Several new production cost-tolerance models and a hybrid-model tolerance optimization formulation for tolerance synthesis are presented. These new models are introduced based upon the empirical cost-tolerance data of typical production processes, including hole producing, turning, milling, grinding and casting. The introduced models fit empirical cost-tolerance data with considerably less errors, and provide more reliable results for tolerance synthesis. In addition, the hybrid-model tolerance optimization formulation provides further modeling error reduction. The systematic evaluation of various cost-tolerance models provides model selection guidelines for tolerance synthesis. A typical tolerance design example is used to illustrate the method.

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract

A numerical model based on cellular automaton algorithm is developed to simulate dendrite growth at the edge of weld molten pool and the solute diffusion during grain growing process in weld solidification is analysed too. By means of two-dimensional square cells and von Neumann neighbourhood, the growing morphologies of the columnar dendritic grains with different cooling rates and different numbers of seeds are simulated. The growth of secondary dendrite arms, tertiary dendrite arms and their competitive growth are also presented. The results illustrate that the final primary dendrite spacing depends on the number of seeds that initially generated. With increasing cooling rate, the growing speed is increasing obviously. It is also indicated that competitive growth exists between different dendrite arms. The tendency of competitive growth in high cooling rate conditions is weaker than the one in relatively small cooling rate conditions.