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Direct extrusion

Extrusion operation where an ingot is pushed through a die.

Illustration of Direct extrusion

The process

The working material consists of a preheated ingot [1] placed in a pressure chamber [2]. A plunger [3] is pushed against the ingot with an applied pressing force which forces the ingot through a die [4] in the bottom of the pressure chamber. The ingot then assumes the shape of the dies cross-sectional area and is pressed out as a solid axially symmetric rod [5].

The force required to press the ingot through the container is high because of the great friction between the ingot and the container wall. As the ingot is cut down and becomes thinner, the force, ate the rear end of the ingot cannot push it through the die with desired results. Because of this, the rear end cannot usually be used.

Advantages and disadvantages
In comparison with alternative methods
Large production runs
Many types of raw materials
Limited complexity of the product
Only uniform cross section
Larger forces and friction than indirect extrusion