ABSTRACT

Folding and sliding are the main forms of failure during Injection Forging; this has been shown to occur when the aspect ratio of the primary deformation zone (T=t/d0, refer to Fig. 1(a)) is beyond a particular value. Folding occurs as a result of the instability of the “strut” between the exit from the injection chamber and the anvil; this is similar to the buckling of cylinders in simple compression, which occurs when the initial aspect ratio of the cylinder is in excess of 3 (Gunasekera, Chitty and Kiridena (1989)). However, the critical aspect ratio for injection upsetting has been clearly demonstrated to be 1.65 (Henry(1971), Balendra(1985)). Buckling limits for simple compression were simulated and verified experimentally, while the evidence for injection upsetting was largely

experimental. The research reported herein, relies on FE simulation and experimental comparison to analyse the influence of several parameters on the stability of the billet during Injection Forging.