Semi-generative System for Manufacturing Process Planning

The generative method is a subject of theoretical and experimental research. Difficulties with its implementation are connected with the lack of formal description of the synthesis of activities constituting the manufacturing process. To overcome the difficulties while developing the huge technological knowledge base, a semigenerative method is often used. In this method the pattern is characterized by the changeable process structure. It gives more freedom to create the various manufacturing processes for a given workpiece. The pattern of the process structure is determined on the basis of technological knowledge and analysis of manufacturing processes for a given set of workpieces belonging to a defined class of workpieces. This paper presents the system architecture for the semi-generative method of manufacturing process planning. CAPP system for pattern generation mode, data base management mode, and process planning mode are described. Based on the results of investigation into decision-making process, the model of knowledge in the form of hierarchical decision nets was developed. The presented approach was used in the development of the expert system for machining process planning. INTRODUCTION The rapid development of computer-aided process planning, the tendency towards real-time process planning, and the use of concurrent engineering methods, are reflected in the papers published all over the world [1-2,7-9]. These papers describe how to solve the process planning problem by using variant and generative methods. These methods utilize various patterns of the manufacturing process used for process planning [5]. Variant methods use process plans prepared earlier: the set of individual processes, group-based process model, or a typical process model. Generative methods involve planning of the manufacturing process without previously built models. The generative method is a subject of theoretical and experimental research, and difficulties with its implementation are connected with the lack of formal description of the synthesis of activities constituting the manufacturing process. To overcome the difficulties while developing the huge technological knowledge base, a semigenerative method is often used. In this method the pattern is characterized by changeable process structure. It gives more freedom to create the various manufacturing processes for a given workpiece. The pattern of the process structure is determined on the basis of technological knowledge and analysis of manufacturing processes for a given set of workpieces belonging to a defined class of workpieces. THE SYSTEM ARCHITECTURE FOR THE SEMI-GENERATIVE METHOD Control knowledge base Process-oriented workpiece model Management module Mode of operation