Evaluation of contact conditions in hot forging of pure aluminum using ultrasonic examination

In isothermal upset forging of pure aluminum, the change in the contact condition and the lubricant behavior were evaluated by continuously measuring the ultrasonic reflection intensity from the contact interface between the tool (die) and workpiece. The relationships between ultrasonic reflection intensity, forging temperature, lubrication, forging pressure and workpiece surface during forging were examined. Depending on forging temperature, the conditions of the lubricant entrapment on the surface of the workpiece exhibited significant changes. The condition of lubricant pools and lubricant film was evaluated during warm and hot forging using the ultrasonic reflection intensity. The change in the contact condition and the lubricant behavior during warm and hot forging were measured with high sensitivity by the proposed ultrasonic measurement. The lubrication conditions can be optimized based on the in situ evaluation of the contact conditions.