Real-time measurement of flow front kinematics using quantitative visualization in injection molding process

This article presents an experimental method for measuring the kinematics of the melt flow front, during the filling stage of the plastic injection molding process. The three main steps were: (i) visualization of the flow front advancement, (ii) image processing of the recorded results, and (iii) calculation of the flow front kinematics. The designed visual mold was capable of monitoring the flow advancement in two different cases: (i) a simple (nonconstrained) plate and (ii) a constrained plate (with an obstacle pin). Variations in instant flow rate, melt front area (MFA), and average melt front velocity (MFV) during filling stage were measured as a function of time. The applied technique could clearly show the flow behavior from which the flow front parameters could be extracted. A particle tracking velocimetry (PTV) method was also applied to study the orientation behavior of the advancing melt front. The time history of the particle's velocity components at the flow front could be easily extracted using the method.