Using the analysis of laser-based back-reflected light to improve piercing and cutting performance for high power fiber lasers

Abstract

Industrial laser cutting systems generally pierce and cut using separate operations, typically with fixed parameter sets for each given material and thickness. The piercing procedure is often programmed for a fixed dwell time, which can result in a loss of machine efficiency and pierce quality, particularly for thick samples with many holes. Pierce detection systems already exist which are based within the cutting workstation but this can result in a more complex cutting head and optical system. Similarly, when cutting bright metals there will typically be stronger back reflections compared to steel cutting which have the potential to interrupt the cutting process and damage the laser or beam delivery system, so it is essential to determine the nature and intensity of back reflected light to consider how it is affecting the laser and the cutting process. In this paper we will show that it’s possible to improve these processes by sensing the light returning from the work-piece to the laser, firstly by considering how piercing can be improved through the use of a laser based pierce detection system, and secondly how analysing the back reflected light can help to optimise cutting performance whilst maintaining safe operation of the laser. Several examples of both piercing and cutting are presented, showing how a range of metals, particularly highly reflective metals can be processed with CW-M fiber lasers operating up to 6kW.Industrial laser cutting systems generally pierce and cut using separate operations, typically with fixed parameter sets for each given material and thickness. The piercing procedure is often programmed for a fixed dwell time, which can result in a loss of machine efficiency and pierce quality, particularly for thick samples with many holes. Pierce detection systems already exist which are based within the cutting workstation but this can result in a more complex cutting head and optical system. Similarly, when cutting bright metals there will typically be stronger back reflections compared to steel cutting which have the potential to interrupt the cutting process and damage the laser or beam delivery system, so it is essential to determine the nature and intensity of back reflected light to consider how it is affecting the laser and the cutting process. In this paper we will show that it’s possible to improve these processes by sensing the light returning from the work-piece to the laser, firstly by cons...