Using ultrasonic sensors for powder injection molding

Previous research efforts concentrating on proof-of-principle studies have shown that ultrasonic nondestructive evaluation can be applied to the process monitoring of a power-injection-molding system. This research has resulted in the successful detection of several injection-molding problems, such as flashing, short shot, sticking, and sink marks. Past techniques, however, have required that the sensors be positioned so that the ultrasonic wave (bulk or guided) directly interacts with the defect. This article reports results from a technique that uses only one sensor for detecting several common injection-molding defects and does not require that the wave interact directly with the defect.