How Is A Weld Bead Defined?
When melting a filler material into the workpiece, the way the torch is moved has an effect on how the puddle advances and the sort of bead that forms in the joint.
Why Is It Necessary to Use Diverse Torch Movements?
As with sewing a seam in cloth, there are a variety of techniques for running a weld bead along with a metal connection. Unlike tailors, though, welders frequently operate in an awkward position while wearing face protection and gloves.
Gravity also plays a role in the deposit of molten metal between metal plates or pipe segments. For example, if you’re welding overhead, you must work quickly. Otherwise, the molten metal will drip onto your face shield rather than filling the joint.
Thus, in addition to properly preparing a joint for welding, selecting the appropriate filler material (e.g., stick, rod, wire, etc. ), and selecting the appropriate machine settings, a welder must also employ a specific hand stroke and move the puddle at the proper speed in order to properly set the bead.
Weld Bead Types & Torch Movements
Torch manipulation is generally similar regardless of whether the weld pool is fed by a separate filler rod, a mechanically fed wire, or a stick electrode. However, several approaches are primarily utilized in conjunction with a single process.
The four most often utilized torch manipulation techniques for creating weld beads are as follows:
The principal welding bead processes are as follows:
- Stringer Beads
- Weave Beads
Techniques specific to the process:
- Whip-like motion (Stick)
- Walking the cup (TIG)
A stringer bead is a simple method that involves either pulling (i.e., “dragging”) or pushing the torch across the joint in a straight line with no or no side-to-side movement.
Dragging is a term that refers to an electrode that is tilted in a “forward” welding direction, hence leading the puddle. It allows for optimal penetration and a sturdy appearance of the weld.
Welders “push” the torch tip while welding heat-sensitive or thin metals, especially when welding vertically. It means angling your torch away from the puddle and welding alongside it.
When welding vertically, the molten metal naturally tends to fall downhill. However, moving the weld away from the puddle keeps the heat away and helps the weld harden quickly.
One of the fundamental disadvantages of pushing is that the molten puddle penetrates the base metal less than when it is pulled (“dragged”). Stringer beads are typically quite narrow and can be welded in any position.
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Even if you’re traveling straight, it’s critical to “tie in” with the toe of the weld on either side of the joint. Bear in mind that the purpose of welding is not only to fill a joint with new metal. Fusion between the weld and the base metal is crucial.
Occasionally, slowing down the torch movement permits the weld puddle to run over both sides of the joint. It may be all that is required to produce satisfactory fusion. As seen below, a modest side-to-side manipulation is required at other times.
Again, maintain a little side-to-side manipulation. If you move too much to the side, you’ll end up with a weave bead. (For more information, see the following section.)
Additionally, stringer beads are utilized in hard facing. This surfacing process helps extend the life of industrial equipment’s scoops, fenders, plows, and other exterior metal components. The beads are not intended to fuse with the base metal in this instance but to form a protective coating.
You can weave from side to side along the junction for large welds. Weaving is the quickest approach to complete a welding project on a large joint.
This is particularly true for groove welds on heavy stock. Weaves are also frequently used in fillet welds.
Naturally, there are numerous weaves, and each welder has a favorite. For instance, you can do a zig-zag, crescent, or curlycue motion with your hand.
Apart from filling a larger bead, weaving is utilized to regulate the temperature of your weld puddle. Additionally, you can pause on each side of the weld to ensure a strong connection to the metal components and to avoid edge undercutting.
However, you’ll want to move quickly across the joint’s center. Otherwise, you risk having a large crown (i.e., a bulge in the middle). As a result, it is preferable to weave with a flat or slightly convex weld face.
A triangle weave is advantageous when filling a steep pocket. For example, when welding vertically up, this weave technique enables you to create a shelf behind the puddle, preventing the molten metal from falling lower.
To prevent the puddle from overheating or growing, try a semi-circle weave with the center point or your stroke crossing the puddle’s front (or just ahead of it). If you wish to increase the amount of heat in the puddle, weave the semi-circle (or crescent) back through it, as illustrated in the preceding illustration.
Weaving overhead can be difficult because gravity tends to draw the molten metal out of the weld. Even with practice, laying down a half-inch or broader overhead weave bead can be a tall job. However, welders learn to weave since it is faster than running several stringer beads.
Whip Movement (For Stick)
On open groove welds, a stick welder often whips his or her wrist during the root pass, which is the initial weld process. The goal is to weld the bottom work plates together with a flat bead of weld metal.
E6010 and 6011 “fast-freeze” rods are the most often used stick electrodes for root passes on low-carbon steel.
The welder advances the electrode up and through the gap. This is critical for complete infiltration. As a result, a keyhole will appear in the aperture at the puddle’s head.
This is one of the most challenging strokes for welders to master. Along with monitoring the puddle, you must also keep an eye on the keyhole size. If it becomes too large (i.e., more than double the diameter of the rod), the two sides will not fuse together. That is why it is critical to maintaining a constant temperature throughout a root pass.
Along with suitable joint design and welder settings, the size of the keyhole can be controlled by the frequency of your whip strokes.
You’ll whip the rod slightly upward and ahead of the weld before the keyhole size swells too much. This motion cools everything down and maintains the size of the keyhole. Additionally, this causes the bead at the puddle’s back to harden.
Once the bead hardens, you whip back to the molten puddle, and another drop of weld metal should fall off your rod (if stick welding), making your next dime.
All of this occurs fairly quickly. As a result, you must exercise caution, and the whipping rate is governed by the amount of heat detected in the weld.
When you first begin a weld, you may not be whipping at all due to a lack of heat. By the time you approach the conclusion of the weld, you may find yourself flipping your wrist continuously due to the intense heat pouring through the base metal.
A variation on the Whip – The J-Weave
A “J-weave” is a variation of the whip motion. It combines crescent and whip strokes and is typically employed on a V-groove joint’s second (or “hot”) pass.
Here, you’ll move your E6010 or other fast-freeze electrodes from toe to toe, pausing briefly on each side, and then whip the rod ahead and upward along one side of the joint for a brief moment.
A longer arc is advantageous for this task. And, as with a root pass, you’ll whip ahead and then return to the next free spot on the left (or right) toe of the weld to repeat the stroke.
Walking The Cup (For TIG)
Welders frequently utilize a TIG torch during a root pass for the pipe. It produces a cleaner, more exact bead than the stick or MIG welding.
Additionally, the method frequently comprises a certain hand sweep dubbed “walking the cup.” The cup is the ceramic insulator that surrounds the tungsten point in this case. Simply rock the cup back and forth along the weld junction, the welder.
It is more straightforward to demonstrate, and the video following goes into greater depth about this technique:
As you can see, successfully filling a joint with the material is highly dependent on how you move your torch, particularly when working with bigger joints. Understanding the various procedures and strategies will help you enhance the quality of your welds.
Not only must you carefully prepare the joint, select the appropriate filler material, and properly set up your welder, but you must also apply the appropriate torch movement technique for the bead you wish to generate.
The four strategies discussed here are a good place to start. However, Remember that these flame manipulation methods have variants and precise subtleties to master. Extensive practice is the most effective method to incorporate all of these skills into your welding repertory.