Small TIG Welds

[down19992000]

at work we do plasma welding with a thermal dynamics welder using 3/32 tungsten welding eight thousanths stainless steel. pain in the a$$ to learn but leaves a pretty weld

[Rocky D]

I realize this is an old thread, but I didn't see anything about technique in producing small welds...we must do this in aircraft welding. In this project, I had to weld a 321 stainless fin .030" to an oil tank that was .035" thick, and have no penetration to the back side...I have never used a tungsten smaller than 1/16" and wire size of .030"...this is the trick...first have a copper backup purge for stainless, and force the rod into the joint, and carefully walk up the rod, leaving a .050" weld...you need good eyes, steady hand and good concentration to do it...soon it will become second nature.

[MadisonHotRods]

Could you explain this "copper backup purge for stainless"? I am familiar with back purging with argon gas only. How is this copper used?

[Aerometalworker]

Could you explain this "copper backup purge for stainless"? I am familiar with back purging with argon gas only. How is this copper used?

I think he meant:

Copper backup , purge for stainless

Meaning use a copper backup....and purge for stainless. This is pretty common for thin stainless work like that.

If im wrong I appologize

-Aaron

[batchelc]

If your thinking about doing thin tubes (like on the piper cub) then the WP-225 torch is worth looking at. It has a flexible neck and you can change the heads out with your gloves on. You can also buy 45, 0 and 90 degree heads:

http://www.arc-zone.com/index.php?ma...cPath=13_18_42
http://www.arc-zone.com/index.php?ma...h=13_18_42_342

Use a 1/16 red tungsten and turn the heat down (start at 50 amps). If you have good foot/finger control you can turn the heat up (75 or so) and pulse the foot control. You want to minimize heat input to the part. Either find the lowest amount of continuous heat that you can use or work of using higher amperage for shorter times (will cause the least warping).

You should be aware with thin stainless you should have an inert gas like argon on the back side or you run the risk of certain types of cracking. For flat plate parts to practice on I would not worry about this but if you do anything structural you will want to do some research first.

[Rocky D]

Could you explain this "copper backup purge for stainless"? I am familiar with back purging with argon gas only. How is this copper used?

Copper plates formed to the shape needed to provide gas in the areas that would be affected by the welding process...to deliver the argon to the precise area, there will be a copper tube welded and there will be holes in it for the gas to flood the area needed...we use copper because it acts as a
heat sink, and will not stick to the penetration, should there be any.
This is a corner purge drawing...this can be made entirely out of copper...for welding a fillet.

[griff01]

Collets and gas lenses are available down to .040 for the Diamondback torch that is supplied with the Miller Syncrowave 250. My bet is they are also available for the torch supplied with the 200. 1.5 to 3mm wide welds are realistic with the 3/32 you said was supplied with your machine.

[fun4now]

can you use strait Co2 for back purge or C-25 maybe ?? or dose it need to be argon. if TIGing the part with strait argon for torch gas, are there any options for purge other than strait argon ??