A recursive tolerancing method with sub-assembly generation

Functional tolerancing of industrial products depends on the assembly sequence and on the relative positioning of parts. The quality of the interfaces between these parts ensures the assembly requirements and the good positioning of functional surfaces. For each geometric functional requirement, we generate a sub-assembly including the influential parts as an attribute graph. A recursive method for tolerancing these parts, based on this graph and positioning tables, is developed. The block and pseudo-block concepts aid the functional tolerancing in complex tolerance chains. An example of an industrial mechanism is used to illustrate the methodology.