A vertical electrical upsetting machine is meticulously designed with a tower-like structure, enabling vertical loading of the metal bar from the top or bottom. The electrodes precisely clamp the bar, and a low-voltage, high-amperage electrical current is passed through the section to be resistance heated. Once the required plastic deformation temperature is achieved (typically in the range of 900–1100°C), a powerful hydraulic or electromechanical ram applies axial pressure to plastically deform the bar, forming a precise upset (bulb) at the heated zone.

This configuration ensures gravitational support and excellent alignment of the forging axis, significantly reducing the risk of bending during the process. The compact design of vertical upsetters makes them ideal for seamless integration into automated production lines, offering near zero rejection rates and superior process control for consistent, repeatable bulb formation with optimal grain flow.