Analytical and experimental study on the quality improvement of 2 cavity injection-molded LCD frame

Abstract

The LCD frame is an important part which supports the BLU of medium/large sized TFT-LCD. To produce it efficiently, it is necessary to achieve the molding process improvement from 1 cavity to 2 cavity system. Because 2 cavity mold is compact and its hot-runner zone is broadened, it is difficult to control the temperature on the mold. In this study, injection molding analysis on the frame in 2 cavity process with FEA(Finite Element Analysis) software is carried out to estimate its quality. The calculated injection molding pressures and maximum deflection in 1 and 2 cavity processes are 41.13 MPa and 1.62 ㎜, 40.49 MPa and 1.66 ㎜ respectively. The measured maximum flexure load and surface roughness of the left and right frame of 2 cavities are 209 N and 0.08 ㎛, 193 N and 0.10 ㎛ while those in 1 cavity are 140 N and 0.13 ㎛. Thermal image shows that the maximum standard deviation of the temperature on left and right side of 2 cavity mold is 1.23 ℃ The simulation and measurement results show that the quality of the frame in 2 cavity injection molding process as a whole is not worse than that of 1 cavity system. But maximum flexure loads of the frame in 2 cavity process are far greater than that in 1 cavity process.