Abstract
This paper presents measurements of acoustic emission (AE) signals during the injection molding of polypropylene with new and damaged mold. The damaged injection mold has cracks induced by laser surface heat treatment. Standard test specimens were injection molded, commonly used for examining the shrinkage behavior of various thermoplastic materials. The measured AE burst signals during injection molding cycle are presented. For injection molding tool integrity prediction, different AE burst signals’ descriptors are defined. To lower computational complexity and increase performance, the feature selection method was implemented to define a feature subset in an appropriate multidimensional space to characterize the integrity of the injection molding tool and the injection molding process steps. The feature subset was used for neural network pattern recognition of AE signals during the full time of the injection molding cycle. The results confirm that acoustic emission measurement during injection molding of polymer materials is a promising technique for characterizing the integrity of molds with respect to damage, even with resonant sensors.
Highlights
Injection molding is still regarded as one of the most important and very popular manufacturing process because of its simple operation steps
In this work we presented an acoustic emission (AE) monitoring system with a resonant sensor that is able to detect the damaged area in an injection molding tool
We made a close comparison of AE signals captured from a new mold and a damaged mold under the same injection molding process conditions
Summary
Injection molding is still regarded as one of the most important and very popular manufacturing process because of its simple operation steps. A typical production cycle begins with the mold closing, followed by the injection of melt into the mold cavity. Once the cavity is filled, holding (packing) pressure is applied to compensate for the material shrinkage. The screw turns, feeding the material for the shot to the screw tip. This causes the screw to retract as the cycle is almost ready. Once the molded part is sufficiently cooled, the mold opens and the part is ejected
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