Metal extrusion, according to the temperature of the billet, there are hot extrusion, cold extrusion and warm extrusion. The extrusion of the metal billet above the recrystallization temperature (see plastic deformation) is hot extrusion; the extrusion at normal temperature is cold extrusion; the extrusion above normal temperature but not exceeding the recrystallization temperature is warm extrusion.
Extrusion, according to the plastic flow direction of the blank can be divided into:1. If the direction of flow is the same as the direction of pressurization, it is positive extrusion;
3. The billet is forward and reverse. Flow in both directions is called coextrusion.