In welding we encounter a number of weld defects that need to be eliminated or we are in an attempt to minimize them within an acceptable
range. One of the basic techniques to minimize these defects, is the right
control of electrode angles. Now you need to know what are electrode angles in arc welding? Normally there are two angles that a welder should know. If one
gains the proper familiarity with these angles, one can be successful
in achieving quality welds by eliminating the following defects;
- Improper fusion (Lack of Fusion)
- Lack of penetration
- Slag inclusion
- Lack of side wall fusion and more
1. Tilt Angle
The angle made by the either side of electrode (one of the two) with the
plate surface. This angle is shown in the figure, called the tilt angle.
In order to achieve sound level of penetration, control of
tilt angle is required. If we displace the electrode from the correct position, the weld will not be deposited equally to either sides of the joint. For example as shown in figure; If the
electrode is displaced from the center line of the joint the weld metal will only be deposited on one side of line, which results in lack of side wall fusion, unweld edges and low strength weld deposit. Tilt angle is quite beneficial in multi-pass welding (temper bead process) where it is desired to make a weld pass on the specific part of joint or previous weld pass.
2. Slope Angle
The angle made by the electrode with the plate surface in
the direction of travel. Sometimes it is referred to as 'lead angle'.
As it is stated earlier, the proper knowledge of controlling the electrode angle, leads one to achieve sound weld deposits. We know flux coating on electrodes are
used to form slag that protects the weld deposit from any contamination in
atmosphere. Slag formation also facilitates solidification of molten weldment and provides protection even after solidification. Now come to the point, the flow of molten slag
is controlled by slope angle of the electrode. If the electrode approaches
to vertical (90 degree), the molten slag will move into the weld pool and create the
blockage between the electrode and plate. This will lead to a cause of many weld defects like slag inclusion, lack of fusion and lack of penetration etc. These defects are common in arc welding types MMA (stick welding), MIG
where flux coated electrodes and flux cored wires are used respectively. So the right travel of electrode with correct lead angle can minimize these imperfections.
Oxyfuel Welding
Now there are some angles in oxyfuel welding that need to be
acquainted with. Normally there are two techniques which are utilized in case of gas welding. Following are the primary concerns about these techniques
- Torch angle
- Filler wire angle
- Direction of movement.
1. Forehand Technique
In this technique the torch moves in the direction of
welding, making the angle of 60-70 degree with the weld deposit as shown in figure.
In the figure you will see the filler rod is leading the torch making the angle of 30-40 with the joint.
2. Backhand Technique
In this technique the torch and filler travels in such a way
that torch is leading the filler wire making an angel of 45-50 degree with the
unweld section.