Acoustic emission analysis for measuring foundry sand grain fineness number

An experimental investigation was carried out in order to verify whether Acoustic Emission (AE) techniques could give information on the grain fineness number of silica foundry sands characterised by different grain size arrangements. The sands used were obtained by mixing silica foundry sands with different grain sizes, resulting in different average grain size and fineness number. To achieve the goal, drop tests were carried out making the different sands to slip on a metallic slanted plane equipped with an AE sensor. The AE emission signals were recorded and their typical parameters were analysed. The AE response was very sensitive to the geometry of experimental set up and test procedures, being mainly affected by the sand falling height and quantity, as well as on the length of the slanted plane. Nevertheless, for a fixed experimental set up and test procedure, the AE energy was strongly correlated with the average grain size, exponentially decreasing with increasing sand fineness. Thanks to its features, this method seems to be promising as an in-process monitoring system, based on a quick evaluation of the grain size.