For the purpose of process optimization of the injection molding process a robust processing point is determined, at which specified characteristics of the parts are met and the process is insensitive to disturbances. The idea of the new optimization concept is to ensure that also around the robust processing point, within the so-called robust processing window, the part geometry is in tolerance and a low standard deviation respectively a high SN-ratio is achieved Instead of reducing the optimization task to a one-dimensional problem by combining the target functions, in this approach one defines lower and zipper bounds for the characteristics to be optimized. These bounds must be fulfilled in the range of the robust processing window and if necessary, might be sharpened or relaxed during the optimization procedure. The corresponding response surfaces ave generated by means of new Scattered Data Interpolation-methods.