Simulation And Experiment Study On Gas-assisted Injection Molding For Short-fiber Reinforced Polymer

Short fiber reinforced polymer gas-assisted injection molding (abr. SFRP-GAIM)is a kind of process in which gas-assisted injection molding is applied to manufactureof short fiber reinforced polymer composite. Its products not only have the prominentmechanical properties, but also they possess outstanding smooth surface. however,the control of process parameters of SFRP-GAIM becomes far more complicated thanconventional polymer injection molding because of introduction of short fiber andhigh pressure gas. Therefore, the optimization of the process parameters combinationof SFRP-GAIM to obtain high-quality products has become significant to boost thisnewly-developing processing technology forward.Based on a rectangular part with strengthening rib, the influence rules of mainprocess parameters on quality of the product are explored by means of simulation andexperiment in this paper. Furthermore, the optimum process parameters combination,when the quality of the product is the best, has been achieved. The results providerelatively high guidance value for the production and application of SFRP-GAIM.Now the main research achievements of the whole paper are summarized asfollows：1、A good gating system is built and a optimal airway entrance is established.Firstly, the model is created by using Pro/E; then, it is imported into Moldflow2010; thirdly, it is meshed and repaired, gate analysis order is selected so as to attainthe best gate location and airway entrance location; At last, both of the gating systemand airway system are perfectly set up.2、The optimization of process parameters is achieved. Based on Orthogonalexperimental design method, six important process parameters(short fiber content、short fibers interaction coefficient、mold temperature、melt temperature、gas delaytime and gas injection time)are chosen to investigate three vital goals: airwaypenetration rate、product’s warpage deflection and injection pressure at the gate. Inthe end, the optimizations of process parameters for a single goal evaluation andmulti-indicator comprehensive evaluation are achieved via with range analysis and signal to noise ratio analysis.3、Influence of each process parameter on each evaluation goal is gained. Basedon the optimum combination of process parameters got under multi-goalcomprehensive evaluation, influence of each process parameter on each evaluationgoal is entirely studied by means of employing single factor research method. Theachievements could offer vital guiding significance for production and application.4、Experimental study not only verifies the correctness of stimulation results andalso points out the difference of fiber orientation in the core layer of samples close tothe airway between conventional injection and gas-assisted injection molding. Withthe help of injection machine and metallurgical microscope and other equipments, theexperimental study of short-glass fiber reinforced PP gas-assisted injection molding(abr. SGFRP-GAIM)are conducted. The effect of fiber content、melt temperature andgas delay time on gas penetration length and product’s warpage deflection is focused.The experimental study results reveal that simulation research is reliable. Furthermore,comparative study between conventional injection and gas-assisted injection moldingis carried out and the difference of fiber orientation in the core layer of the samplesclose to the airway is pointed out.