Illumination for process observation in laser material processing

Process control for laser-material-processing requires access to characteristic features which qualify the operating-point of the process. For laser-based manufacturing-processes, this can either be achieved by detecting the emission of the process or by detecting geometric properties of the process-workpiece interaction. Such illumination is usually provided by lasers emitting in the near-infrared. Inherent properties like coherence of these sources and complex optical systems prohibit a wide adoption. The technological advance in sources such as led's has the potential to deploy small light sources directly to the processing heads but bears new problems in light-ray-delivery, emitter-protection against secondary radiation and cooling. From a scientific point of view, the properties of illumination sources are compared with a special focus on the specific requirements of process observation

Hardware based analysis and process control for laser brazing applications

Laser brazing is widely used for joining metal sheets in industrial applications, in particular in the automotive sector, where the requirements on surface quality are extremely high. Therefore, quality control and process observation cannot be omitted. This paper presents the current works of a camera based process control system. Hardware-based algorithms for estimation of machine parameters during the process are implemented on FPGA technology. In particular the process velocity is measured in real time which makes the system suitable for controlling tasks to react instantaneously on changes of the velocity.First experimental results on a controlled laser brazing process are presented. Additionally an evaluation of the accuracy of the hardware-based velocity measurement is given

Coaxial Control of Aluminum and Steel Laser Brazing Process

Laser brazing has become firmly established as a joining process in the automotive industry. While this process offers many advantages, brazed seams also have to meet particularly high quality requirements. The challenge of creating a suitable online quality control system is magnified by the increasing use of aluminum in automotive engineering. This paper introduces recent works on the development of a system for controlling both aluminum and steel brazing processes. It also discusses some of the challenges connected to this task and discloses some of the results derived from the corresponding process analysis