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Stick Welding With A TIG Machine???

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  • #16
    Cooling

    I hate to correct another Ferguson, ;-) but I think that you are wrong thinking that the gas does not cool the gun.

    I notice that my Syncrowave 200 has a feature built in that increases the post flow time at higher currents, presumably for cooling. The algorithm that they use is 5 seconds minimum, but adding one second for every 10 amps over 50 amps. So for 200 amps, you get 20 seconds of post flow. Kind of a smart feature, I think. I can't imagine any reason that they would want 20 seconds of post flow except to cool the gun and tungsten.

    If you think about it, compressed gas (air, argon, whatever) does cool things down. You have probably experienced this yourself with compressed air. The temperature of the gas is lower than room temperature, as it cools down when it expands, and the high speed of the gas increases heat transfer. Also, the gas is flowing right next to the tungsten, collet, etc, which is the hottest part of the gun.

    TIG welding torches are available in gas-cooled and water-cooled versions. Gas-cooled welding torches are cooled by the shielding gas which flows through, while water-cooled welding torches also have effective liquid cooling using a pump and heat exchanger.
    From Fronius, an Austrian welding machine company.

    Richard
    Last edited by raferguson; 06-01-2011, 10:33 PM.

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    • #17
      The gas can't have "zero" cooling effect because it impinges on hot parts that are not exposed to ambient atmosphere, such as the interior of the torch body and the entire internal gaspath until it exits the cup. There is good reason the companies producing them (Weldcraft excepted, but engineers don't write adverts) refer to the torch heads as being "gas cooled".

      If that sort of gas cooling didn't work, jet engines as we know them wouldn't exist. They are cooled by carefully calculated barriers of fan "bypass" air not used for combustion, which insulates the internal engine components all the way out to the afterburner. Disrupt the cooling air and Very Expensive Parts promptly melt.

      Ambient atmosphere impinges the torch on a much more limited surface area which is insulated by the rubber coating.

      One might measure the temperature drop with an internal thermocouple while letting gas flow through a torch that isn't powered. The A/B comparison doesn't require striking an arc. If internal gas flow does nothing, then there should be no temperature reduction with gas flow.

      We used multiple cylinders or Dewars so I'd demonstrate to students by cracking the torch valve. It got the point across.

      Alternately, blow compressed air (so you don't waste gas) through it and feel the temp drop.
      Note that simple pneumatic blowguns cool considerably when the valve is held open.

      Worth noting is that the heat when TIGing the heat is generated much closer to the torch than when stick welding, so there is probably little risk in shoving a stick rod into your TIG torch if you don't burn it down to a nub.

      http://www.engineersedge.com/heat_tr...vity-gases.htm

      You may also observe that when the postflow is abruptly shut off on a very hot gas-cooled TIG torch, the fine threads holding the collet body and back cap tend to stick, and strip when unscrewed. Running twenty TIG students with manual scratch-start rigs, we had ample opportunity to compare, and directed them to allow sufficient postflow to cool the torch head. You can feel the temperature drop easily. When we had students who killed multiple torch heads, we told them to increase postflow and the problem ceased.
      Last edited by 1930case; 06-01-2011, 10:58 PM.

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      • #18
        What exactly does atmospheric air cool on a gas/air cooled tig torch? The cup and the tip of the tungsten, thats about it (if you have any air moving in your shop). If atmospheric air is all that cools a gas/air cooled tig torch, how would you increase the cooling effect? Put a fan on your weldment and blow away the argon shielding gas?
        If the argon didn't cool anything on my air/gas cooled CK flexlock tig torch with gas valve, the tig torch would have melted along time ago.
        How much scratch start tig welding experience with gas/air cooled tig torches does a sales technician have? Better question, do any of the folks in this thread who say argon does not cool a gas/air cooled tig torch have any experiance at all with gas/air cooled tig welding?
        Myself, I have TSSA pressure pipe stainless weld tickets that have been done with nohting but gas cooled scratch start tig.
        Last edited by snoeproe; 06-04-2011, 01:18 PM.

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        • #19
          I don't particularly agree with running a stick off your tig torch as without a cooling gas such as argon, you'll melt the heck out of your plastic torch covering, in other words, that tig torch will never run gas in it again.

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          • #20
            Originally posted by c wagner View Post
            How close is the tig torch to the weld puddle when tig welding?
            Now how close to the weld puddle would the tig torch be with a 3/32 SMAW rod in it?
            What polarity do you use in the GTAW process?
            Typically what polarity do you use in the SMAW process when burning a xx10 or xx18 series rod?

            Yes if you were planning on burning 5 or 10 lbs of rod as fast as you can put a fresh on in (not very quick with a tig torch I might add) you might overheat the tig torch.
            I also agree that using the GTAW torch for the SMAW process would put the torch at risk of being damaged by spatter, etc., it's not the ideal tool if you plan on switching back and forth between the 2 processes.

            If it was the difference between getting out of the bush or being found dead by a search party one week later then I'll gladly buy myself another tig torch.
            Those are good questions, lets talk about them a bit.
            With smaw we know we use DC+ (reverse) polarity. DC+ polarity put 70% of the heat in the electrode and 30% of the heat in the work. When tig welding in DC we know we use DC- (straight) polarity. DC- polarity puts 70% of the heat on the work and 30% of the heat in the electrode (tungsten). Thats what keeps our tungsten from melting (very important when tig welding last time i checked).
            Now, lets take our gas cooled tig torch and stick a 3/32 6010 5P+ in it and do some smaw. If we set our ploarity on DC+ (which we know we need to run this rod) we will be putting 70% of the heat in the rod which is stuck in our tig torch. In other words, once this weld job is done this torch has been heated wat too hot and will be as good as done. Keep in mind we have no argon flowing through the torch (which does cool the torch) and it compensates an already bad situation. We also know how bad 6010 spatters. Spatter is everywhere.
            Last edited by snoeproe; 06-04-2011, 01:57 PM.

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