Insertable riser base, sand mould, moulding device consisting of the insertable riser base and the sand mould, and method for producing the moulding device

The riser base is an insert produced by manual moulding or by blowing an insulating or exothermal composition, comprising hollow microspheres of aluminium silicate. The mould mainly consists of silica sand and has a main cavity designed to be filled with molten metal in order to produce a casting and at least one auxiliary cavity. The insert fits into the auxiliary cavity made in the mould and has an inner cavity designed to receive molten metal from a supply riser or mini supply riser, and an external geometry that coincides with the geometry of said auxiliary cavity. The at least one auxiliary cavity made in the mould itself is arranged such that, when the riser base is inserted into said auxiliary cavity, the inner cavity of the riser base communicates with said main cavity of the mould (part) in order to allow the passage of the molten metal.