The transition from stable laser cutting conditions to an incomplete cut, which is generally referred to as loss of cut, limits the maximum feed rate of laser beam cutting. In order to investigate this phenomenon, the geometry of the laser cutting front was observed by means of online high-speed X-ray diagnostics. Fusion cutting of 10 mm thick samples of aluminum and stainless steel were recorded with a framerate of 1000 Hz. A quasi three-dimensional geometry of the cutting front and the kerf was reconstructed from the grey scale values of the recorded X-ray images. Comparing cutting of stainless steel and aluminum at stable conditions with the same cutting parameters, it was found that the local angle of incidence in the lower part of the cutting front is smaller and the cutting kerf is wider for stainless steel. During loss of cut, the angle of incidence on the cutting front decreased for both materials and the width of the cutting kerf in the lowest third significantly increased. The reconstructed three-dimensional geometries enable for the first time the determination of the transient changes of the local absorptivity during the loss of cut during laser beam fusion cutting.

从稳定的激光切割条件到不完整切割的过渡（通常称为切割损失）限制了激光束切割的最大进给速度。为了调查这种现象，通过在线高速X射线诊断程序观察了激光切割前端的几何形状。以1000 Hz的帧频记录10 mm厚的铝和不锈钢样品的熔融切割。根据所记录的X射线图像的灰度值，重新构造了切削刃和切缝的准三维几何形状。将不锈钢和铝在稳定条件下的切削与相同的切削参数进行比较，发现在不锈钢前端，切削锋面下部的局部入射角较小，切削切口较宽。在减产期间 两种材料在切削锋面上的入射角均减小，而最低的三分之一处的切缝宽度明显增加。重建的三维几何形状首次实现了在激光束熔融切割过程中切割损失期间确定局部吸收率的瞬态变化。