Experimental analysis and online monitoring/classification of surface formation uniformity and laser remelting process stability using NIR and SWIR emission imaging
Abstract
Surface polishing by laser remelting is a developing surface finishing method utilizing the heat of a laser to create a moving melt pool, resulting in a more uniform surface topography. The melt pool's stability significantly influences the process's effectiveness, as instability leads to the formation of non-uniformities and reduced uniformity. To monitor the melt pool state, two coaxially mounted thermographic cameras, sensitive to short-wave infrared (SWIR) and near-infrared (NIR) wavelengths, were integrated into the laser scanner-based polishing system for data collection. Analysis revealed that the NIR range captured a wider range of process dynamics due to the scanner optics' effects on transmitted melt pool emission. Using the NIR data, novel classification methods capable of identifying melt pool stability and undesired surface features were developed and demonstrated in an industry-relevant process monitoring program. This enables the estimation of surface non-uniformities for tracking, parameter adjustments, and correction, enhancing surface polishing precision.