A flaw that results when a workpiece fails to fill the The machined recess in a die that gives the forging its shape. The machined recess in a die that gives the forging its shape. during the first The process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment.. A seam is formed as subsequent The metal blocks into which forging impressions are machined and from which forgings are produced. force metal over this gap to leave a seam on the workpiece surface. See also Also known as lap or fold. A defect such as lap that forms whenever metal folds over itself during forging. This can occur where vertical and horizontal surfaces intersect..