chrisf
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| posted on 10/8/08 at 09:09 PM |
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TIG help! Burning through tungstens
Hi Gents:
I spent the afternoon having a go with the TIG on some scrap. Well, not really. I spent the afternoon sharpening tungstens. What is happening is
I'll dip into the pedal and get a cold electric arc, then a regular arc as a puddle begins to form after about 2 seconds. Then, my freshly
sharpened tungsten glows red, then dulls completly, round off a nice ball at the end. Sometimes it melts up into the cup! Increading the heat will
make the tungsten DRIP into the puddle.
Here are the specs:
3/32 and 1/6th 2% thoriated tungsten
DC mode
2-stroke high frequency w/ pedal control
torch connected to negative, clamp connected to positive
100% argon
AC balance set to the middle (50%), though I don't think it matters for DC
Start current at 50%, though I'm using the pedal; it doesn't matter though. The tungsten melted it the start current was set to min
Weld current at 120amps
downslope set to 5
post flow set to 2
The workpiece is a 1/16" piece of mild steel. I'm not using any filler. I'm just trying to get a puddle going and control it with
the torch. Any suggestions on how to keep tungsten alive longer? These are rather expensive and I'm burning (literally) through them. It's
almost like a machine setting is wrong.
Oh, it is an ESAB Heliarc 161 inverter-based AC/DC TIG.
--Thanks, Chris
[Edited on 10/8/08 by chrisf]
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madteg
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| posted on 10/8/08 at 09:17 PM |
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Have you got the polarity the right way round, the earth should be in the positve on the set. kev.
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Triton
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| posted on 10/8/08 at 09:21 PM |
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you sure you are not using tungstens for ali welding ?
My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.
www.tritonraceseats.com
www.hairyhedgehog.com
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Peteff
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| posted on 10/8/08 at 09:23 PM |
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2 seconds pre flow? That sounds low try upping it so the gas gets to the torch before you arc up.
Sorry that's your post flow, you don't mention pre flow. What pre flow are you using?
[Edited on 10/8/08 by Peteff]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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mark chandler
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| posted on 10/8/08 at 09:39 PM |
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Negative torch correct so to much current or not enough gas.
1/6" should weld much lower than 120amps, crank it right down.
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chrisf
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| posted on 10/8/08 at 09:52 PM |
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Thanks gents, you're right: the polarity was off. The preflow is set at the gun, right? When the machine starts, two seconds or so of gas flows,
even though I didn't hit the pedal.
I have pure tungstens for the ali, which I haven't tried. I'm just having a go with the mild steel.
After switching the polartity, the arc fires right up and a nice puddle forms. I like how easy it is to control. I even played around with dipping
filler rod, but all I had was .020" mig wire, which seemd quite small.
But most importantly, with the ground connected to the workpiece and my wrist resting on it as well, I shocked the sh_t out of myself when I blew a
hole though the material. Is it common to get a shock whilst TIGing?
I should mention no gloves were worn on the torch hand because it is in a cast.
--Thanks, Chris
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aerosam
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| posted on 10/8/08 at 09:55 PM |
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i'd turn you current down to about 60 amps and press and release your trigger a couple of times before you start up, allowing the post flow
timer to feed argon all the way through the system to the torch. Also make sure your gas regulator is turned up high enough.
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10X
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| posted on 10/8/08 at 11:48 PM |
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I have found this web site very useful when trying to setup for a new process.
http://www.millerwelds.com/education/calculators/tig_amperage_calculator.php
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aerosam
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| posted on 11/8/08 at 04:53 AM |
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quote:
Originally posted by chrisf
I shocked the sh_t out of myself when I blew a hole though the material. Is it common to get a shock whilst TIGing?
I should mention no gloves were worn on the torch hand because it is in a cast.
It's not that uncommon to get a shock - hurts too doesn't it? It is bets to wear gloves as they will protect against shocks and a really
nasty sunburn you WILL get as your hands are so close to the arc.
Personally I wear cut resistant gloves, they are neoprene coated cotton so they give some protection against the elecricity, heat and of course UV.
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