Metal extrusion is a metal forming process where a cylindrical billet is forced through a die to form a part with a fixed cross-sectional profile. There are different types of metal extrusion depending on factors like the direction of extrusion flow, the medium used to apply force, and the working temperature. Direct extrusion uses a stationary die and moving billet container, while indirect extrusion has a stationary billet and moving die. Hydrostatic extrusion applies tri-axial forces via hydraulic fluid to improve formability. Lateral extrusion orients the billet container vertically with a side-facing die. Impact extrusion is a cold process using high-speed impact to extrude softer metals.

1. Extrusion&
itstypes.

2. Metal Extrusion is a metal forming manufacturing process in
which a cylindrical billet inside a closed cavity is forced to flow through
a die of the desired cross-section. These fixed cross- sectional profile
extruded parts are called “Extrudates” and pushed out using either a
mechanical or hydraulic press. The process which was first patented
by Joseph Bramah was first used to extrude lead pipes by Thomas
Burr.
What is MetalExtrusion?

3. Characteristics of
metal extrusion
Able to create complex cross-sections and will be uniform over
the entire length of the extrudates.
Factors that affect the quality of extrusion are die design,
extrusion ratio, billet temperature, lubrication, and extrusion
speed.
Similar to any other metal forming process, it can be performed
either hot or cold, although the process generally is carried out
at elevated temperatures in order to reduce the extrusion force
and improve the ductility of the material
Low cost due to reduced raw material wastage and high
production rate

4. Brittle material can be
deformed without a tear as it
only exerts compressive and
shear forces in the stock part
Parts that are formed have an
excellent surface finish which
minimizes post-processing
machining
The minimum wall thickness
of ~1mm (aluminium) to ~3mm
(steel) could be achieved
Metal extrusion tends to
produce a favourable
elongated grain structure in
the direction of the material.

5. Types of the metal extrusion process
Metalllextrusiiion can be subdiiiviiidedand grouped iiintothe follllllowiiing
categoriiies dependiiing on the diiirectiiionof extrusiiion flllow,,,the mediiium used
to applllyforce,,,workiiingtemperature,,, etc.
DiiirectExtrusiiion
Indiiirect Extrusiiion
Hydrostatiiic Extrusiiion
Lateralll or VertiiicalllExtrusiiion
Hot extrusiiion
CollldExtrusiiion
Impact Extrusiiion

6. Direct
Extrusion

7. Indirect Extrusion
In Indirect Extrusion, the die is located at the end of
the hydraulic ram and moves towards the billet inside
the cavity to push the material through the die.
This process consumes less power due to the static
billet container causing less friction on the billet.
However, supporting the extruded part is difficult
when the extrudate exits the die.

8. Difference
between
Direct &
indirect
extrusion?

9. Hydrostatic
extrusion
In hydrostatic extrusion, the chamber/ cavity is made smaller than the
billet and filled with hydraulic fluid which transfers the force from the
ram to the billet as shown in figure 3. Although tri-axial forces are applied
by the fluid, the pressure improves billet formability on the billet. Sealing
the fluid must be considered at the early stages to avoid any leaking and
reduce pressure issues.
Although the hydraulic fluid eliminates the friction between the wall and
the billet by isolating them, due to the specialised equipment
requirement, the high set-up time and low production rate limit its usage
in the industry in comparison to other extrusion processes.

10. HYDROSTATICMETALEXTRUSIONADVANTAGES
Low power/force requirement due to no friction
Fast production rates & high reduction ratios
Lower billet temperature
Even flow of material due to the balanced force distribution
Large billets and large cross-sections can be extruded
No billet residue is left in the container

11. HYDROSTATICMETAL
EXTRUSION
DISADV
ANT
AGES
Billets need preparing by
tapering one end to match the
die entry angle
Only cold extrusion ispossible
Difficult to contain the high-
pressure fluid

12. Lateral
extrusion
In Lateral Extrusion,the
container is in a vertical
position as shown in the
image and the die is
located on the side. This
process is suitable for
low melting point
material.

13. Impact Extrusion
Impact extrusion is part of the cold extrusion category very similar to
In-direct extrusion and limited to softer metals such as Lead,
Aluminium and copper. As the schematic illustrates, the punch is
pushed down at high speed and has extreme force on the slug to
extrude backwards. The thickness of the Extrude is a function of the
clearance between the punch and the die cavity. The Extrudates are
slid off the punch by the use of a stripper plate.

14. For impact extrusions, a mechanical
press is often used and the part is
formed at a high speed and over a
relatively short stroke
Since the forces acting on the punch
and die are extremely high, tooling
must have sufficient impact
resistance, fatigue resistance and
strength, for extruding metal by the
impact. Impact extrusion can be
divided into the following three
types by the flow of the material.
Forward
Reverse
Combination
In forward impact extrusion, the
metal flows in the same direction that
the force is delivered while it flows in
the opposite direction in reverse
impact extrusion. As the image shows
above, in combination, the metal
flows in both directions.

15. E
X
T
R
U
S
IO
ND
E
F
E
C
T
S
Depending on the material condition and
process variables, extrudates can
develop
many types of defects that could affect the
quality of the end product. These defects
can be grouped under the following three
defects.
Surface
cracking Piping
Internal cracking

16. Presentation made by:
Romil Shankar Gupta (08314803620)
Priyanshu Ranjan (07614803620)
Subject: Production Technology
Subject code: ETME-205
Subject Faculty: Mr. Vikas Sharma
Group: MAE 3rd semester M123