Extrusion

Manufacturing process used for shaping of a material through compression process to get the required cross-sectional shape.

Example of extrusion parts:

1)Railing for sliding doors

2)Window frames

3)Aluminium Leaders

4)Gears

Extrusion Process

1)Hot Extrusion

Keeping the process temperature to above the re-crystalline temperature (for steels temperature between 400 and 700 degree). As temperature is so high so controlling the cooling is a problem.

2)Cold Extrusion

It can defined as the process of shaping a cold metal by striking slug. Often used to produce discrete parts.

Extrusion Types

1)Direct Extrusion

Ram apply force on work billet to move forward to pass through the die opening and to get the desired shape.

2)Indirect Extrusion

Metal is forced to flow through the die in an opposite direction to the ram’s motion.

3)Hydrostatic Extrusion

The chamber which is larger than the billet is filled with the fluid. The fluid is compressed with the ram and pushes the billet forward.

Materials

Common materials used in extrusion are following

1)Aluminium

2)Copper

3)Steels

4)Stainless Steels

5)Magnesium

6)Lead

Advantage of Hot and Cold Extrusion

Hot Extrusion

1)Large variety of materials

2)Less forces required

3)Better material flow

Cold Extrusion

1)Better mechanical properties due to work hardening

2)Good dimensional tolerances

3)No need to heat billet

 

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-Stress Strain Diagram

http://www.electricalengineering4u.com/basic-mechanical-engineering/stress-strain-diagram/