Greensand Mulling Quality Determination Using Capacitive Sensors

Cast iron foundries typically use molds made from a mixture of sand, clay, and water called greensand. The mixing of the clay and water into the sand requires the clay to be smeared around the sand particles in a very thin layer, which allows the mold to have strength while allowing gas to escape. This mixing is called mulling and takes place in a machine called a muller. At present, the industry uses electrical resistance measurements to determine water quantity in the muller. The resistance measurements can not accurately predict the quality of mulling due to binding of the water to sodium and calcium ions in the clay. Poorly mixed greensand has a high resistance when the water is concentrated in a few areas, then a medium mixed greensand has a lower resistance because the water present between the sensors, and a well mulled sand has a higher resistance when the clay binds the water. This paper investigates the feasibility of using capacitive sensors to measure mulling quality using the simulation software Ansoft Maxwell. A second investigation of this paper is to find the ability of capacitance sensors to determine the drying effect of molds delayed in the casting process.