This article is the first in Welding Digest’s two-part series on recent beam welding developments.

Laser and beam developments

Newer green, blue and hybrid wavelength lasers promise to enable laser welding of high conductivity and highly reflective metals like copper, silver, aluminum and gold. Laserline and Nuburu have developed high-powered blue lasers for welding copper and other reflective alloys. Blue wavelength lasers are absorbed three to 20 times better than the current infrared wavelength lasers commonly used today. Blue laser welders will enable process speed gains of two to 10 times compared to conventional lasers.

Poor beam quality has restricted advancement of laser welding in the past. Solid state or diode pumped fiber and disk lasers offer high beam quality compared to older technologies such as flashlamp-pumped Nd:YAG lasers and carbon dioxide lasers. The disk and fiber configuration allow better heat dissipation and the lamps do not need replacement, which can cause contamination of the optical resonator. Fiber and disk laser systems can weld 6xxx aluminum alloys, zinc coated steels with zero gap and steels without spatter.

Figure 1: A welder operates an electron beam welder at Tinker Air Force Base in Oklahoma. Source: U.S. Air ForceFigure 1: A welder operates an electron beam welder at Tinker Air Force Base in Oklahoma. Source: U.S. Air ForceIt is natural to visualize a laser beam as having a gaussian distribution of power density with the highest power in the center of the beam. New optics and beam shaping technologies can produce a range of beam shapes. The beam shape can be optimized depending on the specific welding parameters such as alloy, thickness and joint type. A wide range of beam shapes with varying energy partitioning are available such as flat tops, donuts with different sizes and thicknesses, and flat-top beams surrounded by donuts. Beam shaping can improve keyhole stability and reduce weld spatter and porosity while increasing joint strength and fusion uniformity.

Welding researchers are investigating ultrafast pulsing, high-speed oscillations, hot wire or directed energy deposition, and rapid scanning technologies to enhance beam welding processes. Hot wire laser welding increases the deposition rate by using a hot filler wire, which is heated independently through joule heating.

Laser hot wire and directed energy deposition systems are also useful for cladding, surface repairs and additive manufacturing. Miller Electric offers a laser hot wire system, and Lincoln also provides laser hot wire cladding. Sciaky has wire and powder feed directed energy deposition systems using electron or laser beams.

Ceramic packages are ideal for protecting microelectronics, but sealing the ceramics to protect from moisture ingress without damaging the electronic devices is challenging. In the article “Lasers enable engineers to weld ceramics, no furnace required,” researchers describe how ultrafast pulse lasers are being developed to weld ceramic materials. Researchers at Heriot-Watt University have developed a process to weld glass to metal using picosecond pulsed lasers. The pulses create a microplasma inside the material to bond the glass to metal.

Read Part 2 of this series on laser hybridized welding and more here.