Abstract: Dimensional errors of the final product are determined by stack-up, coupling and propagation of dimensional errors from all operations in multi-stage machining system. In order to analyze logically the dimensional errors propagation in multi-stage machining systems, object-oriented Petri net is used. Based on defining generic objects of error states, the rules of mapping generic objects into machining system are developed. Then subclass objects of error states are derived and encapsulated from generic objects. Finally, relation nets of errors states message transmission are designed. The errors of product dimension-object oriented Petri net (EPD-OPN) model can be used as a tool to analyze the error propagation. The effectiveness and feasibility of the model is validated through a cylinder head machining process. The developed model has some excellent characteristics, such as modularization, reusability, and capability to describe structural logical relationships.

Key words: Dimensional errors, Multi-stage machining system, Petri net