Reply to Thread

Message:: [QUOTE="Hobo, post: 332937, member: 11521"]I'll go along with your theory - to a point. I agree metal will flow from the fields to fill the voids in the dies at the raised central devices. But as soon as those voids are filled (i.e., when the coin becomes fully struck) the metal starts flowing out (radially from the center).   Not necessarily. A die (or any material for that matter) will crack when the stresses exceed the compressive or tensile strength of the material. It is not so much the "pressure" exerted as it is the stresses induced in the dies.  Around the edges of the dies there is nothing to resist lateral forces (in this case "outward" forces). Sharp transitions (e.g., star tips in a die) are usually areas of high stresses. (For example, cracks in concrete, masonry and drywall typically begin at a sharp corner such as a window or door opening.)  So, while other areas of the die may be experiencing the same "pressure" it will be the area where the steel is overstressed that will crack. Remember the old saying "A chain is only as strong as its weakest link"? The same applies with a coin die.[/QUOTE]