Choosing between push or pull in flux core welding depends on material thickness and desired weld quality; push is faster, pull offers deeper penetration.
Understanding Flux Core Welding
Basics of Flux Core Welding
Flux core welding is a common form of arc welding that incorporates a tubular wire filled with flux to facilitate the electric arc. The flux of the core melts during welding, forming a shielding gas that protects the weld pool from contamination. This method of welding is popular because of its adaptability, as it can be performed outside and on materials with a certain degree of rust or paint. Similarly, flux core welding can achieve high deposition rates, which makes it suitable for thick materials. The rate of welding production is normally between 85% and 90%, which significantly minimizes the waste of the material .
Comparison of Push and Pull Techniques in Terms of Flux Core Welding
One of the main differences between these methods is the weld torch’s movement either towards the weld or away from it. The method chosen will affect the penetration of the weld, the shape of the bead, and the overall weld quality.
Push Technique
The first method involves pushing the weld torch, which means that the torch is moved away from the direction of welding. This usually produces lesser penetration and a wider and smoother bead. The push technique usually works best with thin materials, and the angle of application is between 10° to 15°. This will allow for better visibility of the welding spot and reduced spatter .
Pull Technique
On the other hand, the pull technique involves moving the torch towards the weld, which typically yields deep penetration. It is usually used for thicker materials, as lesser ones may become burned through if the pull technique is used. The weld applied at this angle is usually narrower, and the degree of application is between 15° to 45°. It also has a slightly rougher surface, as this method enhances the cleaning action of the arc and also allows a better view of the joint root. Regardless of the method used, the speed at which the weld should move is usually between 10 to 25.4 mm per second instead of inches . Each of these techniques requires a certain amount of skill and an understanding of the welds with which they work best. For instance, the push method will not work on thicker materials since it will not penetrate enough and the weld will not be strong. On the other hand, pulling will compromise the weld on a lower gauge, as it will either burn it or penetrate too much.
Techniques and Applications
Push Technique in Flux Core Welding
The push technique involves the tilting of the welding gun away from the direction of weld travel. This type of technique is popular due to its ability to produce a flat and wide bead with less penetration . As such, the push method is ideally suited to welding thinner materials. The heat transfer is also lower, which leads to less spatter and better visibility of the process, which leads to a cleaner application. The angle of pushing is typically set between 10 degrees and 15 degrees to reduce the chances of the undercutting of the final arc. The push technique is widely used for automotive repairs and fabrication, where thin sheets require greater control of final appearance and penetration.
Pull Technique in Flux Core Welding
The pull technique involves dragging the gun toward the welder, which is typically used for deeper penetration. The bead is typically narrower and deeper and, thus, is best applied to thicker materials that are ideally suited for strong penetrating welds . The increased heat input and penetration led to the method being widely used in construction and industrial purposes. The pull method typically has a steeper angle at which the dragging occurs between 15 degrees and 45 degrees, which enhances the cleaning action and accessibility to the joint’s root. The pull technique is beneficial when welding joints that require a stronger, highly penetrating weld to withstand high stress and pressure.
Selecting the Right Technique for Your Welding Project
The decision as to when each technique is best suited hinges on several factors such as the material’s thickness, the desired strength for the arc, and the appearance at both ends. Ideally, the push method should be used for materials that are less than 3mm thick since the penetration will be lower and the finish will be smoother. Alternatively, materials that are above 3mm in thickness should incorporate the pull method for the strength of the deep penetration. The method in use also depends on the welding position; for overhead or vertical applications, the pull method will ensure superior control of the weld pool, which means that there is less chance of the arc falling and splaying. The method is also linked to speed; while speed can be adjusted at will, the travel speed should be faster for the push technique. The method should also be considered in terms of cost; for most applications that require intensive cleaning to achieve the required end result, the push technique should be used. The pull method will create a stronger, dirtier weld that may require more than a single pass for penetration or additional support.
Advantages and Disadvantages
Advantages of Push Technique
The push technique is widely known in the flux core welding process as it provides better visibility and welding process control than its counterpart. Since the perspective of welding is clearer, it is easier for the welder to produce cleaner, more aesthetically pleasing welds, with less spatter . The chief advantage of the push technique is that it provides less penetration depth . Thus, it is better for welding thinwalled materials since the risk of burn-through is reduced. Moreover, the push technique contributes to a wider and smoother bead, needed for good appearance perceived as important for automotive welding, especially for bodywork. Finally, the process is more rapid as there is no spatter and penetration is less, which allows the welder to move the torch quickly. Additionally, there is less fume, which makes the welder’s working environment better.
Disadvantages of Push Technique
Despite the evident benefits that the push technique provides, it is limited in its application. The primary disadvantage is the shallow penetration, which is not enough for structural welds or welding thicker materials. Thus, in such cases, the weld is weaker in comparison to the ones made with the pull technique. Lastly, applications requiring welding of tight joints, corners, and seams are difficult with the push method, especially when only one side is accessible.
Advantages of Pull Technique
As for the pull technique, it is essential for welding processes requiring deep penetration. The force of the arc that the welder drags generates deep penetration, which is needed for thick materials usually used for industrial structure manufacturing. Moreover, such a technique of dragging the torch to oneself ensures better cleaning action , which is crucial for removing impurities from the weld pool and creating a reliable weld. The advantage of the pull technique is also that it is easier to weld in various positions, such as vertical or overhead welding, where the torch must be held in a way to control the molten pool effectively.
Disadvantages of Pull Technique
The disadvantages of the pull technique are as follows: there is a danger of too deep penetration, which leads to burnthrough in thinner materials, and in some critical applications, it is inappropriate; typically, there is more spatter with the pull technique as compared to the push one, which requires more cleaning . Moreover, the process is slower.