Tig Welding

hiya all,

I have posed this question on the welding forum I am part of but thought I might try here.

I bought a WSE200, chineese stuff (yes I know lets not mention it) as I was on a tight budget.

I weld aluminium pretty much exclusively.

It's a great little welder for 2mm or thicker. so if you are on a budget then it's a good choice.

me on the other hand need to weld 1mm thick. and there is the problem. lots of advice given to me but the results vary so much, that's on the same work piece to boot.

from blowing holes, pitting to awesome weld. so the material isn't really in question

the machine has a pedal which a dial which doesn't indicate low or high amps. I have changed to white tungsten and have 7 - 8 on the argon.

am trying to use as low as possible amps (that's guess work) the balance I lean more to neg as the positive burns up the tungsten pretty quick even when set very low in the positive range.

any how if any one has any tips, ideas etc I'd be chuffed to bits.

many thanks

Becky

Becky,

I have only welded steel with an arc welder and never blown holes in the work. I have oxy - acet. welded steel and blown holes. My instructor said this is because I didn`t keep the flame moving. I have also read others experiences in blowing holes in copper again due to not keeping the flame moving so as to not overheat and melt the work. No experience with Ali but can only assume same applies. Hopefully, there will be other replies with more help. Good luck. John.

Becky, I have an ERFI pocket TIG, which although not marketted as being capable of alloy welding was found by accident (hooking up the cables wrong polarity) that the unit would weld alloy very well indeed, OK it's not a Chinese make (German) but it was at the budget end when I bought it 15 years ago, so probably not a million miles away in similarity to your machine!
My machine doesn't have an Amps indicator either, just numbers on dials, so some experimentation is usually needed!

As you do, I use white tungstens and 7-8 on the argon, I also make sure I keep well out of any draughts from doorways or open windows!

I don't do enough alluminium welding to claim any proficiency, and much of which has been reclaiming corroded areas on alloy cylinder heads, but what I did find was that the area being welded had to be kept scrupulously clean with a stainless steel wire brush, And crucially with my machine, the weld was much easier to start and control if the metal was pre-heated with a blow torch!
If I didn't pre heat, the weld was a pig to start, and the tungten would stick itself to the metal leaving debris that had to be gouged out, ruining the weld!
Is it possible the 1mm (16G?) material you're trying to weld is cooling too fast with the heat migrating away from the seam too quickly?
Just my thoughts as your woes echo the problems I came up against!

John.

Becky,

until recently I had an ESAB 200A unit that weighed around 200kgs...so not portable...which I used for occasional Al TiG work. I had similar results at times to yours but eventually got the hang of it based around cleanliness. TiG for steel needs really clean material, de greased and brushed whereas Al needs  to be an order of magnitude cleaner:

i used to mechanically clean with a stainless brush reserved for the prep task, followed by hosing down with degreaser (brake cleaner or some other Carbon tet substitute) followed by a final brushing with the finishing stainless brush. And then immediately launch into the welding, leaving oxides no opportunity to form. I also found that I needed much higher argon flows that seemed to be recommended - but that was probably my lack of expertise at play.

Compared to steel where I have welded down to less than 1mm, Al seems much much more difficult, probably as much caused by the higher heat loss plus the ac rather than DC current used.

Simon

Edited By Simon0362 on 19/07/2013 15:33:24

I've had great success with hts-2000 repair rods on a small sheet aluminium fabrication that I have just completed.

Take a look here It's quite an easy thing to do, once you've had a little practise and there's virtually no chance of burning through thin material.

Martin.

You'd be wanting a pretty small electrode and wire for 1mm, otherwise it's difficult to control the arc position and dab the filler where you need it. What are you using? Is it the smallest you can get? Also, are you using a copper backing strip? That can help.

Does the pedal control from min to max but you are trying to use just the very fine end of the scale? My machine allows me to set the maximum current for the pedal, so if you are doing fine work, the pedal is scaled back suitably. If you can't do that, it may be making control very difficult. In which case a mechanical stop might help.

Not sure whether balancing is a significant factor. I suspect there are other issues to deal with.

There are loads of Youtube videos that show you how to TIG weld loominum. That and practice are required in abundance before you can hope to make a good weld.

Muzzer

Hello Becky,

Hi, interesting reading this and your other posts about your mobile crane project. I have done some TIG aluminium work both in my job and as a hobby. I have a 200 amp pulse TIG welder from RTech. I have attempted to find specs on your WSE 200 unit but without much success. Does your machine have variable frequency? I feel that frequency of the AC welding current is the key to welding thin material as it really focusses the arc. The other point that is important is having a pulse setting. What this does is modulate your welding current using pulse width modulation.

What this amounts too is that it prevents thermal runaway and everything ending up as a melted mess. You set a maximum and minimum current and the machine switches rapidly between these two. So the pool forms but never gets out of control due to the cooling in the low current switching period. With pulse you can weld right next to an edge without melting it. I guess if the balance was more positive that would keep it cooler too but it is probably best staying with about 50/50. I think also a lanthanated tungsten is best for aluminium.

So, higher frequency if you can and pulse if you have or can afford to get a machine that has it. I am at sea at the moment but I am going to experiment with welding some thin aluminium sheet when I'm back in the UK in about 10 days. I will let you know my findings re frequency etc.

Carl.

Thank you Carl.

I was thinking that frequency was important. Only a recent YouTube video introduced me to pulse controlled.

i will look into a machine with these functions and look forward to your experiments.

Out at sea? Merchant or Royal Navy?

Hi Rebekah,

For good results on thin metal a welder with pulse capability is very beneficial. As others have said, frequency and cleanliness are important. I find cleanliness of the stock and filler wire gives far better results than dirty metal on ferrous material too. If waveform control is available, triangular wave is great for thin aluminum stock also.

The best machine by far that I have used for TIG is a Miller Dynasty 350, but this is an industrial quality welder and they sell for around $8000 in the US. Luckily I have a friend with one. With one of these and some practice, virtually anyone can make top quality welds in just about any metal thick or thin. The cheap China welders, not the case. Any I've tried are fine on mild steel 1/8 to 1/4" thick but otherwise it can be very difficult to get decent results.

JD

My experiance varies to Jeff''s

I have two TiG welders, a Murex / BOC 200 amp TradesTiG on 440v 3 phase and one of the WSE200 Chinese jobbies like Rebekah has.

Fortunately none of my work is thin section but the odd time I have tried the results have been less than spectacular, probably a result of not enough experience.

However what I have learnt is the newer WSE inverter model can run rings round the Murex to the extent it's now been relegated to a spare machine and I'm now giving serious though to examining the inverter models of MiG welder to see how these compare to the older transformer models

Hello Becky,

I started out with a reasonably priced TIG unit that was by Sealey. Although they have links to the UK (Bury St Edmunds) They are in fact made in China...but hey, it had AC/DC functionality and for the price was a great little unit. Trouble was it was only just 150A and no variable frequency or pulse.

I soon realised I needed both these capabilities so I got a unit from RTech. These are a sort of halfway house - part Chinese but re-assembled and checked in the UK and with European power electronics. So still within a sensible budget but more functionality. Quite a good compromise, I thought.

I would echo Jeff's words on cleanliness and triangular waveform, but I reckon if you can get the pulse and frequency right you'll be good. I looked at your website on model truck construction and I have to say it is impressive. Whatever you are doing with your current TIG unit it seems to be working.

Do you have a BOC account for your argon? Another tip I'd like to pass on to you (and anyone else TIg-ing in the UK) is a company called Hobbyweld. They do gas bottles for the likes of us and they are considerably cheaper than BOC. There should be a stockist near you. You can find out here:- www.hobbyweld.co.uk

I am Merchant Navy...sort of. I work in the Offshore Oil and Gas industry. My job is to maintain, modify and fly Remotely Operated Vehicles. These are large underwater robots equipped with robotic arms. They can be fitted with a variety of tooling and are used to build subsea oilfields. A sort of underwater tractor.

You are right to assume a military connection though. I am ex Royal Air Force. I was an Aircraft Technician for 13 years until I left in 2002.

Best Wishes,

Carl.

The Chinese wse200 is a worth while purchase. It's a brilliant welder down to 2mm. If you,re on a budget it's a good choice.

R-tech were very good for advice and service so I feel confident in upgrading with their machine.

Carl,

ROV's hey, any jobs going lol.

I'm working with the RAF at Waddington, avionics techs (fairies)

I tend to use a lot of gas so I have a BOC account, saves going back an forth.

Thank you for the compliment, I take my time and will do things until I'm happy with it.

Hello Becky,

Yes, I was looking at the WSE 200 and it does look like a great machine. It is a lot like my old Sealey unit was. I well remember Waddington, used to often get detached there as I was on Nimrods at Kinloss, we used to go and play with the R's at 51 squadron. Well I say I remember it, at least the bits of it I spent not in the pubs in Lincoln... I assumed you were an Electronics Technician, being Royal Signals.

I have a BOC account as well, but I'm seriously looking at going to Hobbyweld. Works the same as BOC but much cheaper. When the girl at my local stockist explained it to me I thought she was having me on!

Yes, always plenty of positions in ROV's for ex military technicians and especially for someone of the skill and calibre you display. If you are interested in finding out more please feel free to PM me and I can give you more details and give you some people to contact.

Best Wishes,

Carl.

Hello again Becky,

I have just had another thought re the TIg-ing of thin sheet and it relates to another TIG process that I want to have a go at. This is called "TIG Brazing". The idea is that you use the TIG arc to braze the materials together. This means you use much less current - reckoned to be typically half normal values. The TIG brazing rods are a type of Copper - Silicon alloy, and in some cases Aluminium - Bronze. They are generally covered by BS2901. I think this would be a very good alternate method for joining thin sheet as long as the strength wasn't absolutely critical.

From what I've read so far, you need to be pretty quick with laying the bead, but it sounds very interesting as a technique, and might be something that would work well with your models. You can read more about it here:-

www.weldability-sif.com/media/sif_tips/sif_tips_02_tig_brazing.pdf

I want to have a go at this and intend to do so on my return to the UK. Another positive factor here is that you can join dissimilar metals with it.

Hope this helps,

Carl.

Carl,

I'm interested in the hobby gas's.

At the moment I have full size bottles from Air Products, the ones that stand about 5' tall and about 9" in diameter, problem is I don't know what they hold as regards litres.

AP call these 230 and 300 [ litres ? ] One is argon MiG mix and one is pure argon for TiG

This months rental is £6.90 per bottle plus VAT making a total of £16.56.

MiG gas lasts me about 2 months and costs £28.00 odd for the refill.

Argon lasts a lot longer at probably 6 months and costs £48 per refill.

If you have access to hobby gas prices can you post them so i can compare.

I've used the Sif brazing rods to TIG braze and it's very useful for certain applications. I've got the SifSilCopper rods which are 3% silicon, 1% manganese and 96% copper, so it's essentially copper.

You need to keep the arc on the copper rod/puddle and off the base material otherwise it will melt that - but even that isn't the end of the world. There's no desperate rush, it's like soldering but possibly a bit easier - and there's no bead as such. It's not going to burn or degrade unless you lose the gas shield. You can turn the heat up and down like any weld and you can rework it if it didn't turn out quite right first time round. There's no flux but it wets the surface nicely.

I used it to braze a large 1/4" flange plate onto a petrol tank. Even a guru wouldn't dare try to TIG weld them directly due to the vastly different thicknesses involved. It required a fair bit of heat and took a fair while to complete which resulted in some distortion of the tank but nothing problematic. Nice result though.

The downside is that it's like solder ie you add blobs of stuff to the joint, whereas a nice TIG weld may have little or no material addition. You also have to heat the joint up whereas TIG is quite a bit quicker and the heat buildup is much more localised.

There's a myth that you can TIG weld almost any metal with TIG. It would be nice if it were true. Try joining two pieces of copper (central heating) pipe - you'll find that there's a lot of dissolved oxygen that bubbles out when you melt it and makes TIG welding almost impossible.

Muzzer

Edited By Muzzer on 22/07/2013 07:44:17

Have a look at this John

**LINK**

Dosent seem all that cheap though!

peter

Not cheap at all and only 137 bar in a bottle, usually get 200 - 220 bar in an AP bottle.

Hi Muzzer,

Thanks for that. The TIG brazing has seemed almost mythical until now and it is good to know that someone has actually done it.

John/Peter...thats not what the girl I spoke to at my local dealership told me, so maybe you are right and it isn't such a good idea after all.

I have found this chaps series of video's very helpful

**LINK**

Paul