The allowable tolerance for the length of the blanks used in forging is dependent upon the type of equipment used in the process. For example, if the forging process is done using a mechanical press, the allowable tolerance is limited by the press stroke, the die diameter, and the workpiece’s size. For a die-forging process, the tolerance depends on the diameter of the opening, the surface finish of the die, and the material being worked.
In general, the shorter the workpiece, the tighter the tolerance. This is due to the fact that shorter lengths require greater accuracy for the process to be successful. For example, if the length of a workpiece is three inches, the tolerances are in the range of ±0.012” to ±0.020”. If the length of the workpiece is five inches, the tolerances increase to ±0.016” to ±0.028”.
The allowable tolerance for the length of the blanks can also be influenced by any secondary processes being used on the blanks. For instance, a straightening process may require greater accuracy. If a part is going to be annealed, the length tolerance must be loose enough to allow for growth during the annealing process.
Finally, the thickness of the workpiece can also impact the allowable tolerance for length. For example, if the workpiece is two inches thick, the length tolerance would typically be in the range of ±0.006” to ±0.012”. If the thickness is three inches, the range would increase to ±0.008” to ±0.020”.
In conclusion, the allowable tolerance for the length of the blanks used in forging is dependent on the equipment being used, the secondary processes, and the thickness of the workpiece. Typically, the shorter the workpiece, the tighter the tolerance range. The thickness of the workpiece can also impact the allowable tolerance and should be taken into consideration when calculating the size of the allowable tolerance range. Knowing the specifications of the forging equipment and the degree of accuracy required of the final product will help determine the most appropriate allowable tolerance range for the length of the blanks used in the forging process.
