Which practice helps minimize tungsten degradation?

• A. Use AC
• B. Use DCEN with small tungsten diameter
• C. Use DCEN
• D. Not using water cooling

Answer: (C)

Direct current electrode negative (DCEN) minimizes tungsten degradation by keeping the tungsten tip as the negative electrode. When the electrode is negative, the arc heat is directed more to the workpiece and the tungsten experiences less oxidation and erosion. Alternating current or keeping the electrode positive on the arc causes the tip to oxidize and erode more quickly during the positive half-cycle, speeding wear. A smaller tungsten diameter concentrates heat and current at the tip, increasing degradation, while not cooling the system allows excessive heat at the electrode. Not using water cooling would also raise temperatures and wear. So, DCEN is the best practice for extending tungsten life and reducing degradation.