Page 431 of 561

WIRE WELDING

• Insert the wire spool in the wire feeder and straigthen approximately 10-15cm of the wire end. To avoid damaging the liner or getting the wire stuck when feeding it through the liner, it maybe an advantage to round off the wire end with a file. Then insert the wire in the torch cable liner, fasten the feeder rolls and feed the wire through until it protrudes from the torch. Checking the wire feed function

4.03

• Check and if necessary adjust the wire spool resistance. Even at the highest wire feed speed the spooi shall stop immediately when the torch micro-switch is released, without uncoiling excessive wire between spool and feed rolls. • The feed roll pressure should be adjusted to a pressure where they slide on the wire if the wire is stopped at the torch. This is checked by stopping the wire at the torch nozzle while keeping the feed button depressed. Do not touch the wire when testing this unless the equip­ ment has a cold feed switch. The roll pressure may be tested by cutting the wire level with the torch nozzle and using an electrically insulating material to hold the wire back. • To provide best conditions for arc start the wire should be cut off at a sharp angle 10-15 mm away from the nozzle tip before welding starts. The sharp point will provide a better starting point for the arc than a flat wire tip surface, especially for larger wire diameters.

Round off wire tip before inserting wire in liner.

A sharply pointed wire will improve arc start.

Shielding the workplace Strong draft may disturb the shielding gas flow and cause welding faults. When necessary, the weld bead should therefore be shielded. Welding fume extractors must be positioned with care to ensure they do not affect the shielding gas.

430

Strong draft may disturb the gas shield.