Method of casting metal parts such as valve seat insert casting blanks and casting apparatus

A method of casting metal parts, comprising:

• pouring molten metal into a gating system of a mold plate stack having mold cavities wherein mold plates are located between a cover mold and a bottom mold, the gating system including a casting header, down-sprue passing though the mold plates, at least one distribution runner in fluid communication with the down-sprue, at least one up-sprue in the mold plates, and at least one circumferential gate in each mold plate with the circumferential gate in fluid communication with a lower portion of a single mold cavity configured to form a metal part, the gating system optionally including at least one gas release passage in fluid communication with the up-sprue and the mold cavity;
• filling the mold cavities with the molten metal such that molten metal passes into the down-sprue, the distribution runner and into the up-sprue in a lowermost mold plate, then through the circumferential gate and into the mold cavity, rises in the mold cavity and in the up-sprue at substantially the same velocity and at substantially the same height until the molten metal fills the mold cavity, then into the up-sprue of an overlying mold plate and repeats the mold cavity filling process of the lowermost mold plate until all of the mold cavities are filled with the molten metal;
• and solidifying the molten metal to form cast metal parts interconnected by solidified metal in the down-sprue, the distribution runner, the up-sprue, and the circumferential gates.