Choosing Right Current for Tungsten Electrode for DCEN Welding and AC welding

People usually use tungsten electrode for aluminum GTAW. As we know, tungsten electrode has many types, and each type is given an AWS classification and includes a painted stripe around one end so you can easily identify the type, including pure tungsten (EWP), 2% thoriated (EWTh-2), zirconiated (EWZr-1), ceriated (EWCe-2), lanthanated (EWLa-1), and rare earth（EW-G）tungsten electrode.

Pure tungsten electrode has a lot of shortages, so manufacturers usually add various additions to the tungsten electrode for improving electrode’s performance. First, doped with rare earth makes the tungsten less likely to sag or droop at high temperatures. Second, it makes electrode easier for the tungsten to emit electrons, which gives it a higher current-carrying capacity compared to pure tungsten.

In the past, people usually use 2 percent thoriated electrodes direct current electrode negative (DCEN) welding, but although more recently lanthanated and ceriated electrodes have become more popular for this type of welding. Because 2% thoriated tungsten electrode has radioaction and it will harm people’s health. On the other hand, When people started to weld aluminum by GTAW using alternating current (AC), they found out 2% thoriated electrodes really weren’t well perform for that type of welding. In AC GTAW much more energy of it is taken up by the tungsten than is taken up in DCEN welding. So in the past the electrode choices for AC using were limited to pure tungsten or zirconiated tungsten, which could carry more current than a pure tungsten electrode of the same size. Neither of these electrodes was used with a sharpened tip. Instead, they were allowed to form a round ball on the end. So during AC, people prefer to choose lanthanated and ceriated electrodes.

On the other hand, thoriated tungsten can produce to a very irregular in geometry, which produced a fluttery, irregular arc. So pure and zirconiated electrodes were preferred.

When inverter GTAW machines came on the scene, the balance control can be set much further toward electrode negative (EN), but it still getting good arc cleaning action. Since only a little electrode positive (EP) is used, the tungsten electrode stays much cooler. In fact, the best electrodes for AC inverter GTAW machines are generally ceriated, lanthanated, and rare-earth electrodes, which are all sharpened to a point and it can retain the point very well during use. Thoriated, zirconiated, and pure tungsten electrodes are not often used with AC inverter machines.

• < Prev
• Next >