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POLYMER PROCESSING METHOD - Coggle Diagram
POLYMER PROCESSING METHOD
Calendering
The calender is a machine equipped with two,
three or more heavy internally heated or cooled
rollers. It is usually placed above each other
Example is the skin coating or fabrics
Calendering, process of smoothing and compressing a material during production by passing a single continuous sheet through a number of pairs of heated rolls.
The roller rotated is placed opposite direction
It is used for thermoplastic polymer
Extrusion
Extrusion is a process in which metal or other material is forced through a series of dies to create desired shapes
EXTRUSION It is used in continous semi finished product with uniform cross section
In principle the extrusion process
comprises the forcing of molten material through a shaped die by means of pressure.
It is use to produce tubing and pipes, sheet and film and structural parts
Extrusion is used mainly for Thermoplastics, but Elastomers and Thermosets are also may be extruded.
Compression Molding
Compression Moulding is a method of moulding in which the moulding material, generally preheated, is first placed in an open, heated mould cavity.
The principle of the compression molding can be
outlined as follows
The mould is held between the heated platens of
the hydraulic press
A prepared quantity of molding compound is placed in the mould
The platen closes with sufficient pressure to minimize flash at mould parts line
The compounds softens and flows to shape, chemical cure then occurs as the internal mould temperature becomes high enough
The press is opened and the molding removed.
Usually this process commonly uses for thermosetting materials.
Transfer Molding
Transfer molding is a development of compression molding in which reservoir of the molding compound is located in the mold and upon closure is transferred via runner to the cavities.
it is used to give many small parts easily,to reduce the risk of damage or movement of thin or delicate
mold parts and It is claimed to be faster due to better heat transfer trough runners
Injection Molding
The basic principle of injection molding is to inject molten polymer into a closed mold where it is solidifies to give the product.
Methods
the mould is closed when a short of melt is ready
in the injection unit
injection occurs when the valve opens and the
screw acting as a plunger forces the melt through
the nozzle into the mold
the valves closes and screw rotation starts
the molding in the mould has continue to cool
when ready the press & the molud open and the
molding is removed
the mould closes again and the cycle repeats
Blown Film Extrusion
Blown film extrusion is a technology that is the most common method to make plastic films, especially for the packaging industry. The process involves extruding a tube of molten polymer through a die and inflating to several times its initial diameter to form a thin film bubble.
Methods
the extruded materials flow through a tubular die
the melt flow around a mandrel & exits the die as a tube
a cooling ring is placed at the exit of the die to give the tube some dimensional stability
air is introduced through the back of the die and flow upwards inside the middle of the tube of materials
the tube or bubble, continues to expand, cool and crystallize until the radial (tensile) strength of the plastics equals the pressure of the air inside
the bubble is then forced into a flat sheet by the collapsing guides, and moved into the nips rolls
then it travels down over some rollers and it was sealed
Blow Molding
Blow molding moulding is a specific manufacturing process by which hollow plastic parts are formed and can be joined together. It is also used for forming glass bottles or other hollow shapes.
plastic formation process-manufacture of bottles and hollow-shaped parts
processes that utilize air to shape softened
polymer tubes
3 types of blow molding:Extrusion blow molding,Injection blow molding and Stretch blow molding
Rotational Molding
It is used principally for thermoplastic polymers,
but applications for thermosets and elastomers are becoming more common.
It is an alternative to blow molding for making
large, hollow shapes
to favor more complex external geometries,larger parts & lower production quantities than blow molding
Thermoforming
thermoforming -> reshaping of plastics under
the influence of heat and pressure or vacuum. To shape thermoplastic sheet into discrete parts.
Method
. Heat a thermoplastic sheet until it softens.
Force the hot and pliable material against the contours of a mold by using either mechanical, air or vacuum pressure.
Held against mold and allow to cool, and plastics retains its shape.
process can be defined as simply heating a thermoplastic substrate to a temperature where the substrate becomes soft and flexible
Filament Winding
Process to produce a hollow (usually cylindrical) shape and End products; pressure vessel, storage tanks, and aerospace parts such as helicopter blades.
the fibers may be impregnated with resin before
winding & pre-impregnated
Methods
the fibers are passed through the resin
bath
then, continuously wound onto the mandrel
after number of layers, curing is carried out
in an oven or room temperature
mandrel is removed
Pultrusion
Used to manufacture components with continuous lengths and constants cross-sectional shape (rod,tubes, beam, etc)
Methods
curing takes place in the heated die & oven
then,pulled through the heated die
continuous rovings of the reinforcement are
impregnaated with th resins
puller used to pull the whole system with
certain speed
Continuous process, easily automated (production rates are high, hence it is vey cost effective), variety of shapes are possible.