OPTIMIZATION OF INJECTION-MOLDING PARAMETERS FOR THE WARPAGE OF GREEN PARTS OF METAL INJECTION MOLDING BY THE TAGUCHI METHOD

Historically, metal injection molding (MIM) is a fairly new injection-molding technique; it can realize parts with a complex exterior that are otherwise highly difficult to produce and thus remarkable widen the scope of powder metallurgy application. MIM has been applied to the production of precision metal parts due to its advantages of high productivity and high complexity. MIM has been developed as a powerful method for manufacturing high value-added metal components. Control of the injection-molding process is crucial. The combination of feedstock, which is composed of a binder and metal powder, also complicates the rheological behavior. Therefore, powder-binder separation often occurs during the filling stage. Injection-molding simulation is an effective tool for predicting the molding process. The procedure for analysis has two major steps. First, flow front simulation is performed to validate the experimental short-shot results. Second, the experimental design of the Taguchi method is adopted to determine the optimal process parameters to reduce the green parts' warpage. This approach eliminates the inherent uncertainties when operators have different levels of experience. The short-shot results demonstrate that the simulated flow front is similar to the experimental one. Furthermore, the position of the weld line can be well predicted. The Taguchi method for minimized warpage shows improved dimensional precision. Moreover, the optimal process parameters can reduce the cycle time of three seconds compared with the original process parameters, which significantly benefits dimensional precision and the production rate.