Steps in investment casting: (1) wax patterns are produced, (2) several patterns are attached to
a sprue to form a pattern tree. Steps in investment casting: (3) the pattern tree is coated with a
thin layer of refractory material, (4) the full mold is formed by covering the coated tree with
sufficient refractory material to make it rigid. Steps in investment casting: (5) the mold is held in
an inverted position and heated to melt the wax and permit it to drip out of the cavity, (6) the
mold is preheated to a high temperature, the molten metal is poured, and it solidifies. Steps in
investment casting: (7) the mold is broken away from the finished casting and the parts are
separated from the sprue.
Plaster Mold Casting
Similar to sand casting except mold is made of plaster of Paris (gypsum - CaSO4-2H2O)