Patent ID: 8733421

Claim:
An evaporative pattern casting process, comprising the steps of: forming a mold by burying a pattern made of resin foam in casting sand; pouring molten metal into the mold; and evaporating the pattern with the molten metal and thereby casting a product, wherein casting time during founding is set longer as a modulus (pattern volume÷pattern surface area) of the pattern is larger, wherein the pattern volume is equivalent to the volume of the product which does not include a gate, a runner, a sprue, and a gas discharge passage, and the pattern surface area is equivalent to the surface area of the product which does not include a gate, a runner, a sprue, and a gas discharge passage, wherein the casting time is calculated from the following First Formula, wherein the pattern volume is equivalent to the volume of the product which does not include a gate, a runner, a sprue, and a gas discharge passage, and the pattern surface area is equivalent to the surface area of the product which does not include a gate, a runner, a sprue, and a gas discharge passage, First Formula t= ( W/A ′)/(ρ· a·m −b ·√{square root over (2 gH ′)}) (1) t: casting time (5), W: pouring weight (kg), A′: sprue area (cm 2 ), ρ: density of molten metal (q/cm −3 ), a, b: constants, m: modulus (pattern volume÷pattern surface area), g: gravity acceleration, H′: height from a sprue to an upper end of a pattern (cm).