some navigational charts that may or may not be up to date, and forget about raising the periscope because that would result in revealing themselves to their enemy which is paramount to avoid in the first place!!! ;)

So, I hope you understand how important it is to give us as much information as possible Stringer, because I know for a fact that we all want to help you in solving this problem you're currently experiencing. :) :) :)

Respectfully,
Henry

By Lawrence (*****)

Date 09-02-2009 18:52

Henry..

I did say in my original post....:

" I don't recommend going under the hood of one of these things unless you have training to do so. If you local welding supply knows about this issue they may be able to identify the pot # and help you to do this. There are a number of pots under the hood so it's riskey to do this without knowing exactly whats going on."

Don't think I could have been any more clear about the safety issue of internal adjustments.

:::::::shrug

By ssbn727 (*****)

Date 09-02-2009 20:00

Hi Larry!

Look Larry, the last thing I wanted to do is to discredit you online, or offend you as I really do value your friendship tremendously!!! So if I did make you feel as though I didn't take this into consideration, then I vehemently and sincerely apologize for not choosing a better manner of presenting my point of preferring not to share the type of information in question to the owner, or the operator/end user...

Now that I think of it, I probably should have used a PM (Private Message) to express my own opinion of sharing this information with you instead but, but, all i was trying to do with my response was to emphasize to the end user whom in this case is Stringer, not to even think about attempting to make any adjustments without any prior training as well as understanding just how sensitive it is to make these adjustments in these types of power sources... So, please understand that it wasn't my intent to discredit you in any form by saying what I did, and I did read the part where you mention:

" I don't recommend going under the hood of one of these things unless you have training to do so. If you local welding supply knows about this issue they may be able to identify the pot # and help you to do this. There are a number of pots under the hood so it's riskey to do this without knowing exactly whats going on."

All I was saying is that this person shouldn't even attempt to do this even with the help of let's say, a service representative on the other end of a phone conversation and I apologize for not alluding to this example which I should have used in my earlier post!!! So I hope that this clarifies what I was really attempting to convey in my earlier post. ;)

I cannot stress enough how many times I have encountered welding equipment such as power sources, and their associated accessories disabled further by the end user not having the proper training in servicing this equipment when I was a factory trained service person for Miller, Lincoln Electric, Thermal Dynamics, Pow Con/Cyclomatic and Linde Union Carbide/L-Tec/ESAB equipment back in the day...

Even when assisted over the phone by an in-house, or local service personnel who could not for any variety of reasons, be there personally to diagnose/troubleshoot the problem so that the equipment would ultimately be repaired back to good working order. ;) So once again Larry, I apologize if I offended you in any way because, that's the last thing I wanted to do in my previous post my friend!!! :) :) :)

Respectfully,
Henry

By Stephan (***)

Date 09-03-2009 06:39

Lawrence,

thanks for these - as always - valuable information and the 'practical' confirmation of what Professor Norrish has found out during his examinations.

"...Various electrodes produced by different vendors of the same tungsten designation would have wildly different performance values both in arc starting and in effective length of work function..."

I guess you're absolutely right by saying so. In particular the mechanisms with respect to what affetcs the 'work function' of a specific doped electrode type are overwhelmingly interesting, from the physical standpoint. There were some awesome investigations carried out in order to 'look behind this curtain', dealing with some very impressive quantitative models to describe the physics behind this. I would like to recommend papers of the outstanding researchers TANAKA and SADEK.

Thanks!
Stephan

By Steve.E (**)

Date 09-03-2009 10:48

Hi Stephen , very interesting about the foil wrapped ceramic. For as long as I can remember our auto Tig operators have had ignition problems . What works for them is a light rub of the electrode tip with a points file or even a lead pencil just before initiating the arc . Will try your foil technique as soon as possible.

By Stephan (***)

Date 09-03-2009 12:59

Steve,

thanks for the great feedback!

"What works for them is a light rub of the electrode tip with a points file or even a lead pencil just before initiating the arc(...)"

Yes, this works quite awesome. In particular the tip of a lead pencil works tremendously good since the graphite lowers the work function dramatically. It's really like switching the 'blue light' on. :-)

Thanks!
Stephan

By ssbn727 (*****)

Date 09-03-2009 13:11

Hi Stephan!

Lead pencil??? Hmmm, that's a new one on me!!! ;) Oh well, it just goes to show that in this place - one never stops learning. ;)
I definitely have got to try that, and see if any porosity froms as a result of the lead, and if it doesn't, I'll add it to my own list of tricks. ;)

Respectfully,
Henry

By Stephan (***)

Date 09-03-2009 13:22 Edited 09-03-2009 13:25

Hi Henry!

Cheers!

Perhaps it's necessary to 'correct' myself a bit.

It's just like always. I mean to mean that Steve has used the term 'lead pencil' but has actually meant a 'graphite pencil'. :-)

But it's like it is in Germany. We also mean actually a 'Grafit-Stift' (Graphite-Pencil - sorry for using the German terms but it's just to describe it correctly) when we are speaking of a 'Bleistift' (Lead-Pencil). ;-)

Thanks!
Stephan

EDIT: By the way, I have tried to rise the average rating for all of you great guys, since the 'horrible diamond monster' was on the way again! LOL :-)

By ssbn727 (*****)

Date 09-03-2009 13:34

Excellent! Graphite it is!!! ;)

U Da Man Stephan!!! :) :) :)

Respectfully,
Henry

By 803056

Date 09-04-2009 02:45

I am always amazed at the insight provided by members of this forum.

I don't claim to be an expert using GTAW, far from it, so I read posts from Lawrence, Henry, and Stephan very closely. They provides gems of information in every response!

I have seen similar problems, but it wasn't associated with very low end amperages. Instead it was associated with insufficient gas coverage (because the welder terminated the arc and pulled the torch away quickly) causing the tungsten to oxidize. I have also seen situations where the tungsten and the gas nozzle were contaminated with deposits of low melting point materials that apparently volatized and then condensed on the inside surfaces of the gas nozzle providing a conductive path for the arc.

Strange happenings!

Best regards – Al

By Stringer (***)

Date 09-10-2009 05:04

Thanks so much for the replies to my query. I'll try to clean up my end first...The machine is a 350LX and it's about 4 years old, but I've had two or three older Syncrowave 250's that did the same damn thing. I kind of think tungsten quality could be an issue. You wouldn't think such a basic thing could vary, but I've seen variations in the 304L filler rod I use so who knows if my good ole' standby tungsten has been outsourced and cheapened. OK, no ranting. Coverage and contamination aren't a problem, but I will look into the ground idea. Inconsistent ground could definitely explain some of it. And dirty cups aren't a problem (I use new ones) but Al's right...if you fry something and get it on your cup it'll arc everywhere but where you want. I don't see the aluminum foil viable in a production situation, but you can bet I'm trying it first thing in the morning.