Model study on flow behavior for investigating coating conditions in the in-mold coating process

Flow behavior for different coating conditions in in-mold coating (IMC) process was investigated. Silicon oil with viscosities of 100, 350 and 500 cps was used as model coating materials for the process and was injected into the mold cavity by using a syringe pumping machine. Flow patterns were recorded through a transparent poly (methyl methacrylate) (PMMA) window mounted in front of the mold. Flow shape index k, which is defined as the ratio of the downward flow length to the horizontal average flow length, was obtained for each testing condition. The flow characteristics, such as shape, stability, and uniformity, can be expressed in terms of the ratio k. This flow shape index analysis was used to investigate how the flow inside the mold is affected by resin viscosity, coating thickness, and injection rate, which are major parameters in the IMC process.