Profile Monitoring Method For Multi-Stage Manufacturing Processes

With the rapid development of science and technology,the complexity of products is increasing and the manufacturing process is gradually changing from a singleprocess manufacturing process to a multi-process manufacturing process.Compared with the general production process,the multi-process manufacturing process is more complicated.The manufacturing process is composed of multiple sub-processes,and each process is transferable.The quality abnormality of the upstream process will be transmitted to the downstream process and affect it.Therefore,how to conduct quality analysis and effective monitoring according to the characteristics of the multi-process manufacturing process is essential to maintain the stability of the manufacturing process and improve the level of product manufacturing process capabilities.In the traditional multi-process manufacturing process,it is often assumed that the quality characteristics obey a certain distribution,and then the mean or variance is monitored.However,because the multi-process manufacturing process involves multiple quality characteristics,and the data application technology is gradually improving,quality control personnel collect more and more complex data,it is difficult to use traditional statistical process control technology to use these data to control the quality of the production process.In some practical production,functional relationships can describe quality characteristics more adequately than variable distributions,and such functional relationships are called profiles.By introducing the idea of profile monitoring into the quality monitoring of multi-process manufacturing process,the quality monitoring of multi-process manufacturing process can be better achieved by monitoring the functional relationship between quality characteristics.However,due to the transferability of the multi-process manufacturing process,each process is not independent of each other,which is reflected in the model that the quality relationship model of the downstream process includes the process quality characteristics of the upstream process and this process,and there is a strong correlation between each process.Therefore,eliminating the influence of transfer effects on Profile monitoring is the first task to realize Profile monitoring for multi-process manufacturing.To sum up,this paper follows the following ideas to start the research of multiprocess manufacturing process quality control.In view of the characteristics of multiprocess manufacturing process,the state space idea is introduced to build a Profile monitoring model for multi-process manufacturing process,and the C conversion method is proposed to eliminate the quality transfer effect,modify the monitoring statistics of each sub-process,and compare the performance of Profile monitoring control charts before and after eliminating the transfer effect through extensive simulation experiments.Then the whole process Profile monitoring of multi-process manufacturing is carried out based on the C statistical conversion method,including two phases,Phase Ⅰ and Phase Ⅱ.Finally,the practical application of the method is illustrated by a specific case.The simulation experiments and case results show that the improved Profile monitoring method has excellent monitoring capability and effect on quality abnormalities in multi-process manufacturing processes.