Abstract
An analytical model was presented to explain the experimental results of ejection force for injection mold with smooth surface. The model is based on the adhesion theory that the meniscus force is principal component of the ejection force . The meniscus force between core and molded specimen was formulated with surface roughness of two surfaces in contact and liquid film thickness. In the range of Ra < 0.2 μm, the calculated meniscus forces become extraordinarily large and are in good agreement with experimental results. In addition, some ploughing marks are found on the molded specimens for larger values of core surface roughness. Through this experimental and analytical investigation, it was made clear that the meniscus force is main cause of the ejection force for smoother core surface and the resistance force of ploughing for the rougher core surface.
