Green sand control in foundry has always been one of the main goals to be achieved in order to obtain good quality productions and to minimize scraps.
So far, sand control methods were mainly based on the control of return sand moisture and on the consequent water addition to muller to obtain the desired moisture of prepared sand. There are also control systems which determine the compactability of mulled sand and then determine the quantity of water to be added.
All these systems give a partial answer to the demand of quality sand, in particular of constant quality sand. In fact, they do not allow the automatic control of important parameters such as strength, active bentonite, total bentonite, permeability and automatic addition of additives and new sand.