Page 36 - MetalForming June 2011
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Welding of Thin Materials
The screens in this gas lens help distribute shielding gas evenly around the tungsten electrode and the weld puddle.
round weld puddle that concentrates the heat.
As with all welding, the key to obtaining good, consistent weld quality is finding a comfortable position. While most welders will determine the optimum technique that affords the best torch control, they should position their bodies to allow them to clearly see the weld joint and the tip of the tung- sten electrode. They should keep the tip approximately 1⁄8 in. from the base material. This helps maintain a consistent arc length and prevents arc wandering, which could increase heat input to the workpiece. A consistent 1⁄8-in. gap from electrode to workpiece also helps maintain good shielding-gas cover- age and allows visibility of the weld puddle, to help the
welder control travel speed.
7]How does travel speed affect quality when welding thin materials?
A steady travel speed is critical when welding thin mate- rials. Weld too slowly and heat can build up in the base material, or the weld bead can grow too wide. Push the torch forward, as described above, so that the weld puddle remains slightly ahead of the torch and remains visible. The welder should move the torch, and add filler metal when required, at a pace that allows him to create welds whose width is approximately equal to the workpiece thickness.
8]Can a gas lens installed on a GTAW torch help when welding thin materials?
Compared to a torch equipped with a standard collet body, a welding torch outfitted with a gas lens will provide better shielding-gas coverage and more evenly distribute the gas around the tungsten and weld puddle, without the need to increase gas-flow rate.
Gas lenses typically are of brass or copper and contain layered-mesh stainless-steel screens. Improved shielding-gas
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34 MetalForming/June 2011
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