TIG welding advice

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BrendanP

Senior Member
This one is bit from left field but theres such a high level of expertise here on the forum I thought it worth while asking. Somebody might be a welder or have experience with TIG welding on some level.

I have to fabricate some proto aluminium housings for a picaxe driven project.

I have a ESAB 180 amp MIG welder which I can use to weld aluminium if I make a few mods to it.

Is is it possible using the MIG I have to get a good result or am I better off to go and get a TIG to weld light sheet? (~3mm)

I have read that it is common practice to use a push/pull gun on a MIG when using ally wire, is this critical?

I have seen some cheaper TIG welders on ebay, are these worth considering or are they rubbish. I've seen guys on site using Fronius TIGs, I think they're the top end. Am I going to get significantly better result with a top end machine like that as opposed to a cheapo unit?
 
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slurp

Senior Member
Proceed With Care

I'm no welding expert but through previous employment I've seen some of the problems aluminium welding can pose.

You need to be aware of the gases that are given off when welding aluminium. I would not dream of starting without good extraction and a forced air mask.

I doubt I'm the best person to comment on differing welding techniques or benefits of pre-heating material, particularly where there are material of differing sections so I'll stop here.

Best regards,
Colin
 
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manuka

Senior Member
-fabricate some proto aluminium housings for a picaxe driven project.
Click to expand...
Is this really worth a new welder!? I've wrestled with a few modern welding technologies & swear by MIG, but (as I'm sure you know) aluminium welding can involve hassles while techniques are perfected. Why weld anyway? For a prototype bolts/screws/rivets may be more versatile. Stan.
 
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BrendanP

Senior Member
Thanks Stan.

I need to cap off ~100mm ally tube and attach PV panel mounts onto it etc.

Stan, while I've got your attention, any suggestions on a cheap DC current source for anodizing largish ally parts? I was thinking a forklift battery charger. I had also thought using a DC welder (maybe the TIG could do this but the V output is too high I think).

Ive been looking at this guys site and have bought his book.

http://www.focuser.com/atm/anodize/anodize.html
 
slimplynth

slimplynth

Senior Member
Hi Brendan, (I'm not a welder but used to be an approved Rolls Royce weld inspector, though thank you're lucky stars I haven't welded anything on an airframe... it's a work art in my eyes).

We do Aerospace welding of Aluminium - we only use TIG but I can get you more specific info that you might find useful for both TIG and MIG... machine/parameter settings... which Alloy in particular are you using? 2000 Series... a BS Spec or AMS spec number would be handy. Also the temper(Heat Treatment) condition of the material you have.

The melting point of Aluminium Oxide is much higher than Aluminium, this causes a problem in welding, we (in the Lab) always used the following stock answer for dissapointed looking welders, "Cleanliness is next to Godliness"

Best Regards

S
 
slimplynth

slimplynth

Senior Member
With regards to Anodising, as it happens I'm currently (no pun) helping to prepare for a big audit of our Anodise line, was just curious about the reasons for anodising, are you painting or is the idea to anodise & dye to achieve the nice shiny look that tempts me into rock climbing shops?
(Not sure about using the welding gear to perform this - i know I'd be too scared to try... what anodise solution are you planning on using? be very interested to see what results you get with that, there's a few webpages i've seen on home DIY anodise that look interesting but we only use chromic acid, which turns shiny Ally into Dull Ally, ideal for spray painting on.
 
Z

zener

Member
Hi Brendan,

How much welding will you be doing? If it's only a small amount maybe it's worth while getting the experts to this. How much welding have you done?

You will have to use a different gas (argon) for aluminium, and if you were to use the MIG a push/pull is recommended, But if you only have a small amount and to keep the cost down you could get away with using the standard push hand piece, just make sure you keep the lead as straight as possible. This will help stop the wire from coiling up at the push end.

If you were to use a TIG make sure it is suitable for aluminium, by that I mean an AC ouput. TIG machines can be just DC, which is good for welding stainless steel and mild steel but not aluminium.

As far as the types of welder go, I guess the higher end machines may give you a better result but I think it probably has more to do with the operator.

If it was me I would prefer to use a TIG because I have access to one at my work, it's easy to setup, just change the polarity (DC to AC - not all machines are both) and the tungsten. Also I have more experience with TIG/aluminium then MIG/aluminium.

Without knowing exactly what you are making, I think it probably suitable to use either MIG or TIG, It's going to depend on your budget and experience.

Hope the helps
Mike
 
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kevrus

New Member
I,m not a welder but used to repair the machines many, many years ago, (too long ago now).

The push/pull gun is only required if the mig torch is particularly long as the soft ali wire doesnt easily travel through the liner, which incidentally should ideally be changed for a soft teflon/plastic liner as apposed to the normal spring type that is found in the binzel type torches. for really long torches, 'spool-on-gun' set ups can be used although I suspect that this is not required here

Don't have the pinch roller too tight else the wire shape will start to flatten causing feed problems.

Some people also increase the contact tip size to the next size up to allow smooth wire feed.
The shielding gas needs to be changed from an argon/co2 mix to just argon. (there may be other trace gases involved, but we don't need details here...:))


The voltage setting on the mig will probably need to be set lower for a given wire speed than for steel. Your machine should easily cope with 3mm ali, but definitely practice first as the technique required is slightly different to steel
 
hippy

hippy

Technical Support
Staff member
Before spending money, engaging in mods, it may be worthwhile looking around to see if someone can do the job for you. Also consider the alternatives.

For capping could a push-fit rubber or plastic cap or bung and sealant do the job ? Could clamp-on or bolt-through brackets take the PV weight ?

Perhaps consider using material you can weld and then weatherproof that.
 
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SAborn

Senior Member
If it is neatness in the welding you want than TIG will beat a MIG hands down.

The thickness of the metal is also a important factor as thin profiles are best welded with a TIG as aluminium gives little warning when overheated and will result in a big blob falling out compared to blowing a hole in steel.

From what i remember with home anodizing you need a low voltage and high current supply. Like 1-3 volts is best i think.

It is not to hard to make a low voltage high current transformer and i have built a few from transformers out of old microwave ovens.
I hacksaw off the high voltage secondary copper windings from the core and leave the primary untouched.
Then wrap some heavy welding cable around where the secondary windings were removed.

I think it was about 6 turns (wraps) for 3 volts. This is easy to check as all you do is power up the transformer and wrap some light wire around the core and measure the AC voltage across each end.
Increase or decrease the turns till you get the voltage required, then count the turns used and replace the light wire with heavy cable with the same amount of turns.
The voltage will be the same but the amps will increase greatly with the heavy cable.

Rectifier the AC and you have a low voltage high current power supply.

If you need more instructions on the transformer mod then search for "Microwave oven Spot Welders" as there is a lot of information on modding the transformers for this use and many others.

Just dont power the transformer up with the secondarys still attached as the output is in the 1000s of volts range.......very nasty!! :eek:
 
premelec

premelec

Senior Member
Having recently stripped copper from about a dozen transformers [$ high just now] including 5 microwave oven units I can report that a sharp flat 'woodwork' chisel with a big hammer cuts nicely through the copper turns in an E I core - much faster and cleaner than hacksaw which was earlier tool used.... ;-)

On the metal welding I'd not start out trying to do aluminum - though there are some low temperature brazing materials that avoid that dreaded aluminum blob droop / drop with gas welding - however they likely don't do well in weather... It would seem [seam?] sealing could be easily accomplished with epoxy and a metal cap if necessary... whatever works!
 
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alcooke

New Member
tig welding aluminum

Aluminum must be tig welded with ac because aluminum forms an oxide about 15 minutes after cleaning. This oxide rectifies and interrupts one half of the ac cycle and cuts the arc off. Continuous high frequency is necessary to maintain the arc. Fumes are not a problem unless you are working in a phone booth. Stainless steel fumes are bad.
Good luck with your project. - Al
 
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alcooke

New Member
cheap DC current source

, any suggestions on a cheap DC current source for anodizing largish ally parts? I was thinking a forklift battery charger. I had also thought using a DC welder (maybe the TIG could do this but the V output is too high I think).

The power supplies from old computers put out 3 and 5 volts DC at 20 or more amps. Google "electro-machining" for descriptions of how to adapt them.
I've used one to etch brass and copper.

Al
 
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MartinM57

Moderator
SAborn said:
It is not to hard to make a low voltage high current transformer and i have built a few from transformers out of old microwave ovens.
I hacksaw off the high voltage secondary copper windings from the core and leave the primary untouched.
Then wrap some heavy welding cable around where the secondary windings were removed.
I think it was about 6 turns (wraps) for 3 volts. This is easy to check as all you do is power up the transformer and wrap some light wire around the core and measure the AC voltage across each end.
Increase or decrease the turns till you get the voltage required, then count the turns used and replace the light wire with heavy cable with the same amount of turns.
The voltage will be the same but the amps will increase greatly with the heavy cable.
Rectifier the AC and you have a low voltage high current power supply
Click to expand...
I think I'd rather put a PICAXE in my car thanks....
 
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BrendanP

Senior Member
A sincere thank you to everyone for your help.

When I posted I thought Id probably get someone ex. aero space and I wasn't far wrong.

I can MIG and arc no problem, I've had welds I've done on cars engineer passed.

I hope to put the device into production, whilst these are protos my experience is that it is wise to make the protos look good, especially if you are going to hit some one up for venture capital based on the proto!

As soon as I see a housing or even a knob, button etc. on a supposedly commercial product that someone has sourced from a place like dicksmith or jaycar I think amateur hour effort.

The trick is to give the device a pro look without having to layout big bucks for tooling. (Big debt is a killer for a start up in my view). Laser cutting is a huge help in this. If you have components laser cut then weld them together you straight away separate yourself from a lot of would bes.

I think anodizing gives a professional look that is hard wearing and seems simple to perform. The guy in the link I reffered to earlier on says to use around 200 amps at 12V.

http://www.focuser.com/atm/anodize/anodize.html

Theres formula based on the surface area to be treated to give a mil spec finish. I will follow up the links suggested re. DC current source and report back to the forum when I get to that stage.
 
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flyingnunrt

Senior Member
TIG (GTAW) is the neatest way to weld aluminium.
You will need pure argon at about 8l/m
You will need an AC machine with High Frequency.
Zirconiated tungsten is best for Aluminium but Ceriated is OK.
To get that nice stack of coins look takes a fair bit of practice.
Set the AC balance slightly favouring Electrode negative.
Pulse is a bit of a luxury.
Chinese welders are OK, not as fancy as Kempi etc but still work OK. But the after sales service will probably be nil and the operators manual is a bit vague for begginers.
Ensure you have a good ground connection or you will have problems.
3mm would probably weld at about 50 amps - depends on how much heat sinking is going to occur with your set up. A foot pedal is good.
I like a little bit of pre flow and post flow of argon and a couple of seconds of down slope on the current.
Either 5% Si or Mg filler wire will be OK.
Clean job and filler wire with Stainless Steel wire wool and then with acetone.
Try to maintain a very short arc length ie about 1.5mm 2 at the most and you should try to keep the filler wire within the gas envelope whilst your welding.
Don't weld in a breeze as it will blow away the gas shield and you'll end up with a mess.
Use a no 6 ceramic nozzle or use a gas lens with about 6mm electrode stick out.
re grind electrode whenever you have a tip strike or you'll just end up with a big mess.
Check out youtube for some good video clips on TIG welding.
Shouldn't take you too long to get some good welds if you can already stick weld, a few months maybe.
If you want good presentation then farm it out to someone that is experienced.
The rental on a small cylinder of gas will also be quite expensive.
 
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BrendanP

Senior Member
Thanks flyingnunrt. Theres lot of good info in your post.
Your post made me think of one more question, is it big advantage to have the push button handpiece as opposed to the type where you have to strike the arc like you do with a stick welder?
 
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flyingnunrt

Senior Member
Most definately
That is where the High Frequency part comes in
You start with a gap between electrode and the work
press the trigger and a spark ionises the air gap so curremt will flow
you don't ever touch the job with the electrode which would otherwise contaminate it and the work
The foot pedal can also be the trigger switch but I prefer one on the handpiece
 
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PicKidAxe

New Member
alcooke said:
Aluminum must be tig welded with ac because aluminum forms an oxide about 15 minutes after cleaning. This oxide rectifies and interrupts one half of the ac cycle and cuts the arc off. Continuous high frequency is necessary to maintain the arc. Fumes are not a problem unless you are working in a phone booth. Stainless steel fumes are bad.
Good luck with your project. - Al
Click to expand...
1. "i am not a welder", correct, people are not machines. people are weldors.
2. AL does not have to be TIG welded. there are numerous processes that weld AL, from friction stir to MIG. if you use MIG its best to use a spool gun.
3. continuous high freq is not necessary to maintain the arc. a freq overlay helps to stabilize the arc. high freq is used to start a TIG arc.
4. with MIG CO2 is used quite often (its a MAG gas). with TIG you need argon, or a mix of inert gases.
 
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alcooke

New Member
additional info on aluminum welding

2. AL does not have to be TIG welded. there are numerous processes that weld AL, from friction stir to MIG. if you use MIG its best to use a spool gun.
3. continuous high freq is not necessary to maintain the arc. a freq overlay helps to stabilize the arc. high freq is used to start a TIG arc.
4. with MIG CO2 is used quite often (its a MAG gas). with TIG you need argon, or a mix of inert gases.[/QUOTE]

It is true that aluminum doesen't have to be TIG welded. (I'd love to hear what your results are with "friction stir".
MIG as already mentioned does not result in as smooth a weld as TIG. MIG is a DC welding process. TIG which is a much more controllable technique must be done using AC when welding aluminum. The only gases to use are argon or helium with very small additions of other gases. CO2 is fine for steel. High frequency is essential for maintaining the arc when TIG welding aluminum. If the "frequency overlay" is not high frequency what is it?
In a previous post I may have been irresponsible in suggesting that good ventilation is not really important. Welding melts metal at high heat and inevitably vaporizes some of the metal. No matter what metal you don't wANT TO BREATHE IT.(CAPS were accidental but appropriate). Al
 
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BrendanP

Senior Member
microwave oven transformer mod

I've been doing some research on low V high I power supplies for anodizing.

I came across this well written/illustrated article on moding a microwave oven transformer.

http://www.users.on.net/~endsodds/psrewind.htm.

For the younger forum users remember, this is a ~240/100V project/hack, any mistakes and it can kill you. You shouldnt undertake it if you are unsure of what you are doing or you should seek help and advice before proceeding.
 
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slimplynth

slimplynth

Senior Member
BrendanP said:
I've been doing some research on low V high I power supplies for anodizing.

I came across this well written/illustrated article on moding a microwave oven transformer.

http://www.users.on.net/~endsodds/psrewind.htm.

For the younger forum users remember, this is a ~240/100V project/hack, any mistakes and it can kill you. You should undertake it if you are unsure of what you are doing or you should seek help and advice before proceeding.
Click to expand...
Should that be "shouldn't" ? :D just thinking about recent automotive threads
 
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PicKidAxe

New Member
alcooke said:
It is true that aluminum doesen't have to be TIG welded. (I'd love to hear what your results are with "friction stir".
MIG as already mentioned does not result in as smooth a weld as TIG. MIG is a DC welding process. TIG which is a much more controllable technique must be done using AC when welding aluminum. The only gases to use are argon or helium with very small additions of other gases. CO2 is fine for steel. High frequency is essential for maintaining the arc when TIG welding aluminum. If the "frequency overlay" is not high frequency what is it?
In a previous post I may have been irresponsible in suggesting that good ventilation is not really important. Welding melts metal at high heat and inevitably vaporizes some of the metal. No matter what metal you don't wANT TO BREATHE IT.(CAPS were accidental but appropriate). Al
Click to expand...
i was just noting various processes that can weld AL. and a MIG spool gun is used quite often to weld AL. TIG makes a nicer weld, its also tougher to use and requires higher skill level.
 
K

KMoffett

Senior Member
Brenden,

If you decide to do it yourself with a TIG, please come back and let us know how it worked for you. I've done a little TIG-ing of aluminum and it isn't quite as easy as those videos look. Even running a neat "stack of dimes" on the middle of a plain sheet takes a lot of practice. Aluminum gives you no hint that it's going to melt through on you. Running an outside corner bead on a tube end-cap plate will be a challenge for a non-TIG aluminum weldor. If this is a production prototype, take it to an experienced welding shop. You will be much happier in the end.

Since you mentioned anodizing, look at the alloys you're using. Some are best for anodizing and some for welding. Not sure which work for both. And the filler alloy counts in here too.

Ken
 
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BrendanP

Senior Member
Thanks K, I have no doubt that there will be a learning curve, but as I can already arc and MIG well I have no doubt I will master it.

Some time I was rigging at a nearby pulp mill and whilst we were standing around ( which crane crew does a lot of) I got talking to the fitters who were TIG welding stainless pipe. I asked if I could have a go on some scrap and they agreed. I got a reasonable looking weld straight off. Admittedly this was stainless not ally. I realize it doesn't change color before melting.

I will let you know how I go.
 
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KMoffett

Senior Member
Steel and Stainless...I love to TIG...a gentle cross between O/A and arc. Aluminum is a whole different animal entirely.

Ken
 
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regcheeseman

Member
I've welded professionally for several years - mostly TIG stainless. Now I work in another industry and I'd love to have a TIG setup at home but the small volume of jobs I need to do make it far more economical to get someone else to do it.

TIG welding ally is far more tricky than stainless, have you considered ally brazing? Simple inexpensive process which give neat strong results with basic tools.
 
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matherp

Senior Member
Brendan

The only downside of this machine is that the AC is fixed frequency (probably mains). For aluminium it is better to have variable frequency and most seem to find 100-200Hz best.

Also, since they don't advertise IGBT it is probably Mosfet based, no real issue but IGBT seems to give better life expectancy and efficiency. Remember for aluminium to get the foot control so you can control the heat.

Best Regards

Peter
 
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BrendanP

Senior Member
Thanks Peter , I checked, the foot control is standard with the machine.

Is the variable freq ability really critical in your view?
 
D

D n T

Senior Member
Welding ali witha propane torch!!

We use a method of welding aluminium using a propane torch with our students, most first time ali joiners.

You warm up the parent metals with your propane torch and then take the torch away and rub the rod into the hot joint, you have to dab it to test the temp, like you would waiting for a component to get hot enough when you are soldering. Once the rod starts to melt you just wipe it on, its easy to master and its strong enough to fix hole in ali boats.
Have a look at Duraflex easyweld on you tube and the web.
Sorry if it sounds like an ad but it works well and its easier than MIG or TIG and no "ali flu" ( coughing up the grot that you breath in as fumes when you weld)

Have fun.
 
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manuka

Senior Member
I first ran across that much hyped Durafix aluminium "welding" approach in the 1990s, & have used it with mixed success for small jobs. In spite of the seeming ease shown by this YouTube ,heating (& over heating!) was an issue (especially outdoors or on larger items), & MAPP (MethylAcetylene-Propadiene Propane) gas gave better results- MAPP supplies however have become very lean recently. Of course the M.Pt of aluminium is pretty low (660°C) & structure weakening may occur.

Aside from high stick cost,the approach is rather too labour intensive, requiring vigorous s/steel brush cleaning of the heated aluminium, & IMHO it's not suited to professional work.
 
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