Isothermal extrusion is a method of maintaining constant temperature of an extruded section in the bearing zone of the die in order to get stable mechanical properties. Isopressure extrusion is a method of maintaining the load on the die constant throughout the ram stroke in order to get stable dimensions of extruded sections. In this study, an equation for calculating the initial billet temperature that performs isothermal and isopressure extrusion is proposed and confirmed. The idea is derived from the concept that the heat flow from the billet to the container is made to be equal to the heat generation by the shearing deformation of metal close to the container wall. Applying an adequate initial billet temperature obtained from the simple equation, constant temperature and constant die load have been achieved and excellent steady dimensions and mechanical properties have been obtained with the isothermal and isopressure extrusion.
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