The extrusion press is an extremely
sophisticated machine. Today there is a vast range of extrusion press sizes
available. To give an idea of the vast range, extrusion presses from 400
tonnes to 1600 tonnes are quite popular. From the common large extruded
profiles to thin-wall extruded profiles, extrusion presses are geared to
meet virtually any demand of the extrusion industry. Modern extrusion
presses incorporates latest and innovative features like infinitely variable
extrusion speeds, PLC control, reducing an operator's need etc. The
importance of the extrusion press can be comprehended from the fact that it
is the press size that determines the size of an extrusion. In this section
Extrusion presses covering the needs of the aluminium extrusion process is
discussed.
Selecting an Extrusion Press
For selecting an extrusion press following factors play a decisive role:
- Required tolerance
- Wall thickness
- Circle size for each shape
- Billet diameter
- Ordered quantity
Aluminium Extrusion Press

To
get a thorough knowledge of the working of an aluminium extrusion press
requires a proper identification of the press parts and and understanding
their use. The principle of the extrusion press is described through the
image below.
An extrusion press is comprised of a front platen and back platen which is
held together by four tie rods. The parts of the extrusion press are as
follows:
| Parts |
Function |
| Main Cylinder |
hydraulic fluid is pumped here for generating ram pressure and
movement. |
| Hydraulic Pressure |
Pressure applied to move the ram forward. |
| Ram |
Steel rod that is attached to main cylinder with dummy block on the
end. |
| Dummy Block |
Tight fitting steel block connected to the ram, seals the billet. |
| Container |
Chamber in an extrusion press needed for holding the billet. |
| Tool stack |
Solid:
 |
| |
Hollow:
 |
| Press leadout table |
Table which supports extrusion |
| Platen Pressure Ring |
Hardened tool steel ring that is inserted into platen for
supporting die stack |
| Run Out Table |
Table at immediate exit of press leadout device |
| Tie rods |
Connects the front and back press platen |
| Canister |
Used in guiding the aluminum extrusions from the die |
| Cradle |
Bears the billet while it gets pushed into extrusion press with the
pressure from the ram. |
| Die oven |
Here dies are heated up to 750° - 900° F for min of 4-6
hours before it is used. |
| Die lock |
Used for locking die into the die holder. |
| Die holder |
Container for tool stack. |
Low Dead Cycle Time Improves Productivity of
Extrusion Press
Dead cycle time on an extrusion press can be defined as the period of
time which remains non-productive during the automatic mode of the
extrusion press. Therefore a challenge to the extrusion process lies in
minimising dead cycle time. Though speed is fundamental, but this must
be got without inducing shocks. Shocks can result in an excessive strain
to the machine, causing all sorts of problems and an excessive down
time. There is need for a compromise as moving the press quickly is
required along with having a full control. The challenge here is to
balance the conflicting requirements. Only a detailed and broad
understanding of all aspects of the machine can result in the perfect
solution. |