Research On WL And Card-based Control System For Job-shop Production

Research on production control system has always been an important part in the study of production control. With continuous changing of market demands, ordinary production way moves from MTS to MTO, which makes traditional production control system inefficient. As a result, new production control systems, which range from push systems, such as MRP, to pull systems, such as Kanban, WLC, CONWIP and POLCA, are proposed and improved successively. However, all those systems begin to show some limitations as time goes by and production environment changes, especially when the production environment is a Job-shop. Therefore, it has significant value to develop new production control systems which can fit Job-shop environment well.A new production system called Robacca is established in this thesis. It applies WLC theory as well as card control method, aimed to fit Job-shop environment. Firstly, an overview of relevant studies, consisting of WLC theories, Push and Pull concepts and card control method, is provided to lay a solid foundation for latter chapters. Secondly, the card control mechanism is described in detail, which is followed by a comparison of Robacca with POLCA and Cobacabana to show the possibility of the better performance of Robacca. Thirdly, the system parameters is defined and evaluated by queuing theory and some system attributes, and some dispatching rules are proposed to decide which job to process first in different positions in the system according to different goals. Finally, simulation studies of Robacca, POLCA and Cobacabana is carried out using two different production settings of Job-shop which are designed in advance. After comparison and analysis of the simulation results, conclusion is made that Robacca performs much better than POLCA and Cobacabana in Job-shop settings and has higher workload balancing capability and environment adaptability.