Forehand And Backhand Technique In Oxy-fuel Welding

This article describes a few aspects of forehand welding and backhand welding in oxyfuel welding process. Before we get into the specifies, let us understand a few related terms, such as work angle, push angle, travel angle, etc.

Work Angle

For a butt weld between two plates, imagine a plane cutting the base plates perpendicularly. The plane is perpendicular to the direction of welding as well. When you look at this plane, work angle is the angle that the welding torch makes with the plane of the base plates.

Likewise, for a T-fillet weld, work angle is the angle that the welding torch makes with the horizontal member – in a plane that cuts the direction of welding as well as both the base plates perpendicularly.

For a butt pipe between two pipes, imagine a plane passing through the center of the pipes. The plane is perpendicular to the direction of welding as well, that is – the plane cuts the circumference of the pipes at two diametrically opposite points. In this plane, work angle is the angle that the welding torch makes with the surface of the pipes.

Work angle for a fillet weld and butt weld is represented in the figure 1 below.

Work angle in welding

Travel Angle

For a butt weld between two plates, imagine a plane cutting the base plates perpendicularly. The face of the plane is along the direction of welding. When you look at this plane, travel angle is the angle that the welding torch makes with the plane of the base plates.

Likewise, for a T-fillet weld, travel angle is the angle that the welding torch makes with the horizontal member – in a plane that contains the throat of the fillet, and lies along the direction of welding.

For a butt pipe between two pipes, imagine a plane passing through the center of the pipes. The plane is perpendicular to the direction of welding as well, that is – the plane cuts the circumference of the pipes at diametrically opposite points. In this plane, work angle is the angle that the welding torch makes with the surface of the pipes.

Travel angle for a fillet weld and butt weld is illustrated in the figure 2 below.

travel angle in welding

Travel angle is further categorized into two types: Drag angle and push angle. The illustration shown in the figure is self-explanatory. When the welding is done with a push angle, such that the torch points forward in the direction of welding – such technique is called forehand technique of welding, or simply forehand welding.

Forehand Welding

In forehand welding, the angle made by the torch with the vertical is approximately 30°, pointed forward in the direction of welding. The rod is placed a little ahead of the torch. The flame is directed at the spot between the molten pool of metal and the filler rod. See the illustration in figure 3 below.

Forehand welding technique in oxyfuel welding

The flame and the filler rod are moved in semi-circular fashion in opposite directions. That is, when the flame goes left, the rod goes right, and vice-versa. In this manner, the heat of the flame can be distributed for melting the rods as well as melting the sidewalls.

The filler rod is dipped into the leading edge of the molten pool while the rod is being moved along a semi-circular path. The molten pool can also thus be distributed through the width of the groove, along the edges of the groove.

Forehand technique is a suitable method for welding sheet metal, and medium thickness plates. However, it is not so suitable for thicker cross sections. This is because thick plates have wider groove width in a V-groove preparation. A V-groove with included angle of 90° is necessary too, to ensure complete penetration at the root, and good fusion with the side walls.

A wider groove width, when welded with the technique described in above paragraphs, involves a wider larger molten puddle. It is therefore difficult to control such a big puddle. It is difficult to obtain a good weld with a large puddle.

Backhand Welding

Opposite to forehand welding, the backhand welding is done with a drag angle. In this technique, he welder literally drags the torch towards himself. See the illustration in figure 4 below.

Backhand welding technique

In this technique, the torch precedes the filler rod. As the torch proceeds, the filler rod follows behind. The molten metal puddle follows further behind.

The angle made by the torch with the vertical is again approximately 30 degrees. In this technique, less sideways movement is possible than the forehand technique.

The backhand technique is best suited for thicker sections, because a narrow groove is enough to produce adequate fusion with this technique.

Because of lesser transverse movement, the puddle size is smaller. An included angle of 60° is sufficient with this technique. A narrower groove than forehand technique also means that lesser volume of weld metal is enough to make the joint.

So, this was about forehand welding technique and backhand welding technique in oxy-fuel welding. Please share your observations in the comments section below.

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