Study On Injection Molding Process Optimization And Quality Prediction Based On Response Surface Methodology

Injection molding is one of the most important plastic molding processes which has been widely applied in many fields of industry. The quality of injection-molded plastic parts is affected by many factors, an inappropriate setting of the process parameters will result in some undesirable quality and defects such as warpage. At present, the industrial sector depends to a large extent on the designer's experience and trials, which is uneconomical, time-consuming and inefficient in overcoming these problems.Presently, one of the approaches to tackle this problem is to exploit injection molding optimization methodology. This study focused on the impact of processing parameters on the warpage of plastic part based on CAE simulation. To avoid the time-consuming CAE computation in the optimization process, in this thesis, the response surface method (RSM) based methodology for injection molding optimization was studied. The RSM was used to set up a prediction model between warpage and processing parameters, and then a genetic optimization algorithm was applied base on the prediction model to search for the minimum warpage and its corresponding processing parameters. The main work of the study includes:1. An accurate and reliable CAE simulation model was set up. Orthogonal array experiment was done using the Moldflow software to obtain the warpage values. The S/N ratio of the Taguchi DOE method was utilized in experimental data analysis by ANOVA and ANOM to find the impacts of different processing parameters on warpage.2. A response surface model based on least squares method was proposed to fit the non-linear relationship between warpage and parameters. The optimization of processing parameters was achieved by utilizing the GA (genetic algorithm) method integrated with the response surface model. The result was validated by input these parameters into Moldflow software and got the warpage value.3. In this thesis, Microsoft Visual Basic 6.0 was employed as the programming language, a set of application software for quality prediction and process parameters optimization of injection molding was designed utilizing the method of VB and Matlab Hybrid Programming. 4. An injection mold was designed and processed for real injection molding experiment. The products of the injection molding experiments were measured with coordinate measuring instrument to validate the accuracy of the RS model and the effectiveness of optimization algorithms.