Combined extrusion forging is effective in decreasing load and process simplification. However, combined forging is not used widely. The reason for this seems to be the load and metal flow being difficult to assume. Many research studies have been conducted to solve this problem. Although it is considered that extrusion load and metal flow are affected by the shape ratio of a billet (ho/do), research on this subject is insufficient. In this study, the effect of the shape ratio of a billet on extrusion load was examined by experiment and analysis. The extrusion load in both single extrusion and combined extrusion increases with the shape ratio of a billet. When the shape ratio is 1.5, the combined extrusion load corresponded to either of the forward extrusion load or the backward extrusion load, smaller. When the shape ratio is 0.4, the combined extrusion load was smaller than both of the forward extrusion load and the backward extrusion load. When the diameter and height of the billet based on the size of the product were given, the method of predicting a combined extrusion load was proposed.
