Today's user-friendly workplace is far different than the Spartan shop floor dad occupied 50 to 75 years ago. SAW naturally lends itself to the more civilized surroundings. It has always been an environmentally friendly, safe process with minimal fume to be ingested and no arc rays to be shielded from, making it one of the more pleasant welding environments to work in see Figure 2.
It is the technology advances in the power equipment and controls that have made it a reality to perform SAW with greater ease and precision than previously possible. SAW's ability to use multiple arcs in one puddle leads to its extremely high deposition rates, which allows for more rapid heat penetration and stability of the arc. In traditional power supplies, when the wave passes from positive EP to negative EN in its half-cycle, a lag or interruption may occur in the arc, subsequently causing problems in the weld.
While this factor and its related input and output issues previously limited speed and productivity, now it is resolved in advanced power equipment. For starters, it is now possible to weld AC and DC polarity in the same puddle, using the same power source. In the past different machines were necessary, and sometimes the DC and AC welds had to be laid down in different passes. Now two or more machines can be connected together or disconnected to be used alone in other operations.
Today's SAW can put up to five wires in one puddle, offering the opportunity to create a weld faster and with unique, specialized properties. Because of what is happening on the back end of these new machines, welders now have many more options at the arc. Older equipment ran according to a limited set of parameters; today's power sources run and react.
The new equipment is fairly simple for the operators to run. On the input side, it is no longer necessary to use single-phase power only. The new machines can connect to three-phase power and the same power supply used for both.
This is achieved simply by modifying a plug so current and voltage remain stable and consistent. Inverters make it possible to use the same piece of equipment anywhere in the world. State-of-the-art SAW controls are all digital, allowing constant feedback for monitoring and changing voltage, amperage, wire feed speeds, and so forth Digital PLCs are set up to interface with the application selected at the power source, and in some cases one controller can handle any choice of AC, DC CV, or DC CC.
Storable settings allow the operator to input three or four different programs, and put them down one after another, without having to remember optimal heat and power ranges for a given job.
Once the parameters are entered, they can be recalled and used again in the same application. Deposition and heat ranges can be programmed, and the system will ensure that the operator stays within those ranges. The programmability of the controllers allows companies to deal with real-world business conditions.
For some applications, experienced operators can coach and manage inexperienced welders without having to risk losing control of one or more variables. Reporting capability is also available through monitoring software using network communications. Like a CNC machine, the welding power source can be programmed remotely and monitored on a network. What can be viewed locally also can be viewed anywhere in the world. Data about penetration and deposition heats, rates, and quality can be e-mailed.
The flexibility of the new power sources allows manufacturers to focus on faster travel speeds, which enhance quality in high-deposition welds. Now they are much smaller and can work faster," Fisher said. One of the concerns with early SAW was variable feed speeds of the tractor. Now tractors equipped with speed control can change speed when the load changes, keeping other variables more constant. Adaptability is still the name of the game, so even modular tractors can be taken apart without tools to be passed through small spaces where they are reassembled to perform necessary operations.
These high-end tractors are extremely versatile in what they can do. In the same way the industry has improved the power and application systems, so too have the consumable materials been updated to meet current requirements. Tubular wires, also called metal-cored wires, have a metal wire on the outside and metal powder on the inside composed of alloys that are application-specific, such as a flux mixture.
These wires allow operations that previously required multiple passes to be completed in one or two passes. They also enable the use of more generic and less expensive flux.
Flux manufacture and delivery also have stepped up to match the production demands of SAW. Tubular-cored flux can be application-specific and provide additional strength and quality to the weld.
Regular flux now can be purchased in bags as large as 3, lbs. The electron beam welding process, which uses a focused beam of electrons as a heat source in a vacuum chamber, was developed in France. Stohr of the French Atomic Energy Commission made the first public disclosure of the process on November 23, In the United States, the automotive and aircraft engine industries are the major users of electron beam welding.
Some other developments in welding included: The breakthrough of electron beam welding, making deep and narrow welding possible through the concentrated heat source. Following the invention of the laser in , laser beam welding debuted several decades later, which has proved to be especially useful in high-speed, automated welding.
Magnetic pulse welding MPW is industrially used since Friction welding was developed in the Soviet Union which requires rotational speed and upset pressure to provide friction heat. It is a specialized process with many applications where a sufficient volume of similar parts are to be welded because of the initial expenses for equipment and tooling. Lase welding has been one of the newest processes so far which was originally developed at the Bell Telephone Laboratories as a communications device because of the tremendous concentration of energy in a smaller space, it proved to be a powerful source of the heat as it can also be used for cutting metals and nonmetals.
Continuous pulse equipment is also available in which the laser is finding welding applications in automotive metalworking operations.
Although robots were firstly introduced into the US industry during s, Robot welding is relatively a new application of robotics. It is the use of mechanized programmable tools robots which completely automates the welding process by performing the weld as well as handling it efficiently. The number of robotic usage in industries has been growly tremendously as, in , it had been reported that more than , robots were used in North American industry for welding purposes.
The manipulator is what makes the robot move, and the design of these systems can be categorized into several common types, such as SCARA and cartesian coordinate robot, which uses different coordinate systems to direct the arms of the machine.
The robot may weld a pre-programmed position guided by the vision of a machine, or by a combination of the two methods. However, many benefits of robotic welding have proven to make it a technology that helps many original equipment manufacturers increase accuracy, repeat-ability and reach a higher standard of market. Log in to leave a comment. WhatsApp us. Sign in. Log into your account. Sign up. Password recovery. Recover your password. Thursday, November 11, Subscribe to our Magazine Advertise with Us Contact.
Forgot your password? Get help. Create an account. Weld Fab Tech Times. Home Flash Back Birth of Welding. It was not until the 19th century that welding as we know it today was invented.
Edmund Davy of England is credited with the discovery of acetylene in The production of an arc between two carbon electrodes using a battery is credited to Sir Humphry Davy in In the midth century, the electric generator was invented and arc lighting became popular. During the late s, gas welding and cutting was developed. Arc welding with the carbon arc and metal arc was developed and resistance welding became a practical joining process.
Auguste De Meritens, working in the Cabot Laboratory in France, used the heat of an arc for joining lead plates for storage batteries in the year It was his pupil, a Russian, Nikolai N.
Benardos, working in the French laboratory, who was granted a patent for welding. He, with a fellow Russian, Stanislaus Olszewski, secured a British patent in and an American patent in The patents show an early electrode holder. This was the beginning of carbon arc welding. Benardos' efforts were restricted to carbon arc welding, although he was able to weld iron as well as lead.
Carbon arc welding became popular during the late s and early s. In , C. Coffin of Detroit was awarded the first U. This was the first record of the metal melted from the electrode carried across the arc to deposit filler metal in the joint to make a weld.
About the same time, N. Slavianoff, a Russian, presented the same idea of transferring metal across an arc, but to cast metal in a mold. Approximately , Strohmenger introduced a coated metal electrode in Great Britain. There was a thin coating of clay or lime, but it provided a more stable arc. Oscar Kjellberg of Sweden invented a covered or coated electrode during the period of to Stick electrodes were produced by dipping short lengths of bare iron wire in thick mixtures of carbonates and silicates and allowing the coating to dry.
Meanwhile, resistance welding processes were developed, including spot welding, seam welding, projection welding and flash butt welding. Elihu Thompson originated resistance welding. His patents were dated In , a German named Goldschmidt invented thermite welding that was first used to weld railroad rails. Gas welding and cutting were perfected during this period as well. The production of oxygen and later the liquefying of air, along with the introduction of a blow pipe or torch in , helped the development of both welding and cutting.
Before , hydrogen and coal gas were used with oxygen. However, in about a torch suitable for use with low-pressure acetylene was developed. World War I brought a tremendous demand for armament production and welding was pressed into service. Many companies sprang up in America and in Europe to manufacture welding machines and electrodes to meet the requirements. Immediately after the war in , 20 members of the Wartime Welding Committee of the Emergency Fleet Corporation, under the leadership of Comfort Avery Adams, founded the American Welding Society as a nonprofit organization dedicated to the advancement of welding and allied processes.
Alternating current was invented in by C. Holslag; however, it did not become popular until the s when the heavy-coated electrode found widespread use. In , automatic welding was introduced. It utilized bare electrode wire operated on direct current and used arc voltage as the basis of regulating the feed rate.
Automatic welding was invented by P. Nobel of the General Electric Company. It was used to build up worn motor shafts and worn crane wheels. It was also used by the automobile industry to produce rear axle housings. During the s, various types of welding electrodes were developed. There was considerable controversy during the s about the advantage of the heavy-coated rods versus light-coated rods.
The heavy-coated electrodes, which were made by extruding, were developed by Langstroth and Wunder of the A. Smith Company and were used by that company in In , Lincoln Electric Company produced extruded electrode rods that were sold to the public. By , covered electrodes were widely used.
Welding codes appeared that required higher-quality weld metal, which increased the use of covered electrodes. During the s there was considerable research in shielding the arc and weld area by externally applied gases. The atmosphere of oxygen and nitrogen in contact with the molten weld metal caused brittle and sometimes porous welds. Research was done utilizing gas shielding techniques.
Alexander and Langmuir did work in chambers using hydrogen as a welding atmosphere.
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