2016-04-15 Fri

The most common form of die failure is a fracture line that crosses the die face, called as the die crack. The length, width, shape, trajectory, and end points of die cracks could vary. Some extend from the edge of the die and end somewhere in the field and design, others extend between two points on the edge. Some divide the die face into equal or sub-equal portions.

When die cracks are spread apart, coin metal rises to form a ridge. The 1976 Mexico 5-peso coin displays a number of wide, intersecting die cracks that weave through the reverse.

Bi-level die cracks are less common. They have vertical displacement and can occur only in the presence of subsurface deformation.

Horizontal offset are rarer where one side of the crack slides along the other side, producing a discontinuity in portions of the design.

Spreading and sliding movements occur in the case of severe rim-to-rim die cracks, asymmetrical split dies, and retained cuds. A retained cud is a die fragment that is separate from the die neck but held in place.