Usually a flat surface cut to an exact depth below the (1) The line along the surface of a forging where the dies meet, usually at the largest cross section of the part. Flash is formed at the parting line. (2) The plane that divides the two forging die halves. in each The machined recess in a die that gives the forging its shape. to widen the material so as to more nearly cover the next A cavity, or series of cavities (multiple), machined into a forging die to produce a desired configuration in the workpiece during forging..