Abstract: Mechanism of error sourcing and propagation for rigid part assembly is the important work for mechanical precision predicting. The concept of meta-action assembly unit is proposed based on the structure decomposition using PFMA for CNC machine tool. The deviation source that affects assembly precision or accuracy is clustered into five types: Deviation of geometric location and orientation, variation of geometric form and deviation of part location and orientation etc. Error sources and statistical evaluation model is established. In addition, mechanism of deviation propagation between two mating surfaces or key characteristics is discussed. Propagation linkage graph and, the error propagation linkage network for five kinds of error sources are built to express the error in vision and cooperate with error in visual expression. Error transfer linkage figure is comprehensively considered, and build assembly linkage network model and error transfer function expression. To simplify the error transfer linkage in the network diagram calculation and save of all kinds of error propagation model, the linkage for the entire product assembly error propagation linkage matrix is built. Finally, an example with deviation sourcing and propagation is introduced to verify the effectiveness of each model.

Key words: assembly precision controlling, assembly situation deviation, error propagation, error source, meta-action assembly unit