3-D printed casting shell and method of manufacture

A method of 3-D printing a hydraulically bonded casting shell of, the method comprising:

• forming at least one exterior casting shell, the method comprising:
• intermittently applying in a step-wise manner, a layer of a powder component comprising in part at least 25 percent by weight of a calcium aluminate cement in a first predetermined area, and a volume of an at least one liquid component comprising at least 50 percent by weight of a distilled water over the top of the powder component in a first predetermined location,
• hardening the at least one exterior casting shell to form at least one solid exterior casting shell comprising a plurality of hydraulic bonds at a first location of overlap between the powder component and the at least one liquid component, wherein the solid exterior casting shell includes an interior cavity corresponding to a shape of an object to be cast forming least one core casting shell, the method comprising:
• intermittently applying in a step-wise manner, a layer of the powder component in a second predetermined area and a volume of the at least one liquid component over the top of the powder component in a second predetermined location,
• hardening the at least one core casting shell to form an at least one solid core casting shell comprising a plurality of hydraulic bonds at a second location of overlap between the powder component and the at least one liquid component,
• wherein the solid core casting shell has an exterior surface that corresponds to a shape of a void in the object to be cast;
• and
• wherein at least one of the solid exterior casting shell and the solid core casting shell comprises at least a first shell portion and a second shell portion;
• and
• wherein the hydraulic bonds of the first shell portion are stronger than the hydraulic bonds of the second shell portion.