Monitoring metal fill profile in lost foam casting process using capacitive sensors and metal fill time estimation

Lost foam casting (LFC) is one of the most important casting methods used in the production of complex metal castings. Several casting defects may result due to an improper metal fill process during LFC; hence, monitoring the metal fill profile is important so that failures in the process can be quickly discovered. This paper presents a monitoring process based on capacitive sensors developed by the research team. In this application, an array of metallic electrodes is mounted around a target area and a set of capacitance measuring circuits are used to measure the mutual capacitances between these electrodes. Measuring the change in capacitance as grounded molten metal displaces the foam pattern provide a simple nondestructive method of acquiring metal fill information. An iterative algorithm for the estimation of metal fill time is also presented. This estimation utilizes better filtration and outlier detection techniques to provide a good prediction of the filling time. The proposed system also makes use of a wireless sensor network for transmitting data between the sensor boards and a computer running our metal fill monitoring application software; thus making this system suitable for the harsh foundry environment.