Investigating cut quality degradation due to heat accumulation during the laser cutting of high thickness mild steel plates

Cut quality degradation due to heat accumulation is a phenomenon which can significantly hinder the performance and output of laser cutting systems. As the workpiece temperature increases, boundary conditions to the process are modified and the cut quality can be significantly affected. In the present investigation, the degradation of the cut quality is investigated through a methodological framework to relate it to the workpiece temperature, thus identifying critical conditions for the cutting of mild steel sheets of different thicknesses. An industrial 6 kW fiber laser cutting system is employed both to pre-heat under controlled conditions and cut the mild steel material. In-line measurement of the workpiece surface is achieved by means of a calibrated MWIR thermal camera whilst roughness measurements of the cut profile allowed to characterize the quality in accordance with ISO 9013. Finally, different mitigating strategies are presented to avoid or compensate defect formation.