Wireless in‐mold melt front detection for injection molding: A long‐term evaluation

Wireless sensing technology for injection molding is of increasing interest in literature. Recently, a purely mechanical in‐mold sensor for melt front detection was introduced. The sensor system is based on building resonant structures into the mold which are excited by the passing melt front generating structure‐borne sound, from which the melt front position is derived. A big advantage of this system is the possibility to implement a plurality of resonant structures while just having one receiver. One important aspect is the need to separate and assign the recorded impinging sounds. A novel algebraic approach was introduced separating the resonant structures by reference to their oscillatory behavior. In this article, measurement results for over 450 injection molding cycles are given proving functionality of the separation process. In addition, it is shown that the melt front detection is reliable and robust when comparing it with results obtained by cavity temperature sensors. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40346.