METHOD FOR MANUFACTURE OF REMOVABLE INVESTMENT CASTINGS Russian patent published in 2002 - IPC

FIELD: mechanical engineering. SUBSTANCE: method involves manufacturing investment castings from powdered mixture of single-component investment material of 0.1-1.6 mm fraction and ammonium nitrate of 0.1-2.5 mm fraction. Volumetric ratio of mixture components, %: investment material 20-65; ammonium nitrate 35-80. Investment material is dosed into casting mold in an amount providing for manufacture of investment castings of 3-10% porosity. Investment material is pressed without preliminary heating by aligning casting mold detachment surfaces. During pressing powdered investment material is caked without substantial phase deformation processes and with formation of open capillary porosity, which compensates expansion of investment casting during heating in the process of melting from ceramic enclosure. EFFECT: increased dimensional and geometric precision of investment castings and ingots. 1 tbl