August 1, 2009
A beginning stick welder can produce better welds by paying attention to the five basic elements to establish a good, consistent technique: current setting, length of the arc, angle of electrode,manipulation of electrode, and speed of travel.
For those who are new to it or perhaps who don't weld every day, stick welding—also known as shielded metal arc welding (SMAW)—is one of the more difficult processes to learn. Experienced welders who can pick up a stinger, pop an electrode in, and lay down great welds time after time can inspire great awe in other welders. They make it look easy.
The rest of us may struggle with it, however. That doesn't have to be the case if you pay attention to five basic elements involved in establishing a good, consistent technique:
Together, this is known as CLAMS. Properly addressing these five basic areas can improve your stick welding results.
While stick welding may be the most forgiving process on dirty or rusty metal, don't use that as an excuse for not properly cleaning the material. Use a wire brush or grinder to remove dirt, grime, or rust from the area to be welded. If you don't, you're hurting your chances to make a good weld the first time. Unclean conditions can lead to cracking, porosity, lack of fusion, or inclusions.
While cleaning the material, make sure you have a clean spot for the work clamp. A good, solid electrical connection is important to maintain arc quality.
Next, position yourself so you have a good view of the weld puddle. For the best view, keep your head off to the side and out of the smoke; this gives you a clear view to ensure you're welding in the joint and keeping the arc on the leading edge of the puddle. Maintain a comfortable stance so that you can support and manipulate the electrode with ease.
Pulling all the CLAMS points (current setting, length of arc, angle of electrode, manipulation of the electrode, and speed of travel) together may seem like a lot to think about while welding, but it becomes second nature with practice. Don't get discouraged. After all, learning to stick weld requires a learning curve. Everyone sticks the electrode to the workpiece in the early days, leading most to wonder if that's how the process got its name.
Current Setting. The electrode you select will determine whether your machine should be set up in DC positive, DC negative, or AC. Make sure you have it set correctly for your application. (Electrode positive provides about 10 percent more penetration at a given amperage than AC, while DC straight polarity, electrode negative, welds thinner metals better.)
The correct amperage setting primarily depends on the diameter and type of electrode you select. The electrode manufacturer usually indicates the electrode's operating ranges on the box or in enclosed materials. Select your amperage based on the electrode (see Figure 1), welding position (about 15 percent less heat for overhead work compared to a flat weld), and visual inspection of the finished weld. Adjust your power source by 5 to 10 amps at a time, until the ideal setting is reached.
If your amperage is too low, three scenarios may occur:
Once you get an arc going, if the puddle is excessively fluid and hard to control, your electrode chars when it's only half gone, or the arc sounds louder than normal, your amperage might be set too high (see Figure 3) . Too much heat also can affect the electrode's flux properties negatively. If the electrode starts to glow, you have a problem.
Length of Arc. The correct arc length varies with each electrode and application. As a good starting point, arc length should not exceed the diameter of the metal portion (core) of the electrode (see Figure 4). For example, an 0.125-in. 6010 electrode is held about 1/8 in. off the base material.
Holding the electrode too closely to the joint decreases welding voltage. This creates an erratic arc that may extinguish itself or cause the electrode to freeze faster. The result is a weld bead with a high crown (see Figure 5).
Excessively long arcs (too much voltage) produce spatter (see Figure 6), low deposition rates, and undercuts, which is when the area outside of the weld is concave or recessed. Long arcs also often leave porosity.
When first attempting to stick weld, it seems natural to use a too long arc, possibly to help get a better view of the arc and puddle. If you have trouble seeing, move your head, don't lengthen the arc. Start by finding a good body position that gives you an adequate view of the puddle, while also allowing you to stabilize and manipulate the electrode. A little practice will show you that a tight, controlled arc length improves bead appearance, creates a narrower bead, and minimizes spatter.
Angle of Travel. Stick welding in flat, horizontal, and overhead positions uses a drag, or backhand, welding technique (see Figure 7). Hold the electrode perpendicular to the joint, and then tilt the top in the direction of travel approximately 5 to 15 degrees. For welding vertical-up, use a push, or forehand, technique and tilt the top of the electrode 0 to 15 degrees away from the direction of travel.
Manipulation of Electrode. Each welder manipulates the electrode a little differently than the next. Develop your own style by observing others, practicing, and noting which techniques produce the best results.
Note that on material 1/4 in. and thinner, weaving the electrode is typically not necessary because the bead will be wider than necessary. In many instances, a straight bead is all that's needed.
To create a wider bead on thicker material, manipulate the electrode from side to side, creating a continuous series of partially overlapping circles in a Z, semicircle, or stutter-step pattern (see Figure 8). Limit side-to-side motion to 2.5 times the diameter of the electrode core. To cover a wider area, make multiple passes or use stringer beads.
When welding vertical-up, if you focus on welding the sides of the joint, the middle will take care of itself. Move across the middle of the joint slowly enough so that the weld puddle can catch up, and pause slightly at the sides to ensure solid tie-in to the side wall. If your weld looks like fish scales, you moved forward too quickly and didn't hold long enough on the sides.
Speed of Travel. Your travel speed should allow you to keep the arc in the leading one-third of the weld pool.
Traveling too slowly produces a wide, convex bead with shallow penetration and the possibility of cold-lapping, in which the weld appears to be simply sitting on the surface of the material (see Figure 9).
Excessively fast travel speed also decreases penetration, creates a narrower or highly crowned bead, and possibly underfills or undercuts. Note toward the end of the bead in Figure 10 how the bead appears inconsistent, as if the puddle were trying to keep up.
These tips, along with practice and patience, will get you headed in the right direction.
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