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Notes on welding process
Because of the various differences in the important points for welding in the different types of electrodes, we are only
talking of the common electrodes for normal structural steels, the rutile cellulose electrode, are introduced here.
If you want to weld other electrodes, the electrode manufacturers supply upon request all relevant information for the
special electrode to be used.
Always make some trial welds on scrap material. Select electrode diameter and welding current as per Table 1. Attach
earth clamp to work piece and place electrode into electrode holder as described earlier. Now hold the electrode approx.
2 cm above the starting point of your weld seam. Hold the welding visor in front of your face and draw the electrode with
a short stroke along the groove. Through the welding shield you observe the arc, keeping it at a length of 1 to 1.5 times
the electrode diameter.
wrong
The correct arc length is important, because with too short or too long an arc both welding current and working voltage
change. A low working voltage causes insufficient penetration. Too high or too low welding current gives a poor welding
seam. Too long an arc does not sufficiently melt the base metal, resulting in high spray losses, and the atmosphere with
its detrimental substances like hydrogen and nitrogen, may seep into the melting pool.
For a good weld the work angle of the electrode to the workpiece is of substantial importance. The angle should be 70
- 80° to the normal welding direction. If the angle is too steep, the slags will run under the melting pool, and if angle is
too flat, it causes the arc to spatter, in both cases the result is a porous, weak welding seam (see figure 5 - 7).
wrong
welding direction
> 80°
(Pic. 5)
You must ensure that the arc must always remain of equal length, i.e. the burning off by the light arc is constantly adjusted
by tracking the electrode.
At the same time, the welder has to watch the melting pool for uniform penetration and width.
Welding is always done from left to right (backhand welding).
At the end of the welding seam, the electrode cannot simply be lifted or pulled from the weld, this creates porous end
craters, which weaken the weld. The correct way is to hold for a short moment at the end of the weld seam, then to lift
in an arc over the seam.
wrong
(Pic. 8)
Remove slag only after it has cooled down and is no longer glowing.
If an interrupted weld is to be continued, the slag at the end of the starting point must be removed. Then the light arc
can be ignited either in the groove or on the weld, as described earlier, and then moved to the end of the weld, which
has to be thoroughly melted and then welding is continued normally.
arc too long
(Pic. 3)
wrong
welding direction
(Pic. 6)
correct
approx. 1 - 1.5 the electrode-Ø
(Pic. 4)
< 70°
correct
correct
welding direction
70-80°
(Pic. 7)
(Pic. 9)
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