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PLASTIC FORMING TECHNIQUES - Coggle Diagram
PLASTIC FORMING TECHNIQUES
EXTRUSION
An extrusion is the continuous semifinished product with uniform cross
section.
In principle, extrusion process comprises thr forcing of molten materials through a shaped die with pressure.
Eg: Windshield wiper and squeegee blades, plastic rain gutters, and automotive trim
CALENDERING
A machine equipped with two, three or
more heavy internally or cooled rollers
The rollers will rotates in opposite directions
and operate at even or uneven speeds
In this process, the extrudate is extruded
directly into the nip area between the rolls
Eg: Rubber sheet
INJECTION MOLDING
The basic principle of injection molding to inject molten polymer into a closed mold where it is solidifies to give the product.
The mould is closed which a short of melts is ready in the injection unit. Next, the valves closes and screw rotation starts which pressure develope against the closed nozzles of the screw moves backwards to accumulate a fresh shot of melt in front
Eg: bottle caps, automotive parts and components and toys
FILAMENT WINDING
A process to produce vessel, storage
tanks and aerospace
The method is the fibers were passed through the resin bath. Then, it will continously wound onto the mandrels
After number of layers, curing are carried out in an oven or RT.
Mandrels are removed
Eg: pipes, golf clubs, Reverse Osmosis Membrane Housings, oars, bicycle forks, bicycle rims
BLOWN FILM EXTRUSION
The extruded materials flow through a tubular die. Then, the melt flow around a mandrel and exits the die as a tube. After that, a cooling ring is placed at the exits back of the die to give some dimensional stability.
The tube or bubbles continues to expand,cool and crystallize until the radial strength is equal with air outside.
Eg: Plastic wrap
COMPRESSION MOLDING
The principle of the compression molding is the mould is held between the heated platens of the hydraulic press.Next, a prepared quantity of moulding compoundare place in the mould and the platens closes with sufficient pressure to minimize flash at mould part line.
The process employs thermosetting resin in a partially cured stage either in the form of granules
Ceramics and thermoset plastics such as melamine and phenolics, and fiber composites and cork are the example of products.
TRANSFER MOLDING
It is developement of compression molding which is molding compound is located in the mold and upon closure is transferred via runner to the cavities
Used to give many small parts easily and to reduce the damaged and claimed to be faster due to better heat transfer through runner
Eg: gas valves, electronic circuits, and sparkplugs with wires
ROTATIONAL MOLDING
The rotational molding uses of gravity inside the rotating mold to achieve a hollow form.
Principally for thermoplastic polymer.
The process consists of predetermined amount of polymer loaded into cavity of split mould. The mould is heated and simultaneously rotated on two perpendicular axis. Then the mould is open and the part is unloaded.
Eg: storage tanks
THERMOFORMING
The thermoforming is a process which reshaping a plastic under the influance of heat and pressure or vacuum.
Thermoforming is amanufacturing process which for utilize thermoplastic sheet or film.
Basic principle is heat a thermoplastic sheet until it softens. Next, force the hot pliable materials against the contours of a mould.
Eg: Plastics Materials Used in the Food Industry
PULTRUSION
Pultrusion is used to manufacture components with continuous length and constant cross-sectional shape
Pultrusion method which is the continuous roving of the reinforcement are impregnated with the resins. Next, it will be pulled the heated die, Then, curing take place in heated die and oven. Lastly puller are used to pull whole system with ceratin speed.
-Eg: various rods and bar section, ladder side rails
BLOW MOLDING
Blow molding process are used to melt the resin which done in extruder to form into a cylinder or tube
The parison is placed inside the mould and inflated to make sure the plastic are push outwards against cavity wall
Eg: water bottles, shampoo and other small bottles