Abstract: In accordance with the principle of hicrarchical planning, an applied algorithm for operation sequencing problem is presented. The problem is divided into five layers. Each layer includes some smaller and easier problems or tasks and constraints to solve the problems. The system resolves the problems layer by layer under the constraints of each layer. Through properly arranging tasks and defining constrains at different layers, the algorithm was simplified, and witch makes the algorithm practical and flexible. It is possible to separate the inferring engine from the rule-like knowledge, especially from form features of parts, witch re the key points to the development of an applied or commercial CAPP system. The algorithm has been successfully used in a commercial CAPP system.

Key words: CAPP, Multi-layer-constrained-based planning, Operation sequencing