Trends and basic investigations in high power laser material processing

Abstract

Continuous application development in combination with advancements in laser sources and accessories enabled several trends in laser material processing. This paper will show investigations in process understandings based on modern process diagnostics like high speed videos. We will focus on applications related to thick sheet welding, welding with wobbling techniques, hot forming materials and dissimilar materials. Additionally we link the gained process understandings to possibilities how to successfully introduce the knowledge in industrial applications. IntroductionOngoing improvements of 1 µm disk and fiber lasers in combination with a consequent application development lead to a high number of applications which have been transferred from lab status to industrial 24/7 applications. In this paper we will show interesting results in thick sheet welding of mild and stainless steel. We continued our investigations on metal vapor plumes and focused on welding with shielding gas in combination with removal of the plume itself. Additionally the investigation of different batches of mild steel generated interesting results. We could achieve comparable results regarding process windows of 1 µm compared to 10 µm CO2 lasers, which are still the benchmark regarding high quality and process windows in very thick sheet welding.On the other hand, trends in electricity and batteries (e.g. for cars) increase the interest for high power thick sheet welding of copper materials. Hence we investigated the behavior of copper welding in thin and thick sheets up to 6 mm thickness. Beside the possibility of welding thick materials there is a clear trend of weight reduction and hence of light weight constructions. Therefore more and more lightweight materials like aluminum and hot formed steels are used. We will show weld preparations of hot formed steels with nanosecond short pulse lasers (removal of AlSi layers) and focus on further process steps like welding and cutting.