As the welding industry continues its broad transition into automation, one process in particular stands out from the rest: hybrid laser arc welding (HLAW).
According to Ed Hansen, welding automation product manager for ESAB Welding and Cutting Products (Florence, SC), this innovative technology is the most disruptive in a generation. He estimates hybrid laser arc welding will be a core welding process in the next five to ten years. "By reducing or eliminating thermal distortion in the joining process," he explains, "HLAW allows manufacturers to rethink their approach to designing and building steel structures in ways that will reduce material and energy consumption and achieve higher levels of automated fabrication and assembly."
WHAT IS HLAW?
Of course, this isn't exactly breaking news, because the combination of laser light and an electrical arc into an amalgamated welding process dates back to the 1970s. But in those early days, laser sources still had to prove their suitability for industrial use, whereas now they are standard equipment – a big reason why HLAW is ratcheting up in popularity.
Combining laser welding with another weld process is called a hybrid welding process because the laser beam and an electrical arc act simultaneously in one welding zone, influencing and supporting each other. There are essentially three main types of hybrid welding processes, depending on the arc being used: TIG, plasma arc or MIG augmented laser welding. While TIG augmented laser welding was the first to be researched, MIG was actually the first to go to market and is now commonly known as hybrid laser welding.
HLAW combines laser beam and gas metal arc welding (GMAW) within a fully automated process that merges the best of both worlds: the depth of penetration and low heat input of laser beam welding with the efficiency and good gap tolerance of GMAW. Combining these two processes and adding filler metal creates wider weld bead and improved stability. The deep, narrow penetration welds HLAW produces have good tolerance to joint fit-up. The laser source can be CO2, Nd:YAG or Yb fibre/disc laser, and can be used with a GMAW, GTAW or plasma arc.
WHY CHOOSE HLAW?
According to the American Welding Society, the advantages of HLAW over laser beam welding alone include higher process stability, higher bridgeability, deeper penetration, lower capital investment costs (because of savings in laser energy) and greater ductility. The advantages of HLAW over GMAW alone include higher welding speeds, deeper penetration at higher welding speeds, lower thermal input, higher tensile strength, and narrower joint welds.
HLAW can handle the larger weld gap tolerances usually found in heavy industries while, at the same time, guarding the deep penetration and low heat input benefits of laser welding. Adding a relatively modest amount of filler metal creates a wider weld bead that is capable of bridging much larger weld gaps than conventional laser processes can handle – up to four times as wide as other laser welding processes. But due to its high weld penetration capability, HLAW does not require large weld joint geometries. This drastically reduces filler metal usage and produces even faster weld speeds and greater robustness, promising a fast return on investment.
Adding GMAW to the welding mix enhances a finished part's metallurgical stability. With its slower cooling rates, the effects of GMAW produce welds with greater strength and less brittleness, which is especially beneficial for higher strength steels sensitive to hot cracking. Adding GMAW as a secondary energy source improves process efficiency and overall productivity, improves weld quality, lowers production costs and offers more versatility than conventional welding processes.
HLAW can generate huge increases in productivity (it can run up to 200 ipm), and with the decreased heat input, it dramatically reduces distortion. The most substantial obstacle to implementing HLAW for many is the cost of the equipment. These machines are very expensive – usually ranging from $1 million to $4 million. Prices vary widely and depend on many factors, such as the amount of power required, the amount of tooling and fixturing for the application, and the level of automation needed.
Ultimately, the total cost involved will depend on the user. However, the benefits are usually well worth the costs. Hansen has seen return on investment times ranging from as short as four months to three and a half years. Additionally, the process usually results in lower production costs.
Fortunately, as with most technology, the cost of these machines will drop overtime as HLAW gains in popularity and usage (think of the cost of a desktop PC ten years ago versus today).
Furthermore, because HLAW allows for high energy density but low total energy use, users may actually save on energy costs. Total operating costs of HLAW are often less than half that of conventional GMAW.
IS HLAW THE FUTURE?
One of the most important things to keep in mind regarding HLAW is that, because the process is fully automated, it points to the competitive future of the welding industry. HLAW is already gaining popularity in Europe. It's only a matter of time before it catches on in the U.S. Why?
One of the primary reasons the industry is moving to automate is the skilled labor shortage in the American job market. Hansen estimates that by 2010 we will see a deficit of 200,000 welders in the U.S. This bleak prediction has already prompted some larger companies to offer more pay to entry-level welders than to engineers because competing in today's economy appears to be limited to either sending work offshore or investing in automation. Since that first option simply isn't practical many times due to the high cost – perhaps even the inability – to ship very large weldments across the ocean, installing automation has now become a mandate.
In terms of HLAW technology, the U.S. remains slightly ahead due to the research efforts of major OEMs, companies that are on the cutting edge of research and development, and organizations like the U.S. Navy.
For example, ESAB has one lab facility in Florence, SC and another in Sanford, ME that are dedicated to the research of hybrid laser technology and have been developing HLAW for the past ten years, partnering with advanced technology companies to bring it into the commercial marketplace with an emphasis on reducing total costs to the consumer.
WHAT ARE THE CONSIDERATIONS?
Certain competitive factors must be considered before installing a hybrid laser arc welding system. The industry in which you compete must be assessed from the outset, because the dynamics of your industry drive all the other factors.
HLAW is ideal for conditions where machined components, expensive fixtures and tooling aren't practical. It works best with long, continuous welds, high-duty cycles and is perfect for the shipbuilding, transportation, and structural steel industries, to name a few, and can be used for a wide variety of applications.
Right now, HLAW is not a fit for customized build-to-order jobs or orders involving lots of small, complex parts with small features and tight areas, or complex 3D welding, though all of this could change in the near future as technological research advances.
Before considering HLAW, "Ensure that your upstream processes can deliver parts that are consistently of the quality necessary for automatic welding. You must ensure that both upstream and downstream operations can accommodate the high throughput of the hybrid welding system," Hansen advises.
One thing is certain, adds Hansen: "It's cool technology and lots of fun to improve traditional processes so significantly. We're going to see much more of it in the near future."
Kyndall Brown is the assistant editor of Fabricating & Metalworking.
ESAB Welding and Cutting Products, 411 S. Ebenezer Road, PO Box 100545, Florence, SC 29501, 843-669-4411, 843-664-4458, www.esab.com.
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