3:52 PM , Posted in Indirect or Backward Extrusion
Indirect extrusion or backward extrusion
In order to completely overcome the problem, the backward hot extrusion as shown in figure, in this process the metal is confined fully by the cylinder, the ram which houses the die also compresses the metal against the container , forcing it to flow backward to the die in the hollow plunger or ram.
It is termed backward because of the opposite direction of the flow of the metal. Thus the billet in the container remains stationary and hence produce no friction. Also the extrusion pressure is not effected by the length. In the extrusion press since the friction is not loss. The figure of the backward extrusion is shown;