Optimal Tolerance Synthesis by Genetic Algorithm under the Machining and Assembling Constraints

The purpose of this research is to develop a computer aided method of tolerance synthesis. The assembly was represented by solid model, and dimensional and geometrical tolerances were formulated as a set of inequalities constraining substitute features. Differential coordinate transformation and linear programming were used to analyze the tolerance stack-up. The cost data base described the machining, inspectional and assembling costs for tolerances. Tolerance synthesis was represented as the combinatorial optimization problem under the stack-up conditions. Genetic Algorithm (GA) was applied to solve the problem. The coding method and genetic operators were discussed. The algorithm was evaluated through a gear box example.