Design of Tooling for Compressing a Cylindrical Billet with Consideration to Tolerance Specifications on the Billet Diameter

The compression of a cylindrical billet of work hardening material in either a single or double layer container is discussed. Theory is derived for predicting the final billet diameter as a function of the magnitude of the compressing load and the container design. Values determined from the theory are found to agree very closely with results from experiments and it is shown that if billets are compressed by loads over a certain minimum value extremely small variations in the final billet diameter can be expected even if there is considerable variation in the loads. The paper concludes with a discussion of the relevance and application of this result to the design of containers and tooling for processes where tolerance specifications require close control of formed diameters.