Assuring Process Quality with a Preset Confidence Probability via Quality-Oriented Statistical Tolerancing

The statistical tolerancing models and design approach for assuring a preset process quality target are presented. A set of standardized process quality indices (PQIs) is introduced for meeting the measurement and evaluation to process yield, process centering and quality loss. Quality-oriented statistical tolerancing technique is introduced to concurrent design for assuring process target. The comprehensive application of this new approach is shown by a case study. The main advantages of this new approach are that PQIs can be assured with a desired confidence probability under four different cases. Process quality, statistical tolerances (STs) and SPC parameters can be concurrently designed, coordinated planned and quantitively analyzed.