Profile Setting of Injection Velocity

The quality of an injection molded part depends on the characteristics of the material, the performance of the molding machine, the mold design, and processing conditions. For a given material, mold, and machine, the part quality is mainly determined by its processing conditions, among which injection velocity during the filling stage plays a particularly important role. Studies [161–170] have shown that injection velocity can affect the degree of orientation and residual stress, as well as surface properties of the molded parts. In view of its importance, advanced control techniques [172–174] have been developed for the control of injection velocity. With such advanced controllers, the injection velocity can accurately follow any reasonable profile. But for a given mold and material, how should the injection velocity be profiled to produce a good-quality part? A method for profiling the injection velocity based on a constant melt-front-velocity strategy will be presented in this chapter.