Welding is the most common way of permanently joining metal parts. In this process, heat is applied to metal pieces, melting and fusing them to form a permanent bond. Because of its strength, welding is used in shipbuilding, automobile manufacturing and repair, aerospace applications, and thousands of other manufacturing activities. Welding also is used to join beams when constructing buildings, bridges, and other structures and to join pipes in pipelines, power plants, and refineries.
There are over 80 different welding processes that a welder can employ. Some are performed manually, and the work is entirely controlled by the welder. Others are semiautomatic, and the welder uses machinery, such as a wire feeder, to perform welding tasks.
One of the most common types of welding is arc welding. Standard arc welding involves two large metal alligator clips that carry a strong electrical current. One clip is attached to any part of the piece being welded. The second clip is connected to a thin welding rod. When the rod touches the piece, a powerful electrical circuit is created. The massive heat created by the electrical current causes both the piece and the steel core of the rod to melt together, cooling quickly to form a solid bond. The speed with which the welder works can affect the strength of the weld.
Two common and advanced types of arc welding are Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) welding. TIG welding often is used with stainless steel or aluminum. The welder holds the welding rod in one hand and an electric torch in the other hand. The torch is used to simultaneously melt the rod and the piece. MIG uses a spool of continuously fed wire instead of a rod, which allows the welder to join longer stretches of metal without stopping to replace a rod. The welder holds the wire feeder, which functions like the alligator clip in arc welding.
Like arc welders, soldering and brazing workers use molten metal to join two pieces of metal. However, the metal added during the soldering and brazing process has a melting point lower than that of the piece, so only the added metal is melted, not the piece. Soldering uses metals with a melting point below 800 degrees Fahrenheit; brazing uses metals with a higher melting point. Because soldering and brazing do not melt the piece, these processes normally do not create the distortions or weaknesses in the piece that can occur with welding. Soldering commonly is used to join electrical, electronic, and other small metal parts. Brazing produces a stronger joint than does soldering and often is used to join metals other than steel, such as brass. Brazing can also be used to apply coatings to parts to reduce wear and protect against corrosion.
Skilled welding, soldering, and brazing workers generally plan work from drawings or specifications and use their knowledge of welding processes and base metals to determine how best to join the parts. The difficulty of the weld is determined by its position—horizontal, vertical, overhead, or 6G (circular, such as in large pipes)—and by the type of metals to be fused. Highly skilled welders often are trained to work with a wide variety of materials, such as titanium, aluminum, or plastics, in addition to steel. Welders then select and set up welding equipment, execute the planned welds, and examine welds to ensure that they meet standards or specifications.
By observing problems during the welding process, welders can compensate by adjusting the speed, voltage, amperage, or feed of the rod. Some welders have more limited duties, however. They perform routine jobs that already have been planned and laid out and do not require extensive knowledge of welding techniques.
Automated welding is used in an increasing number of production processes. In these instances, a machine or robot performs the welding tasks while being monitored by a welding machine operator. Welding, soldering, and brazing machine setters, operators, and tenders follow specified layouts, work orders, or blueprints. Operators must load parts correctly and constantly monitor the machine to ensure that it produces the desired bond.
The work of arc, plasma, and oxy-gas cutters is closely related to that of welders. However, instead of joining metals, cutters use the heat from an electric arc, a stream of ionized gas called plasma, or burning gases to cut and trim metal objects to specific dimensions. Cutters also dismantle large objects, such as ships, railroad cars, automobiles, buildings, or aircraft. Some operate and monitor cutting machines similar to those used by welding machine operators. Plasma cutting has been increasing in popularity because, unlike other methods, it can cut a wide variety of metals, including stainless steel, aluminum, and titanium.
Work environment. Welding, soldering, and brazing workers often are exposed to a number of hazards, including very hot materials and the intense light created by the arc. They wear safety shoes, goggles, hoods with protective lenses, and other devices designed to prevent burns and eye injuries and to protect them from falling objects. They normally work in well-ventilated areas to limit their exposure to fumes. Automated welding, soldering, and brazing machine operators are not exposed to as many dangers, and a face shield or goggles usually provide adequate protection for these workers.
Welders and cutters may work outdoors, often in inclement weather, or indoors, sometimes in a confined area designed to contain sparks and glare. Outdoors, they may work on a scaffold or platform high off the ground. In addition, they may be required to lift heavy objects and work in a variety of awkward positions, while bending, stooping, or standing to perform work overhead.
Although about 50 percent of welders, solderers, and brazers work a 40-hour week, overtime is common, and nearly 1 out of 5 welders work 50 hours per week or more. Welders also may work in shifts as long as 12 hours. Some welders, solderers, brazers, and machine operators work in factories that operate around the clock, necessitating shift work.
| 1. | Operate safety equipment, and use safe work habits. |
| 2. | Weld components in flat, vertical, or overhead positions. |
| 3. | Ignite torches or start power supplies and strike arcs by touching electrodes to metals being welded, completing electrical circuits. |
| 4. | Clamp, hold, tack-weld, heat-bend, grind and/or bolt component parts to obtain required configurations and positions for welding. |
| 5. | Detect faulty operation of equipment and/or defective materials, and notify supervisors. |
| 6. | Operate manual or semi-automatic welding equipment to fuse metal segments, using processes such as gas tungsten arc, gas metal arc, flux-cored arc, plasma arc, shielded metal arc, resistance welding, and submerged arc welding. |
| 7. | Monitor the fitting, burning, and welding processes to avoid overheating of parts or warping, shrinking, distortion, or expansion of material. |
| 8. | Examine workpieces for defects, and measure workpieces with straightedges or templates to ensure conformance with specifications. |
| 9. | Recognize, set up, and operate hand and power tools common to the welding trade, such as shielded metal arc and gas metal arc welding equipment. |
| 10. | Lay out, position, align, and secure parts and assemblies prior to assembly, using straightedges, combination squares, calipers, and rulers. |
| 11. | Chip or grind off excess weld, slag, or spatter, using hand scrapers or power chippers, portable grinders, or arc-cutting equipment. |
| 12. | Analyze engineering drawings, blueprints, specifications, sketches, work orders, and material safety data sheets to plan layout, assembly, and welding operations. |
| 13. | Connect and turn regulator valves to activate and adjust gas flow and pressure so that desired flames are obtained. |
| 14. | Weld separately or in combination, using aluminum, stainless steel, cast iron, and other alloys. |
| 15. | Determine required equipment and welding methods, applying knowledge of metallurgy, geometry, and welding techniques. |
| 16. | Mark and/or tag material with proper job number, piece marks, and other identifying marks as required. |
| 17. | Prepare all material surfaces to be welded, ensuring that there is no loose or thick scale, slag, rust, moisture, grease, or other foreign matter. |
| 18. | Select and install torches, torch tips, filler rods, and flux, according to welding chart specifications, or types and thicknesses of metals. |
| 19. | Remove rough spots from workpieces, using portable grinders, hand files, or scrapers. |
| 20. | Position and secure workpieces, using hoists, cranes, wire, and banding machines or hand tools. |
| 21. | Clean or degrease parts, using wire brushes, portable grinders, or chemical baths. |
| 22. | Repair products by dismantling, straightening, reshaping, and reassembling parts, using cutting torches, straightening presses, and hand tools. |
| 23. | Fill holes, and increase the size of metal parts. |
| 24. | Dismantle metal assemblies or cut scrap metal, using thermal-cutting equipment such as flame-cutting torches or plasma-arc equipment. |
| 25. | Check grooves, angles, or gap allowances, using micrometers, calipers, and precision measuring instruments. |
| 26. | Signal crane operators to move large workpieces. |
| 27. | Gouge metals using the air-arc gouging process. |
| 28. | Guide and direct flames or electrodes on or across workpieces to straighten, bend, melt, or build up metal. |
| 29. | Estimate materials needed for production and manufacturing; maintain required stocks of materials. |
| 30. | Develop templates and models for welding projects, using mathematical calculations based on blueprint information. |
| 31. | Cut metal plates and structural shapes to dimensions, and contour and bevel as specified by blueprints, layouts, work orders, and templates, using powered saws, hand shears, or chipping knives. |
| 32. | Preheat workpieces prior to welding or bending, using torches or heating furnaces. |
| 33. | Use fire suppression methods in industrial emergencies. |
| 34. | Melt lead bars, wire, or scrap to add lead to joints or to extrude melted scrap into reusable form. |
| 35. | Set up and use ladders and scaffolding as necessary to complete work. |
| 36. | Join parts such as beams and steel reinforcing rods in buildings, bridges, and highways, bolting and riveting as necessary. |
| 37. | Hammer out bulges or bends in metal workpieces. |
| 38. | Mix and apply protective coatings to products. |
| 39. | Operate metal shaping, straightening, and bending machines such as brakes and shears. |
| 40. | Operate brazing and soldering equipment. |
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