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Practical TIG Welding: Using A Gas Lens

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Using A Gas Lens


00:00 - In the earlier gas lenses and cups module, we introduced you to the gas lens and its benefits in diffusing the gas through a series of metal screens, designed to create a smooth laminar flow of argon over our weld arc.
00:13 This differs from the regular collet body and nozzle that your machine would have been supplied with.
00:18 In situations such as aluminium welding, this regular collet body can work just fine but as motorsport enthusiasts we don't tend to leave anything stock for long and your first modification should be a gas lens.
00:31 The effect of a gas lens can be difficult to see when we're welding in perfect conditions with very short tungsten stick out lengths.
00:38 However its laminar flow can equip us with the ability to get into some of the more difficult locations that we often find ourselves in with motorsport fabrication.
00:47 For this demonstration, we're going to perform a back to back weld test using a regular collet and nozzle combination followed by a gas lens in a number 12 cup to show the differences in not only the shielded arc but also the shielded heat affected zone.
01:02 To start, we're going to set our gas flow rate to 12 litres per minute which is the equivalent of 25 cubic feet per hour.
01:10 Welding with the regular collet and nozzle can be a little different to a gas lens and the physical length of the nozzle can make the torch difficult to get into those tight areas and the stick out length of our tungsten is restricted by the lack of gas coverage.
01:25 During the DC TIG welding process we can get an indication of the performance and coverage of our shielding gas by looking at the heat affected zone.
01:33 When our materials are bright and shiny, we can see the reaction to the atmosphere as a colouring of the metal.
01:39 In this case, you can see the heat affected zone is only partially shielded with the gas.
01:44 The colouring that is starting to present itself in this area shows that the shielding gas may not be sufficient or is suffering from the turbulence that is known to occur through a regular collet body's design.
01:56 Changing over to the gas lens is an easy and effective way to increase gas coverage and prevent these reactions in the heat affected zone.
02:03 For this comparison, we won't change the gas flow rate from the 12 litres per minute that we used with the regular collet setup and we'll see a large improvement in the shield of gas with this number 12 cup.
02:16 Even though this cup has a much larger diameter, its design allows for a far greater range of tungsten stick out and therefore this improves accessibility into the weld joint.
02:27 This, combined with the laminar flow of gas created by the fine mesh screen gives us results that are far superior to the regular collet body.
02:35 This is evident in the resulting weld.
02:37 You can see the reduced colouring of the heat affected zone that surrounds the weld bead.
02:42 This weld bead also benefits from the increased visibility and shortened arc length due to the accessibility of the larger tungsten stick out that we can use with the gas lens.
02:53 Because of the longer tungsten stick out, it's important to add in a little pre and post flow gas to shield the argon both on ignition of the arc and termination as the tungsten will be susceptible to contamination from the atmospheric air surrounding it if we fail to do so.
03:09 When looking at both welds side by side, it's important to understand that both require the same amps, the same gas flow rate and the same technique but the part welded with the gas lens attached produced a much neater and stronger weld due to the increased accessibility and shielding that the gas lens offers.
03:27 Remember that in general, we'd also increase the gas flow rate with these cups which would further improve our results.

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