在工艺实验的基础上，建立了切割面分层理论模型。实验研究和模型分析均表明：切割面近下缘处是切割质量的最薄弱环节，此处粗糙度最高，切割前沿在下缘处的温度是决定下缘质量的主要因素。提出以近下缘粗糙度作为切割质量评价和检测的主要指标，建立了火花簇射的视觉检测系统，从侧面研究了切割过程中的火花簇射行为，发现火花簇射视觉图像特征与切割速度以及切割面近下缘粗糙度之间具有良好的对应关系：随着切割速度的变化，最高的火花簇射出口温度(亮度)对应于最低的切割面近下缘粗糙度，此时的切割速度为该工艺条件下的最佳切割速度，从而实现了对切割面下缘质量的在线检测。

A laminated model of cutting face for evaluating cutting quality has been built up on the basis of cutting experiments. The experimental results and the theoretical analysis of the model show that, the lower part of the cutting face, adjacent to the bottom edge, has the worst cutting quality due to its worst roughness. The quality of the bottom face is mainly depended on the temperature of the lowest part of cutting front. Therefore, the method with this roughness as the main criterion for quality evaluation and detection is reasonable. The behavior of sparks has also been investigated by side imaging the sparks jet. It is found that the sparks behaviors are related to both the cutting speed and the roughness of the bottom face. The maximum temperature at the exit of sparks occurs at the status of the best roughness of the bottom face, which relates to the optimal cutting speed. Based on the method, on-line quality monitoring of lowest part of cutting front has been realized.