A Beginner's Guide to TIG Welding

TIG welding, short for “Tungsten Inert Gas Welding”, is a process known for creating precise, clean welds on various materials. It's especially useful for critical welding jobs in aerospace, food equipment, high-purity processing, and motorsports.

In this beginner's guide, we'll cover:

• The Basics of TIG welding
• Advantages of TIG Welding
• How to choose the right TIG welder
• Setting up your TIG equipment
• Selecting the Correct Tungsten
• Useful Tips for New Starters
• TIG Welding Troubleshooting Tips

What is TIG Welding?

TIG welding uses a special torch with a tungsten electrode to heat the metal that is being welded. This process is protected by a shielding gas, typically argon, to keep out impurities, this is also fed from the torch. The power source generates an arc from the tungsten electrode to the workpiece which creates a molten metal pool. The reason that the electrode is made from tungsten is so that it does not get consumed, and filler metal is added into the molten pool separately. The key to good TIG welding is carefully manipulating the weld pool and consistently feeding the filler wire.

Advantages of TIG Welding

TIG welding offers several advantages, making it a preferred choice for many applications:

• Welding Versatility: TIG welding can be used to join a wide range of metals, including low alloy steels, stainless steels, aluminium, and more.
• High-Quality Welds: TIG welding provides excellent control over the welding process, allowing for clean and precise welds, making it ideal for projects where both appearance and weld integrity matters.
• Clean Process: TIG welding is clean, with no sparks, spatter, or slag generated, reducing the need for post-weld cleaning.
• Welding in Any Position: TIG welding works well in all positions.

How to Choose TIG Welding Equipment

Selecting the right equipment is essential for your welding needs. Here are some things to consider:

• Material Type: Determine what materials are to be welded. A DC-only power source is sufficient for steel or stainless steel, while an AC/DC power source is essential for welding aluminium and some other materials.
• Material Thickness: Make sure the power source can deliver sufficient power for the thickness of the materials to be welded.
• Electrical Supply: Consider the type of power supply available in the welding bay, is it 110V or 230V.

TIG Equipment Setup

Proper setup is crucial for successful TIG welding. Here is a checklist of steps to follow:

1. Connect Torch: With an air-cooled torch, use the adapter provided in the accessory package to connect the torch to the front of the welding machine. Attach the gas hose and regulator.
2. Connect Remote Control: If a remote controller is being used, plug this into the welding machine.
3. Connect Earth Clamp: Attach the earth clamp to the welding machine, pay attention to the required polarity, (see point #4). Clamp the other end securely to the workpiece or worktable as close as possible to the weld.
4. Select Polarity: Ensure that the correct polarity for the base material and filler metal recommendations are being followed. Typically, these are AC, mainly for aluminium and DCEN (DC current, Earth Negative) for most other alloys.
5. Prepare Tungsten: For most TIG welding, ensure that the tungsten electrode is ground to a point. The length of the taper to the point should be approximately two and a half times the diameter of the tungsten. Use a 200-grit or finer grinding wheel that is dedicated to tungsten preparation. Whilst the tungsten is not considered a consumable, it will wear with use and become blunt, in this case the tungsten needs to be replaced or reground.
6. Assemble Torch as per the manufacturer’s instructions.
7. Install Tungsten: Insert the tungsten into the collet, the length of stick out affects to performance of the arc.

   1. Short Stick-Out Length (3 to 5 mm):

      • Provides better arc control.

      • Enhances stability and precision.

      • Suitable for thin materials and intricate welds.

   2. Medium Stick-Out Length (5 to 6 mm):

      • Balances control and accessibility.

      • Commonly used for a wide range of applications.

   3. Longer Stick-Out Length (Greater than 6 mm):

      • Can be used for increased reach and better visibility in some situations.

      • May be suitable for fillet welds or joints with limited access.

8. Check and Connect Power: Ensure that the power supply matches the rating of the equipment as indicated on the manufacturers label. Connect the plug to the appropriate power outlet.
9. Select the appropriate Shielding Gas: Verify the type of gas is suitable for the base material/filler metal combination and set the flow rate as recommended by the filler metal manufacturer.

With the equipment set up correctly, it is ready to start welding.

Selecting the Right Tungsten for TIG Welding

Tungsten selection plays a critical role in achieving quality welds. Factors like material type, thickness, and the equipment being used influence the choice of tungsten. Different tungsten alloys are identified by colour bands painted on one end.

Here are some common tungsten types and their applications:

• 2% Ceriated (Gray) Tungsten: This is a versatile tungsten suitable for AC and DC TIG welding on steel, stainless steel, and aluminium. It provides easy arc starting, good stability, and a long lifespan.
• Pure (Green) Tungsten: Typically used for AC TIG welding on older transformer-based TIG welders, modern inverter-based machines may not perform well with green tungsten due to poor arc starting characteristics.
• 2% Lanthanated (Blue) Tungsten: This tungsten is best suited for DC TIG welding and is known for its precision in specific applications.

In the context of this article, it's important to highlight a crucial point regarding the selection of tungsten electrodes. Historically, thoriated tungsten electrodes were the go-to choice for TIG welding, and they are still commonly used in many regions. However, it is essential to note that thoriated tungsten contains 1-2% thorium which is radioactive, this has led to their prohibition in several European countries.

Useful Tips for Beginner TIG Welders

Here are some simple tips for beginners:

1. Safety First: Always wear appropriate personal protective equipment (PPE), including a welding helmet with a proper shade, gloves, long sleeves, and safety boots. Ensure good ventilation in your workspace to avoid inhaling welding fumes.
2. Cleanliness is the Key: Ensure that all the work surfaces are free from dirt, oil, paint, and rust. Clean the filler rods with acetone.
3. Understand your equipment: Familiarise yourself with the TIG welding machine, its controls, and settings. Consult the user manual for guidance. Learn how to set the correct welding parameters for the material you are working on.
4. Practice Welding Techniques: Practice on scrap pieces of metal before working on the actual project. This helps develop correct technique and helps to get comfortable with the welding process. Experiment with different joint types, positions, and welding speeds.
5. Control Travel Speed: Control the speed at which the torch moves along the weld joint. Moving too fast can result in a lack of penetration, while moving too slowly may cause overheating. Find a comfortable travel speed that allows for a smooth and consistent weld bead.
6. Adding Filler Metal: Add filler metal at the correct angle and in a controlled manner. The most important aspect of TIG welding is consistency, with both welding speed and the feeding of the filler metal into the weld pool.

TIG Welding Troubleshooting Tips

1. Incomplete Penetration:
   • Cause: Insufficient heat or welding too quickly.
   • Solution: Increase the welding amperage, slow down your travel speed, or both. Ensure proper joint preparation for better penetration.
2. Excessive Penetration:
   • Cause: Too much heat or slow travel speed.
   • Solution: Reduce the welding amperage or increase your travel speed. Adjust your technique to achieve a more controlled weld.
3. Tungsten Contamination:
   • Cause: Tungsten electrode touching the molten pool or filler metal.
   • Solution: Maintain a proper arc length and ensure the tungsten electrode is sharp.
4. Porosity:
   • Cause: Contaminants on the surface of the metal, inadequate shielding gas coverage, or improper gas flow.
   • Solution: Clean the metal thoroughly before welding, ensure proper gas coverage, and check for gas leaks. Adjust the gas flow rate according to the welding machine specifications.
5. Cracking:
   • Cause: Rapid cooling or excessive heat input.
   • Solution: Control heat input by adjusting the amperage and travel speed. Preheat the material if necessary and avoid sudden stops during welding.
6. Inconsistent Arc:
   • Cause: Unstable arc due to poor gas coverage, incorrect tungsten type, or improper settings.
   • Solution: Check gas flow and coverage, use the correct tungsten electrode, and ensure proper machine settings. Examine electrical connections for any loose or damaged components.
7. Irregular Bead Appearance:
   • Cause: Uneven travel speed, inconsistent torch angle, or improper technique.
   • Solution: Practice maintaining a consistent travel speed and torch angle. Experiment with different techniques on scrap material to find the most effective approach.
8. Undercutting:
   • Cause: Excessive heat leading to melting and removal of base metal.
   • Solution: Reduce amperage or increase travel speed. Ensure proper joint preparation and use a smaller electrode for better control.
9. Weld Spatter:
   • Cause: Contaminants on the metal surface or improper gas flow.
   • Solution: Clean the metal thoroughly and check gas flow. Adjust gas flow rate if necessary and ensure proper gas coverage.
10. Arc Starting Issues:
    • Cause: Contaminated or improperly prepared tungsten electrode, incorrect high-frequency settings, or poor electrical connections.
    • Solution: Ensure the tungsten electrode is clean and properly prepared. Check and adjust high-frequency settings. Inspect and secure all electrical connections.
11. Weld Discoloration:
    • Cause: Excessive heat or improper shielding gas.
    • Solution: Reduce amperage or increase travel speed to control heat input. Ensure proper shielding gas coverage and adjust gas flow if needed.

Always refer to the welding machine's manual for specific troubleshooting guidelines and recommended settings. Additionally, seek advice from experienced welders or instructors to address specific challenges.

Conclusion

In summary, mastering TIG welding can be a rewarding journey for beginners. By understanding the fundamentals, selecting the appropriate equipment, and adhering to best practices, it is possible achieve clean and precise welds across various applications. With dedication and practice,

TIG welding can become a valuable skill in any welding toolkit.

For further insights into TIG welding, make sure to explore the following articles on ESAB University:

1. A Beginner’s Guide to TIG Welding
2. Preventing Porosity in TIG Welding: Tips and Techniques