Shielded Metal Arc Welding uses an electric arc between a consumable electrode and the workpiece to join metals. The equipment is relatively simple and affordable compared to other welding types. Stick welding is highly versatile and effective on materials that are not perfectly clean, such as those with rust or paint, because the electrode’s flux coating helps burn through contaminants. The process is also less sensitive to wind, making it a practical choice for outdoor repairs and general fabrication projects.
Essential Safety and Protective Gear
Safety must be the first consideration, as welding generates intense light, heat, and fumes. Protecting your eyes from arc flash requires a welding helmet with a minimum shade level of 10 for stick welding up to 200 amps. The arc emits powerful ultraviolet and infrared radiation that can cause severe eye damage, so the helmet must be worn before striking the arc.
The skin must be completely covered to prevent burns from sparks, spatter, and UV radiation exposure. Flame-resistant (FR) clothing, such as a leather jacket or treated cotton sleeves, is necessary, as synthetic fabrics like polyester can melt onto the skin. Heavy-duty, insulated leather welding gloves protect the hands from heat and electrical shock, and high-top leather boots shield the feet from falling hot metal.
Environmental safety involves managing the toxic fumes released when the electrode’s flux coating burns, which can contain metal oxides and gases. Welding should be done in a well-ventilated area, ideally with local exhaust ventilation to pull the smoke away from the breathing zone. Fire prevention is mandatory, meaning the work area must be cleared of all flammable materials, and a fire extinguisher should be kept nearby.
Understanding Your Equipment and Settings
The core equipment consists of the welding machine, the electrode holder (stinger), and the work clamp (ground clamp). Modern machines are often inverter-based, which are smaller and more efficient than older transformer models, supplying the electrical current needed to create the arc. The work clamp completes the electrical circuit by attaching to the workpiece, ensuring a stable path for the current to flow.
Amperage is the primary setting that controls the heat input and is adjusted based on the electrode diameter and the thickness of the metal being welded. A general rule is to start with approximately one amp for every thousandth of an inch of electrode diameter, then fine-tune the setting based on the weld appearance. Too little amperage causes the electrode to stick, while too much can lead to excessive spatter and burn-through.
Polarity determines the direction of the current flow and affects penetration and deposition rate. Direct Current Electrode Positive (DCEP or DC+) directs more heat into the workpiece, providing deeper penetration, and is typically used for electrodes like E7018. Direct Current Electrode Negative (DCEN or DC-) directs more heat into the electrode, resulting in a faster melt rate and less penetration, which is preferred for thinner materials.
Electrode selection is guided by the American Welding Society (AWS) classification system, where the “E” stands for electrode, and the first two digits indicate the minimum tensile strength in thousands of pounds per square inch. For beginners, E6013 and E7018 are common choices. The E6013 offers a smooth arc and easy slag removal, making it forgiving for general-purpose welding on thinner materials. The E7018 is a low-hydrogen electrode that provides a stronger weld (70,000 psi tensile strength) and is preferred for structural applications requiring high integrity and deep penetration.
Mastering the Basic Welding Technique
The first physical skill to master is arc striking, using either the scratch or the tap method. The scratch method involves dragging the electrode across the metal like striking a match, while the tap method uses a quick, sharp tap to initiate the arc. Immediately after the arc ignites, the electrode must be lifted slightly to prevent it from fusing to the workpiece.
Maintaining the correct arc length is the next step, defined as the distance between the electrode tip and the molten weld puddle. This distance should be kept very short, ideally no more than the diameter of the electrode’s core wire (typically about 1/8 inch). A short arc produces a stable, focused heat, whereas an arc that is too long will sputter, create excessive spatter, and result in a wide, flat, weak weld.
The electrode angle, or travel angle, is important for controlling the weld bead shape and penetration. For flat and horizontal welding, a drag or backhand technique is used, where the electrode is tilted 5 to 15 degrees in the direction of travel. This slight angle helps the arc force push the molten metal and slag behind the weld puddle, ensuring a clean fusion zone.
Travel speed dictates the amount of heat input into the metal and the final size of the weld bead. The goal is to move at a speed that allows the molten puddle to form and fill the joint without excessive buildup or undercutting the edges. If the travel speed is too fast, the bead will be narrow and lack proper penetration, but if it is too slow, the weld metal will pile up and create a wide, convex bead. A consistent, rhythmic movement is necessary to create a uniform stringer bead.
Troubleshooting Common Beginner Issues
One frequent problem beginners encounter is the electrode sticking to the workpiece, usually immediately after striking the arc. This issue is often caused by setting the amperage too low, which does not generate enough heat to sustain the arc, or by holding the electrode against the metal for too long. Increasing the amperage by 10 to 15 amps or practicing a quicker lift motion after the initial contact can resolve this problem.
Porosity, which appears as small holes or voids in the finished weld bead, is a common defect. This is typically a sign of contamination, where moisture in the electrode coating or rust, oil, or paint on the base metal releases gas into the molten puddle. The fix is to thoroughly clean the metal surface before welding and ensure that electrodes, especially low-hydrogen types like E7018, are stored in a dry environment.
Poor penetration occurs when the weld metal sits on top of the base material without fusing deeply into the joint, resulting in a weak connection. This lack of fusion is caused by insufficient heat input or a travel speed that is too fast. To correct this, the welder should increase the amperage setting to generate more heat and slow the travel speed to allow the arc to melt the base metal more effectively.