Introduction
TIG welding is a popular method for welding aluminum due to its ability to produce high-quality welds. To ensure successful results, it is essential to understand the process and follow the correct procedures. This article will provide a detailed guide on welding aluminum with TIG, including the necessary equipment, techniques, and best practices.
The Basics of TIG Welding Aluminum
TIG welding aluminum requires specific equipment and techniques to achieve optimal results. Firstly, a shielding gas, typically argon, is used to protect the weld area from contamination. Additionally, a tungsten non-consumable electrode and a clean surface are crucial to remove any oxide buildup.
The reason for removing oxide is that it has a higher melting point than aluminum, making it essential to eliminate it before welding. For efficient TIG welding, it is necessary to use a welding machine specifically designed for this purpose or one equipped with the required accessories.
To control heat buildup during welding, a leg current control is necessary. As the weld progresses, less heat is required from the electrode towards the end of the weld. AC (Alternating Current) with high frequency is recommended for best results, as it reduces the risk of contamination by eliminating the need for the tungsten electrode to come in contact with aluminum. Direct current can be used as an alternative, but it may result in higher heat levels and poor oxide scavenging on the electrodes.
The torch nozzle selection is also crucial, especially when welding aluminum. Changing the diameter of the electrode allows for a wide range of heat inputs suitable for different metal thicknesses. In the hands of a skilled welder, TIG welding provides superior aesthetics and sealing compared to MIG aluminum welding, which is preferred for thicker metal pieces. Furthermore, newer aluminum alloys, such as HTS-2000, offer a cost-effective welding solution that can be used with any heat source.
AC TIG Welding
When performing AC TIG welding on aluminum, the electrode tip shape should be a “ball,” which is typically 1 to 1½ times the diameter of the tungsten. Amperage control can be achieved through various methods, including using the AMPtrol on the torch, foot pedal control, or machine settings. Remote control allows for starting with higher heat and gradually reducing the amperage as the weld progresses.
Torch cooling is crucial to prevent overheating, especially when using high amperage. Air-cooled torches rely on gas flow for cooling, so caution must be exercised to avoid excessive heating of internal torch parts. On the other hand, water-cooled torches use a pump to circulate water, allowing for operation at high amperage and extended use. A slight leading angle enables better visualization of the weld puddle, especially when adding filler metal.
Aluminum Alloys
Several aluminum alloys have been developed for TIG welding aluminum. The most commonly used alloys are pure aluminum 1xxx and aluminum manganese alloy 3003. Aluminum can also be repaired or fabricated using aluminum brazing, which offers strong and cost-effective welds. Aluminum alloys are identified using a 4-digit system, with the first digit representing the metal alloyed with aluminum.
- 1xxx: 99% pure aluminum, no alloys
- 2xxx: aluminum copper alloy
- 3xxx: aluminum manganese alloy
- 4xxx: aluminum silicon alloy
- 5xxx: aluminum magnesium alloy
- 6xxx: magnesium, silicon, and aluminum alloys
- 7xxx: zinc and aluminum alloy
- 8xxx: tin or other metals and aluminum
Recommended Filler Metals
Choosing the right filler metal is crucial for successful TIG welding of aluminum. It is important to use high-quality filler metals that are free from contamination. The following table provides recommendations for various aluminum alloys:
| Base Metals | Recommended Filler Metals (for maximum as-welded strength) | Recommended Filler Metals (for maximum elongation) |
|---|---|---|
| 1100 | 1100, 4043 | EC 1260, 1100, 4043 |
| 2219, 3003, 3004, 5005 | 2319, 5183, 5356, 5554 | 1100, 4043, 5183 |
| 5051, 5052, 5083, 5086 | 5356, 5183, 5554 | 5183, 5356 |
| 5050, 5052, 5083, 5086 | 5356, 5554 | 5183, 5356 |
| 6061, 6063, 7005, 7039 | 4043, 5183 | 5356, 5183 |
Please note that these recommendations are for plate of “0” temper.
Sample Amperage Chart
The amperage required for TIG welding aluminum depends on the base metal thickness and the filler rod diameter. The following chart provides a general guideline for selecting the appropriate amperage:
- 0.010″ – 0.035″ filler rod diameter: 5 – 25 amperage
- 0.035″ – 1/8″ filler rod diameter: 20 – 85 amperage
- 3/32″ – 1/4″ filler rod diameter: 50 – 180 amperage
- 3/16″ – 3/8″ filler rod diameter: 171 – 250 amperage
- 5/16″ – 1/2″ filler rod diameter: 200 – 320 amperage
Notes
- When starting the welding process, break the tungsten and let it ball or ball the copper plate before proceeding.
- Aluminum turns into a mirror color when melted.
- Aluminum requires higher amperage than steel of the same thickness due to heat dissipation.
- Always determine the aluminum base type before welding to ensure proper procedures.
- Some aluminum alloys may not be weldable using the TIG welding process.
- Adding more filler metal to the aluminum weld is recommended for optimal results.
Advantages and Disadvantages of Aluminum TIG Welding
TIG welding aluminum offers several advantages, but there are also some drawbacks to consider.
Benefits:
- Filler rod may or may not be necessary, depending on the application.
- AC polarity allows for welding aluminum and magnesium.
- High-quality and aesthetically pleasing welds.
- Suitable for all position welding.
- Can be used on a variety of metals.
- Excellent for very thin materials.
- Fusion welding is possible.
- No trauma or splatter during welding.
- High efficiency.
Drawbacks:
- Lack of portability due to shielding gas cylinders and hoses.
- Not ideal for outdoor welding, as shielding gas is susceptible to wind and drafts.
- Requires a clean base material for successful welding.
- Low deposit rate compared to other welding methods.
- High operational skills are required.
- Welding process can be slower compared to other methods.
Metal Cleaning Methods
Proper cleaning of aluminum surfaces is crucial for successful welding. The following table outlines common methods for cleaning aluminum surfaces:
| Types of Cleaning | Welding Surfaces Only | Full Piece |
|---|---|---|
| Oil, grease, moisture, and dust | – Wipe dry with mild alkaline solution. – Wipe with a hydrocarbon solvent such as acetone or alcohol. – Wipe with proprietary solvents. – Dip the edges, using any of the above. |
– Lack of steam – Sprinkle degrees – Lack of steam – Dip in alkaline solvent – Immerse in proprietary solvents |
| Oxides | – Dip the cutting edge in a strong alkaline solution, then water, then nitric acid. Rinse with water and dry. – Wipe with proprietary deoxidizer. – Remove mechanically, such as by wire-brushing, filing, or grinding. For critical applications, degrease all joints and adjacent surfaces immediately prior to welding. |
– Dip in strong alkaline solution, then water, then nitric acid. – Finish by rinsing with water and drying. – Immerse in proprietary solution. |
Brazing Rods as an Alternative
Another alternative to TIG welding aluminum is the use of brazing rods. This method simplifies the process and offers strength comparable to TIG welding. All that is required is a heat source, such as mapp gas or propane, a turbo tip, and a brazing rod. This method is suitable for aluminum and various aluminum alloys.
5 Tips for Understanding Aluminum TIG Filler Metals, Setup, and Welding
To achieve optimal results when TIG welding aluminum, consider the following tips:
-
Choosing the Right TIG Filler Metal: Select the appropriate filler metal based on the specific alloy and application. Commonly used alloys include 4043, 4047, 4943, and 5356. Refer to the filler metal selection chart for the best choice.
-
Properly Prepare the Base Material: Thoroughly clean the surface using an unused paper towel or rag and a cleaner such as acetone. Remove the oxide layer using a stainless steel wire brush designed for aluminum.
-
Adjust Machine Settings and Parameters: Use a TIG AC welding power source with 100% argon shielding gas. Ensure the machine provides sufficient amperage for the job, following the recommended amperage per material thickness.
-
Follow the “Hot and Fast” Rule: Weld hot and fast to overcome lack of fusion or other welding issues. Start with enough amperage to establish a puddle quickly and maintain a good travel speed.
-
Properly Handle and Store Filler Metals: Store and handle filler metals correctly to avoid contamination. Use separate containers for each filler rod and store them in a dry place without extreme temperature fluctuations. Acclimate the rods to room temperature before welding to prevent condensation.
Conclusion
Welding aluminum with TIG can be a rewarding and valuable skill. By following the proper procedures and using the right equipment, you can create beautiful and durable welds. It is essential to understand the specific details and precautions for welding aluminum, as they can significantly impact the quality of the weld. With practice and experience, you can master the art of TIG welding aluminum and enjoy the satisfaction of creating long-lasting welds. So, don’t hesitate to embark on your journey of learning how to weld aluminum with TIG!