WELDING TECHNIQUES

-There are two usual methods depending upon the ways in which welding rod and welding torch are used.
1-Leftward technique or forehand welding method.
2-Righward technique or Backhand welding technique.

1)Leftward Technique
-The welder holds welding torch in the right hand and filler rod in the left hand.
-The welding flame is directed away from the finished weld i.e. towards the un-welded part of the joint.filler rod when used is directed towards the welded part of the joint.(fig-)
-The weld is commenced on the right hand side of the seam, working towards the left-hand side.The blowpipe or welding torch is given small side way movement, while the filler rod is moved steady across the seam. The filler rod is added using the backward and forward movement of the rod allowing the flame to melt the bottom edge of the plate just ahead of the weld pool.
-Since the flame is pointed in the direction of the welding, it preheats the edges of the joint.
-Good control and a neat appearance are characteristics of
the leftward method.
-Leftward technique is usually used on relatively thin metals, i.e having thickness less than 5mm.
-When workpiece thickness is over 3mm bevel the plate edges to produce a V-joint so that good root fusion may be achieved. The included angle of V-joint is 80-90 degree. This large volume weld is uneconomical in terms of time, weld metal deposited and quantity of gases used and may
also over-distort weldmentt and welding thick materials.
Long welding time also leads to overheating of the weld area and thus the weld metal may have coarse grain.
-When welding materials over 6.5mm thick, it is difficult to attain even penetration at the bottom of the V and therefore the quality of the weld decreases as plate thickness increases.
-The leftward technique requires careful manipulation to
guard against excessive melting of the base metal and filler metal. The influence of the base metal on the properties of the weld metal can be very deep.
-Another disadvantage associated with leftward technique
is that the look of the joint edges is interrupted and it
is necessary to remove the end of the rod,(which slow down the welding process) this itself resulting in the oxides formed on the tip of the rod being deposited into the weld pool when the weld is recommenced.

2)Rightward Technique:
-The welder holds the welding torch in the right hand and the filler rod in the left.
-Welding begins at thew left hand end of the joint and proceeds towards the right, hence the name rightward technique.
-The direction of welding is opposite to that when employing the leftward technique.
-The torch flame in rightward technique is directed towards the completed weld and the filler rod remains between the flame and the completed weld section.
-Since the flame is constantly directed towards the V ahead of the weld puddle no side-wise motion of the welding torch is necessary. As a result a narrower V groove can be utilized than in leftward welding.This provide a greater control and reduced welding cost.
-During welding the filler rod can be moved in circles(within the puddle) or semi-circles (back and
forth around the puddle).
-In rightward welding the weld puddle is less fluid and this result in a slightly different appearance of the weld surface. The ripples are heavier and spaced further apart.
-The rightward techniques is used on heavier or thicker
(above 5mm) base metal.Weld with penetration of approximately12mm can be achieved in a single pass.