In the rigid connection automatic line, there is no material storage device between processes, and the processing and delivery process of the workpiece has a strict rhythm. When a device fails and stops, it will cause a complete shutdown. Therefore, there is a high requirement for the reliability of various devices in a rigid connection automation line.
In the flexible connection automatic line, a material storage device is arranged between each process (or section), and the cycle of each process does not have to be strictly identical. A certain device can pause for a short time, and the storage device can act as a balancing agent within a certain period of time. It will not affect the normal operation of other devices. Comprehensive automatic lines, assembly lines, and long automatic lines for combined machine tools often use flexible couplings.