Real-time observation of laser cutting fronts by X-ray transmission

In laser cutting, industry practitioners have long demanded higher cutting speeds and better quality cuts. There is thus much interest in the elucidation of related processing phenomena. Cutting quality is known to be affected by ejection behavior of generated melt, which itself is thought to be influenced by the profile of the laser cutting front. It would thus be desirable to directly observe the cutting front in real time, but this is not easily done in practice, mainly because laser cutting speeds are relatively high and visible light generally cannot pass through workpieces. In this study, we used an X-ray transmission system to perform fluoroscopic observation of cutting fronts in real time during actual processing. Further, we discuss the effect of the cutting parameters (cutting speed, etc.) on cutting front profile and melt ejection. We find that both the profile of the cutting front and the ejected melt behavior were stable when a sound cut was produced. We directly confirmed that the cutting front profile changed along with cutting speed.