A method of NC machine tools intelligent monitoring system in smart factories

•The paper introduces a framework of bi-directional data and control flow between machine tools and upper-level applications;•Several key problems in this field are presented, and corresponding solutions are subsequently analyzed and discussed;•To bridge the gap between the monitoring data and higher applications, the means of monitoring data processing and analysis is described;•Based on the uniform data bus, an NC machine tool intelligent monitoring and data processing system in smart factories is developed, which validates the concept and performs well in the complex manufacturing environment.