Burning method of ceramic shell mold for precision casting

A method of burning a ceramic shell mold for use in precision casting, which ceramic shell mold has a shaped cavity, defined therein, and at least one opening leading into said shaped mold cavity, said burning method being carried out by the use of a heating kiln of a type comprising heating and combustion compartments divided by a ceramic filter, said heating compartment being positioned immediately above said combustion compartment and accommodating therein a mass of sand, and a source of heating medium of elevated temperature, said burning method comprising the steps of:

• positioning said ceramic shell mold from top into the mass of sand within the heating compartment while said mass of sand is fluidized by the application of compressed air flowing upwardly through the ceramic filter at a pressure within the range of 1.0 to 2.5 kg/cm.sup.2 , said ceramic shell mold being positioned such that the opening leading into the mold cavity projects outwardly from the top level of said mass of sand within said heating compartment;
• interrupting the supply of the compressed air;
• and
• supplying the heating medium composed of a blast of hot gas from the combustion compartment into the heating compartment through said ceramic filter to heat said mass of sand and, in turn, said ceramic shell mold at a predetermined curing temperature for a predetermined time, said gas pressure being such as to avoid fluidization of the sand particles during this curing time.