TIG (Tungsten Inert Gas) welding is known for producing clean and precise welds. However, improper machine setup or incorrect usage can easily lead to poor weld quality, tungsten contamination, or unstable arc. Below are some common mistakes and how to avoid them.
1. Incorrect Tungsten Selection
Using the wrong tungsten type or size for the material can cause arc instability and poor penetration. For example, aluminium welding requires AC mode and suitable tungsten (e.g. pure or zirconated tungsten).
2. Wrong Polarity, Mode, or Torch Connection
A common mistake is incorrect polarity selection or connecting the torch to the wrong terminal.
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For DC TIG welding (steel, stainless steel):
The torch should be connected to Negative (–) and the work clamp to Positive (+).
This provides a stable arc and prevents tungsten overheating. -
For AC TIG welding (aluminium):
The machine automatically alternates polarity, but correct torch and work clamp connections are still essential.
3. Poor Gas Flow or Wrong Gas
Insufficient shielding gas flow or using the wrong gas will result in oxidation and porous welds. Pure argon is recommended for most TIG welding applications.
4. Contaminated or Improperly Ground Tungsten
Touching the tungsten to the workpiece or filler rod contaminates it. A dirty tungsten will cause unstable arc and spatter. Always regrind tungsten properly when contamination occurs.
5. Incorrect Amperage Setting
Too much current can burn through thin material, while too little current leads to lack of fusion. Always adjust amperage according to material thickness.
6. Poor Torch Angle and Travel Speed
Holding the torch at an incorrect angle or moving too fast or too slow affects bead appearance and penetration. A stable hand and consistent travel speed are essential.
7. Inadequate Cleaning of Base Material
Oil, rust, paint, or oxide layers can cause porosity and weak welds. Always clean the base material thoroughly before welding.
Conclusion
Proper TIG welding starts with correct machine setup and good welding habits. By avoiding these common mistakes, welders can achieve better weld quality, longer consumable life, and more consistent results.
