Variation Of Quality Modeling And Analysis For Multi-stage Process

Product quality improvement is the eternal subject.The amount of products made in China has been in advanced,but the quality still need to be improved.At the same time,the trend in development of manufacturing industry is complex,short life cycle,many varieties of products and small scale of batch process,and the traditional quality management theory couldn’t meet the need.Based on the characteristics of multi-stage manufacturing system, method and technology of modeling and analysis for multi-stage process is studied.Method of variation of quality modeling and analysis for multi-stage process is aimed at studying the principles of variation propagation,and providing the basis for quality forecast,quality diagnosis and quality improvement.Based on describing the characteristics of multi-stage process,the multi-stage process is divided into multi-process machining process and multi-station assembly process,and detail forms of quality characteristic and quality variation are obtained.With the theory of state space equation,the general variation propagation models are established.A product of a manufacturing enterprise is taked as an example and matrixes are calculated with the physics relation.The variation propagation from machining process to assembly process is simulated and the effectiveness of the model is validated.Quality forecast could be achieved by calculating output with different input.Based on the model established,susceptivity analysis is used to study the relationship between the parameters and outputs of the model,the most important stage and variation effects are distinguished. And then robustness is used to evaluate the different process design proposals,and the influences of locating pin and process design of are distinguish.lt provides a new way to control of the variation of quality and improve the process design progress.