Automatic Tolerancing of Mechanical Assemblies

Dimensional and geometric tolerances should be estimated for proper assemblability and design functions as well as manufacturability of mechanical assemblies. Tolerance analysis of mechanical assemblies by manual procedure is easy but it is time consuming and error prone and also more human interaction is required which make the manufacturing cost of the product high. Therefore automation of tolerance analysis is necessary to reduce the above drawbacks. In this work dimensional tolerance analysis has been done based on the modified worst case and root sum square methods. The common methods do not consider the sensitivities so these are applicable only for symmetric tolerances. But the modified models use the sensitivities which make them to handle the asymmetric tolerances. The percentage contributions of the upper and the lower tolerance bounds of the manufactured dimensions or independent variables on the upper and the lower tolerance bounds assembly or dependent variables by using the new relations for both the models are also presented. The procedure is implemented in MATLAB for few examples of linear and non-linear problems.