Machinery's Handbook, 31st Edition
1590 Flux-Cored Arc Welding versatile consumables for thin and thick steel sections are the 0.045 in. for GMAW and the 0.062 in. for FCAW electrodes. The approach to a welding application is critical to achievement of optimum weld quality at minimum cost. In many applications, minimal consideration is given to weld costs. Half of every man-hour of welding in many shops could be saved with selection of the correct electrode diameter used with optimum parameter settings. A practical point that is often overlooked in selection of FCAW electrodes is that the larger the electrode diameter, the more restricted is the application thickness range. Large FCAW electrodes such as the 3 ∕ 32 in. (2.4 mm) are neither suitable nor cost-effective for the common steel thickness range of 1 ∕ 4 to 1 ∕ 2 in. (6.4 to 13 mm). Smaller FCAW electrodes such as the 1 ∕ 16 -in. (1.6-mm) diameter, are suitable for both thin and thick applications. A 1 ∕ 6 -in. diameter FCAW electrode used in the 300- to 350-amp range provides excellent deposition rates with superior welder appeal and negligible smoke. Large-diameter 3 ∕ 32 -in. (2.4-mm) electrodes are popular for manual applications. How ever, from a practical point of view, this electrode size is often better suited to mechanized high-current welding in which the high currents required for optimum deposition rates may be safely used without health risks. Use of an electrode at 60 to 80 percent of its weld ing current capability indicates that the correct diameter electrode has been selected for the application. When an electrode is used at its maximum-current capability, it shows that the next size larger electrode should be preferred, and when the low end of the current capability is in use, the electrode selected is typically too large. The 0.062-in. (1.6-mm) Diameter, E70T-X Electrode.— The 0.062-in. (1.6-mm) diam eter FCAW electrode is the most practical size of its type and will provide excellent depo sition rate potential with a practical current range and the broadest application range. Settings for the common 1 ∕ 16 -in. diameter E70T-1 electrode are shown in Fig. 7. With the GMAW process, a 3 ∕ 8 - to 7 ∕ 16 -in. (9.6- to 11-mm) minimum-weave fillet weld is typically the maximum size that can be made in a single pass. The 0.062-in. ( 1 ∕ 16 -in, 1.6-mm) FCAW electrode can easily produce a 3 ∕ 4 -in. (19-mm), nonweave, single-pass fillet weld. This size of electrode is also a practical choice for welding steel of 1 ∕ 4 in. (6.4 mm) or greater thick ness. From a cost perspective, FCAW consumable electrodes should be used whenever the GMAW process is not suitable.
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Fig. 7. Settings for 1 ∕ 16 -in. (1.6-mm) FCAW, E70T-X Electrodes The average deposition efficiency of a flux-cored electrode is 85 percent, which means that for every 100 lb or kg of electrode material used, 85 lb or kg ends up as weld material. In contrast, the average deposition efficiency of a GMAW electrode used with argon mix tures and correct equipment settings should be a minimum of 99 percent.
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