When welding, especially when someone who is just learning to weld, generally they do not know what kind of current is appropriate.
It is either large or small.
So how can we judge the current through the welding process? How to judge the size of the current is summed up in two words “one listen, four look”.
1. Listen to the sound
During welding, the current can be judged from the sound of arc. When the current is large, it makes the rushing sound, just like a big river.
When the current is small, it makes a “hissing” sound and is easy to break the arc. When the current is moderate, it will make a “rustle” sound and a crisp “crack” sound at the same time.
2. Four things to look
1. Look at the splash
When the current is too small, the arc blowing force is small, and it is difficult to distinguish molten slag from molten iron.
When the current is too large, the arc blowing force is large, large hot metal particles can be seen splashing outside the molten pool, and there is a loud explosion during welding.
2. Check the melting state of the welding rod
The current is too small, the welding rod is difficult to melt, and it is easy to stick to the weldment. When the current is too large, when the electrode melts to half, the remaining electrode will be in red hot state, and even the coating will fall off.
Related reading: How to Choose the Right Welding Rod?
How to know the welding current by observing the welding process? as follows：
3. Check the condition of the molten pool
In the welding process, observing the condition of the molten pool and adjusting the whole operation method is a common method to obtain the expected ideal weld shape.
The shape of the molten pool reflects the current.
How to know the welding current by observing the welding process?
When the following current is large, the molten pool presents a long shape (a);
When the current is small, the molten pool is flat (b);
When the current is moderate, the shape of the molten pool is like duck egg (c).
4. See weld formation
When the current is too large, the penetration is large, the weld is wide and low, undercut is easy to occur on both sides, and the welding wave is rough;
When the current is too small, the weld is narrow and high, and both sides are poorly fused with the base metal;
When the current is moderate, both sides of the weld are well fused with the base metal, the weld formation is good, the welding wave is beautiful, the height is moderate, and the transition is smooth.
When the current is moderate, both sides of the weld are well fused with the base metal, the weld formation is good, the welding wave is beautiful, the height is moderate, and the transition is smooth.
There are many bases to determine the welding current during welding, such as electrode type, electrode diameter, weldment thickness, joint form, weld position and number of layers. But the main is the electrode diameter and weld position.
1) Relationship between welding current and electrode diameter:
The selection of electrode diameter depends on the thickness of weldment and the position of the weld.
Comparison table of welding thickness, current and electrode diameter:
| Serial number | Weldment thickness / mm | Electrode diameter / mm | Electrode diameter / mm | Welding current / A |
| 1 | 1.6 | 25-40 | ||
| 2 | <4 | 2.0-3.2 | 2.0 | 40-65 |
| 2.5 | 50-80 | |||
| 3.2 | 100-130 | |||
| 3 | 4-12 | 3.2-4 | 3.2 | 100-130 |
| 4.0 | 160-210 | |||
| 4 | >12 | 4.0 | 160-210 | |
| 5.0 | 200-270 | |||
| 6.0 | 269-300 |
The melting speed of the welding rod is directly proportional to the current.
The greater the current, the faster the metal melts, the greater the melting depth and the greater the metal splash.
At the same time, it is easy to produce defects such as burn through and undercut;
If the current is too small, it is easy to produce defects such as incomplete penetration and slag inclusion, and the productivity is low.
When determining the welding current, factors such as electrode diameter, weldment thickness, joint type and welding position shall be taken into account, among which the main one is electrode diameter.
2) Relationship between welding current and weld position:
When welding flat welds, it is easy to transport the strip and control the molten metal in the molten pool, so a large welding current can be selected for welding.
However, when welding at other positions, in order to avoid molten metal flowing out of the molten pool, the molten pool should be as small as possible, so the welding current should be smaller than that of flat welding.
Generally, when using alkaline electrode, the welding current is smaller than that of acid stove.
