22-03-2012, 11:46 AM
Extrusion
04_Extrusion.pdf (Size: 1.45 MB / Downloads: 125)
Objjectiive
• This chapter aims to provide useful information on different
extrusions processes, which can be mainly divided into direct
and indirect extrusion processes. This also includes basic
background on hydrostatic extrusion, extrusions of tubing and
production of seamless pipe and tubing.
• Principal background and concept of extrusion will be
addressed along with the utilisation of mathematical approaches
to understand the calculation of extrusion load.
• The role of lubricants on the deformation process which results
in the improvement in extrusion products will be provided.
• Finally, defects and its solutions occurring in the extrusion
process will be emphasised.
What iis extrusiion?
Extrusion is the process by which a block/billet of metal is reduced
in cross section by forcing it to flow through a die orifice under
high pressure.
• In general, extrusion is used to
produce cylindrical bars or hollow
tubes or for the starting stock for
drawn rod, cold extrusion or forged
products.
• Most metals are hot extruded
due to large amount of forces
required in extrusion. Complex
shape can be extruded from the
more readily extrudable metals
such as aluminium.
* The products obtained are also called extrusion.
Extrusiion products
Example: Aluminium extrusions are used in
commercial and domestic buildings for window
and door frame systems, prefabricated
houses/building structures, roofing and exterior
cladding, curtain walling, shop fronts, etc.
Furthermore, extrusions are also used in
transport for airframes, road and rail vehicles
and in marine applications.