Optimization of a light guide plate injection molding stability process by integrating Taguchi quality engineering and the gray sequencing method

Abstract

The light guide plate is an essential key component in the development of the panel industry. In pursuit of lighter and thinner computer, communication, consumer (3C) electronics products, the panel industry continuously introduces new types of products to meet contemporary needs. Applications of a thinner light guide plate have become increasingly important. However, in the thin injection molding process, the control of geometric size and surface quality may be difficult to achieve owing to variations in conditions, such as injection pressure and temperature. Under the pressure of pursuing higher injection molding speed and lower cost, the injection industry strives to improve injection process capabilities to achieve higher quality yield, reduced production costs and processing time, and enhanced processing quality to maintain profits. Regarding the control of the Y-axis size of injection molding, this study proposed an experimental design method for injection quality improvement and injection process performance enhancement. The relevant injection parameters included temperature, back pressure, holding (dwell) pressure, and length measurement. The purpose of this study is to identify the best light guiding injection parameters to establish stable injection conditions and improve process capability. By employing the five stages of define, measure, analyze, improve, and control, this study conducted empirical research on the injection molding size stability processes of a photoelectric light guide plate, in a specific injection molding plant in Taiwan, in order to establish a process optimization model for injection molding Y-axis size stability. The research methodology integrated the parameter design method of Taguchi quality engineering and the gray sequencing method to identify the combinations of optimization parameters and experimental levels in injection molding. The experimental results suggested that C pk has been improved from 0.6 to 1.44, with a significant increase in process capability. The prediction result error rate meets accuracy requirements, which can help improve the control of capability, stability, and quality of the light guide plate injection molding size process. The research findings can provide Taiwan’s injection molding precision processing industry with a reference in quality.