Abstract: A machine and its associated process for upset forging the ends of deformed reinforcement bars are disclosed. The machine includes 2 split clamping dies and an upsetting die, and they are housed in separate casings so that the clamping action is independent from the upsetting die. The clamping dies and the upsetting die form a continuous cavity for accommodating the forging of long bars. The upsetting die has a upsetting cavity with radial closed cross-section, and the whole forging process is performed inside this closed cavity to ensure it's a true closed-die forging process, which results in precise upset diameter with improved roundness of the rebar.