what is stack-up analysis
Instead of summing tolerances, as in worst-case analysis, statistical analysis sums dimension distributions. It is important to understand that the inputs values for a worst-case analysis are design tolerances, but the inputs for a statistical analysis are process distribution moments (e.g., standard deviation).Worst-case analysis (also called tolerance stack-up analysis) can be used to validate a design.Statistical analysis (also called variation analysis) can be used to predict the actual variation of an assembly based on the variation of the part dimensions.f the analysis involves part dimensions that are not parallel to the assembly measurement being studied, the stack-up approach must be modified since 2D variation such as angles, or any variation that is not parallel with the 1D direction, does not affect the assembly measurement with a 1-to-1 ratio.