Arc blow in Welding: Causes & Prevention

Arc Blow in Welding

Arc blow in welding is a phenomenon that can occur while welding, in which the arc becomes unstable and wanders or oscillates away from the point of welding.

This can lead to poor weld quality (unsatisfactory welds) and increased risk of burn-through, especially in thin materials.

There are several causes of arc blow, including:

1. Magnetic fields: Arc blow can be caused by external magnetic fields, such as those produced by nearby equipment or materials. This can be particularly problematic when welding in close proximity to other metal objects.
2. Electrical current: Welding with alternating current (AC) can be more susceptible to arc blow than welding with direct current (DC).
3. More as explained later in this post in depth.

It is not possible to eliminate the welding arc blow however it can be reduced or controlled to an acceptance level using various techniques as explained in this article.

Arc blow welding definition

Arc blow is a welding defect which is encountered during Stick Welding, also called shielded metal arc welding (SMAW), (manual metal arc welding –MMAW in UK).

It occurs when the arc becomes unstable and begins to wander or wander off the intended weld path, resulting in a poor-quality weld.

Arc blow in manual metal arc welding is caused by can be caused by a variety of factors, including the presence of a magnetic field, the proximity of ferromagnetic materials, and the orientation of the weld.

How to prevent arc blow in welding?

Unfortunately, Magnetic arc blow in welding can’t be completely eliminated. However, it can be reduced to controlled within an acceptable level during welding.

In electric welding arc blow can be avoided by several ways such as:

1. Change Current type: Changing from DC to AC will remove the arc blow effect in Stick Welding, especially when welding with an amperage more than 240 amps.
2. Using short arc length: It is proven that short arc length compared to longer arc length are less prone to arc blow effect in welding.
3. Change the welding angle: Changing the electrode angle opposite to the arc blow direction will counter the arc blow as shown in figure 3-45.
4. Increase the distance between the electrode and the workpiece: A larger distance between the electrode and the workpiece can help reduce the influence of a magnetic field on the arc.
5. Change in welding position: Changing welding position to flat can help to minimize arc blow. Horizontal & vertical downhill are more prone to arc blow.
6. Use a welding current with a lower frequency: A lower frequency current can help stabilize the arc and prevent arc blow.
7. Use a shielded metal arc welding (SMAW) technique that is less prone to arc blow: There are several SMAW techniques that are less prone to arc blow, such as the weave bead technique in place of stringer bead technique.
8. Use a non-conductive backing strip: A non-conductive backing strip can help reduce the influence of a magnetic field on the arc.
9. Wrap your earthing wire around the work: Keeping your earthing wire cable in a circle around the workpiece will generates additional magnetic field that can neutral existing magnetic field to control arc blow.

What causes arc blow in stick welding

There are several factors that can cause arc blow in shielded metal arc welding (SMAW), also known as manual metal arc welding (MMA):

1. The presence of a magnetic field: A magnetic field can cause the arc to become unstable and wander, leading to arc blow.
2. The proximity of ferromagnetic materials: The presence of ferromagnetic materials, such as iron or steel, can cause the arc to become unstable and wander, leading to arc blow.
3. The orientation of the weld: Horizontal welding position & vertical-down position are more prone to arc blow.
4. The welding current: A welding current with a high frequency can cause the arc to become unstable and wander, leading to arc blow.
5. Residual magnetic field in material: Presence of residual magnetic field in a material will cause arc blow in welding.

How Arc Blow affect welding Quality?

Arc Blow is an unpredictable phenomenon in welding, which can cause a variety of problems that impair the quality and strength of welds.

It occurs when an electrical current is carried away from the arc by magnetic forces rather than through the workpiece.

This causes welders to experience problems such as poor welds, excessive welding spatters, a lack of fusion between the two pieces being welded, undercut along the joint, porosity within the weld joints and even incomplete fusion.

It’s important for welders to understand what arc blow is and how it affects their work if they want to ensure they’re producing high-quality welds consistently.

Arc blow can be caused by many factors in a welding environment such as electrical fields originating from nearby power lines or large machinery, incorrect polarity settings on equipment or high levels of magnetic force present during welding operations.

Learn about other welding defects:

• Lack of Fusion.
• Undercut in Welding.
• Overlap in Welding.
• Welding Spatters.
• Tungsten inclusion in welding.
• Welding Burn Through.