In the foundries is very important to understand and to control all the phenomena taking place at the contact (and under the action) of liquid alloy on the moulds. These phenomena are very complex, but a convenient way to treat this problem is to devide it into slices. One slice of the problem is the static action of liquid alloy on the drag (bottom part of the mould). This paper is an attempt to present in a logical thread the calculation of the metalo-static force on the drag in order to keep on the precision tolerances of the casts.