Arc Blow

Arc blow, also known as arc magnetic blow, is a common phenomenon in the arc welding process. It refers to the arc not burning along the axis of the electrode or wire during welding, but deviating from the predetermined path, usually manifested as the arc tilting forward, backward or sideways. This phenomenon will seriously affect the welding quality, leading to defects such as lack of fusion, slag inclusion, spatter, porosity, etc., thereby reducing the quality and stability of the weld.

There are several main reasons for arc blow:

Magnetic field effect: During welding, the imbalance of the magnetic field around the arc is the main cause of magnetic blow. This imbalance may be caused by the asymmetry of the magnetic conductive material around the arc, or the change in the distance of the ground wire access point. For example, direct current generates a magnetic field around the conductor (such as the ion flow between the welding rod or the weld). When the magnetic field is compressed and deformed at the junction of the metal and the air, it will generate thrust on the welding arc, causing the arc to deviate.

Gas flow: The uneven distribution of the shielding gas or the influence of strong external winds will cause the arc to deviate due to uneven force. In addition, poor ventilation conditions in the welding area will cause changes in local gas concentration, which will also affect the stability of the arc.

Welding rod and workpiece factors: The welding rod coating is damp or deteriorated, resulting in arc instability; the workpiece surface is not clean enough, and there are impurities such as oil and rust, which affect the normal burning of the arc; the irregular shape of the workpiece or the large assembly gap make it difficult to keep the arc centered.

Welding equipment problems: large fluctuations in power supply voltage lead to unstable arc voltage; wire feeding mechanism failure, uneven wire feeding speed, affecting arc length and stability.

Solutions to arc blow
For different causes of arc blow, the following measures can be taken to prevent and solve them:

Adjust the magnetic field: ensure that the welding cable is connected correctly to avoid generating an induced magnetic field; keep the welding equipment away from large ferromagnetic objects when possible; use AC power for welding to reduce the impact of the magnetic field on the arc; if DC power must be used, ensure that the workpiece has no residual magnetism or use welding rods of the same polarity.

Improve gas flow: ensure uniform distribution of shielding gas and take measures to prevent external strong wind interference; strengthen ventilation management in the welding area to maintain stable gas concentration.

Optimize welding rod and workpiece handling: keep the welding rod dry and avoid using damp or deteriorated welding rods; improve the cleanliness of the workpiece surface and remove impurities such as oil and rust.

Inspect and maintain welding equipment: regularly check the stability of the power supply voltage to ensure the constancy of the arc voltage; maintain the normal operation of the wire feeding mechanism to ensure the uniformity of the wire feeding speed.

Adjust welding technology: Use short arc welding to reduce the swing range of the arc; choose a suitable welding speed to avoid excessive or insufficient current fluctuations; adjust the electrode angle to change the force direction of the arc; use auxiliary tools, such as magnetic clamps or magnetic plates, to guide the arc and reduce arc blow.

The above measures can effectively prevent and solve the problem of arc blow and improve welding quality and efficiency.