Abstract: The quality stability of multi-stations assembly process is investigated for the transformation from production to process in quality control. The assembly process is regarded as one dimension discrete variant system and modeled by state space equation which contains the physical structure information of assembly process in its system matrix. By compared ideal state with actual condition, the model of stream of variation can be obtained. From the view of stream of variation, the conditions to judge if the process is stable and the index-“stability degree” to show the degree of stability are proposed under the concept of BIBO stability of system. A sheet metal assembly process with three stations, in the white body assembly of car, is given for illustration and verification.

Key words: Multi-stations assembly process, Quality stability, Stability degree, Stream of variation