amt 623 welding (smaw) p2 2019 2nd sem.pdf

amt 623 welding (smaw) p2 2019 2nd sem.pdf - Flux Coated...

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Unformatted text preview: Flux Coated / Covered Electrode Metal Arc Welding Electrode is coated with a flux. The purpose of the flux is: ▪ To slow down the rate of cooling ▪ The wire core melts in the arc stream and droplets of metal are transferred across the arc to make the molten puddle and provide the filler metal to fill the gap or groove between two base metal. ▪ The flux covering also melts in the arc stream to stabilized the arc, to provide a shield around the arc to keep free from atmospheric impurities and to form a slag covering to protect the weld. Flux Coated / Covered Electrode The chemical coating from the electrode dissolves into shielding gasses to protect the weld free of air, atmosphere. This is known as.. Shielded Metal Arc Welding Flux Coated / Covered Electrode This shows how the coating on a coated (stick) electrode provides a gaseous shield around the arc and a slag covering on the hot weld deposit. Shielded Metal Arc Welding Process ▪ Electric current from a welding machine produces an Arc, between the base metal and a consumable electrode, which is the welding rod (electrode) that the flux coating are burn creating gasses that shield the weld area from coming in contact with oxygen in the air. ▪ The gasses surrounding the are super heated causing the base metal to melt while the filler metal from the rod is being deposited into the molten puddle. Shielded Metal Arc Welding Process ▪ As the core rod, flux coating, and work pieces heat up and melt, they form a pool of molten material called a weld puddle. ▪ The weld puddle is what a welder watches and manipulates while welding. 1/8” E6013 at 125 Amps AC Shielded Metal Arc Welding Process Shielding Gas ▪ A shielding gas is formed when the flux coating melts. ▪ This protects the weld puddle from the atmosphere preventing contamination during the molten state Shielding Gas Shielded Metal Arc Welding Process Solidified Weld Metal ▪ As the molten weld puddle solidifies, it forms a joint or connection between two pieces of base material. ▪ When done properly on steel, it results in a weld stronger than the surrounding base metal. Shielded Metal Arc Welding Process Slag ▪ Slag is a combination of the flux coating and impurities from the base metal that float to the surface of the weld. ▪ Slag quickly solidifies to form a solid coating. ▪ The slag also slows the cooling rate of the weld . ▪ The slag can be chipped away and cleaned with a wire brush when hard. Electrode Electrode ▪ Is a consumable - it gets melted during the welding process. ▪ Is composed of two parts ▪ Core Rod (Metal Filler) ▪ Carries welding current ▪ Becomes part of the weld ▪ Flux Coating ▪ Produces a shielding gas ▪ Can provide additional filler ▪ Forms a slag Electrode Electrode Classification E60XX Electrode Tensile in Ksi Welding Position: 1 = All Position, 2 = Flat & Horizontal Type of Current and Coating Electrode Classification Tensile Strength E: indicates a welding electrode used in arc welding. E60XX Electrode Classifications Tensile Strength ▪ The first two or three digits represent the tensile strength ▪ E70XX = 70,000 psi, E100XX = 100,000psi ▪ Psi: Pounds per square inch ▪ May also be shown as ksi ▪ Ksi: Kilopounds per square inch ▪ 70 ksi = 70,000 psi E60XX Electrode Classifications Welding Position ▪ The second digit from the right indicates the recommended position of the joint that the electrode is designed to weld. ▪ EXX1X: Will weld in all positions ▪ EXX2X: Are used for welds in the flat or horizontal welding position only. EXX1X Electrode Classifications Type of Current and Coating ▪ The last two digits need to be looked at together. ▪ The two digits give the welder information on the electrode covering, current to use and position to use the electrode. ▪ *Refer to chart for more information E60XX Welding Safety ▪ Welding can be safe when sufficient measures are taken to protect yourself and others from potential hazards ▪ Students should read and understand the following before welding: ▪ Warning Labels ▪ Material Safety Data Sheets (MSDS) Welding Safety Understand and follow all warning labels found: ▪ On welding equipment ▪ With all consumable packaging ▪ Within instruction manuals Welding Safety Material Safety Data Sheets (MSDS) are: ▪ Required by law and OSHA ▪ Created by the manufacturer of a product per OSHA guidelines ▪ Designed to inform users ▪ Shipped with every box consumable product ▪ Available free online Welding Safety MSDS outlines a product’s: ▪ ▪ ▪ ▪ ▪ Identity and composition Potential hazards Safe use Handling information Manufacturer contact information Welding Safety Protect yourself and others from potential hazards including: ▪ Fumes and Gases ▪ Electric Shock ▪ Arc Rays ▪ Fire and Explosion Hazards ▪ Noise ▪ Hot objects Welding Safety Fumes and Gases Fumes and gases can be hazardous to your health ▪ Keep your head out of the fumes ▪ Use enough ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area ▪ See product labeling and MSDS for ventilation and respirator requirements Welding Safety Electric Shock ▪ Electric shock can kill ▪ Do not touch live electrical parts ▪ Primary Voltage –230, 460 volt input power ▪ Secondary Voltage – 6 to 100 volts for welding ▪ Insulate yourself from work and ground ▪ Follow all warnings on welding equipment Welding Safety Arc Rays ▪ Arc rays can injure eyes and burn skin ▪ The welding arc is brighter than the sun ▪ Precaution must be taken to protect your eyes and skin from UV radiation ▪ Wear correct eye and body protection Welding Safety Fire and Explosion Hazards ▪ Welding sparks can cause fires and explosions ▪ Sparks and spatter from the welding arc can spray up to 35 feet from your work ▪ Flammable materials should be removed from the welding area or shielded from sparks and spatter ▪ Have a fire extinguisher ready ▪ Inspect area for fires 30 minutes after welding Welding Safety Noises ▪ Loud noises can damage your hearing ▪ Keep loud noises at a safe level by using proper hearing protection such as: ▪ Ear plugs ▪ Ear muffs Welding Safety Welders must wear protective clothing for ▪ Protection from sparks, spatter and UV radiation ▪ Insulation from electric shock Protective clothing includes … ▪ ▪ ▪ ▪ ▪ Fire-proof clothing without rolled sleeves, cuffs or frays Work boots Welding gloves, jackets, bibs, and fire-proof pants Welding cap, helmet and safety glasses Ear protection – ear plugs and muffs ...
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  • Spring '19
  • Arc welding, Gas metal arc welding

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