Cause Analysis :

1. Excessive current; 2. Unskilled operation techniques, the tungsten electrode is in contact with the base material; 3. Wrong selection of the tungsten electrode, including diameter and variety; 4. The tungsten electrode protrudes too long; 5. The tungsten electrode sharpens too long; 6. The impure argon gas causes the tungsten needle to oxidize; 7. The flow of argon gas is too large or too small, which causes the tungsten needle to contact with the air, and the tip oxidizes.

solution：

1. Control the allowable current value to adjust the current; 2. Contact arc starting operation should be proficient or switch to high frequency, pulse arc starting, avoid tungsten electrode contact with the base metal during welding; 3. Choose a larger diameter tungsten needle, In the case of welding, choose pure tungsten electrode (green head) or zirconium tungsten electrode (white head); 4. The extension length of the tungsten electrode should be adjusted according to the argon gas flow and the size of the porcelain nozzle; 5. The sharpening angle should be appropriately increased. For details, see "Guide to the Shape and Angle of Tungsten Pole Sharpening"; 6. Ensure that the argon is dry and moisture-free, and the purity is above 99.9%; 7. Adjust the argon flow to moderate.