Wire entry
The location of wire entry into the weld pool is critical. For hot wire GTA welding, wire entry is normally at the rear of the puddle with the wire deposited in the depression behind the arc at the rise of the weld pool. This permits faster travel speed than with cold wire GTAW where wire entry is at the leading edge of the puddle. Hot wire travel speeds of 8-9 IPM (203-228 mm/min) are typical compared to about 4 IPM (101 mm/min) for cold wire GTAW. Wire extension from the contact tip of the wire guide tube to the inside edge of the electrode is set to nominally 0.750 to 1.062 inches (19-26.9 mm). A manipulator is used to adjust the wire to tungsten distance which is the space between the tungsten tip and the wire which, depending on the application, is in the range of 0.125 inches (3.1 mm) and 0.156 inches (3.9 mm). The wire entry angle is nominally 45° or higher, to control the wire entry into the weld pool.