CONCURRENT TOLERANCE CHARTING FOR COMPONENT AND ASSEMBLY USING MODIFIED TREE APPROACH

The interaction between components in an assembly plays a major role i n the performance and reliability of the assembly. However, in convent ional design, the dimensions and tolerances of components are usually assigned intuitively to satisfy design constraints. Tolerance analysis is then performed to determine the critical tolerance accumulation th at results from the assembly. The tolerances are then modified so that the interaction requirements are satisfied. This approach relies on t he experience of the designers and the results may not be an optimum. This paper presents a direct method to determine the working dimension s and tolerances of components that allows control of the assembly int eraction The model is easy to construct and it provides a clear pictur e of the entire process and assembly links. Using the model, a set of linear equations is formulated directly based on the design constraint s and interaction requirements. With appropriate constraints derived i n terms of the process capabilities, the desired working dimensions an d tolerances can be determined using LINDO, software for solving the l inear programming problem. This approach allows the wet-king dimension s and tolerances of all components in an assembly to be determined con currently.