Based CAE Software Investigated The Co-injection Process

Co-injection molding was a novel process for manufacturing polymer produces with a sandwich structure. It was very important and worthy that it was investigated the content of core material and the uniformity of core material under avoiding break-though phenomenon. But the traditional experiment could not afford the result of comprehensive and fast. Moreover it also could not afford the reference of choosing material, compounding material and optimizing its process. This paper choose three kinds of material of LDPE, HDPE and PS to investigated the influence of material property and the process settings of co-injection to the content of core material and the uniformity of core material by the way of simulation in the MPI software of MOLDFLOW company.The result of simulation displayed that the influence of the viscosity ratio core/skin to the content of core material and the uniformity of core material is tremendous. When the viscosity ratio core/skin was increase, the content of core material and the uniformity of core material were improved. The process of settings of melts temperature and the flow rate of melts had tremendous influence to the content of core material and theuniformity of core material. The result of increasing skin melt temperature and the result increasing core melt temperature were contrary. The increasing of core melts temperature should decrease the content of core material and the uniformity of core material. But the increasing of skin melts temperature should increase the content of core material and the uniformity of core material. The increasing of flow rate of core had a little influence to the content of core material and the uniformity of core material. But the flow rate of skin had tremendous influence to the content of core material and the distribution of core material. The increasing of flow rate of skin should decrease the content of core material and the uniformity of core material. Different material had different sensitivity to temperature and flow rate. When the material is more sensitivity to temperature, temperature change of the material should have more influence the result than shear rate. But when the material is more sensitivity to shear rate, shear rate change of the material should have more influence the result than temperature. Mold temperature had a little the content of core material and the uniformity of core material. Only when the material of skin is high sensitivity to temperature, the increase of mold temperature should improve the uniformity of core material.