Multiple In-Mold Sensors for Quality and Process Control in Injection Molding

Abstract

The simultaneous improvement of injection molding process efficiency and product quality, as required by Industry 4.0, is a complex, non-trivial task that requires a comprehensive approach, which involves a combination of sensoring and information techniques. In this study, we investigated the suitability of in-mold pressure sensors to control the injection molding process in multi-cavity molds. We have conducted several experiments to show how to optimize the clamping force, switchover, or holding time by measuring only pressure in a multi-cavity mold. The results show that the pressure curves and the pressure integral are suitable for determining optimal clamping force. We also proved that in-channel sensors could be effectively used for a pressure-controlled SWOP. In the volume-controlled method, only the sensors in the cavity were capable of correctly detecting the end of the filling. We proposed a method to optimize the holding phase. In this method, we first determined the integration time of the area under the pressure curve and then performed a model fit using the relationship between the pressure integral and product mass. The saturation curve fitted to the pressure data can easily determine the gate freeze-off time from pressure measurements.

Out-of-Mold Sensor-Based Process Parameter Optimization and Adaptive Process Quality Control for Hot Runner Thin-Walled Injection-Molded Parts

“…Xu et al [ 13 ] proposed a method based on the variation in clamping force to determine the optimal clamping force, showing that the optimal setting for the clamping force could be found when the clamping force variation was zero. Párizs et al [ 14 ] proposed the feasibility of controlling the injection process using cavity pressure sensors in multi-cavity molds, reporting that the sensors could effectively detect the filling end time to determine the appropriate V / P switchover point, fit the pressure curve to determine the proper filling time, and analyze the pressure curve and pressure integral to determine the suitable clamping force. Huang et al [ 15 ] found that setting the V / P switchover point too early or too late would significantly impact the cavity pressure curve and product quality.…”

Effect of Processing Parameters and Wall Thickness on the Strength of Injection Molded Products

“…The final properties of a plastic part are greatly affected by the production parameters. The best way to control the process is to use sensors in the mold [4,5]. In case of injection molding, melt temperature, mold temperature, injection rate, holding time, and holding pressure significantly affect the properties of injection molded parts [6][7][8][9][10][11][12][13].…”

Time and Spatially Resolved Operando Small-Angle X-ray Scattering Measurements during Injection Moulding of Plastics

“…There is much interest in the framework of Industry 4.0 in providing feedback during the injection moulding process. The current work on operando SAXS measurements provides one approach to providing feedback on multiple scales, but the role of more traditional "sensors" should not be overlooked, and reference [22] gives an excellent coverage of such possibilities.…”