Laser material interactions – taking laser processing from lab to applications

Lasers are incredibly versatile and flexible tools, which can be used in many applications from heavy engineering, such as laser cutting and welding, to highly delicate processes, such as soldering and marking of electronic components. This is possible thanks to the possibility of independent control of the spatial distribution of energy and the total energy of lasers. This means that a given energy can be applied to a small spot size of the order of tens of microns sufficient to induce vaporisation of metals, which is used in drilling or welding. On the other hand, the same laser energy can be widely spread across the material providing only heating of its surface, which is used in laser hardening or cleaning. Lasers provide precise control over applied energy spatially and temporarily. However, this flexibility imposes many challenges and complications on laser processing. There are many complex phenomena taking place during laser material interaction, which are sensitive to any change in processing parameters. This means that in certain applications laser processing is difficult to control and development of processing parameters is time consuming.

Welding Engineering and Laser Processing Centre at Cranfield University has a long tradition of working with heavy industry, such as pipeline, aerospace and shipbuilding in application of laser welding. The group has been working actively on applying research to industrial problems to improve robustness of joining technology. Often processes developed in the laboratory conditions do not give full scale of challenges that can be encountered in industrial environment. In particular lasers with sensitive optics, low fit-up tolerance and high cooling rates are not often perceived by industry as attractive technology. In this lecture different aspects of laser material interactions in laser welding will be presented with the emphasis on industrial challenges. Processes such as laser welding of pipelines, hybrid laser welding of shipbuilding panels and powder bed additive manufacturing will be discussed from the perspective of material response. Some of the main limitations of laser technology and future challenges will be discussed.