Arc-length welding combines manual and automated processes to weld a single uninterrupted bead without the need for a filler rod. It is ideal for welding slender or small-diameter tubes and pipes, as it produces a continuous weld with minimal heat input. Arc-length welding involves two operators: one at the manual torch side and another at the automatic welding table side. The operator at the torch side manually feeds filler wire into the weld joint; however, instead of using the traditional hand-welding technique, he triggers the automated welder on his end when he’s ready to make another pass on the torch. This approach eliminates gaps between beads while increasing efficiency. This article explains what arc-length welding is and its benefits, as well as its limitations and how to get started with this process.
Arc Length Welding Defined?
Arc-length welding is a type of welding in which the electrode and weld puddle are consumed at the same rate so that there is no buildup of excess filler material. It’s sometimes called short-circuit welding because the current flow between the electrode and workpiece arcs across the shortest possible distance, creating an extremely high heat input. Arc-length welding produces a very smooth, attractive weld bead with reduced distortion and little or no spatter. Its chief disadvantage is its low deposition rate, which makes it unsuitable for heavy-duty applications.
Why Perform Arc Length Welding?
- Arc-length welding provides a continuous weld bead on the inside of tubes and pipes. This is ideal for applications in which the tube or pipe diameter is too thin for traditional TIG welding or GTAW.
- Arc-length welding does not require a filler rod, which can make it easier to access tight areas that are difficult to reach with a traditional torch.
- Arc-length welding works well on thick weld joints, as it can be used without the need for backing material. This lets you weld over existing material without having to grind through it first, saving time and money on each pass of the torch.
- Arc-length welding produces high deposition rates due to its automated system, which allows you to weld at higher speeds than ever before possible with manual TIG or MIG processes.
- Arc-length welding produces consistent results when used on thin materials up to 3/8 inch in diameter diameters that are difficult or impossible to weld with manual processes.
- Arc-length welding is ideal for the welding of small-diameter tubes and pipes, as it produces a continuous weld without gaps, even on thin materials.
- Arc-length welding allows for a higher deposition rate than MIG and TIG welding, which can save time and money on each pass of the torch.
Limitations Of Arc Length Welding
1. Manual Operation
When using arc-length welding, the operator at the torch end must manually feed the filler wire into the weld joint. If a high volume of welds is needed, this can be time-consuming and may pose a challenge for production. However, for jobs requiring small weld joints or gaps between beads, this manual approach is ideal.
2. No Filler Rod
Arc-length welding requires no filler rod, which makes it ideal for small-diameter tubes and pipes with minimal heat input. It also causes less spatter than manual arc welding because there are no slag deposits from filler rods.
3. Heat Input Control
The operator at the torch end manually feeds filler wire into the weld joint; however, instead of using the traditional hand-welding technique, he triggers the automated welder on his end when he’s ready to make another pass on the torch tip. This approach eliminates gaps between beads while increasing efficiency by minimizing heat input.
4. No Heat Distribution
Arc-length welding does not provide a uniform heat distribution across the weld joint, which can lead to excessive localized heat and poor weld penetration. To minimize these issues, the operator at the automatic welding table side feeds filler wire into the weld joint at a slower speed than that of the operator at the torch end. The operator at the automatic welding table then triggers a second automated welder when he’s ready to make another pass on the torch tip. This approach allows for uniform heat distribution and minimizes localized overheating.
5. Manual Electrode Selection
Manual electrode selection is vital in arc-length welding; however, this may be a challenge for some operators who have never used this technique before, as they must take into account both material properties as well as application conditions (e.g., temperature). For example, if you are welding stainless steel, you would need to use an electrode that is optimized for stainless steel.
6. Welding Speed Control
The operator at the torch end must manually control the welding speed of the electrode by using a hand-controlled welder. However, in arc-length welding, automatic welding takes place at a slower rate than manual welding. This means that the operator at the automatic welder table side is able to optimize for both material properties and application conditions (e.g., temperature) without having to manually control the welding speed of the electrode.
Things To Consider Before Committing To Arc Length Welding
1. The Welding Process
Arc-length welding uses an arc-current machine, which consists of a horizontal welding head and an arc-current tungsten torch. The weld joint is made at the end of the horizontal welding head, which is connected to the automated welder. The operator at the manual side of the welding table manually feeds filler wire into the joint; however, he does not use a hand-welding technique and triggers the automated welder on his end when he’s ready to make another pass on the torch. The operator on the manual side can continue feeding filler wire into the joint until he gets tired or reaches his desired bead size.
2. The Welding Joints
Arc-length welding uses a continuous bead. The joint is made by a combination of manual and automated processes. The operator at the manual side manually feeds filler wire into the joint; however, he does not use a hand-welding technique and triggers the automated welder on his end when he’s ready to make another pass on the torch. The operator on the manual side can continue feeding filler wire into the joint until he gets tired or reaches his desired bead size.
3. Welding Processes Used In Arc-Length Welding
Arc-length welding has three processes: arc-current welding, automatic torch welding, and manual torch welding. Arc-current welding is made by an arc-current machine that consists of an arc-current head and a tungsten torch; it is used to weld thin sections of tubing and pipe without air gaps, which are caused when filler wire is fed manually into the joint (Figure 1 and 2). Automatic torch welding is made by an arc-current machine that consists of a horizontal welding head and an arc-current tungsten torch; it is used to weld thin sections of tubing and pipe without air gaps, which are caused when filler wire is fed manually into the joint (Figures 1 and 2). Manual torch welding is made by a manual welding head. The operator manually feeds filler wire into the joint; however, he does not use a hand-welding technique and triggers the automated welder on his end when he’s ready to make another pass on the torch.
Conclusion
Arc-length welding is a manual-automated hybrid process that produces a continuous weld with minimal heat input. This is ideal for welding slender or small-diameter tubes and pipes, as it produces a continuous weld with minimal heat input. Arc-length welding is also a good choice for welding high-strength materials such as austenitic stainless steel, nickel-based superalloys, titanium, and zirconium. Arc-length welding is appropriate for welding materials that have low tensile strength, low heat conductivity, and high outgassing potential. When welding materials that have low tensile strength, you should select a filler wire with low strength. Similarly, when welding materials that have a low heat conductivity, you should select a filler wire with a low heat conductivity. Finally, when welding materials that are prone to outgassing, you should select a filler wire that is prone to outgassing.
