Tolerance-robustness optimization design

To solve coordination problem between manufacturing cost and quality robustness, a new mathematical model on tolerance optimization for quality robustness was proposed. Based on the idea of tolerance-robustness design, considering the fuzziness of product quality, and taking the ratio of the variance of probability density function of deviation distribution for the close-loop to the probability of high-quality product as design objectives, the objective function of the loss of quality robustness for this tolerance optimization design was established. Methods to determine the ratio of high-quality product and the variance of deviation distribution of the close-loop were also studied. The multi-objective optimization model was constructed by taking manufacturing cost and loss of quality robustness of product as objectives and reliability of fuzzy assembly and allowable tolerance range as constraints. Examples were provided to illustrate the application of this tolerance-robustness optimization design, and the genetic algorithm was used to complete the multi-objective design of tolerance. Results showed that this method could effectively coordinate manufacturing cost of component and the cost of loss on its quality robustness with best performance of optimization index.