[mk1_oz]

Experienced TIGgers I need your help........

Recently bought this;

https://www.welding.com.au/equipment...arc-200i-ac-dc

I am trying to teach myself but may seek out a local course depending on how it goes (not well so far!!).

I started out the first morning working with steel on DC. After some rubbish welds I did some not so rubbish ones. With more time I think I can easily iron out the issues and start having something presentable.

That afternoon I moved to aluminium on AC with HF start. I quickly had some butt joints happening although there was alot of variation in appearance (prettyness, width, height) that I struggled to understand fully. I started to get a slight feel for balance, frequency and amps though. Then.....without changing any settings the thing just would not strike an arc. When I pressed the torch button it would spit out a quick arc then immediately stop and try again (other forum posts seem to imply this is the HF?) - spat at around 2Hz. I cleaned the material even more (dedicated stainless steel wire brush), re-ground the tungsten for the millionth time, checked settings etc but no dice. I gave up.

This morning I have been at it again. I setup the machine from scratch, grabbed some fresh cleaned aluminium and viola it worked straight away (and quite reasonably.....maybe....see pic weld #1 below). I again welded away, changing some settings as I went so that I could see the results. Then after around about the same amount of welding the machine again started to not strike an arc!!! This time I can pin-point what I did before it 'failed'. The thin strips of aluminium were getting hot so I quenched it in some water then dried it off. I could not see water anywhere including in the butt joint area. Once I started welding again....no arc.

I think it would be easy to say that the water quench was the cause but I have some doubts as I dried thoroughly. Maybe it caused a huge amount of oxidation build up?

I have been struggling with keeping the tungsten out of the pool and with not pushing the filler rod into the tungsten. I am standing up which I am finding very uncomfortable for TIG (chair in design). I have re-ground the tungsten regularly on a brand new fine grinding wheel using the recommended technique.

I have noticed that the tungsten goes blue alot although I think I have fixed that by having more post flow and holding the torch in place until it cools. I seem to get a BIG ball on the tungsten sometimes which from what I can tell is not really a requirement on an inverter machine. Other times the point stays to some degree.

I don't want to jump down the path of this being a weld unit fault as I am new and don't know enough to go there. However, I am at a loss as to why the same thing happened after a similar duration and both times without any setting changes. The machine did not show either the voltage or over temp fault lights. At 77amps it has a 100% duty cycle and 15% at 200A so me welding around 90-110 I should have a high DC so that should not be the issue.

This second time I was able to get an arc to strike and hold ONLY IF I turned the balance up to at least 70% however once started the arc seemed to have little power and was not creating a weld pool. I had not touched the amp control but it was like it was running at much lower amps. Could be oxide related but I have wire brushed the heck out of the material and cleaned it afterwards with carby cleaner and still no dice.

I turned the machine off and went to have a coffee returning after maybe 15 minutes. I did not touch anything other than the on/off switch and........she worked perfectly. Now explain that!

I am at a loss and need suggestions. I realise you cannot fix things from the other side of the world but maybe somebody has seen this before or just knows what the cause is.

My settings at time of failure;
Frequency 119
Pre-flow 0.5s
Initial Amps 95
Ramp Up Time 2.0s
Amps 95
Ramp Down Time 4.0s
Crater Amps 50
Post-flow 7.0s
Balance 66%
Cup Size #6
Gas Flow 6lpm
filler rod 2.3mm
tungsten: 2% ceriated 1.6mm
stock 3mm
gas 100% argon

Not that I want to distract from my immediate issue but the welds in the pics are numbered in order. Ignore the area between 4 & 8 as they have been impacted by welds I ran on the back. An example of things changing when I don't understand why is that #1 and #2 I consider reasonable for a beginner but then the same settings results in #3 and #4 being flat and wide with #4 being very indented. My best guess is that the heat from the proceeding welds meant I should have lowered the amps for #3 and #4. There may have been some time passed by the time I got to #8 or maybe I changed the amps but it came out reasonable again. #1,2 & 8 had some weld material through the backside but not much in the way of full penetration (not sure if that is the goal with TIG on aluminium?).

20180819_103202.jpg (150.57 KiB) Viewed 3037 times

20180819_103217.jpg (45.18 KiB) Viewed 3037 times

[cj737]

For 3mm material, you need at least 150 amps welding in AC. That’s problem #1.

Once you get a weld, the material is now very hot, and will probably allow you to weld with far less amps, though getting your puddle started, will still need more than 125-130 amps. Problem #2

The flattened beads is indicative of welds that are heat soaked. Add more filler or quench more frequently. Problem #3

As for the won’t restart, it could be a couple of things. One, the tungsten does get contaminated a bit while welding, especially if you are running a balance below 65%. You don’t need to be that low anyway. Stay close to 70%. If you have this issue, try “gently scratching” the material then romp the pedal. This can get the arc to restart by rubbing the oxidation layer off the tungsten tip just enough to get a good ground again. Water on the backside can also interfere with getting your ground. Try clamping to the stock directly.

[Junior Welder]

Oh and for your other problems you really need to watch Jodys videos

Weldingtipsandtricks on youtube

[mk1_oz]

@cj737 - when you say 70% on the balance I assume that is 70% EN? It gets confusing with different machines working back t front on AC balance. Thanks for the tips.

@Junior - I have watched a fair few and look at more each day. Helpful stuff - will look to purchase his DVDs


I have spoken with the welding company who sold me the rig. Their technical department thinks there is nothing obviously wrong with what I am doing. He thinks the cooling fan is not coming on as much as it should so he wants to take a look at the unit and test it. I am sure it is me though!

[cj737]

Yes, 70% EN. EN gives you the penetration side of the arc, EP performs the cleaning.

The more EP you out into the tungsten, the more contamination you contend with since the electrons are flowing towards the torch.

[Junior Welder]

Sorry about posting to the wrong thread.
Did you try the test I suggested?

[mk1_oz]

Sorry about posting to the wrong thread.
Did you try the test I suggested?

Not yet as not been in shed. I think your suggestion appears to be related more to poor steel welding whereas my issue is with aluminium. I was able to tig steel quite well (for a first timer).

[mk1_oz]

More practice. It's getting quite expensive buying all this aluminium to weld!!

Several things I have discovered;

• I was moving too slow. I have started to move faster and the stack o'dimes effect now shows
  snapping off the end of the tungsten does seem to help clean things up a bit
  I have been trying to weld with insufficient amps so have upped the amps a bit
  I need to focus MUCH better on the torch angle and arc length - I believe I am melting the filer material with the arc rather than the edge of the puddle
  I am consuming what I feel is a massive amount of gas. I am flowing at around 6LPM (~12CFH) with a #6 or #7 cup. The cylinder is an E size so 4000L. I have probably welded say 7m of bead (an estimate) and have used 25% of the cylinder. This seems a lot to me and may or may not be part of my problems?

A particular issue that I don't understand is that when I do start having issues getting an arc, it makes the high pitch HF noise but almost immediately makes a very metallic sounding noise that is similar in frequency but higher pitched and very metallic sounding. When it makes that noise I definitely have no chance of it arcing or even producing the HF arc. Any ideas on that one? Sorry it's hard to describe noises!!


I am getting a lot of contamination in the bead still. Sometimes the whole bead has a dark appearance and a rough surface but other times it is approaching a reasonable bead but with black pot marks on it. I think this relates o my arc length and torch angle so will persevere.

The welder is being looked over by the service people next week so an issues with the unit or torch should be found....

[cj737]

12CFH is perfect. Use a gas lens and that will help with many of your shielding issues that create soot.

Don’t snap your tungsten; grind it off. Snapping will create micro fractures up its length that will cause a very erratic arc.

[bruce991]

Still I would run amps up a lot your using a pedal correct? I set mine to 200, and pedal control to get a puddle then lean off and move along.

[mk1_oz]

I took the unit back to the seller's service area and had their bloke weld some aluminium. He gave me some hands on tips which was great. Eventually the issue I have been happening (not maintaining an arc) started for him. A gas change showed it not to be gas related so he concluded the unit has an internal error. He also pointed out that my reg gauge is very inaccurate!

I have got a suitable chair to sit on now and that did start to help my welds a little as I have concluded that some of my issues are related to having too long an arc.

He also showed me how to connect the pedal correctly (which annoyingly is not described in the manual!!!!!). I felt the machine was down on amps before which is was. He has now connected the pedal to have full amps.

Hopefully when I get it back it will be more consistent allowing me to experiment and to understand the settings better.

[cj737]

Nothing beats some proper instruction when learning to weld. Glad it got sorted out for you.