Key techniques for using welding electrodes

The correct use of welding electrodes is crucial for ensuring welding quality, involving several technical aspects such as arc initiation, electrode manipulation, finishing, and electrode drying. The following are core techniques summarized from professional welding processes:

I. Arc Initiation Techniques: Stable Arc Initiation, Avoiding Defects

Arc initiation is the starting point of welding and directly affects weld formation and porosity.

Scratching method: Suitable for basic electrodes, the operation is similar to striking a match. After ignition, quickly lift the electrode 2-4mm to maintain a stable arc. Note that the movement should be quick to prevent the electrode from sticking to the workpiece.
Tapping method: Suitable for applications requiring high surface quality. The electrode lightly touches the workpiece and is immediately lifted, without damaging the base metal, but requires skillful control of force.
Arc initiation position: The arc should be initiated 10-20mm before the starting point of the weld, and then pulled back to the starting point for welding. This prevents cold metal droplets from falling into the molten pool and causing porosity, especially with basic electrodes.

If the electrode sticks to the workpiece, it can be detached by swinging it left and right; if it cannot be detached, the power should be immediately cut off, and the electrode removed manually after cooling.

II. Three Elements of Electrode Manipulation: Feeding, Oscillation, and Forward Movement

Good weld formation depends on three basic movements of the electrode:

Feeding the electrode into the molten pool:
To maintain a stable arc length, the feeding speed should match the melting speed. Too fast can cause short circuits, and too slow will cause arc interruption.

Lateral oscillation:
Controls the weld width. Common techniques include:

Straight line: Suitable for butt welding of thin plates, resulting in deep penetration and narrow weld bead.
Sawtooth or crescent shape: Used for wider welds or vertical welding, enhancing fusion.
Triangular shape: Suitable for filling the root of fillet welds.

Forward movement along the welding direction:
Too fast a speed can lead to lack of fusion, while too slow can cause burn-through or weld bead defects. The speed should be adjusted flexibly according to the current, plate thickness, and gap.

III. Operating Points for Welding in Different Positions
Vertical welding: Use a short arc, with the electrode angled downwards at 40°~60°, using low current and thin electrodes (e.g., φ3mm) to prevent metal from sagging.
Overhead welding: The most difficult position, requiring control of the arc length, using a small crescent or inverted figure-eight oscillation to prevent molten droplets from falling. Pipe Welding: Slag inclusion is prone to occur at the bottom 6 o'clock position; sufficient preheating is required, and the welding rod should dwell longer on both sides to ensure the flux coating is full and square before moving upwards.
IV. Electrode Drying: Preventing Porosity and Hydrogen Embrittlement

Electrodes must be dried according to regulations before use, especially alkaline low-hydrogen electrodes:

Alkaline electrodes: Dry at 350~400℃ for 1 hour to prevent moisture absorption and hydrogen porosity.
Acidic electrodes: If damp, dry at 70~150℃ for 1 hour.
Precautions:
After drying, store in a 80~100℃ insulated box and take out as needed.
For outdoor work, re-drying is required the next day.
The drying process should involve slow temperature increase and decrease to prevent flux coating cracking.
V. Finishing Treatment: Avoiding Arc Crater Cracks

If the weld seam finishing is not handled properly, arc craters, shrinkage cavities, or cracks may occur.

Circular finishing method: Suitable for thick plates; the electrode makes a circular motion to fill the arc crater before breaking the arc.
Repeated arc breaking method: Suitable for thin plates and high-current welding; the arc crater is filled by multiple arc strikes, but this is not suitable for alkaline electrodes to prevent porosity.