| Abstract: | Currently, the controllers for achieving a desired injection velocity setpoint profile are independent of processing conditions in plastic injection molding. The dynamics of the reciprocating screw during injection mold filling is complex and temperature‐dependent. This complexity is based on process parameters that are nonlinear, which can vary spatially in time. Open‐loop tests were performed on two polymers at three melt temperatures and three mold‐fill velocity regimes: low, medium, and high. These tests were based on close‐loop injection mold‐fill setpoints and a derived voltage velocity relationship for the injection velocity hydraulic valve. The results of the open‐loop tests show that mold‐filling injection velocity is polymer‐ and melt temperature‐dependent. Polym. Eng. Sci. 44:1925–1933, 2004. © 2004 Society of Plastics Engineers. |
