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Arc Welding or SMAW

By Xylyn-Aguro Mar 12, 2015 1440 Words
Arc Welding or SMAW

Generally known as stick or arc welding. Arc welding is the most basic of all welding types, is easy to master in a home welding situation. Stick welding can be used for manufacturing, construction and repairs, very much well suited for heavy metal size 4 millimetres upwards. Thinner sheet metals and alloys are usually more suited to the mig welding types.

1. Gather your materials. You should have a welding machine, electrode holder with lead, ground clamp with lead, electrodes, and metal to be welded. You will also need are a chipping hammer to get rid of the slag and a wire brush to clean the welds. 2. Put on your safety gear. This includes a welding helmet (shade #10 or higher), welding jacket or cotton sweatshirt, pants without cuffs, work boots, gloves, and safety glasses. DO NOT wear tennis shoes, frayed clothes, pants with cuffs, a t-shirt, a shirt with open pockets, or sleeveless shirts. 3. Prepare the area to be welded in. Remove all flammable material and find a good surface to weld on. Although you can put the ground connection right on the piece you are welding, most shops have a large metal workbench that the ground is hooked up to. If there are other people present, set up welding curtains around the work area. This will protect them from UV damage. 4. Set up the machine. Most welding machines are fairly straight forward. You should most likely be using an amperage of around 90-120 amps, although this should be adjusted for metal thickness and electrode diameter. 5. Use the correct electrode. DCEP (direct current electrode positive) sets the arc to go from the metal to the electrode, heating the metal more. DCEN (direct current electrode negative) has the reverse effect. For stick welding, DCEP will give your weld more penetration. You should select the electrode appropriate for AC or DC welding, depending on your machine. Make sure the electrodes are dry.

6. Clean the metal before welding. This can be done by brushing the surface(s) to be welded with a wire brush or a grinder. Remove as much rust or paint from the metal as possible.

Use acetone to clean oils off the metal, especially aluminum. Never use a chlorinated solvent, as the reaction when heated with a welder can kill you instantly. Just because the metal is shiny, doesn’t mean it is clean. Use a hard grinding disc to remove the layer of mill scale and get down to the bare metal. This is most applicable to steel. 7. Set the joint. Use clamps and vises to ensure that the joint you are welding is precisely and firmly held together. 8. Strike a welding arc. This is accomplished by tapping the metal and quickly pulling up or striking it like a match. You are completing the circuit and pulling away, which causes the electricity to jump from the electrode to the metal.

Most modern welding helmets allow you to see clearly until you strike the arc, and then darken automatically to protect your eyes from UV damage. Some older or cheaper helmets just use a tinted lens that is too dark to see through unless welding. In this case, you should find where you want to start welding and flip the helmet down with your other hand, then strike the arc. 9. Build up a weld pool. When a stable arc can be maintained, ignore the end of the electrode and instead watch the pool of molten metal. To create a good pool, you should stay where you started for a second or two before moving.

The arc gap should be no wider than 1/8" from rod tip to metal. This gap dimension should be maintained by feeding or gently pushing the electrode toward the molten weld puddle. If the gap gets too wide, it will lead to excessive spatter. 10. Start moving the weld pool across the metal. Keep the electrode at an angle a few degrees shy of 90°. Don't travel too fast; as a general guide you want to use about an inch of electrode for each inch of weld. When moving the weld pool, you can go in a straight line (a stringer bead) or move around in small circles.

It is important to maintain a constant arc length, or distance from the tip of the electrode to the metal. This can be hard at first since the electrode is constantly burning down.

Continue moving the pool towards the end of the metal. Again, make sure your travel speed and arc length are steady. 11. Finish the weld. Pull the electrode back from the metal and allow it a few seconds to cool. The metal will still be very hot at this point, but it should no longer be red hot. 12. Clean the slag. Slag is a residue left from the welding process. During the weld, the slag protects the hot metal from contaminants. The slag covering does not cool at the same rate as the weld bead, which can cause the slag to pop off the weld. Use the chipping hammer to break the slag off the weld.

Safety glasses should be worn while welding so that when the shield is raised the eyes are protected.

Tap the slag only hard enough to loosen the slag and avoid putting hammer marks in the new weld.

Use the wire brush to clean the weld. Remove as many excess particles as possible, especially if you are going to do another pass. 13. Examine the weld. A welder's first welds are often poor and do not take stress well. However, practice changes this. Make another pass to fix any gaps or incomplete welds. 14. Allow the metal to cool. If this is only practice, dipping the metal in water will cool it faster. Cooling in water will make the weld brittle, so allow any structural welds to cool by air instead.


+ Electric shock
Electric shock is one of the most serious and immediate risks facing a welder.  Electric shock can lead to severe injury or death, either from the shock itself or from a fall caused by the reaction to a shock. Electric shock occurs when welders touch two metal objects that have a voltage between them, thereby inserting themselves into the electrical circuit. For instance, if a worker holds a bare wire in one hand and a second bare wire with another, electric current will pass through that wire and through the welding operator, causing an electric shock. The higher the voltage, the higher the current and, thus the higher the risk for the electric shock to result in injury or death. + Fumes and gases

It’s no surprise that overexposure to welding fumes and gases can be hazardous to your health. Welding fume contains potentially harmful complex metal oxide compounds from consumables, base metal and the base-metal coatings, so it’s important to keep your head out of the fumes and use enough ventilation and/or exhaust to control your exposure to substances in the fume, depending on the type of rod and base metal being used. +Fire and explosions

The welding arc creates extreme temperatures, and may pose a significant fire and explosions hazard if safe practices are not followed. While the welding arc may reach temperatures of 10,000 degrees Fahrenheit, the real danger is not from the arc itself, but rather the intense near the arc and the heat, sparks and spatter created by the arc. This spatter can reach up to 35 feet away from the welding space. To prevent fires, before beginning to weld, inspect the work area for any flammable materials and remove them from the area. Flammable materials are comprised of three categories: liquid, such as gasoline, oil and paint; solid, such as wood, cardboard and paper; gas, including acetylene, propane and hydrogen. +Injuries from insufficient PPE

Personal protective equipment (PPE) helps keep welding operators free from injury, such as burns – the most common welding injury – and exposure to arc rays. The right PPE allows for freedom of movement while still providing adequate protection from welding hazards. +Other safety considerations

Welders should also be aware of other safety considerations within the work environment. For example, those working in a confined space or in an elevated area make need to take extra precautions. In any welding situation, welding operators should pay close attention safety information on the products being used and the material safety data sheets provided by the manufacturer and work with their employer and co-workers to follow appropriate safe practices for their workplace.


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