Fiber Orientation And Mechanical Properties Of Injection Molding Layer In All-plastic Hybrid Technology

Abstract:All-plastic hybrid technology, which consists of both hot embossing and injection molding, has became a new direction of injection molding and automotive industry field. It not only has the advantages of light weight, high strength and excellent structures which are inherited from plastic-metal hybrid injection technology, but also avoids defects such as distortion, stress concentration and low bond strengh which are resulted from the incompatibility between plastic and metal. The existence of hot embossing preset piece impacts the contact environment at interface during injection, which bring difference between all-plastic hybrid and conventional injection. To ensure part quality and promote the development of the technology, it is essential to investigate the effects of fiber orientation in fiber reinforced thermoplastics(FRTP) and process parameters on the mechanical properties of injection molding layer and bonding interface.Compared with conventional injection molding, effects of preset piece’s existence on fiber orientation and mechanical properties of molded part in all-plastic hybrid technology were investigated through simulation. Effects of process parameters on the mechanical properties of all-plastic hybrid molding part and the relationship between fiber orientation and mechanical properties were studied though experiments. Bonding interface between preset piece and injection molded part was researched to verify the reliability of the simulation.The investigation shows that preset piece’s existence changes the molding interface environment, which makes a more uniform fiber orientation levels, declines the layering effect of fiber orientation, and greatly affects the fiber orientation at weld lines caused by sudden change of melt flow. The results indicate that mold temperature and melt temperature have a significant influnce on the part mechanical properties and interface strength. Tensile strength and bending strength are enhanced with the mold temperature. When melt temperature arises, tensile strength decreases, and bending strength will decrease after a slight rise.Fiber crossing at the contact surface makes a fine adhesion between the preset piece and molding part, which will be enhanced by a higher mold temperature. Reasonable change of preset piece’s surface structures, which results in micro-mechanical interlocking, can effectively improve the overall performance of all-plastic hybrid molding products. There are61figures,16tables and65conferences.