Fragmentation is the process by which the casing of an artillery shell, bomb, grenade, etc. is shattered by the detonating high explosive (HE) filling. The correct technical terminology for these casing pieces is fragments (sometimes shortened to frags), although shards or splinters can be used for non-preformed fragments. The fragments can also be preformed and of various shapes (spheres, cubes, etc.) and sizes. Preformed fragments are normally held rigidly within some form of matrix or body until the HE filling is detonated. The resulting high velocity fragments produced by either method are the main lethal mechanisms of these weapons, rather than the heat or overpressure caused by detonation.
The term shrapnel is often incorrectly used to refer to fragments produced by any explosive weapon. However, a shrapnel shell functions differently than a high explosive shell. A shrapnel shell consists of a shell casing filled with steel or lead balls, with a small explosive charge at the base of the shell and a nose fuse. When the projectile is fired, it travels a pre-set distance before the fuse ignites the explosive charge (often black powder) in the base of the shell. The fuse also typically fractures the nose of the shell to open a path for the balls. Upon ignition, the explosive charge shoots the balls from the shell in a forward cone.[1] The casing of a shrapnel shell does not fragment like a high explosive shell, thus, technically, the balls shot from the shrapnel shell are "shrapnel" whereas the pieces of shattered shell casing of a high explosive shell are "fragments" or "splinters." [2]
Another artillery round similar to shrapnel is canister, sometimes called case shot. Canister is a simple sheet metal casing filled with steel or lead balls. Upon firing, the casing fractures as it exits the muzzle of the gun and dispenses the balls from the gun’s muzzle much like a shotgun.[1] The practical differences between canister and shrapnel is that canister is only effective at short range (less than 200 yards/183m),[3] whereas a shrapnel shell can travel hundreds of meters downrange before the fuse activates the explosive charge, thus it can be effective at much longer ranges.