Page 394 of 561

TIG WELDING

Preparing the torch

Always disconnect the torch from the power supply before changing nozzles or adjusting the electrode. This is easily done, by disconnecting the Dix Connector at the end of the torch cable.

Ensure that correct and unharmed nozzle, heat shield, collet body, collet and electrode are used. If the welding current is to be 100A or lower, the small nozzle 6 (ø 9mm) should be used, together with the 1.6 mm (1/16”) electrode, collet and collet body.

For welding above 100A it is recommended to use the large nozzle 7 (ø 11mm) and 2,4 mm (3/32”) electrode, collet and collet body. Check if the work at hand makes it necessary to use the short back cap. Ensure that collet body, nozzle, and back cap are properly tightened, and that the electrode is properly pointed. The electrode shall protrude 3-6mm outside the gas nozzle.

6 3–

mm

Check electrode protrusion

Connection to Gas Supply Connect the gas hose to the argon regulator, and make sure all connections are properly tightened.

Open gas cylinder valve fully, open torch valve 3/4 turn and adjust the regulator to a flow of 9-10 I/mm. Let the gas flow a few minutes so that the whole gas system is thoroughly purged, with inert gas. This will prevent contamination of the welds. Then set correct flow for the job at hand and close the torch valve. For flow setting see table on welding parameters.

If additional gas supply for backing gas is needed, this should be taken from a separate gas supply. By taking backing gas from the same regulator that supplies the torch, it will be impossible to adjust to correct gas flow for the torch.

Connection to Welding Machine Two-thirds of the total heat developed in the TIG arc is developed on the positive side of the arc, which is bombarded by the electron flow. The TIG torch must therefore always be connected to the negative pole of the welding machine (straight polarity). If connected wrong, the tungsten electrode tip will melt, and the nozzle and torch head may be damaged.

The return clamp should preferably be fastened directly to the work piece, and the return cable shall be connected to the welding rectifier’s plus pole.

4.02

If available, connect the remote control to the welding machine and have the current regulator available at the work site. For current setting see table on welding parameters.

393