Shielded Metal Arc Welder

Welding Guidelines (Continued)

NOTE: Weld bead width (W) W should be approximately

twice the diameter fo the electrode rod used.

Normal Amps, Arc Length, Speed

Amperage Too Low

Amperage Too High

Figure 9 - Weld Appearance

Arc Length Too Short

Workpiece

Speed Too Fast

Speed Too Slow

Arc Length Too Long

For most applications, a 45º travel angle and 45º work angle is sufficient. For specific applications, consult an arc welding handbook.

NOTE: Right handed welders should weld from left to right. Left handed welders should weld from right to left. The electrode should always point into the weld puddle as shown.

ARC LENGTH

Arc length is the distance from the work piece to the tip of the electrode, the distance which the arc must travel. A proper arc length is essential to generate the heat needed for welding (See Figure 9). An arc that is too long produces an unstable arc, reduces penetration, increases spatter, and causes flat and wide beads. Too short an arc does not create enough heat to melt the work piece, the electrode has a tendency to stick, penetration will be poor, and uneven beads with irregular ripples result. A proper arc should be no longer than the diameter of the rod. The sound of a proper arc is a steady, crisp sizzle, similar to bacon frying.

TRAVEL SPEED

The travel speed is the rate at which the electrode is moved across the weld area (See Figure 9). When the speed is too fast, the bead is narrow and bead ripples are pointed as shown. When the speed is too slow, the weld metal piles up and the bead is high and wide. To control travel speed, watch the width of the weld bead (not the arc) when welding. The weld bead is the orange, molten metal behind the arc. The width should be approximately twice the diameter of the welding rod. Control travel speed to obtain a consistent bead width.

SLAG REMOVAL

Wear ANSI approved safety

glasses (ANSI Standard Z87.1) and protective clothing when removing slag. Hot, flying debris can cause personal injury to anyone in the area.

After completing the weld, wait for the welded sections to cool. A protective coating called slag now covers the weld bead which prevents contaminants in the air from reacting with the molten metal. Once the weld cools to the point that it is no longer glowing red, the

slag can be removed. Removal is done with a chipping hammer. Lightly tap the slag with the hammer and break it loose from the weld bead. The final clean-up is done with a wire brush. When making multiple weld passes, remove the slag between each pass.

WELDING POSITIONS

Four basic welding positions can be used; flat, horizontal, vertical, and overhead. Welding in the flat position is easier than any of the others because welding speed can be increased, the molten metal has less tendency to run, better penetration can be achieved, and the work is less fatiguing.

Other positions require different techniques such as a weaving pass, circular pass, and jogging. A higher skill level is required to complete these welds.

All work should be performed in the flat position if possible. For specific applications, consult an arc welding h a n d bo o k .

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