Brilliant Progress in High-Powered Laser Technology to Enable Advanced Plastics Welding

Scientists are developing high-brilliance laser beam sources, which enable the laser welding of plastics for improved and rapid production of complexly-shaped parts, and could therefore lead to important advances in the manufacturing of polymeric products.

The plastics industry supplies the materials for a plethora of components and products. As most products require a combination of two or more parts, laser joining processes have revolutionized the manufacturing process of polymeric products.

The EU-funded project 'Extending the process limits of laser polymer welding with high-brilliance beam sources' (Polybright) is focused on the application of diode and fiber lasers in the near-infrared (NIR) spectral range, as well as flexible beam shaping and high-speed scanning techniques. Technology is planned to enable reconfigurable assembly machines accommodating a variety of joining geometries with sub-second cycle times. The same technology would probably also help additive manufacturing (3D-printing) machines for metal and ceramics, which also employ high-powered and scanning lasers.

A high-power Erbium-doped active fiber laser was developed and manufactured to achieve this goal. Partners also developed a novel concept for fiber lasers with enhanced pulsed output (quasi-continuous wave (QCW)). In the context of the FP7-funded project, the scientists report their results so far, having "designed a beam expander and the coating of a lens package in the NIR range. Novel optics to produce a highly collimated laser line for high-resolution mask welding were included, as was a spatial light modulator (SLM).

Development of advanced Intelligent Power Control (IPC) enabled even more flexible use of the quasi-simultaneous laser welding (QSLW) process for shorter welding times of complex geometries. In addition, a versatile laser beam shaping system accommodated frequently changing weld contours, which reduced time and cost. The SLM setup successfully demonstrated modification of the laser beam shape within seconds."

As a result of the previous innovations, experimental setups were built and evaluated for six different types of laser welding, the scientists reported. Also, first test case samples for the medical sector were produced and prototypes were developed for the automotive sector.

The Polybright research project, which was initiated in 2009 and is managed by the Fraunhofer Institute for Laser Technology ILT in Aachen, Germany, is expected to have a major impact on the use of high-brilliance lasers for increased productivity and reduced costs in making plastic parts. Technological advances are projected to benefit not only the manufacturers of polymers but also the laser industry itself.