Arc welding is the process of joining two metal workpieces together using a flux covered electrode which is melted in an electric arc and becomes a fused part of the pieces being welded. Arc welding requires time, effort and patience to master as the weld rod position is very delicate to the position of the workpiece. The following is a simple guide to learn the basic technique of arc welding.
There are 4 basic steps to perform an arc welding:
Strike the arc. This is the process of creating an electric arc between the electrode and the workpiece.
Moving the arc to create a bead. The bead is the metal from the melting electrode flowing together with molten metal from the base metal to fill the space between the pieces being joined by welding.
Shape the weld bead. This is done by weaving the arc back and forth across the weld path either in a zig zag or figure 8 motion so the metal spreads to the width that you want your finished weld bead to be.
Chip and brush the weld between passes. Each time you complete a pass, or trip from one end to the other of your weld, you need to remove the slag, or the melted electrode flux material, from the surface of the weld bead so only clean molten metal will be filling the weld on the subsequent passes.
Things to take note in arc welding
Prepare the metal to be welded
Arc welding is more tolerant to slightly rusty metal than other electric welding processes but at the least, you should remove any paint, grease, rust, or other contaminants with metal brush, sandpaper or abrasive grinder to avoid weld contamination or inclusion.
Attach clamps on workpieces and grounding
Ensure there is a clean location so that the electrical circuit can be completed with minimal resistance at the ground location. Again, rust or paint will interfere with the grounding of your work piece, making it difficult to create an arc when you begin welding.
Select the correct rod and amperage range for the work you are attempting
As an example, 1⁄4 inch (0.6 cm) plate steel can be welded effectively using an E6011, 1⁄8 inch (0.3 cm) electrode, at between 80-100 amps.
Rod Angle (lead angle)
When welding on the workpiece, the rod should be angled around 10 to 20 degrees from vertical and pulled in the direction towards the welder. The angle of the rod prevents the slag overtaking the rod (inclusions in the weld will occur if welding is carried over the slag). Use your spare hand to support the top of the electrode to improve control of the electrode if necessary.
The arc length is the distance between the electrode and the weld pool. It should be roughly the same as the diameter of the rod. You will get used to the arc length after some practices.
The arc length can be easily determined by the sound and visible light from the arc. The arc should be kept short and hide the majority of the light from the weld without pushing the rod into the slag pool. A good short arc length will result in a consistent sharp crackling sound. The appearance of the completed weld will provide further clues.
Maintaining Lead Angle and Arc Length
As the welding rod gets shorter during the weld process, takes a mindful effort to reduce the length of the arc. Excessive arc length will lead to an unstable arc with excess heat and undercutting. This is one of the most common mistakes by beginners.
The angle of the rod should be maintained over the length of the weld. Practice is necessary to avoid decreasing the lead angle as the weld progresses, as this can lead to slag inclusions and even cause the arc to stall. The easy approach to maintain rod angle is to focus on moving the rod holder rather than the rod as the weld progresses
After welding, you may want to remove the slag and clean up your weld. Chip off the slag and wire brush the weld to remove any foreign material and remaining slag. Ensure eye protection is worn as the brittle slag can fly off to distance. A clean weld after grinding is easier to examine for any pitting, puddling or other defects.