This document discusses the manufacturing process of extrusion. Extrusion is a compression forming process that forces metal to flow through a die opening to produce a desired cross-sectional shape. There are two main types of extrusion: direct extrusion where the ram forces the billet through the die, and indirect extrusion where the die is mounted to the ram. Extrusion can be performed hot or cold, and defects may occur such as center-bursting or piping due to excessive stresses during the process. Variations on extrusion include impact extrusion for discrete parts and hydrostatic extrusion which uses pressurized liquid to reduce friction.

1. MANUFACTURING
TECHNOLOGY – I
CRAFTED BY:
RAMESH KUMAR A
Assistant Professor
Sona College of Technology
Salem
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2. EXTRUSION
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3. EXTRUSION
A compression forming process in which the work metal is forced
to flow through a die opening to produce a desired cross-
sectional shape
PROS:
variety of sections possible (hot extrusion)
grain structure and strength enhancement (cold)
close tolerance (cold)
no material wastage
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4. TYPES OF EXTRUSION
Direct Extrusion
The ram forces the work billet metal to move forward
to pass through the die opening
Indirect Extrusion
The die is mounted to the ram rather than at the
opposite end of the extruder container housing
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5. DIRECT EXTRUSION
Friction increases the extrusion force
Hollow section is formed using a mandrel
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6. INDIRECT EXTRUSION
Metal is forced to flow through
the die in an opposite direction
to the ram’s motion
Lower extrusion force as the
work billet metal is not moving
relative to the container wall
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7. EXTRUSION PROCESSES
Hot extrusion
 Keeping the processing
temperature to above the re-
crystalline temperature
 Reducing the ram force,
increasing the ram speed, and
reduction of grain flow
characteristics
 Controlling the cooling is a
problem
 Glass may be used as a
lubricant
Cold extrusion
 Often used to produce discrete
parts
 Increase strength due to strain
hardening, close tolerances,
improved surface finish,
absence of oxide layer and
high production rates
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8. EXTRUSION
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9. IMPACT EXTRUSION
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combination

10. IMPACT EXTRUSION
Impact extrusion is performed at higher speeds and shorter
strokes than conventional extrusion
It is for making discrete parts
For making thin wall-thickness items by permitting large
deformation at high speed
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11. HYDROSTATIC EXTRUSION
 The billet is completely surrounded by pressurized liquid, except where the
billet contacts die
 Using hydrostatic system to reduce the friction and lower the power
requirement
 Sealing is the major problem
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12. EXTRUSION DEFECTS
 Centre-burst
 Internal crack due to excessive
tensile stress at the centre
possibly because of high die
angle, low extrusion ratio
 Piping
 Sink hole at the end of billet
under direct extrusion
 Surface cracking
 High part temperature due to low
extrusion speed and high strain
rates
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13. EXTRUSION DEFECTS
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