Analysis And Control Of The Production Processes In Mechanical Manufacturing Enterprises Using The Characteristic State Method

A new methodology for modeling, analyzing and controlling the mutil-stage and mutil-product production processes in mechanical manufacturing enterprises is developed, which is based on the characteristic state space method supported by the National Natural Science Foundation of China under Grant No.61074135, No.50775016, No.50475154 and No. 50775016. According to the production processes and the production data of Bingshan Group Dalian Refrigeration Co. and DHI-DCW Group Co., a number of case studies were provided to reveal the feasibility and validity of the new methodology.First, local production process models are set up. Basic production activities are regarded as basic analysis units after they are defined. Characteristic state vectors are established using the variables for representing the time, the quality and the cost of the materials and the other production resources before and after those flow though the basic analysis units. Characteristic state equations are set up according to the changes of the characteristic state vectors. Then, the performance of the basic production activities are described intuitively and quantificationally in terms of characteristic transformation matrices.Second, global production process models are set up. Two relationships of the basic production activities, which are called supplying materials and sharing capacity respectively, are defined for the mutil-stage and mutil-product production processes in mechanical manufacturing systems. The sequential relationships and the parallel relationships of the basic production activities are represented by multiplication and addition of the characteristic state vectors respectively. Then, the model of the mutil-stage and mutil-product production processes in terms of characteristic state equations is established according to the materials flows and the energy flows in the processes. The methodology for implementing the characteristic state equations on computer systems is also discussed.Third, the geometric meaning and the associated properties for computing of the proposed production process model are discussed. The characteristic state space of a mechanical manufacturing system is defined and its properties are discussed. Based on these properties, the production processes are studied in the characteristic state space and the bottleneck analysis and the production control of the mechanical manufacturing systems are considered as gradient analysis and path-planning in the space, respectively. This study provides a new way for the bottleneck analysis and the production control and presented the relevant theories on which they are based. Forth, based on proposed production process model and its properties, the approaches of simplifying, analyzing and controlling production processes are introduced in details. The production processes are described by simplified characteristic state equations by finding the critical paths using the symbolic computation of the equations. The bottlenecks of the mechanical manufacturing systems are measured quantificationally using the derivatives of the simplified equations. The measures of the bottlenecks are also the gradients of the object functions of the medium to long term production control problems. Consequently, the gradients can be used to guide the neighborhood-generation in a neighborhood search algorithm in order to accelerate convergence and short the run time of the neighborhood search procedure. A number of actual cases and hypothetical cases are computed for testing the production process model, the proposed bottleneck analysis method, and the modified neighborhood search algorithm. Compared to the classical methods, the computational experiments show relatively positive results. These studies pave a new way for analyzing and controlling the Production Processes in Mechanical Manufacturing Enterprises.Finally, a web-based kanban system is designed and developed using the proposed theories and methods, based on the production management information systems of the Bingshan Group Dalian Refrigeration Co. and DHI-DCW Group Co. The production processes are monitored, the bottlenecks of the manufacturing systems are detected and measured, and several typical production control problems are solved by means of the web-based kanban system.