The main objective of this study is to improve the quality of injection-molded lenses with the implementation of DMAIC procedures based on the Six Sigma approach. At first, critical-to-quality factors (CTQ) are determined according to customer requirements for quality. The causal factors for the lens properties are identified within the processing window being tested. Adopted for the analysis procedures, the Taguchi design-of-experiment method (DOE) is employed for screening pertinent process parameters in the injection process. After completing the DOE procedures, confirmation experiments are conducted with selected combinations of factors and levels. The experimental results show substantial improvement for the profile accuracy on molded lenses. As a further step, an optimal set of factors and levels are taken during the mass-production processing conditions. In conclusion, the Six Sigma approach can effectively improve the upper process capability index CPU from 0.57 to 1.75, i.e., 0.07 defects per million, without an upgrade of production equipment or an increase of production costs.
關聯:
The International Journal of Advanced Manufacturing Technology
