Optimal tolerance allocation based on fuzzy comprehensive evaluation and genetic algorithm

It is very important to know how to allocate tolerances economically for pa rts in a CAD/CAM system because this directly affects the machining costs o f the purrs. A nerv approach based on fuzzy comprehensive evaluation (FCE) and a genetic algorithm (GA) is presented to obtain a rational tolerance al location for the parts. First, the current methods for tolerance allocation are reviewed in detail. Then, FCE is used to evaluate the machinability of a part; a new optimal,model, which can fully exploit DFA (design for assem bly) and DFM (design for manufacturing), is established by combining the fu nctional sensitivity factors and machinability factors of purrs. A genetic algorithm (GA) is developed and used to optimise the above model. Finally, an actual example is used to verify the feasibility of the above method; th e computed result shows that the method can produce tolerance allocations e conomically and accurately.