Abstract: Modeling of assembly processes is crucial in predicting quality of precision instruments and machine tools. A state space model for assembly processes is developed to describe variation propagation and accumulation of type-I assembly. A part model which integrates the parameters of orientation, position, and quality characteristics of part surfaces is built for quality analysis. The single part assembly process is divided into two stages. Correspondingly, part datum deviation and fit datum deviation are defined and their models are formulated. A state space model for the whole assembly processes is developed. The results of the industrial case study illustrate that the proposed model can accurately predict assembly quality and effectively analyze assembly variation.

Key words: Mechanical assembly, Prediction and control, State space model, Variation propagation