Welding knowledge and techniques
The process of welding metals with flux-clad wires. It is a process that relies on arcing. Between the tip of the weld wire and the forged workpiece is a continuous and complete weld line. Skills from a welder will be required to operate. It is therefore essential that welders or operators It is necessary to know the techniques for performing the tasks as follows:
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- Arc starting Arc starting is often a problem for beginners who are new to welding practice. A common problem is that the wire sticks to the welding workpiece. or the arc is always extinguished Therefore, it should be practiced to be proficient. Such problems will be solved. There are generally two methods of arc initiation:
- Method of tapping (Tapping) or tapping the welding wire, which has the following methods
1.1 Hold the welding wire in a position perpendicular to the workpiece.
1.2 Press the welding wire down, tap or tap the steel plate lightly, then quickly lift it up when the arc occurs and allow the welding wire to move forward about 2-3 mm.
1.3 Follow the sequence of steps continuously. and many times until proficiency
- Scratching method or wire drawing method which has the following methods
2.1 Hold the welding wire in a tilted way along the line to be welded.
2.2 Flick the welding wire so that the tip touches the workpiece and lift it up quickly.
2.3 When an arc occurs, the arc distance must be correct. by reducing the arc distance slowly
2.4 Follow the procedure continuously and many times until proficiency.
Beginning and end of welding
The quality of the weld is not directed at any specific part but must be viewed throughout the line. Many welders are not as successful as they should be. because of neglecting the default action and the end of the weld Therefore, the following practices should be considered.
- Start welding should be prepared to clean Free from things such as grease, oil, rust because it will cause the weld to not have the desired quality. Starting point welding The beginning of the weld begins with the arcing. When an arc has occurred, raise the welding wire.
about 2 times the diameter of the welding wire Make welding angles according to the characteristics of various types of joints, which the welding angle will vary. After that, create a smelting pond which is about 1.5 – 2 times the diameter of the welding wire. and must be penetrated regularly
- Method of welding at the end of the welding line When welding, the final point of the weld will be a metal basin at the end of the weld (Crater), which is the point of minimum strength of the weld and the starting point for cracks to occur. Therefore, it is necessary to fill the welding wire at the end of the metal puddle. by walking back a little then stop filling the puddle at the end of the welding line to be full
- Welding connection Flux-covered electric wire When welding until approximately 38.10 mm. of the wire remains, the wire must be replaced and the new wire is replaced. There must be a welding connection. which must be in line with the original line And it must be strong and have the same properties as the original line. The method of connecting the welding line has the following practices.
3.1 In the event that the pool at the end of the weld is still hot to connect immediately no need to knock clean The arc is initiated ½ – 1 inch forward from the original melting pool as shown in Figure 133. The arc is initiated at point A and then reversed back to point B, the original melting tank of the weld. (This way, if the welder lacks skill, slag will be embedded in the weld.)
3.2 In the event that the weld pool has cooled Clean it with a hammer to knock out the slag and use a wire brush to clean it again. After that, the arc is initiated ½ inch – 1 inch forward from the original melting pool, starting the arc at point A, and then reversing back to point B, the melting pond of the original welding line
Notes on welding connections A new arc should not be initiated next to the metal basin. the end of the weld because it will not heat enough to melt the weld homogeneously And the filling of the connecting wire must be controlled not too much. Because it will make the welding line more convex than the original line, but if adding too little welding wire This will cause the weld to be flat and cause cracks.
- Rope welding means welding without oscillating the welding wire while welding, just controlling the arc distance. angle of welding wire and the welding speed only which connects this line of rope It is generally used for welding in parallel position. and the posture is connected down Because if the welding wire oscillates, it may cause the welding line to be incomplete, especially cracks.
- Welding wire runout means dragging the wire to the side to make the welding line wider. Generally, the weld width should not exceed 5 times the weld diameter. Choosing a shape or type of welding wire must take into account the type of joint, the size of the weld and the position of the weld port. This technique is commonly used for welding V-groove joints for heavy work and for filet welds on different joints or for multi-layer reinforcement welding. one for arc welding But it must be remembered that Any changes in welding, such as changes in the angle of inclination, arc distance Weld wire oscillation pattern It has a direct effect on the quality of the weld, besides the oscillation of the weld wire in some cases. This is done only to make the welds have beautiful scales. Regardless of the other benefits, weld wire oscillations may be classified according to their location.