Thread Content
In DC arc welding, the phenomenon in which the welding arc is deflected due to electromagnetic forces is known as magnetic deflection. It has a significant negative impact on the welding process and quality; only by overcoming it can welding quality be ensured. There are many factors that cause magnetic deflection. Specifically: First, during arc initiation and termination while welding at the edge of the workpiece, the magnetic flux density is compressed and deformed, resulting in uneven magnetic flux densities in front of and behind the arc. The magnetic flux density is higher near the edge of the workpiece than farther from it; according to the physical law governing the force exerted on current in a magnetic field, this results in the arc bending forward during arc initiation ； The magnetic deflection phenomenon in which the arc is deflected backward at arc extinction. Remedial measure: Add arc initiation plate and arc termination plate ； Change the travel angle of the electrode (or wire) (toward the side where the arc is deflected). Second, the ground wire is not in the correct position and the welding direction is incorrect; since the magnetic flux density behind the arc is greater than that in front of it, the arc is pushed forward. Remedial measure: Connect the ground wire to the arc-capturing end ； Change the travel angle of the electrode (or wire) ； Use non-magnetic line clamps. 3. When multiple arcs are used near each other during the welding of T-joints or corner joints, in order to reduce welding deformation and improve welding efficiency, it is common to weld on both sides of the vertical plate at the same time. However, if this welding technique is not implemented properly, it can lead to magnetic deflection of the arc. Remedial measure: Use both AC and DC power sources for welding ； Change the travel angle of the electrode (or wire). 4. Uneven workpiece thickness: When welding workpieces of different thicknesses, magnetic deflection occurs (the arc is drawn toward the thicker side of the workpiece), as the stronger magnetic field generated by the thicker piece exerts a greater attraction on the charged arc particles. Remedial measure: Use short-arc welding ； Use a larger angle between the welding rod and the flat plate ； The ground clip is on the side of the thick plate (change the position of the ground wire). 5. Weld arrangement: The arrangement of welds has a significant impact on magnetic deflection. Magnetic deflection is highly likely to occur in two situations: first, when the groove depth of the butt weld is large; second, in internal fillet welds. Remedial measure: Use short-arc welding ； Increase the number of tack welds ； Weld using an AC power source. 6 Welding direction and sequence: When the weld is long, using straight-through welding not only leads to significant welding deformation but also causes magnetic deflection. In this case, the desoldering method is the best way to avoid magnetic deflection. 7. Clamps and shims: Clamps and shims also have a significant impact on magnetic deflection. Using non-magnetic materials for fixtures and shims, as well as adding additional plates, are effective measures to reduce magnetic deflection.