of the workpiece material possibly in both the up and down directions is approximately equal to horizontal movement of the workpiece material stated differently it is desirable that all distal surfaces of the die cavity including the end surfaces of any relatively long narrow portions of the cavity are contacted by the workpiece material at substantially the same time during the forging stroke this prevents rollover and other forging phenomena from occurring which may cause imperfections in the finished parts when a die cavity has centralized elongated portions such as the die cavity in die set 20 the use of a workpiece having a centralized mass results in the workpiece material reaching the distal surfaces of all of the cavity portions substantially simultaneously the workpieces may also be of other shapes having a large mass near the center portion such as a generally cubic shape or a generally spherical shape of course for certain other part configurations and thus other cavity configurations axi symmetrical workpieces such as cylindrical workpieces may be the optimally shaped workpieces to effectively and efficiently produce the desired part configuration as stated the volume of the workpiece 30 is substantially equal to the volume of the as forged rocker arm 30 39 this is accomplished by selecting a workpiece having the appropriate height and diameter the volume of the workpiece may be optimized by adjustment of the geometry at the design stage for example as shown in fig2 a and 2b an optimized volume is achieved with formed bevel surfaces 30a on the.