Automated hybrid laser welding technology offers numerous benefits to the fabrication industry, notably increased production times, improved weld quality and reduced production and labor costs.

Some of the technology's most exciting contributions are found in new design capabilities, such as the metal sandwich panel, that were not practical until the advent of newer welding technologies.

Background

Hybrid laser welding technology combines the best attributes of laser welding with those of conventional gas-metal arc welding (MIG) welding.

The laser welding component offers deep weld penetration with very low heat input and small heat affected zones (HAZ). The addition of the MIG welding component vastly expands the tolerance of joint gaps, surface conditions and impurities; improves gap filling and contouring; and enhances control of the weld metallurgy.

ESAB's hybrid laser technology was developed to provide a more cost effective means to produce beams from high strength plate for use in shipbuilding and has only recently become commercially available.

A key to the success of this technology was the development of a real-time closed-loop process control and an automated quality assurance system that includes active joint tracking and measurement; in-process weld monitoring; real-time, closed-loop control of all critical welding parameters. This system also provides automated weld surface inspection, measurement and quality attribute checking; automatic weld flaw identification, flagging and/or repair; and complete weld process and quality documentation and reporting.

ESAB's systems have welded beams from ordinary and high-strength plate at rates that are 5 times to 10 times faster than conventional welding processes, with finished beams produced to tolerances that are ¼ to 1/10 of the allowed tolerances for hot rolled beams.

Extensive testing has demonstrated that these laser-welded structures perform as well as or better than conventionally welded structures in all respects. Additionally, these tests have shown that the laser welds can achieve fatigue lives that are 2 times to 3 times as long as conventional GMAW and submerged arc welding processes.

Sandwich Panels Maximize Strength & Stiffness; Minimize Weight

Another structure easily produced by hybrid laser welding is the steel sandwich panel.

Sandwich panels can be simply defined as a three-layer structure that consists of two thin, outer skins of high-strength material separated by a low-density and low-weight core material. The core material separates the face sheets that provide most of the strength to the structure.

This creates a panel with excellent stiffness and weight characteristics. The core can assume a number of configurations. The most common is a corrugated structure similar to corrugated cardboard.

Until recently, the majority of sandwich panels have been designed with fiber-reinforced polymer composite or metallic skins glued to structural foam, wood or elastomeric cores. The development of all-metal sandwich structures had been inhibited by the limitations of conventional welding processes.

The first metallic sandwich panels were developed for shipbuilding in the mid 1980s but research was abandoned because no manufacturing system was available that had the capability to mass produce the panels cost effectively.

The new laser welding techniques, however, have finally made such structures practical and shipbuilders are now re-engaged in developing these structures for use on future ships.