4 WELDING VOLTAGE Although discussed in Chapter 3, it should be re-emphasized that the voltage setting directly controls the arc length. In addition, a certain range is required to maintain arc stability at any given welding current level. ARC TRAVEL SPEED The arc travel speed is the linear rate that the arc moves along the workpiece. This parameter is usually expressed as inches or meters per minute. Three general statements can be made regard ing the arc travel speed: 1)   As the material thickness increases, the travel speed must be lowered. 2)   For a given material thickness and joint design, as the welding current is increased, so is the arc travel speed. The converse is also true. 3)   Higher welding speeds are attainable by using the forehand welding technique. WELDING TECHNIQUES The first general welding technique that affects weld characteristics is torch position. This refers to the manner in which the torch is held with respect to the weld joint. The position is usually described from two directions – the angle relative to the length of the weld and the angle relative to the plates as illustrated in 7-4 and 7-5 respectively. Both backhand and forehand welding techniques are shown in 7-4. The backhand method means the torch is positioned so that the wire is feeding opposite to the direction of arc travel. Filler metal is being fed into the weld metal previously deposited. For the forehand method, the torch is angled so that the electrode wire is fed in the same direction as arc travel. Now the filler metal is being deposited, for the most part, directly on the workpiece. It should be noted that a change in welding direction is not required to facilitate forehand or backhand welding, only a reversal in the longitudinal torch positioning. Generally, operators find that the backhand technique yields a more stable arc and less spatter on the workpiece.
Effects
Weld Bead
Torch Position
Characteristics

 

 

 

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