Chapter 8 Gas Metal and Flux Cored Arc Welding 223 Copyright Goodheart-Willcox Co., Inc. When the small oval pattern is used, the arc goes out to the front, or leading edge, of the weld pool and then circles back over the center of the weld pool. See Figure 8-47A. Small ovals on fl at plate are made quickly. When this technique is used to make a fi llet weld or to fi ll a groove weld, the ovals are slightly larger and made slightly slower as shown in Figure 8-47B. This oval weave pattern is a good skill to develop. You can use it in all welding positions. The W-weave pattern is performed by moving the arc from one side of the weld pool to the opposite side. Keep the arc near the front edge of the weld pool. You can delay slightly at the end of each side-to-side motion. See Figure 8-47C. A Z-weave is used in the vertical position. Move from one side of the weld joint to the other in a straight line. Then return along a diagonal line to the starting side as shown in Figure 8-47D. This diagonal motion advances the weld pool. The Z-pattern is repeated as you advance the weld pool along the plate or along a weld joint. The Z-weave is used to make fi llet welds or fi ll groove welds. Another use of the Z-weave is to bridge a gap between parts or to fi ll a wide root opening. Get another piece of carbon steel and make weld beads with a weave. Practice both the oval weave and the W-weave patterns. Weld a lot of weld beads. The skills you learn welding on these plates will help you when welding joints in all welding positions. Another skill to learn and practice is to stop and properly restart a weld bead. Both GMAW and FCAW use a continuous electrode wire. You can weld for long distances without stopping, but you will have occa- sions to stop a weld bead and restart. Do not fi ll the crater if you are not at the desired end of the weld. Before restarting, clean the previous weld bead. For GMAW, thoroughly wire brush the surface to clean it and remove any silicon. For FCAW, chip the slag away and then thoroughly wire brush the previ- ous bead. A power grinder with a wire brush wheel can be used to remove slag. Always wear a full face shield, heavy gloves, and leathers when using a power grinder with a wire brush wheel. Make sure the weld- ment is securely clamped to a fi xed surface. Position your gun and electrode wire about 1/2″ (13 mm) in front of the existing crater. Remember not to fi ll the crater if you are not at the end of the weld. Pull the trigger and move the arc backward to almost the rear of the existing crater. This will remelt the exist- ing crater. Move the arc to the leading edge of the weld pool and continue the weld bead. See Figure 8-48. A B C D Goodheart-Willcox Publisher Figure 8-47. Weave techniques produce a wider and flatter weld bead. A—Small oval weave for bead on plate or the root of a groove or fillet weld or small weld beads. B—Larger oval motion used for wider weld passes. C—W-weave pattern. D—Z-weave pattern. 1/2″ (13 mm) 1 3 2 1. Strike arc 3. Start moving forward to continue weld 2. Quickly move to back of crater Goodheart-Willcox Publisher Figure 8-48. Steps to take to restart a weld bead. 1—Start 1/2″ (13 mm) in front of the existing crater. 2—Move the arc to the rear of the existing crater to remelt the crater. 3—Move the arc to the crater front and continue the weld bead.