In an arc welding process, the key to excellent consistent welding is to observe the weld puddle and then make steps accordingly. Observance of a weld puddle makes you to change the variables like voltage, amperage, arc length and lead angle
in order to achieve correct heat settings. Puddle shape tells you that what you have to do, either to speed up or slow down the travel pace and what should be the arc length and amperage. So the examination of weld puddle directs you what you need to change. A welder must know the factors and mistakes that cause weld defects like porosity
, blow holes and result in non-uniform or inconsistent welds. Also some elements that may cause convex or concave look and even spatter in your welds. Many people talk about convexity and concavity issues and this tutorial is about how to minimize above mentioned problem areas Listed below are the primary concerns in Shield Metal Arc Welding (also commonly named as Stick Welding), which are quite helpful to produce quality welds.
- Travel Speed
- Drag angle
- Slag removal
- Arc length
Here two points to discuss; too high current and too low current. How these high and low ends of amperage range, affect your weld? Normally with low current settings, the outcome is
- We get a convex shape weld.
- Little penetration in plate.
- Narrow weld bead.
Now if you go for with higher end of current range, to produce weld. In that case higher current may lead to wider weld bead with a lot of spatter. So the key to avoid this, try with the moderate current value somewhere between low and high end of amps range.
2. Travel Speed
c) fast travel effect d) slow travel effect
Making the weld with too slow travel speed, results in wider and highly convex weld bead. On the other hand the weld outcome with faster travel speed has no proper size, with weld bead outrunning the puddle. So in this case, we need to slow down a little bit to achieve proper size weld.
Easy slag removal is one of the indication for correct settings and uniform welding. So if slag is removed quiet easily, best look quality welds will be achieved.
Voltage has direct relation with arc length that is to say; longer the arc length, higher the voltage and shorter the arc length, lower the voltage. If you hold arc length tight, voltage drops. On the contrary if the arc length is kept longer, voltage rises up. Holding the arc at suitable length helps to achieve good heat settings and consequently spatter problem can be reduced.
6. Arc length
e) short arc length effect f) long arc length effect
One of the most important factors in arc welding, is the contact tip to work distance. We know as the arc length increase, the voltage boost up that causes the weld to spread and may cause spatter. Here we will discuss both cases with too short of the arc length and too long of the arc length.
1. So making weld bead by keeping the electrode close to the joint or plate, the arc length gets shortened. And convex look weld is obtained as an outcome. Remember in that case the voltage is dropped because of the tight arc length.
2. While making the weld by holding the arc at the considerable distance, the voltage rises and as a result the arc getting longer and wider. In that situation the weld outcome is
- Non-uniform and Inconsistent weld.
- No proper ripples.
- Wider and flat weld bead.
- Spattering occurs.
Proper adjustment of above mentioned factors by just observing the weld puddle, is the key to produce sound welds. Each factor has upper and lower limit and a welder has to produce welds within these limits. They can be quite helpful to eliminate convexity/concavity issues, spatter, blow holes, cavities etc.