TIG & ARC

[MattF]

Just wondered if anyone might be able to answer this. I have a general idea of the differences between the two in use, but what's the difference in the way the actual welding units themselves work, as in voltages etc.? TIG obviously has the addition of argon and and creates an arc just to generate the heat, but not been able to find mention of the basic operating differences between how the two work at the basic level, so thought I'd ask. For example, bar the tungsten versus carbon rods/tips, how does TIG differ from single rod carbon ARC? Just curious.

 

[TurtleDude]

Great question, I'd also be interested to know the mechanics of this as a total noob.

 

[Maker]

I assume by "arc" you mean MMA/stick welding? Technically MIG, TIG and MMA are all arc welding.
As to your question, I've got no idea.

 

[MattF]

Yup, stick welders.

 

[Bill Edwards]

From what I've picked up, there is very little difference as to how the electrical side of the two processes work.

Machines that will do TIG can also do MMA, and generally speaking the reverse is usually true as well.
Both process use constant current, I think TIG will often be at a slightly lower voltage than MMA, but not by much. You see the result of this where it allows a machine to have a slightly higher output in TIG mode than MMA, but it's not great - e.g, a 180a MMA unit might deliver 200a in TIG.

There are basic features which can make a TIG nicer to use. The most basic TIG inverters - which are mainly designed for MMA - use scratch start TIG, which probably requires no fancy electronics whatsoever - no different to starting with a fluxed rod.
Then there is lift tig, where the machine senses the short circuit, and once broken (i.e the tungsten is lifted off the work piece) it delivers the power. Again, basic stuff.
HF start can also be an option, again nothing too fancy really to give it that extra to start the arc without contact.

Variable current control, in the form or up/down slope or pedals, pre and post gas flow are all extras which some machines have, but that's hardly worth mentioning as the basics of the welding process shouldn't change, it's just dressing up the edges a little.

 

[Maker]

As to your question, I've got no idea.

That was a lie, I remembered something. There is more heat at positive side* ,Tig is run with the electrode negative so the work is positive and receives the most heat, the other way round and the tungsten melts because it gets hotter. Because an MMA elecrode is designed to melt, it can be done either with EP or EN.

*side meaning electrode or workpiece.

MOD - Tidyup & remove flaming

 

[MattF]

Cheers chaps. So theoretically you could add a TIG torch with gas supply to a ARC/stick machine and do basic TIG work? Is TIG DC only, or does that use AC as well? What's the general operating voltage, (output), of TIG?

 

[TurtleDude]

WAY out of my depth here, (and happy to admit it, rather than blag it like some ahem).

As I understand, an MMA welder will only do 'stick/rod'.

There are also MMA/lift or scratch start TIG units which will do TIG with no 'hot start' or HF to make it easier to start the arc.

Then there are 'pulse TIG' / MMA units like I've just bought, that supposedly allow greater control over the TIG weld function.

So in theory, if your machine is MMA/TIG compatible then with the TIG torch and gas, you're good for both.

Unless it's an Ac/Dc machine you won't be able to do Aluminium as I understand it, but DC will do mild steel, stainless and so on.

Voltage will normally be the electrical supply, either 230v single phase (home/office supply) or 415v 3 phase industrial supply.

Amps are the 'power factor' for welders (it seems) and so the higher the amps, the thicker the material one can weld.

That is my limited knowledge based on research, not experience.

 

[MattF]

Voltage will normally be the electrical supply, either 230v single phase (home/office supply) or 415v 3 phase industrial supply.

I was a bit vague on that bit. I've edited my other post to reflect that I was referring to output voltage from the unit.

That is my limited knowledge based on research, not experience.

Not easy trying to find info on the specifics, is it. I started looking days ago and have managed to find practically nothing on the underlying principles of TIG. Either my searching abilities are sorely lacking else there's little info out there.

 

[Welderpaul]

Can we stick to the subject chaps please and avoid playground bickering?

 

[TurtleDude]

I was a bit vague on that bit. I've edited my other post to reflect that I was referring to output voltage from the unit.




Not easy trying to find info on the specifics, is it. I started looking days ago and have managed to find practically nothing on the underlying principles of TIG. Either my searching abilities are sorely lacking else there's little info out there.

In the same situation I asked a welder (logical) and apparently the torch has a hard tip which 'melts' the material for want of a better expression on a rod held in the other hand, a bit like a sparky, exciting version of soldering,

Seems to me it's a bit like MIG and MMA disciplines rolled into one, you've got the gas (like MIG), the rod (like MMA) and the torch tip (unique to TIG).

If this is wrong, please excuse me, as it really is the blind leading the blind here lol.

 

[eSCHEn]

There's some nice history on GTAW/Heliarc on this chap's site and the original patents for a torch can be seen on Google's Patents site.

 

[Kent]

Application purpose is all I really care to know. The difference that actually matters? I feel fairly sure in saying voltage might be different set to set at given settings and consumables / semi consumables and although I might sound cynical I don't trust charts and dials as much as what I see happening

 

[Maker]

single rod carbon ARC

Can you weld with that? I thought carbon arc always needed two electrodes and was only used for gouging?

 

[MattF]

Application purpose is all I really care to know. The difference that actually matters? I feel fairly sure in saying voltage might be different set to set at given settings and consumables / semi consumables and although I might sound cynical I don't trust charts and dials as much as what I see happening

All of that stuff is what I'm having a problem finding info on. Info on the fine tuning and the fancier features are fairly inconsequential at the moment, but trying to merely find some info on the basic process is the current road block.

I have the stuff here for doing stick and carbon ARC, and it was the latter which started me off thinking about TIG. Inquisitive minds and all. I went off on the tangent of wondering whether it's worth experimenting with the stick unit at some later date with regards to adding a basic TIG assembly, as the base TIG equipment seems very similar to the carbon arc setup, bar the obvious differences between gas and tip material choice, in my mind. I don't mind experimenting, but neither do I like just blindly experimenting without at least some basic reference, hence my current predicament regarding lack of info. Fancy is something I'm not aiming for. Merely a basic, sound implementation is my goal at the moment.

Can you weld with that? I thought carbon arc always needed two electrodes and was only used for gouging?

Both single and double rod setups are viable for brazing, from what I gather, (I'm still currently in the process of reading up on the stick and carbon arc processes at the moment, to get as much info on those as possible), though the twin rod setup is the more reliable/controllable of the two, it appears. Gouging requires the addition of an air supply to the single rod setup, from what I've gathered so far, though I've not paid much note to the gouging process as yet.

 

[MattF]

There's some nice history on GTAW/Heliarc on this chap's site and the original patents for a torch can be seen on Google's Patents site.

Cheers. Just been reading through that patent page, and the suggested voltage he mentions is 40V to 60V, so at least I'm getting somewhere now. I ought have known to reference Heliarc instead of TIG. The olden day designers were usually far more obliging with regards to info than the current day ones.

Various stages in the formation of a butt-weld are shown in Figs. 4, 5 and 6. For magnesium sheets from .040 to .1 inch, an open circuit generator voltage of from 40 to 60 volts may be used with amperage varying from to '75 amperes in accordance with the demand required. Helium is then flowed at low pressure, say about onethird pound per square inch in the nozzle, through the pipe-line I, so that it emerges from the open end II on nozzle II, immediately around the tip II of tungsten rod I1.

 

[eSCHEn]

Aye it appears the author worked for Linde for some time and has some really interesting bits on his page.

I'm almost at the stage of emailing him to ask why the hoses are 12.5' long.

 

[Richard.]

Like Kent I have no idea regards to the circuitry voltage and elastic bands that are different between the two processes and to me that side of things does not matter. GTAW and MMAW are the same in the respect they are both constant current, can both be struck up from permanently live. The differences which I'm sure you know already is with GTAW when you start throwing options at the process. Ie hf start to avoid contact and contamination, pre and post gas, pulse welding,
Mr fuzzy made a good point. In GTAW the electrode is not the consumable so in this instance penetration is deeper with heat into work piece (DC-). With mma it's the other way around deeper pen in DC+
AC tig fluctuates between the two for aluminium and it's other non ferrite friends.
Mma has a few optional extras too like hot start and arc force. They are probably the same process at the dins connection but at the torch they could not be any different.

 

[MattF]

I'm almost at the stage of emailing him to ask why the hoses are 12.5' long.

I was wondering that too. His explanation was extremely vague, wasn't it.

 

[MattF]

Cheers Richard. It's definitely sounding like it's worth having a play with the idea at some point then. I know it wouldn't be a fancy setup, but I'm thinking it's one of those itches I'm going to have to scratch, (no pun intended ), in finding out how a stick welder with minimal modifications can cope with doing TIG.

If my current thinking is correct, a TIG torch adapted, (else with an adaptor lead), to connect to the box, a bottle of Argon and regulator and possibly a rectifier for having the option of DC output would be all that would be required to try the basic tests/process?

I'm guessing the HF start is merely a momentary high voltage, low current spark introduced to jump the gap and create an initial contact arc from which the main arc then takes over from? I can't say as I've spent too much time playing around with HT, (worked around, but not played with), or high current arcs for jollies in the past, so that last sentence may be way off the mark.