Remote ablation cutting with continuous wave laser radiation is a process commonly used for the surface pretreatment of large area metallic parts before joining of metal-polymer hybrid structures, due to their cost-effectiveness and high average powers when compared to short-pulsed lasers. The process requires high power-densities and multiple irradiations at high scanning speeds to achieve the desired kerf depth. In this work a fast modulated cw fiber laser is used to investigate the possibilities of increasing the material removal rate by periodically dropping the laser power and therefore modifying the recoil pressure at the vapor-liquid interface in the interaction zone to assist in melt expulsion. It was found that power modulation with frequencies in excess of 10 kHz can lead to an increased material removal rate when compared to continuous wave processing at comparable average and peak power levels, enabling higher kerf aspect ratios in a single irradiation.
2.0 μm fiber lasers provide a high beam quality and a high‐power output, which makes them ideal for welding and cutting a wide variety of commercially used plastics, as well as marking plastics, metals or even food. At 2.0 μm wavelength the intrinsic absorption of most thermoplastics is high enough to weld or cut without applying any absorbent additives or coatings. Compared to commonly used near‐infrared systems, welding with 2.0 μm lasers can improve heat distribution and gap bridging and enable transmission welding for challenging materials.
Fiber lasers are increasingly replacing the commonly used diode lasers in laser transmission welding of plastics for challenging applications due to their superior beam quality and the ability to use long working distances and small spot sizes. At the same time, these smaller spot sizes increase the risk of thermal degradation. In this work, we investigate different scanning strategies that allow controlling the weld seam widths. These strategies are characterized regarding the demands on the performance of the scanner system, the risk of thermal degradation and the mechanical properties of the resulting welds.