Moulds for metal casting and sleeves containing filters for use therein

Abstract From the Canadian patent

A mould for metal casting has a mould cavity and a sprue communicating directly with the mould cavity and located in the sprue a sleeve of refractory material having a cellular ceramic filter fixed therein. The mould, which has no running system apart from the sprue, may be a sand mould or a metal die for producing castings by gravity or low pressure diecasting. The cellular ceramic filter may be a honeycomb type of structure having cells which extend between two outer surfaces of the filter or a structure having interconnecting cells such as a ceramic foam.