How to Arc Weld (with Pictures)

2024 Author: Samantha Chapman | [email protected]. Last modified: 2024-01-09 13:41

Shielded metal arc welding is the process of joining two pieces of metal using a coated electrode that is melted in an electric arc and becomes a molten part of the pieces to be welded. This article describes the use of a coated electrode ("stick") and a simple welding machine powered by a transformer.

Steps

Step 1. Understand how arc welding works

L' electric arc it forms at the tip of an electrode when current passes between the metal you are welding and the air gap that divides them. Here are some of the terms and their description used in this article:

• Welding machine. This is the term used to describe the machine, which converts alternating current from 120-240 volts to the voltage required for soldering, typically 40-70 volts alternating, but also a variety of direct voltages. Such a device generally has a large transformer, a voltage regulator circuit, a cooling fan and a selector for amperage. The person who welds is called a welder. A welder needs a welder to use it.
• Cables. These are the copper insulated conductor cables that carry the high amperage and low voltage electricity to the piece of metal to be welded.
• Electrode holder, or "sting", is the end of the cable that contains the electrode, and is the part that the welder holds to carry out the weld.
• Ground and clamp. This is the ground cable or the one that closes the circuit and precisely the clamp that is attached to the metal being processed, which allows the current to flow through the metal to be welded.
• Amperage. It is the electrical term, used to describe the electric current supplied to the electrode.
• Direct current and reverse polarity. This is a different configuration used in arc welding, which offers greater versatility, especially in general welding applications and for using certain alloys that do not easily weld with alternating voltage. The welding machine that produces this current has a rectifier circuit or takes current from a generator. This type of machine is much more expensive than a typical AC voltage soldering iron.

• Electrodes. There are different types, specific for certain welds, used for different alloys and types of metals, such as cast iron or malleable iron, stainless steel or chromium, aluminum and tempered or concentrated carbon steel. A typical electrode consists of a bar of semi-finished metal in the center (wire rod), covered with a special coating (flux) that burns when you use the arc, consuming oxygen and producing carbon dioxide in the weld zone, to prevent the metal from settling. oxides or burns in the arc flame during the welding process. Here are some of them, and their uses:

  • The E6011 electrodes, made of mild steel and coated with cellulose fiber. In identifying the electrodes, the breaking load is important, which is measured in PSI x 1, 000. In this case, the performance of the electrode would be 60,000 PSI.
  • E6010 electrodes, with reverse polarity, are commonly used for welding steam and water pipes and especially for bottom welding as the metal remains in place in the liquid state as it is melted by the flow of forward current, which passes from the electrode to the metal being processed.
  • Other E60XX electrodes are also available for specific welds, but they will not be covered in this article as E6011 electrodes are common and E6010 electrodes are common for polar reverse welding.
  • The E7018 electrodes have a low hydrogen content, with a breaking load of approximately 70,000 PSI. They are used to weld construction material and in processes where a stronger and more resistant material is needed. Although these electrodes provide more power, they make it very difficult to get a good result on working dirty metals (paint, rust or galvanized). They are called low hydrogen electrodes due to attempts to obtain a low concentration of hydrogen. These electrodes should be stored in an oven at a temperature between 120 and 150ºC. Since this temperature is higher than the boiling point of water (100 ° C), it prevents the accumulation of moisture (condensation) on the electrode.
  • Electrodes in nickel and alloy. These are used to weld soft and malleable iron and have a higher yield, to allow for expansion and contraction of the metal being welded.
  • Different electrodes. These electrodes are made of a special alloy which gives better results for welding hard or tempered steel.
  • Aluminum electrodes. They are more recent and allow to weld aluminum with a conventional welding machine instead of one with gas flow, such as MIG (metal) or TIG (tungsten), often referring to a "heliarch" welding since helium is the gas used. The official names created by the American Welding Society (AWS) for arc welding are: Metal-Protected Arc Welding (SMAW), Tungsten Arc Welding (TIG), and Metal Arc Welding (MIG).
  • The measurements of the electrodes. The electrodes are available in a variety of cuts, obtained by measuring from the diameter of the metal center of each electrode. Mild steel electrodes are available with a diameter of 1.5 to 9.5 mm and the size to be used is determined by the amperage of the welding machine and the thickness of the material to be welded. The choice of measure varies according to the amperage. Selecting the correct amperage for a given electrode will depend on the material to be machined and the penetration, so in this article we will only deal with the specific amperages.

• Safety equipment. A key part of welding is knowing how to use the equipment correctly to ensure efficient safety. Here are some typical items that are needed for safe soldering.

  • Welder's helmet. It is the mask that is worn to protect the person working from the bright flash of the arc and the sparks that are generated during welding. The lenses of the mask are very dark to protect the eyes from the exposure of the bright flash which could burn the retina. The minimum level of darkness of the lenses is 10. The best masks are those with the dark layer that can be lifted leaving a transparent protective layer, in order to allow a more fluid work. The masks produced today are the best. They have slightly darkened lenses that can also be used with edgers and cutting torches. However, when you use the arc to weld, the lens automatically darkens to level 10. Most modern masks have additional auto-darkening levels.
  • Gloves. They are special gloves in insulated leather that reach 15 cm on the wrists and protect the hands and forearms. They also protect you from electric shock if you accidentally touch the electrode while you are welding.
  • Leather protection. This is a jacket that covers the shoulders and chest of the welder, when welded from below to prevent sparks from falling on you and burning your clothes.
  • Boots. You have to wear them and tie them up to 6 '' on the leg to prevent sparks from burning your feet when you are welding. They must have an insulating sole and must be made of a material that does not melt or burn easily.

  

  Step 2. Learn the steps to weld properly

  Soldering is more than just moving metal back and forth and joining it together. The procedure begins in positioning the pieces to be welded well. Blunt chunky pieces a little to fill them well and weld them effectively. Here are the basic steps to complete a simple weld.

  • Form the arch. This is the procedure for creating an arc between the electrode and the workpiece. If the electrode allows current to pass through the workpiece, there will not be enough heat to melt and join them.
  • Move the bow to create a "bead". The bead is the electrode metal that is melted and mixed with the melt metal of the workpiece to fill the space between the pieces to be fused together.
  • Work the beads. Do this by waving the arc back and forth along the weld, move the arc in a zig zag or 8 shape, so that the metal is distributed in width to obtain the desired joint shape.
  • Scrape and scrape the weld as you go. Each time you complete a "step" - from one end to the other - you need to remove the "slag" - the loose electrode coating - from the surface of the welded bead so that you have clean molten metal in the next step.

  

  Step 3. Put together the material and tools you will need to start welding

  That is, the welding machine, the electrodes, the cables, the clamps and the metal to be welded.

  

  Step 4. Prepare a safe area to work, preferably a table made of steel or other non-flammable material

  Practice with a few pieces of mild steel about 4.5mm thick.

  

  Step 5. Prepare the metal to be welded

  If the metal consists of two pieces that need to be joined in the welding process, file them along the areas to be joined together. This will allow the bow to achieve sufficient penetration that will melt the two parts into a single bubble of molten metal, penetrating in turn through the entire thickness. Either way, you must first remove paint, grease, or other surface materials to work with clean molten material as you weld.

  

  Step 6. Use clamps to hold the metal pieces together

  Pliers, jaws, vise or clamps will be fine. You will need to adapt and combine the use of these items according to the work to be done.

  

  Step 7. Attach the ground clamp to the larger piece to be welded

  Be sure to place it in a "clean" spot to allow the electrical circuit to close with minimal resistance. As previously mentioned, rust or paint will interfere with the job making it difficult for arcing when soldering.

  

  Step 8. Choose the appropriate electrode and the right amperage for the job at hand

  For example, a 6mm thick sheet of metal can be effectively welded using a 3mm E6011 electrode at 80-100 amps. Place the electrode in the electrode holder making sure the conductive material of the clamp at the end of the electrode is on the clean metal.

  

  Step 9. Turn on the welder

  You should be able to notice the hum coming from the transformer. Fan noise may not be heard. Some fans only turn on when needed. If that's not your case, check the electrical circuit or switches in the meter. Soldering irons require a lot of power to operate, often a circuit equal to or greater than 60 amps and 240 volts.

  Step 10. Hold the electrode holder by the handle with your dominant hand, placing the electrode in a position where the tip can touch the metal to be welded in the most natural movement possible

  Keep the visor of the helmet raised so you can see the movements to be performed, ready to lower it when you start welding to protect your eyes. Try tapping the tip of the electrode against the metal to be welded to "get used to it" before switching on, but remember to always protects the eyes

  

Step 11.

• Choose the starting point.

  Place the tip of the electrode close to the metal, then lower the visor. Tap the tip of the electrode against the metal to close the electrical circuit, then quickly pull it back a little to create the electric arc between the electrode and the metal to be welded. Another way to make a bow is to rub it like lighting a match. This air gap creates good resistance in the electrical circuit that produces the flame or "plasma" and the heat needed to liquefy the electrode and adjacent metals.

  

• Rub the electrode on the surface of the metal, bringing it back a little when you see an electric arc forming. You need a lot of practice to do this as each different electrode and amperage measurement requires a different gap between the electrode and the workpiece, but if you can keep that gap constantly, an electric arc will then form. Normally, this gap should not exceed the diameter of the electrode itself. Practice with the arc, holding the electrode at a distance of 3 - 4.5 mm from the workpiece, then move along the area to be welded. As you move the electrode, the metal will be melted thus creating the weld.

  

• Practice moving with the electrode, along the area to be welded until you can get a steady arc by moving at a good speed while keeping it aligned. Once you have learned to keep the bow, you will need to learn how to build beads. These are the material that binds the two pieces together. The technique for doing this depends on the width of the gap to be welded and the depth. The slower you move the electrode, the deeper the weld will go into the piece; to increase the size of a bead, zigzag or wave the electrode.

  

• While balancing, keep the bow stable. If the electrode sticks to metal, move the electrode holder to unlock it. If the arc is lost because you move the electrode too far from the metal surface, stop the process and clean the residue from where you work so that when you redo the arc to continue, there will be no slag in the weld area to contaminate the new one. Never form a bead on slag as the slag would melt creating bubbles in the new layer, soiling and weakening the weld.

  

• Practice the electrode by making a brush-like motion to form larger beads. This will allow you to better fill the weld in one pass, leaving it cleaner. Move the electrode sideways in a zigzag, curved or 8-shaped motion.

  

• Adjust the amperage according to the material used and the desired penetration. If you get an uneven weld, with cracks around the beads or with the adjacent metal being burnt, gradually reduce the amperage until you reach the desired conditions. While, if you have trouble rubbing or holding the bow, it will need to be increased.

  

• When you're done, clean the weld. After you are finished, remove the slag from the weld to allow the paint to stick better or simply for aesthetic reasons. Spatula and scrape to remove any remaining slag. If the surface needs to be flat (in order to fit the welded part with another) use an angle grinder to fix the weld. A clean weld, especially after planing, is easier to examine to see if it is pitted, if there are any small cracks or other defects.

  

• Paint the weld with anti-rust paint to protect it from corrosion. Freshly welded metals tend to corrode quickly when exposed to certain elements such as humidity and condensation.

  

Advice

• When you are welding pieces that are too large to join together with a vise, join them first with small interval welds to prevent them from moving.
• Some listen to the sound produced by the arc to judge the quality of the weld. Pops and clicking noise could indicate flimsy arcing or improper amperage.

Warnings

• Metals stay hot for a long time after soldering, so keep pets and children away until they have cooled down.
• Check the cables and connections from time to time to avoid accidents and electric shocks.
• Welders use very dangerous amperage, so use cables and connections with caution. Never weld in damp conditions or on wet material without the necessary experience.
• Protect yourself from sparks by covering yourself with gloves, helmet and protection according to the welding to be done. Never weld without a helmet.
• Avoid breathing the fumes produced by the welds. This is especially true for galvanized metals and for those painted with toxic paint.
• The intense light from an electric arc can cause burns like the sun, so wear appropriate clothing and protective gear to reduce exposure.
• Check the quotes below for additional warnings and precautions.