What Is a Weld Bead?
A weld bead is created by depositing a filler material into a joint between two pieces of metal. A deposit of filler metal from a single welding pass. Also known as a welding bead.
Bead is deposited filler metal on and in the work surface when the wire or electrode is melted and fused into the steel. A stringer bead is a narrow bead with only a dragging motion or light oscillation, while a weave bead is wider with more oscillation.
A good weld is easy to distinguish. It will be straight and uniform with no slag, cracking, or holes. There will be no breaks in the weld. It shouldn’t be too thin and there should be no dips or craters in the bead.
As you melt a filler material into the workpiece, how you move the torch will impact how you advance the puddle and the type of bead you leave in the joint.
Why Use Different Torch Movements?
Like sewing a seam in cloth, there are several ways to run a weld bead along a metal joint. Yet unlike tailors, welders frequently need to perform their work in an awkward position while wearing a face shield and gloves.
Gravity also plays a role in how molten metal gets deposited between metal plates or pipe sections. For instance, if you’re welding overhead, you need to move fast. If you don’t, the molten metal will end up dripping on your face shield instead of filling the joint.
So, after preparing a joint for welding, selecting the appropriate filler material (e.g., stick, rod, wire, etc.), and choosing the right machine settings, a welder must also use a specific hand stroke and move the puddle at the right speed to get the bead down properly.
Types of Welding Bead
1. TIG Welding Beads
TIG welding beads generally have a “stack of dimes” type of look. This is because as the TIG arc is traveling, the welder is adding evenly spaced “dabs” of filler metal with their other hand. Each one of these dabs makes a circular shape as they are stacked on top of each other.
The timing of the dabs can greatly affect how the weld looks. Feeding the filler metal faster will result in the closer spacing of the dimes, and vice versa. TIG welds can be some of the prettiest welds due to this look.
TIG welds don’t always have the “stack of dimes” look. Sometimes welders will “walk the cup “. This is where the filler wire is being held, laying on the piece being welded. The welder walks the TIG cup back and forth as they move forward in their weld.
This melts the filler rod and spreads it across the weld joint – think of applying cream cheese to a bagel! This technique is especially popular with pipe welders. Sometimes 2 or 3 filler rods are used at once to increase the amount of filler being deposited. Think of walking the cup as a “weave” instead of a straight weld.
2. Stick Welding Beads
Stick welds can have multiple bead characteristics. The low hydrogen family of rods is quite versatile. A 7018 low hydrogen rod can be dragged as a straight bead. These are known as “stringer” beads because they are even and narrow.
This is popular with flat, horizontal, and overhead stick welding. Vertical 7018 weldings can benefit from using a weave-type pattern. Working uphill, the welder can use a variety of patterns to spread the filler metal into the joint. Weaves are much easier on vertical tests, but sometimes CWI ‘s will only allow stringer passes.
Below is our favorite reference chart for welding symbols. Symbols will dictate what type of weld is called for – which will determine your bead size and type.
Cellulose stick rods ie. 6010s and 7010s must be run with a specific “whip and pause” technique. The ending result has the dime look similar to a nice TIG weld. These welds generally don’t look as great as a proper TIG weld – but the dime effect is visible nonetheless.
With this technique, the welder will strike an arc and hold the rod in position to make a dime. They will then whip out and come back to deposit the next dime. For open roots on pipe and plate, 6010 cellulose rods can be dragged like a 7018 and they work great. Some visuals on 6010 welds can be found below. This video is by Jody Collier of Welding Tips and Tricks
3. MIG beads
Hardwire MIG is very versatile because there are so many techniques for creating a good weld. Some prefer to push the puddle, and some prefer to pull the puddle. There has always been a debate on whether pushing or pulling is stronger. Since there is no flux coating involved with hardwire MIG, the user isn’t forced to drag their puddle.
There is common welding saying “If it has slag, you gotta drag”. This is because in most cases if you push a stick rod or flux core MIG gun, the slag will get trapped in the weld. This creates porosity. With flux-coated welding techniques, the dragging technique allows the slag to form and harden at the back of your puddle as you continue forward.
A lot of MIG welders won’t weave or use any pattern. They will simply run a straight stringer bead. Although this can produce a sound weld, using a weave pattern can be beneficial for wider joints and vertical welds. It spreads the filler metal out more, resulting in a flatter bead.
A more recent trend is the “MIG like TIG” craze. This is where certain MIG settings can result in a bead that looks like the TIG dimes we mentioned above. This is also largely due to a specific technique with a low wire speed.
These beads aren’t as strong because the low heat penetrates the metal a lot less than normal. However, they have come to be standard in the off-roading culture because they are such clean-looking welds (especially on car parts). This technique can be fun to play around with. There is a great video on it by 5th Street Fab found below.
4. Flux Cored MIG Beads
Flux core MIG (especially dual shield) can deposit a ton of filler in a short amount of time. Most’s flux-cored beads are running by simple stringers. Vertical Flux-cored welds will usually require a weave to manage the puddle. Weaving a flux-cored bead will prevent you from getting a “drip” halfway through your weld. This is when the weld gets too hot and the molten metal drips off of your piece of material onto the floor.
Types Of Weld Beads Techniques
Generally speaking, torch manipulation is much the same whether you’re feeding the weld pool with a separate filler rod, a mechanically fed wire, or a stick electrode. But there are some techniques used mostly with one process.
Main welding bead techniques:
- Stringer beads
- Weave beads
1. Stringer Beads
A stringer bead is a straightforward procedure in which you either pull (i.e., “drag”) or push the torch across the joint in a straight line with no or minimal side-to-side movement. Dragging means the electrode is angled in the “forward” welding direction, leading the puddle. This enables maximum penetration and a robust-looking weld.
For heat-sensitive or thin metals, or when welding vertically, welders “push” the tip of the torch. This requires leaning your torch away from the puddle, and you follow it as you weld. When welding up on a vertical joint, the molten metal wants to fall downward. But pushing the weld keeps the heat away from the puddle and allows the weld to solidify quickly.
One of the major drawbacks to pushing is that you get less penetration into the base metal than pulling (“dragging”) the molten puddle. Stringer beads are generally not very wide and can be used in any welding position.
Even though you’re moving in a straight line, it’s still important to make sure you get “tie in” with the toe of the weld on either side of the joint. Remember, the object of welding is not just to fill a joint with new metal. It’s critical to get a fusion between the weld and the base metal.
Sometimes, moving the torch slow enough allows the weld puddle to flow over both sides of the joint. This may be all it takes to achieve good fusion. Other times a slight side-to-side manipulation is necessary, as illustrated below.
Again, keep the side-to-side manipulation slight. If you move too far from side to side, you will create a weave bead. (See the next section below.) Stringer beads are also used in hard facing. This is a surfacing operation that helps extend the life of scoops, fenders, plows, and other exterior metal parts on industrial equipment. In this instance, the beads are not meant to fuse with the base metal but to create a protective layer.
2. Weave Beads
For wide welds, you can weave from side to side along the joint. For a fat joint, weaving is the fastest way to knock off a welding assignment. This is especially true in the case of groove welds on thick stock. Weaves are also common on fillet welds.
Of course, there are different types of weaves, and every welder has his or her favorite. For example, your hand can perform a zig-zag, crescent, or curlicue motion. Weave bead patterns. The dots indicate pause points that apply additional heat and metal at the edge of the bead where it is most needed.
Besides filling a wider bead, weaving is used to control the heat in your weld puddle. In addition, you can pause on each side of the weld to achieve a good tie-in to the metal pieces and prevent undercutting of the edges.
However, when you move across the center of the joint, you’ll want to hurry. Otherwise, you may end up with a high crown (i.e., a bulge in the middle). Therefore, it’s better to have a flat or just slightly convex weld face when you weave.
A triangle weave is useful when you need to fill a steep pocket. In vertical-up welding, for instance, this weave technique allows you to build a shelf behind the puddle, which keeps the molten metal from sliding downward.
To keep the puddle from overheating or expanding, you can try a semi-circle weave, with the center point or your stroke crossing the front of the puddle (or just ahead of it). If you want more heat in the puddle, weave the semi-circle (or crescent) back through the puddle, as shown in the previous drawing.
Weaving in the overhead position can be challenging since gravity tends to pull the molten metal out of the weld. Even with practice, laying down an overhead weave bead a half-inch or wider can be a tall order. But welders learn to do it since weaving saves time compared to running multiple stringer beads.
As you can see, filing a joint with material relies heavily on how you move your torch, especially with wider joints. Knowing the various methods and understanding these techniques can improve the quality of your welds.
Not only do you need to properly prepare your joint, pick the right filler material, and set up your welder correctly, you must also use the right torch movement technique for the particular bead you want to create.
The four methods covered provide a solid start. But keep in mind there are variations and fine details to master for these torch manipulation methods. The best way to add all of these techniques to your welding repertoire is through practice, lots of it.