THE EVOLUTION OF THE HYBRID LASER ARC WELDING REVOLUTION
Moving Beyond “Wait and See”: The hybrid revolution is building momentum as manufacturers embrace the higher travel speeds, increased depth of penetration and deposition rates of a ‘hybrid’ materials-joining process that captures the unique advantages of two distinct sources of energy – laser power and arc welding.
The hybrid revolution is building momentum. Take for instance, the public’s acceptance of hybrid vehicles over the last ten years (vehicles using two or more sources of propulsion power, i.e. internal combustion and electric) has led to a variety of technology advances in fuel efficiency, power, and driving range.
The manufacturing world is now moving beyond the ‘wait and see’ attitude of industrial lasers and is likewise embracing and reaping the benefits of a ‘hybrid’ materials-joining process that captures the unique advantages of two distinct sources of energy – laser power and arc welding (Hybrid Laser Arc Welding (HLAW)), and has led to a variety of productivity advances including higher travel speeds, and increased depth of penetration and deposition rates.
First-time users of the process have remarked positively on the progress toward the ease-of-integration of the hardware, and a variety of technology initiatives such as a synergic mode that enables the user to vary multiple laser and arc welding parameters by adjusting a single variable, and an adaptive fill mode that varies the parameters in response to joint variations have both gained favorable reviews for their impact toward ease-of-programming.
The acceleration in implementation of HLAW has been driven by improvements in new high brightness lasers (fiber and disk) which are fiber delivered. These new lasers have expanded the application window for materials-joining, their greater efficiency have led to more compact designs which allowed for easier integration into systems, and lower ownership cost has positively impacted the return-on-investment of the process.
Unique to these lasers, the flexibility of the technology allows for welding and cutting to be performed using the same unit. For example, using a tool changer that can select between various processing heads, a 10 kW laser utilized for welding can be integrated with an internal beam switch for an on-the-fly process change to precision cutting or heat treating from the same robot.
The laser can be applied on any metal, including low carbon steel, stainless steel, aluminum, brass, and copper, as well as the many high strength steels or nickel and titanium alloys that many industries are adopting.
For most “hybrid” applications, the GMAW is assisting the laser process. The GMAW assists the laser process by:
- Permitting welds to be made in joints with greater fit-up issues and gaps than can be normally welded by autogenous laser welding.
- Altering the chemistry and strength properties of the weld metal with unique filler metal additions.
While HLAW implies an “arc”, there are many other “hybrid” processes that are being developed and implemented that combine laser with other processes. In these other cases the laser is being used as a precision heat source.
An example of one of these “non-arc” hybrid processes is hybrid laser brazing. This process uses resistance heating between the part and the tip of the wire feeding system to increase the temperature of the wire. The laser then is used to take the brazing alloy, usually a bronze alloy, to a melting temperature while at the same time heating the substrate to a high enough temperature to allow for wetting without flux. This can occur at very high speeds (> 5 m/minute) and result in joint quality that can be painted over.
Another “borderline” HLAW process is laser cladding. This can be accomplished like laser brazing without an arc and using simply resistance heating in conjunction with laser, or the laser can be combined with GMAW process for the deposition of a consumable wire. Usually these processes are used to repair a worn or damaged surface and match the chemistry of the substrate or the material being deposited to tailor the surface of the part for improved corrosion and/or wear resistance.
Industries that stand to reap early gains as qualified procedures are documented and successfully realized in a production environment include automotive, aerospace, power generation, pipe, structural steel, construction, mining, agriculture, shipbuilding, and maintenance and repair.
These increases in hybrid applications are also driving examination of what is an acceptable hybrid weld. DNV (Bærum, Norway) and Lloyds (London, England) have already developed standards for hybrid welding for shipbuilding applications. But with recent activities for HLAW in other industries, there have been additional interest / needs for the development of other standards/specifications by other organizations.
The American Society of Mechanical Engineers (ASME; New York, NY) and the American Welding Society (AWS; Miami, FL), both of which have had laser specifications for years, are both active in the development of standards recommended practices for hybrid processing. Both organizations are reacting to requests for specifications by companies that using their specifications to develop their Procedure Qualification Record (PQR) and their Welding Procedure Specification (WPS). These standards will address what parameters need to be documented and how much variation or change will be allowed before a process must be partially or full qualified.
The first exploratory step for a company investigating the use of a laser/hybrid process is to work with a reputable firm that has the capacity to perform a thorough part evaluation where the focal points are productivity and return-on-investment. A review of how to capture additional part design cost savings and how to fixture the parts are some of the keys to realizing the full benefits and optimization of the laser.
Seeing how a system can be programmed first-hand, and witnessing actual applied procedures allows the ability to review actual productivity rates, quality, and an accurate depiction of an overall system design with accurate start-up costs for this evolving and revolutionary technology.
About the Author: Geoff Lipnevicius is the operations manager for the automation division at The Lincoln Electric Company, 22800 Saint Clair Avenue, Cleveland, OH 44117-8542, 216-383-8027, Fax: 216-383-8823, www.lincolnelectric.com, email@example.com.