Wading through the world of welding
Recent tradeshows highlight latest technologies
Two big tradeshows, Schweissen & Schneiden (Essen, Germany) and the FABTECH® International/AWS Welding Show (Chicago) highlighted several of the trends that have emerged in the welding industry during the last couple of years. Senior Editor Eric Lundin reviews many of the recent developments in arc and laser welding, and the growing use of another joining technology, adhesive bonding.
|Many high-tech gadgets that once were handy extras are becoming indispensable in the workplace. A personal digital assistant (PDA) device makes programming a welding power supply faster and easier than manual programming. Photo provided by The Lincoln Electric Co.|
Developments in welding processes over the last few years have been motivated by either economic or technical forces, according to the German Welding Society (Deutscher Verband fr Schweissen und verwandte Verfahren e.V., or DVS). The economic motivator is the ongoing desire for higher efficiency in production welding. The technical motivator is the interest in finding a new material or a material combination that provides the most cost-effective finished product. These drivers have led to developments in nearly every welding process, according to DVS.
Schweissen & Schneiden and FABTECH® International/AWS Welding Show provided a good look at advancements in welding processes and the industries in which they are used. Both expos offered insights into applications such as joining dissimilar metals and technology advancements that have made welding more precise and efficient. Schweissen & Schneiden also emphasized the growing use of another joining process, adhesive bonding.
Developments in Arc Welding
Automotive applications continue to play a large role in manufacturing developments. Interest in reducing automobiles' weight drives the industry's desire to use relatively low-density materials such as aluminum and magnesium and find ways to join them to steel.
Cold metal transfer, a technique developed by Fronius Intl. GmbH, is an automated gas metal arc welding (GMAW) process that extends the wire electrode toward the materials to be joined until current starts to flow. As soon as the circuit is complete, the wire retracts. This process delivers a relatively small amount of heat to the parent material, hence its name. The process repeats up to 70 times per second.
EWM Hightec Welding GmbH also is making progress in welding at low temperatures. Its cold arc technique, which is either manual or automated, can join sheets as thin as 0.3 mm. It is suitable for joining aluminum to steel and aluminum to magnesium. The heart of the process is an inverter switching device that works in conjunction with a quick digital current regulator; this component combination reduces the power in the arc when it reignites, which makes for a cooler arc. The low heat input provides good gap bridging and helps ensure low distortion, according to DVS.
Energy is another industry that drives innovation. Rising energy prices are driving two divergent trends—more exploration and pumping of crude oil to take advantage of higher oil prices, and the expansion of wind turbines to trim dependence on fossil fuels.
The oil country tubular goods (OCTG) industry's increasing use of higher-grade steel leads to an increasing need to heat the pipe before it is welded. Miller Electric responded to this need by developing the ProHeat 35, according to Henk van Zijl, managing director for ITW Welding Products. It uses an inverter power source, which provides 90 percent efficiency, to develop a quickly reversing magnetic field that heats the pipe. It also imparts a level of safety—the heat is concentrated on the pipe's ID and distributes very little heat to the OD.
"A welder can lean his forearms on the pipe while he's welding," van Zijl said.
The unit provides precise, uniform heating, eliminating the energy waste associated with overheating the pipe, according to van Zijl. This is especially advantageous for laying underwater pipe, which is an extremely costly operation.
While much of the growth in OCTG involves new infrastructure in countries such as India and China, a great deal of it is in replacement work in countries that have an existing infrastructure, such as Saudi Arabia, according to John Emmerson, president of Magnatech. Another, newer application is for liquefied natural gas (LNG), which is a growing market in Algeria, Qatar, and Malaysia, he added. Natural gas, which often is found in the same locations as crude oil, was simply burned off until it became economical to compress it and ship it, opening up another application for pipe.
Wind power has been making progress in Europe for years. A German study released in May 2005, the dena report, determined that integrating wind turbines into the electrical distribution grid in Germany was technically and economically feasible; in September the International Energy Agency published a working paper that agreed in that it identified no technical barriers for large-scale wind turbine integration into existing grids. The European Wind Energy Association projects an 80 percent increase in wind turbine generating capacity in the EU-15 from 2005 to 2010, from 41,300 megawatts to 75,000 megawatts.
Submerged arc welding (SAW), which is suitable mainly for thick-walled joints and achieves high deposition rates, has a niche in manufacturing masts for large wind power stations. Using an extreme narrow-gap technique reduces the necessary energy, filler metal, and fabrication time, according to DVS. ESAB demonstrated a complete mast fabrication system at Schweissen & Schneiden. The system uses SAW to make longitudinal welds in plate that has been bent into cylindrical sections.
The system uses two heads to deposit a total of four 2.5-mm wires in a process the company calls Tandem Twin SAW™. The first head delivers DC and the second head delivers AC. The system produces 1,200 amps; travels at 1.5 meters per minute; and deposits 40 kilograms (kg) of wire per hour, which the company claims is the highest deposition rate in the industry.
Advances in Cutting
Integrated nesting programs have led to better material utilization, according to DVS. Raw material price increases have made better material utilization a requirement for profitability.
"The price of steel is an incentive for efficiency," said Ben TerreBlanche, president and CEO of SigmaTEK Corp., the manufacturer of SigmaNEST nesting software. In addition to nesting, the software provides detailed remnant tracking, enhancing the use of skeletons, which further reduces waste.
In addition to traditional markets such as North America and western Europe, software demand is growing in eastern Europe, TerreBlanche said. Many manufacturers in Poland, Hungary, and Turkey purchased new cutting machines over the past few years, and now they are catching up by investing in more advanced software.
"For many, this is a big step," TerreBlanche said.
Reducing time and labor continues to drive fabricators to eliminate secondary operations whenever possible. To address the use of thin-wall stainless steel tubing, used in industries such as food and beverage production, chemical and biochemical processing, and semiconductor manufacturing, Georg Fischer manufactures portable tube cutters (PS 4.5 and PS 6.6) that are designed specifically for these applications. According to the company, they make burr-free cuts that in some cases are ready for orbital welding, which eliminates the facing step.
Fronius developed a time- and labor-saving innovation in plasma cutting. The company markets a manual plasma cutting system that uses liquid as the ionizing medium. The torch heats water and turns it into steam, which conducts the plasma arc. It produces little smoke and less noise than conventional plasma and cuts faster, according to the company. Another advantage is that it doesn't require a source of compressed air, making it more convenient to transport around a job site.
Technology advancements are perpetual, and nowhere is this more evident than on a tradeshow floor. Increasingly complex combinations of electronic hardware and software continue to make their way into modern welding equipment.
Taking advantage of the trend toward automated welding, Meta Vision Systems has developed a control platform for joining components along linear and nonlinear seams. The system senses luminosities of the workpieces to be joined and, based on the difference in their luminosities, determines the seam location. It projects five laser lines that run perpendicular to the weld direction and interpolates the points between the five laser lines to determine the weld path. An optical filter blocks nearly all light except the laser light, allowing the system to track gap widths as little as 0 mm, according to Pierre Huot, vice president of sales.
The relentless reduction in component size, especially in electrical and electronic devices, allows Servo-Robot Corp. to offer an automated laser welding system that tracks, welds, and inspects. The unit is approximately half the size of three separate components, according to Jeffrey Noruk, president. The company also offers a small inspection camera, Quicktrac, that is well-suited to automotive welding and other applications in which fixtures and clamps leave little room for a camera.
Servo-Robot uses Ethernet connections for easy component integration and high-speed data transfer. In addition, one controller can run two workcells, which reduces system cost, Noruk said.
TRUMPF has taken this type of approach with some of its laser equipment. A setup marketed in Europe involves one laser and several workcells, which divides the cost of the laser and greatly increases the beam-on time, according to Jrg Ellerkmann, bending technology sales manager.
Voice-activated equipment has made inroads in applications such as inspection and warehousing. VLH Controls Inc. has introduced this technology to other industries, with a focus on manufacturing. Its system, Active Listening Voice Command (ALVC), connects wirelessly to equipment that normally operates manually or semiautomatically.
Howard Green, president, demonstrated at FABTECH that voice activation can control a welding power supply. A single-word command can activate a power supply, put it on standby, or shut it off in an emergency.
Modern technologies such as the Internet and personal digital assistants (PDAs) have become so commonplace that they are becoming standard offerings on welding equipment. For example, Lincoln Electric uses the Internet to help in monitoring welds and upgrading software. It offers production monitoring capabilities that track welding specifications. Monitoring isn't enough, though—when it detects out-of-spec welding, it sends a notification to production personnel by e-mail.
The company makes its Power Wave software updates available through its Web site, so fabrication shops can download the latest software for its welding machines, even if they were purchased at different times and initially were equipped with different software versions, according to Deanna Postlethwaite, product manager of high technology products. Another program, Weld Manager, allows users to customize power supply parameters via a PDA device. An upgrade that once took up to an hour per machine now takes just a few minutes per machine, Postlethwaite said.
For the first time in Schweissen & Schneiden's history, Structural Bonding International (SBI) made an appearance at the expo. According to DVS, structural bonding has about 10 percent of the joining market.
The automotive industry has relied on adhesives to join body panels for more than 10 years. The BMW 7® series has 150 m of crashworthy adhesives, according to Jan Rttger, market development manager of body structural enhancement for Dow Automotive.
"Adhesives that have elastic properties are advantageous in bonding dissimilar metals, because such metals usually expand and contract at different rates," said Kurt Scherrer, project leader of Collano AG. Elastic adhesives provide bonds that resist cracking in such situations.
They also have found a niche in shipbuilding, where they absorb vibrations, thereby enhancing comfort. The use of adhesives allowed Stadlerrail to reduce the weight of a shuttle by 25 percent compared with a similar shuttle joined with traditional methods. The potential for weight reduction makes adhesives attractive for other weight-sensitive applications, too, such as aircraft and spacecraft.
Industrieverband Klebstoffe (Industrial Adhesives Association) projects growth of 3 percent per year. Technological trends are impossible to stop, and there's no telling where this will lead. Will it push traditional welding shops to become joining shops, offering a combination of welding skill and adhesives knowledge to provide two kinds of joining technology? Only time will tell.
Collano AG, www.collano.com
Dow Automotive, www.dow.com
EWM Hightec Welding GmbH, www.ewm.de
FABTECH® International/AWS Welding Show, www.fmafabtech.com
Fronius International GmbH, www.fronius.com
Georg Fischer, www.georgfischer.com
Industrieverband Klebstoffe, www.klebstoffe.com
The Lincoln Electric Co., www.lincolnelectric.com
Meta Vision Systems, www.meta-mvs.com
Miller Electric Mfg. Co., www.millerwelds.com
Schweissen & Schneiden, www.schweissenuschneiden.de
Servo-Robot Inc., www.servorobot.com
SigmaTEK Corp., www.sigmanest.com
VLH Controls Inc., www.vlhcontrols.com
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.