Tolerance analysis has been the topic of many research publications in the recent past. It is a method to evaluate the quality of products in terms of functional tolerances. Most of the assessment procedures in process planning are based on trial-and-error runs, which are costly and time-consuming. There is also a distinct lack of research focus in the area of process plan verification in which input variables are generated from experiments. This paper first provides an overview of tolerance analysis. The limits of previous studies are explored. A method to overcome problems in manufacturing tolerance analysis is then proposed. This method is based on the Model of Manufactured Part (MMP) and deviation domains to obtain mathematical formulations. These formulations are applied to manufacturing tolerance analyses in which experimental data are used as input variables. The results obtained are then used to verify process plan relative to functional tolerances or to identify achievable functional tolerances taking into account a given process plan and a given ppm (parts per million) value. A summary of the method used to obtain the experimental data is presented.