The research presents methodologies to identify and simulate manufacturing defects in three-dimension, and simple indicators for evaluating the global quality of a fixture. We then developed a model for simulating positioning defects of a workpiece that is fixed on a three-jaw chuck. This model is a combination of three methods: design of experiments, finite element simulation, and Monte Carlo simulation. Three factors, which are assumed to be the most important in positioning defects, are used in this model. Based on the simulated results, the influences of these factors are estimated. The...