![]() ![]() Note that when exposed to air (which contains 79 percent nitrogen, 20 percent oxygen, and 1 percent other elements), molten metal naturally absorbs nitrogen and oxygen. Proper arc length is paramount, and CV power sources help maintain that This longer, broader arc has more exposure to the atmosphere. ![]() Higher voltages increase the arc length, which in turn broadens the arc cone or arc width. In the self-shielded process, once the arc ignites, nothing lies between molten weld metal and the atmosphere except for the slag and internally produced shielding gases. However, with FCAW-S, you must properly dial in the correct voltage for the job at hand. Depending on the application, gas-shielded processes may give you a wider voltage window, which still produces satisfactory results. Dial in the VoltageĪll self-shielded flux-cored wires are sensitive to changes in voltage and so require a constant-voltage (CV) power source for good arc stability. This problem often is not as pronounced as it used to be, but it is still a concern. Knurled drive rolls can dig into the copper coating on solid GMAW wires and cause them to flake. ![]() Note, if you do switch back to GMAW after FCAW, be sure to change your wire feeder to the smooth V-groove drive rolls. To attain the same pushing force without squeezing so hard, FCAW-S wires require knurled V-groove drive rolls that grip the wire sheath, providing pushing force without deforming it. Unfortunately, the smooth V-groove’s tight squeeze can deform cored wires. In GMAW, a smooth V-groove in the wire feeder’s drive rolls grips the solid wire to feed it through the welding gun. Most FCAW-S wires work best in direct-current electrode-negative (DCEN) polarity, but a few are most stable with DCEP. The recommended or most stable polarity for FCAW-S, though, depends on the specific core elements (arc stabilizers) in a particular wire. GMAW (MIG) and most gas-shielded flux-cored (FCAW-G) wires weld best on direct current electrode positive (DCEP). In fact, working with some wires, using extended electrical stick-out procedures, you can deposit more than 20 lbs. an hour downhand (that is, flat and horizontal positions), depending on the wire used. an hour out of position and more than 12 lbs. ![]() However, withįCAW-S, you could deposit up to 8 lbs. With SMAW electrodes such as E7018, that might jump to 4 to 5 lbs. With stick electrodes like E6010 and E6013, you might deposit 2 to 3 pounds of metal an hour. Deposition rates are equivalent and, in some cases, exceed those achieved with gas-shielded wire welding. However, unlike SMAW, the self-shielded flux-cored process offers much higher productivity levels. Like SMAW, FCAW-S does not use an external shielding gas, so it is convenient for outdoor work (see Figure 1 and FigureĢ). Welders experienced in SMAW often pick up FCAW-S quickly, while those who know only short-circuit gas metal arc welding (GMAW) may take a little longer. All at once it produces its own shielding to help protect the arc, handles contaminants on the steel, deposits weld metal that meets structural requirements, and forms a fast-freezing slag over the weld metal.įCAW-S is more like shielded metal arc welding (SMAW), or stick, and less like other gas-shielded wire processes. Self-shielded flux-cored arc welding (FCAW-S) wire is the industry’s multitasker. Figure 1: Self-shielded flux-cored arc welding is used often for out-of-position work. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |