A nondestructive online method for monitoring the injection molding process by collecting and analyzing machine running data

Nondestructive online monitoring of injection molding processes is of great importance. However, almost all prior research has focused on monitoring polymers in molds and damaging the molds. Injection molding machines are the most important type of equipment for producing polymeric products, and abundant information about actual polymer processing conditions can be obtained from data collected from operating machines. In this paper, we propose a nondestructive online method for monitoring injection molding processes by collecting and analyzing signals from injection molding machines. Electrical sensors installed in the injection molding machine, not in the mold, are used to collect physical signals. A multimedia timer technique and a multithread method are adopted for real-time large-capacity data collection. An algorithm automatically identifies the different stages of the molding process for signal analysis. Moreover, ultrasonic monitoring technology is integrated to measure the cavity pressures. Experimental results show that our nondestructive method can continuously monitor the injection molding process in real time and automatically identify the different stages of the molding process. The packing parameters, including the filling-to-packing switchover point and the packing time, can be optimized based on these data. Furthermore, the ultrasonic reflection coefficient and the actual cavity pressure have similar trends, and our technique for measuring the cavity pressure is accurate and effective.