Sumber: http://en.wikipedia.org/wiki/Extrusion
Extrusion
For the process that creates volcanic rock, see extrusive (geology).
Extruded aluminium; slots allow bars to be joined with special connectors.
Extrusion is a manufacturing process used to create long objects of a fixed crosssectional profile. A material, often in the form of a billet, is pushed and/or drawn through
a die of the desired profile shape. Hollow sections are usually extruded by placing a pin
or piercing mandrel inside of the die, and in some cases positive pressure is applied to the
internal cavities through the pin. Extrusion may be continuous (producing indefinitely
long material) or semi-continuous (producing many short pieces). Some materials are hot
drawn whilst others may be cold drawn.
Extrusion of a round blank through a die
The feedstock may be forced through the die by various methods. A single or twin screw
auger, powered by an electric motor, or a ram, driven by hydraulic pressure (for steel
alloys and titanium alloys for example), oil pressure (for aluminum), or in other
specialized processes such as rollers inside a perforated drum for the production of many
simultaneous streams of material.
Extrusion simulation tools help to understand the extrusion process and to optimize
development of tools and products.
Commonly extruded materials include metals, polymers, ceramics, and foodstuffs.
Metal
Metal extrusion is used by industry for various purposes such as:
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Copper pipe for plumbing
Aluminium extrusion profiles for tracks, frames, rails, and mullions
Steel rods or track
Titanium aircraft components including seat tracks, engine rings, and other
structural parts
Steel and titanium extrusions use glass powder as a lubricant. Invented in France in 1935
by Mr. Séjournet, this process was patented throughout the world and helped launch
industrial steel extrusion, and was later applied to titanium.[citation needed]
Plastic
Sectional view of a plastic extruder showing the components
Plastic extrusion commonly uses plastic chips or pellets, which are usually dried in a
hopper before going to the feed screw. The polymer resin is heated to molten state by a
combination of heating elements and shear heating from the extrusion screw. The screw
forces the resin through a die, forming the resin into the desired shape. The extrudate is
cooled and solidified as it is pulled through the die or water tank. In some cases (such as
fibre-reinforced tubes) the extrudate is pulled through a very long die, in a process called
pultrusion.
A multitude of polymers are used in the production of
plastic tubing,[1] pipes, rods, rails, seals, and
sheetsCeramic
Green Play-Doh with can and accessory extruder toy
Ceramic can also be formed into shapes via extrusion. Terracotta extrusion is used to
produce pipes. Many modern bricks are also manufactured using a brick extrusion
process.[3] Some Play-Doh toy products also make use of extrusion. Play-Doh is a
modeling compound with similar physical properties to clay, but it is not actually
ceramic.
or films.[2]
Food
Extrusion has found great application in food processing. Products such as pastas,
breakfast cereals, Fig Newtons, prefab cookie dough, Sevai, Idiappam, and ready-to-eat
snacks are now manufactured by extrusion. Softer foods such as meringue have long been
"piped" using pastry bags. Extrusion is also used with grains such as wheat, corn, and
rice. In feed industry it is used for process with floating and slow sinking feed
Catalysis
Extrusion is also a very important unit operation in shaping a catalyst. The shape of a
catalyst is directly related to its working conditions. A high specific surface can be
obtained by extrusion.
Roadmarking compound
"Painted" roadmarkings are often done with extruded two- or three-component
compounds. Thermoplastics are also common. This is a low-pressure, high-flow process
with very good contour and thickness control. Extrusion has more or less completely
replaced the older "sliding mould" method. Benefits are much better economy, higher
speed, and general appearance