TIG welding machine, AC/DC.

Hi! I am considering buying a TIG welder with HF start and, since aluminium is something I would also like the ability to weld, it
should be AC/DC.
After having studied what is available in my (European) neck of the woods, I have narrowed my search to 2 or three machines, all of the inverter type. Recent machines, because the progresses in those small inverters seem such that the new generation is smaller, more powerful, has more features and is cheaper, so...
Still, even cheaper, it's quite some money and DC only would be quite cheaper. I understand that aluminium can also be welded on DC (electrode positive) with helium. A bottle of helium is less expensive than a welder, but I also read that TIG with helium is so difficult (because the arc gap must be kept constant and very short), that it is only really relevant for robotic welding. So is helium tig usable or not?
Second, the new inverters, being computerised, offer lots of adjustable features. I understand that being able to adjust the ratio between + and - is the minimum, adjusting the frequency is good and adjusting the length of the pulses is also good. One of the machines advertises a "dual wave" process in which it would weld aluminium by switching every half second or so between AC and DC. Is that a gimmick or is that likely to be useful?
Thirdly, I got inconsistent numbers on the thickness of aluminium that can be welded with the same intensity (I got consistent figures for steel). Are the figures the same than steel or do you need double the intensity? Can I weld 3 mm aluminium with, say, 150 A? Or to put it the other way round: what can I weld with, say, 150 A and 200 A? Same question for stainless.
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Jerry, it sounds like you got the hang of TIG and are going to enjoy it. I would spend the money on a good medium range machine. Like the Lincoln Squarewave 175 or the Miller SD180...it will let you tinker with most of what you want and be a durable machine.
My .02 Marty
jerry snipped-for-privacy@yahoo.com (jerry_tig2003) wrote in

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I said in my post that I am not in the US. I do not think Miller is presnt where I live, although Lincoln is. However, and I do not mean to be rude or anything, the local brands seem to be more advanced and cheaper than what is available in the US, maybe because they can always operate at 220V. In any case, I expect better service in case of problems from a local supplier.
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Inverters are more common in Europe. I can only surmise that it is because they were invented by Goran Hedberg in Sweden about 30 years ago, so they had a head start in Europe, but also they make more sense in Europe where you have some truly arcane power distribution systems in some areas. Inverters, being more efficient, just make more sense.
There are only 2 companies making Inverters in the USA; Miller and Arcon. Arcon was founded a few Years ago by Goran Hedberg.
http://www.arconweld.com/company/about_arcon.htm
He had to take 7 years out of the industry after selling Powcon to ITW.
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From travels I made in the US, I do not think that power distribution is less advanced in Europe. Still inverters make more sense once the electronic components are getting cheaper and this is more and more the case. We'll se in 5 years. The machine I am considering outputs 210A (55%) or 160 A (100%) from a single phase 220V output and weights a mere 8 Kg. You can adjust all you ever need. It will run from less than 220V if you need long lines or a generator.
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it.
I'm real curious about what you consider to be "more advanced"? Please be specific.
JTMcC.
maybe because they can

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I mean that they use more modern electronics. The progresses in high power transistors have been quite fast in the past 20 years which translated into different generation of equipment for, say, energy distribution, electric train motors or welding machines. If you look at those, you will easilly recognise the generations: big copper transformers, the same with electronic regulation, first generation inverters, etc... I have found recent European inverters to be one generation ahead of their US conterpart (or at least the ones I saw). Typically, they are twice as small with better efficiency and more advanced features (features are easy to add once the whole current control is electronic).
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Hi Jerry,You are correct ,there are a number of very good AC/DC inverters in Europe and I have very good experience with Kemppi Mastertig 2000 AC/DC.It is 200amps , 240V input and will confortably weld 1/4" Aluminium without preheat.It has good AC/DC balance control,50-200Hz frequency control and has pulsing and memory facilities. Another good manufacturer is fronius,Hitachi and even Lincoln.
--
Gwyn Phillips

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Pure helium isn't used much because of the difficulty in arc starting. Argon/Helium mixes are much easier to use and have some wonderful effects.

That is a new feature creeping into high end inverters. It makes for extremely clean welds.
Miller has a new power supply called the Axess 450 that actually switches between CC and CV as you weld.

Aluminum and steel are both 1 amp per 0.001inch (0.025 mm) of thickness.
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Is that meant to say that one can actually weld aluminium with a Ar/He mix and a DC inverter?

What do you mean by CC and CV? I have only heard of AC and DC.
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Yes, in fact it is quite good, but you will get a lot of heat build up in your torch if it is air cooled. DCEP puts most of the heat back into the torch, so while it does work, you wouldn't want to build a boat with it.
It works quite well on aluminum up to 3/16" thick, for short durations. The thickness is linited by the size of the tungsten, notr the amperage of the machine. Your tungsten needs to be at least as thick as your metal or thicker.
If you use a 5/32" Lanthanated Tungsten, you can just barely weld 3/16" aluminum. 1/8" is a breeze.

CC = Constant Current, which is what all Stick and TIG machines are. CV = Constant Voltage, which is what MIG machines are.
Somehow they are blending the CC and CV waveforms on one output. Kind of freaky.
Panasonic makes a high end robotic TIG power supply that blends AC and DC output for aluminum TIG welds. Also kind of freaky.
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Now I remember.

I don't understand how this would work.

This I understand better. It seems to be the same than the process used in the (non robotic) machine I am talking about.
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Are Stel machines available to you? They are very good quality. I have one of their inverters that is sold in the US under the HTP name. It seems to work very well (much better than my skills!!)

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Some are, but I did not find an AC/DC model.
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http://www.stelgroup.com/Prodotti/Salda/TIG200E.asp
This is the same one I bought just rebadged for the US market. It is AC/DC
Jamie

one
to
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Interesting link, but this machine needs 3-phase, which is not always convenient.
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Hmmmmm....my unit uses single phase, 220. You could try calling HTP here in the US to see if they could get one shipped to you from Stel. www.usaweld.com
J

AC/DC
convenient.
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Where abouts are you based ?
As Miller has several outlets in the UK

AC/DC
convenient.
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Take a look at the Stel brand if you can get it where you are. I bought their 200 amp inverter as it is rebranded in the US as HTP. I'm very happy with it.
J

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