TIG welding, or tungsten inert gas welding, is a type of arc welding that uses a non-consumable tungsten electrode and an inert gas (usually argon) to create a weld pool and a filler metal to join two pieces of metal together. TIG welding is especially suitable for welding aluminum, as it produces high-quality welds with minimal distortion and spatter.
However, TIG welding aluminum is not as easy as it sounds. Aluminum has some unique properties that make it challenging to weld, such as its high thermal conductivity, low melting point, and tendency to form an oxide layer on the surface. Therefore, beginners need to follow some steps and tips to master the art of TIG welding aluminum.
The first step to TIG weld aluminum is to choose the right equipment and materials for the job. You will need:
A TIG welder that can handle AC (alternating current) output.AC is necessary for welding aluminum, as it helps to break down the oxide layer and provide better penetration and cleaning action. To know Megmeet MetaTIG 315/400/500 ACDC welders.
A TIG torch with a gas lens and a ceramic cup. The gas lens helps to improve the gas flow and shield the weld pool from contamination. The ceramic cup protects the tungsten electrode from overheating and melting.
A tungsten electrode with a 2% thoriated or lanthanated tip. These types of electrodes are more resistant to erosion and provide better arc stability than pure tungsten electrodes.
An argon gas cylinder with a regulator and a flow meter. Argon is the most common shielding gas for TIG welding aluminum, as it provides good arc stability and cleaning action. The regulator controls the gas pressure, while the flow meter measures the gas flow rate.
A filler metal that matches the base metal in composition and temper. The filler metal is usually a thin rod that is fed into the weld pool manually. The most common filler metals for TIG welding aluminum are 4043 and 5356 alloys, which have good corrosion resistance and strength.
A base metal that is clean and free of dirt, oil, grease, paint, or any other contaminants. The base metal should also be preheated to around 150°C to reduce thermal shock and cracking.
The second step to TIG weld aluminum is to set up the welder and prepare the workpiece for welding. You will need to:
Connect the TIG torch, the ground clamp, and the foot pedal to the welder. The foot pedal controls the amperage of the welder, which affects the heat input and the size of the weld pool.
Set the polarity of the welder to AC. This will allow the current to switch between positive and negative cycles, which will help to break down the oxide layer and clean the surface of the base metal.
Set the balance control of the welder to around 70%. This will determine how much time the current spends in each cycle. A higher percentage means more negative cycles, which will provide more penetration and less cleaning action. A lower percentage means more positive cycles, which will provide more cleaning action and less penetration.
Set the frequency of the welder to around 120 Hz. This will affect how fast the current switches between cycles. A higher frequency means faster switching, which will result in a narrower arc cone and more focused heat input. A lower frequency means slower switching, which will result in a wider arc cone and more dispersed heat input.
Set the amperage of the welder according to the thickness of the base metal. A general rule of thumb is to use 1 amp per 0.025 mm of thickness. For example, if you are welding a 3 mm thick base metal, you will need around 120 amps of current.
Clamp the workpiece securely to a metal table or a welding fixture. Make sure that there is good electrical contact between the workpiece and the ground clamp.
Clean the surface of the base metal with a stainless steel brush or a solvent. This will remove any oxide layer or contaminants that might affect the quality of the weld.
Sharpen the tip of the tungsten electrode to a point with a grinder or a sander. This will improve the arc initiation and stability.
Insert the tungsten electrode into the TIG torch and adjust it so that it protrudes about 6 mm from the ceramic cup. Make sure that there is no gap between the electrode and the gas lens.
The third step to TIG weld aluminum is to start welding. You will need to:
Put on your safety gear, such as gloves, helmet, goggles, and apron. TIG welding produces intense heat, light, and sparks, which can cause burns, eye damage, or fire hazards.
Hold the TIG torch in your dominant hand and the filler rod in your other hand. Position the torch at a 10° to 15° angle from the vertical and about 3 mm away from the workpiece. Position the filler rod at a 90° angle from the workpiece and about 10 mm away from the weld pool.
Press the foot pedal lightly to initiate the arc. You should see a bright blue cone of plasma forming between the electrode and the workpiece. This is the arc, which will create the weld pool by melting the base metal and the filler metal.
Move the torch slowly along the joint line, maintaining a steady arc length and angle. As you move, feed the filler rod into the weld pool at a consistent rate. The filler rod should melt as soon as it touches the weld pool, without touching the electrode or the base metal.
Control the size and shape of the weld pool by adjusting the amperage with the foot pedal. A higher amperage will create a larger and deeper weld pool, while a lower amperage will create a smaller and shallower weld pool. The ideal weld pool should be about 3 times the diameter of the electrode and have a smooth and uniform appearance.
When you reach the end of the joint, release the foot pedal gradually to terminate the arc. Do not lift the torch abruptly, as this might cause porosity or cracking in the weld. Let the weld cool down naturally, without applying any external force or quenching.
TIG welding aluminum can be tricky, but with some practice and patience, you can achieve excellent results. Here are some tips and tricks to help you improve your skills and avoid common mistakes:
Choose a suitable welding position. The best position for TIG welding aluminum is flat or horizontal, as this will allow you to control the weld pool better and prevent it from sagging or dripping. Avoid vertical or overhead positions, as they are more difficult and require more skill and experience.
Use a push technique. A push technique means moving the torch in the same direction as the weld pool, rather than pulling it away from it. This will help to create a cleaner and smoother weld, as it will push away any impurities or oxides from the weld pool.
Keep a steady travel speed. A steady travel speed means moving the torch at a consistent rate along the joint line, without stopping or hesitating. This will help to create a uniform and even weld bead, without any gaps or overlaps.
Use a filler rod that matches or exceeds the strength of the base metal. A filler rod that matches or exceeds the strength of the base metal will ensure that the weld is strong and durable, without compromising its ductility or corrosion resistance.
Clean your equipment and materials regularly. Cleaning your equipment and materials regularly will prevent any contamination or damage that might affect your welding performance. For example, you should clean your tungsten electrode with a cloth or a wire brush after each use, replace your ceramic cup if it cracks or chips, and store your filler rods in a dry and cool place.
TIG welding aluminum is a rewarding skill that can open up many opportunities for you in various industries and applications. If you want to learn more about TIG welding aluminum, you can check out these resources:
TIG welding aluminum is a skill that can be learned and mastered with practice and patience. By following the basic steps of TIG welding aluminum, such as preparing the equipment and workspace, setting up the weld, and making adjustments as you go, you can achieve high-quality results and avoid common mistakes. TIG welding aluminum offers many benefits, such as versatility, precision, and strength, making it a valuable technique for various applications and industries. Whether you are a beginner or a seasoned welder, TIG welding aluminum can help you create beautiful and durable welds that meet your needs.