Numerical Simulation Of Plastic Part Shrinkage Rule On Gate Design Of Mould

Plastic parts are widely used in industries such as electronics, communications, household appliances, machinery, automobiles and aerospace, because they have light weight and low price as well as excellent integrated mechanical properties. The shrinkage in plastic molding is a critical factor for products' quality and size precision, especially in injection moulding. It that affects the application of the products or cause economic losses often results in deformation and oversize of products. From manufacturing practices, it denotes that the gate design of mould is one of the most important factors that influence the shrinkage of plastics. Therefore, it is an important content of mould industry that to determine the reasonable gate position, gate size, and then the shrinkage rules of plastics based on the plastic configurations.Based on the shrinkage theory of injection moulding and experimental results, the effects of material characteristics, process conditions and mould structures on the product shrinkage as well as their interrelationship are lucubrated in the thesis. As far as it goes, there are many deficiencies of shrinkage predicting methods in injection moulding and shrinkage calculating in mould design. In the light of these disadvantages and plastic manufacture as well as mould design, the effect of gate design on the shrinkage of plastic is simulated by CAE technology and Moldflow software. The mobile shell and test equipment's cap are studied, by changing complexities of their structures, different configurations are attained. Three different materials (PP, PA66 and ABS) are injected with changes including different gate types, positions, sizes and numbers respectively, and their effects on shrinkage are analyzed. The effect of gate design on shrinkage is studied by analyzing structural change and pressure field distributing. The simulation results are dealt by orthogonal method, the interrelationships among these factors and their effects on shrinkage rules are studied by range analysis and contribution rate. The results indicate that structural characteristics, gate position and gate number have distinct effects on shrinkage, while gate size has little effect.Finally, the shrinkage rules of an actual electrical shell plastic is studied by experiment and aforementioned simulation results. It shows that they consistent with each other. The results indicate that the shrinkage rules summarized in this paper are good guidances to actual mould design.