ALUMINIUM

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ALUMINIUM EXTRUSION
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• Extrusion is a manufacturing process where a
  material, often in the form of a billet, is
  pushed and/or drawn through a die to create long
  objects of a fixed cross-section.
• Hollow sections are usually extruded by placing a
  pin or mandrel in the die. Extrusion may be
  continuous (producing indefinitely long material)
  or semi-continuous (repeatedly producing many
  shorter pieces).
• Some materials are hot drawn while others may be
  cold drawn.

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• The feedstock may be forced through the die by
  various methods by an auger, which can be single
  or twin screw, powered by an electric motor by a
  ram, driven by hydraulic pressure (for steel
  alloys and titanium alloys for example), oil
  pressure (for aluminum ) or in other specialised
  processes such as rollers inside a perforated
  drum for the production of many simultaneous
  streams of material.
• Commonly extruded materials are copper (pipe for
  plumbing), aluminium (various extrusion profiles
  for tracks, frames, rails, mullions), steel (rod,
  track), titanium (aircraft components, including
  seat tracks, engine rings, structural parts),
  rubber (tire tread and sidewalls), and a
  multitude of plastics (pipes, rods, rails,
  seals).

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• Aluminium extrusions are made from solid
  aluminium cylinders called billets, which are
  continuously cast from molten aluminium.
• Billets are available in a wide variety of
  alloys, pretreatments and dimensions, depending
  upon the requirements of the manufacturer.
• The extrusion process involves aluminium metal
  being forced through a die with a shaped opening.
  This is made possible by preheating the billet to
  450-500C and then applying a pressure of between
  500 and 700 MPa (equivalent to the pressure found
  at the bottom of a 60km high water tank!).

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• The heated and softened metal is forced against
  the container walls and the die by a hydraulic
  ram, the only exit is the geometric cross-section
  of the die opening, and the metal is squeezed
  out.
• The extrusion leaves the die at a temperature of
  around 500C and the exit temperature is
  carefully controlled in order to achieve
  specified mechanical properties, a high quality
  surface finish and good productivity.

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• The Press
• The press supplies the force necessary to squeeze
  the billet through the extrusion die.
• It consists of
• The container where the billet is put under
  pressure.
• The main cylinder with the ram for pushing the
  billet into the container and through the die.
• The front platen giving counter support to the
  die package.
• The main columns fixing the front platen and the
  cylinder together.
• The die is supported by a series of back dies or
  backers and bolsters for transferring the main
  press load to the front platen.

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The principle of an extrusion press
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An extruded component
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• Applications
• Aluminium extrusions are used throughout the
  construction industry, particularly in window and
  door frame systems, prefabricated houses/building
  structures, roofing and exterior cladding and
  curtain walling. Extrusions are also used in road
  and rail vehicles, airframes and marine
  applications.

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• Steel and titanium extrusions use glass powder as
  a lubricant. This process was invented in France,
  in 1935 by Mr Séjournet. This solution was
  patented throughout the world and helped launch
  industrial steel extrusion. The process was later
  applied to titanium.
• Plastic extrusion commonly uses plastic chip,
  which is heated and extruded in the liquid state,
  then cooled and solidified as it passes through
  the die. In some cases (such as fibre reinforced
  tubes) the extrudate is pulled through a very
  long die, in a process called pultrusion.

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• Extrusion has found a great application in food
  processing. Various products like pastas,
  breakfast cereals, and ready to eat snacks are
  now manufactured by extrusion. Softer foods such
  as meringue have long been piped using pastry
  bags.
• Extrusion simulation tools help to understand
  extrusion process and to optimize development of
  tools and products.
• From "http//en.wikipedia.org/wiki/Extrusion"

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Extrusion Moulding

• Extrusion Moulding is a manufacturing process
  used to make pipes, hoses, drinking straws,
  curtain tracks, rods, and fibres.
• The machine used to extrude materials is very
  similar to an injection moulding machine. A motor
  turns a screw which feeds granules of plastic
  through a heater. The granules melt into a liquid
  which is forced through a die, forming a long
  'tube like' shape. The shape of the die
  determines the shape of the tube. The extrusion
  is then cooled and forms a solid shape. The tube
  may be printed apon, and cut at equal intervals.
  The pieces may be rolled for storage or packed
  together. Shapes that can result from extrusion
  include T-sections, U-sections, square sections,
  I-sections, L-sections and circular sections. One
  of most famous products of extrusion moulding is
  the fiber optic.
• From "http//en.wikipedia.org/wiki/Extrusion_Mould
  ing"

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Impact Extrusion

• A commonly used to make collapsible tubes such as
  toothpaste tubes, cans usually using soft
  materials such as aluminum, lead, tin. Usually a
  small shot of solid material is placed in the die
  and is impacted by a ram, which causes cold flow
  in the material.

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Hydrostatic extrusion is a form of impact
extrusion, uses a fluid hydrostatic pressure
instead of a mechanical ram. This is useful for
making parts out of materials such as Molybdenum,
Tungsten that are relatively hard to extrude
using normal extrusion methods.
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• Extrusion Coating/Lamination

• In extrusion coating and lamination, resin is
  melted and formed into thin hot film, which is
  coated onto a moving, flat substrate such as
  paper, paperboard, metal foil, or plastic film.
  The coated substrate then passes between a set of
  counter-rotating rolls, which press the coating
  onto the substrate to ensure complete contact and
  adhesion.
• Extrusion laminating, also called sandwich
  laminating, is a process related to extrusion
  coating. However, in this case, the extrusion
  coated layer is used as an adhesive layer between
  two or more substrates. A second layer is applied
  to the extrusion coating while it is still hot
  and then the sandwich is pressed together by
  pressure rolls. The extrusion coated layer may
  also serve as a moisture barrier.
• In film lamination, a fabricated film is adhered
  to a moving substrate by application of heat and
  pressure. Film lamination methods include hot
  roll, belt, flame, calender lamination and sheet
  extrusion each type providing a different
  combination of heat and pressure. The laminated
  film can add a functional surface to a substrate,
  or be used between two substrates to stick them
  together.
• Substrates that can be coated with polyolefins
  include paper, paperboard, biaxially-oriented
  polypropylene (BOPP), biaxially-oriented nylon
  (BON), polyester and other plastic films, metal
  foil, fabrics, glass fiber mat, metal sheet and
  flexible foams.

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Lamination with Film Substrates

• Hot Roll/Belt Lamination
• Hot roll and belt lamination use heat and
  pressure as their means of bonding. The Dow
  Chemical Company's (Dow) adhesive films to your
  desired substrate. As shown below, the adhesive
  film and substrate are drawn onto heated rollers
  where the materials are heated and pressed
  together. The heat activates the adhesive film,
  creating a bond when pressed against the
  substrate material. Hot roll and belt lamination
  of Dow's engineered adhesive films allow for
  continuous in-line lamination and an even
  distribution of adhesive.
• With your needs in mind, Dow has developed a
  portfolio of products that bond to a variety of
  substrate materials. Dow's adhesive films are
  composed of thermoplastic polymers that allow
  them to be reheated and molded in subsequent
  operations.

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Flame Lamination

• Flame lamination is often used to bond film
  and/or fabric to soft polyurethane foams. The
  process, shown below, involves the passing of the
  soft foam over an open flame, which creates a
  thin layer of molten polymer. The film and/or
  fabric are quickly pressed against the foam while
  it is still in the molten state. The strength of
  the bond depends upon the film, fabric and foam
  selected and the processing conditions (i.e., gas
  type, flame height and spread, foam burn-off and
  nip pressure).
• Flame lamination is a continuous process that,
  depending on the equipment, adheres fabric or
  film to one or both sides of the foam in a single
  pass. Using The Dow Chemical Company's (Dow)
  engineered adhesive films in your flame
  lamination process will provide an opportunity
  for an even distribution of adhesive.

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Calender Lamination

• Calender lamination of The Dow Chemical Company's
  (Dow) engineered adhesive films allows for
  continuous in-line lamination and provides an
  opportunity for an even distribution of adhesive.
  Calender lamination, similar to hot roll
  lamination, uses a heated three-roll stack to
  heat and activate Dow's adhesive films. The
  adhesive film and substrate, shown below, are
  drawn into a stack of heated rolls where the film
  is heated, activated and applied to the
  substrate. Material selection is critical in
  providing a strong, long-lasting bond between the
  film and the substrate. That's why we encourage
  you to STICK WITH US and work with Dow's
  adhesive films team for your dry adhesive needs.

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Sheet Extrusion

• Thermoplastic polymers are often extruded into a
  sheet for subsequent forming/processing. The Dow
  Chemical Company's (Dow) engineered adhesive
  films allow for in-line lamination and even
  distribution of adhesive in your extrusion
  process. The polymer sheet, shown below, is
  extruded and then brought into contact with the
  adhesive film. The residual heat from the
  extruded sheet activates the adhesive. The
  strength of the bond depends upon material
  selection and processing conditions. That's why
  when you STICK WITH US Dow will work with you to
  determine the best combination of materials for
  your processing conditions

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Profile Extrusion

• Profile and pipe extrusion is normally carried
  out using a single screw extruder which melts and
  conveys the pellets through an annular die. Under
  vacuum (pressure sizing is less common), the
  profile/pipe is then formed by cooling in a water
  bath with its outside diameter dimension
  controlled by a calibration sleeve. The
  profile/pipe is continually taken away from the
  die head by a haul-off and then cut to size.
• Profiles and pipes can vary in diameter with
  corresponding increases in wall thickness.
  Processing pellets into pipes and profiles for
  such a large range of sizes presents different
  extrusion challenges. However, basic pipe
  extrusion requirements hold good for most sizes.