How do Rolls Royce grow a single grain to make a blade for a turbine? Does anyone any idea?

source: google.  i don't think it sounds like rolls royce is the only one that does that

"There are several different manufacturing methods that are used in practice to create single crystal turbine blades. The manufacturing methods all use the idea of directional solidification, or autonomous direction solidification,where the direction of solidification is controlled. A common method is the Bridgman method to grow single crystals. In this method a casting furnace is used for crystal growth. In this process, a mould must first be made of the blade. Molten wax is injected into a metallic mould of the desired turbine blade and left to set and take the form of the turbine blade. The wax model is then used to create a ceramic mould to use for production of the single crystal turbine blades. When the ceramic mould is created, it is heated to raise the strength of the mould.[8] Once the mould is sufficient for use, the wax is melted out from the inside of the mould. The mould is now filled with the molten form of the nickel based superalloy. The molten superalloy contained within the mould is placed in some type casting furnace, often a vacuum induction meltingWfurnace, which uses Bridgman techniques."

https://www.appropedia.org/Single_Crystal_Turbine_...