Patent ID: 8192657

Claim:
A method of making a product having a solid body and having one or more cavities inside that solid body, comprising the steps of: providing a liquid material within a mould, the mould having an interior surface; controlling a factor that determines solidifying speed of said liquid material, the factor being controlled as a function of position along the interior surface, the solidifying speed being made lower adjacent said intended one or more cavities; driving out the liquid material within said intended one or more cavities, when said liquid material has solidified adjacent said intended one or more cavities but not yet in said one or more cavities; and wherein said factor is temperature of the interior surface, the method comprising controlling the temperature of the interior surface as a function of position along the interior surface such that the solidifying speed is slower adjacent one or more cavities, the slower solidifying speed being achieved by a temperature control structure having a localized widening shape at a position corresponding to at least one of the one or more cavities.