fiber reinforced plastic composite material...
TRANSCRIPT
Fiber Reinforced Plastic
Composite Material Processing
Mechanics of Composites (ME 4129)
Content*
Pulforming
Thermo-forming
Injection Molding
Blow Molding
* Only remaining topics are included here.
Pulforming
It is the subsequent step to make semicircular profile
from length and to change cross section at one or more location.
This process is used to manufacture components of irregular shapes.
The long parts that are curved instead of being and whose cross section vary throughout length.
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Pulforming
2 Source: counterpointmagazine.org
Fig. 1: Pultrution Process
Pulforming
3 Source: Fundamental of modern Manufacturing, M.P. Groover, 4ed.
Fig. 2: Pulforming Process
Applications
Beams and girders used in roof structures
Bridges
Ladders
Frameworks
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Thermo-Forming
Thermoforming is a manufacturing process in which
a composite sheet is heated to a pliable forming temperature,
formed to a specific shape in a mold.
Thermoforming is a plastic processing technique, so it is a
polymer processing technique in which the thermoplastic
sheets are formed with the application of heat and pressure
in a mold.
The components manufactured are thin sheets and thin walled
sections.
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Keywords Thin Sheets
Heat
Pressure
Mould
Thermoplastic sheets
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Classification
Vaccum Thermoforming
Pressure Thermoforming
Matched Die Thermoforming
Vacuum Thermoforming
7 Source: techminy.com
Fig. 3: Vaccum Thermoforming
Vacuum Thermoforming
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Vaccum is applied to form the heated thermoplastic sheet.
The thermoplastic sheet is clamped with help of claming unit.
Sheet is heated till it is soften and then vaccum is applied
quickly.
Air is pulled out quickly between mold cavity and sheet
Vaccum is created and sheet takes the shape of mold cavity.
The formed product is cooled and ejected from mold cavity.
Steps:
Pressure Thermoforming
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It is similar to vaccum thermoforming.
The air pressure required is higher as same
compared to vaccum thermoforming.
The heated plastic sheet is placed on the mold
surface and then air-pressure is applied instantly on
the sheet.
A high pressure is developed between soft steel and
pressure box.
Steps:
Pressure Thermoforming
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Due to high pressure the preheated plastic sheet
deforms instantly and takes the shape of mould
cavity.
The deformed plastic sheet is allowed to cool for
some time.
The formed part upon solidification is ejected.
The appendages are trim and polished for end use
Pressure Thermoforming
11 Source: https://bioplasticsnews.com/
Fig. 4: Mechanical Thermoforming
Fig. 5: Pressure Thermoforming
Matched Die-forming
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It is also named as mechanical forming.
Mold comprises of two parts i.e. die and punch.
Themoplastic sheet is soften by application of heat.
Preheated sheet is placed on die and mechanical
pressure is applied through punch.
Matched Die-forming
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Air between die and sheet is removed using vaccum
pump.
Subsequently sheet takes the shape of mould.
The formed part upon cooling takes shape of mold.
The appendages are trim and polished for end use
ABS Plastics
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A common thermoformed plastic, ABS is comprised of
acrylonitrile, styrene and butadiene.
Applications
Protective headgear
Golf club heads
Musical instruments, like recorders
Toys
HIPS Plastics
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Applications
Packing peanuts
Food and drink Items
Bottles and disposable cutlery
HIPS plastic are also known as polystyrene.
Characteristics
Clear and Brittle
Used for protective packaging
HDPE Plastics
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Applications
Plastic bags and bottles
Water Pipes
Cable installation
HDPE (high-density) polyethylene is a stronger
thermoformed plastic comprised of petroleum
Characteristics
Exceptional strength to density ratio.
PVC Plastics
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Applications
Sewage pipes
Electric cables
Flooring
Faux leather clothing
polyvinyl chloride is created with suspension
polymerization
Characteristics
Strong, hard structure and rigid plastic.
Can withstand extreme temp. and pressure
PET Plastics
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Applications
Synthetic Fibers
Bottle Production
polyethylene terephthalate is dried to increase its
resistance.
Characteristics
Have great resistance and barriers
Most recycled types of plastics
Advantages
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Initial cost of setup is low
Production cost is low
Thermal stresses are low
Posses good dimensional stability
Flexibility in design
Rapid prototyping
Disadvantages
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Finishing in terms of trimming is required
Surface finish is of poor quality.
Products may not have uniform thickness
Few materials can be used
Limited to thin plastic sheets
Injection Molding
It is a manufacturing process for producing parts by
injecting molten material into a mold.
Injection molding can be performed using wide range of materials as metals, glasses, thermoplastic , thermosetting polymers etc.
The general process includes heating of material and feeding the same into a heated barrel, mixing then injecting into a mold cavity.
The charge is then cooled and hardened to the configuration of the cavity.
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Injection Molding
22 Source: ecomolding.com
Fig. 6: Steps in Injection Molding Process
Injection Molding
23 Source: injectionmouldingworld.com
Fig. 7: Steps in Injection Molding Process
Types of Injection Molding
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Reciprocating screw type injection molding
Plunger type injection molding
Hand injection molding
Hand Injection Molding
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Hand level is used to move plunger.
Plunger then applies the pressure to molten plastic.
Molten plastic is pushed in mold cavity and takes the shape of die.
Manu. of Small plastic buttons for shirts.
Fig. 8: Hand Injection Molding Machine
Source: plastictoday.com
Plunger type injection molding
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Fig. 9: Plunger type injection molding Machine
Source: argomold.com
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Powder or the raw material comes from hopper.
The raw material enters into cylinder.
Same is heated through cylinders through entire length of cylinder.
The heated plastic then melts and same is pushed by piston in the molds.
Plunger type injection molding
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Mold consist two parts movable and fixed
Fixed part is attached to nozzle and movable part can slide in longitudinal direction.
The cooling of finished product can be liquid or air.
The plunger force is regulated by hydraulic means.
Plunger type injection molding
Reciprocating Screw Inj. Molding
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Fig. 10: Reciprocating injection molding Machine
Source: adplastics.co.uk/
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Rotating screw pushes molten plastic through
nozzle into the mold.
Movable platen slides over the tie rods and
moves in longitudinal direction.
Raw material comes from the feed hooper and
is heated and melted in barel.
Reciprocating Screw Inj. Molding
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The difference between plunger type and
screw type injection molding is through which
molten metal is pushed in mold cavity.
In plunger type injection mechanism we use
piston or plunger.
In screw type injection molding we use
rotating screw.
Reciprocating Screw Inj. Molding
Advantages
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Detailed Features and Complex Geometry
High Efficiency
Enhanced strength
Ability to use multiple material simultaneously
Automation to save manufacturing cost
Advantages
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Wide range of material can be used.
Low scrap rates
Good Color Control
Reduced finishing requirement
Product consistency
Enhanced Strength
Disadvantages
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High tooling costs and long set up lead times
Part design restrictions
Small runs of parts can be costly
Rapid cooling is often required
Experienced operator
Applications
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Wire Spools
Packaging
Bottle caps
Automotive Dashboards
Pocket Combs
Toys, Musical Instruments, One Piece Chairs
Blow Molding
Blow molding is a molding process used to create
hollow objects made of plastic. Like other molding processes, it involves the use of heated, liquid material that’s forced into a mold cavity under pressure.
Blow molding, also known as blow moulding, is a molding process in which heated plastic is blown into a mold cavity to create a hollow object.
The defining characteristic of a blow molding is that it’s used to create hollow objects.
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Blow Molding
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Fig. 11: Blow molding process
Source: https://in.pinterest.com/
Blow Molding Vs Injection Molding
Blow molding is used to create hollow objects,
whereas injection molding is used to create solid objects.
For hollow objects, only blow molding offers a fast and effective solution.
For injection, the plastic is sealed in the injection chamber and mold throughout the entire process.
The blow mold begins when the mold is removed from the plastic, which gives some more freedom for the blowing to expand the product.
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Types of Blow Molding
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Extrusion blow molding
Injection blow molding
Extrusion blow molding
It is simple blow molding process.
A hot tube of plastic material, called a parison, is dropped from an extruder and captured in a water cooled mold.
Once the molds are closed, air is injected through the top or the neck of the container, similar to blowing up a ballon.
The hot plastic material is blown up and touches the
walls of the mold the material "freezes"
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EBM-Advantages
Lower mold cost
It is simple blow molding process.
Multi layer capability
Window stripe on bottles, angled and offset necks,
handleware, and multiple necks
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EBM-Disadvantages
With increase in dia. of mold, the corners and areas
with the thinnest walls have close tolerance.
Extrusion molding has longer cooling times than
injection molding.
It is not possible to mold in holes except after the
molding.
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EBM-Applications
Plastic bottles, jars, and Jugs
Plastics, including HDPE, PVC, PC, PP, and PETG
Bottles requiring multi-layer technologies
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Injection blow molding(IBM)
It is process of inflating a hot, hollow thermoplastic
parison inside a closed mold so that it takes shape of
mold cavity.
Injecting the plastic into tube to form a plastic tube.
Blow the tube into a cavity mold to form the hollow
part.
Ejecting the part
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IBM-Advantages
Exact neck dimension.
Thick even walls.
Invisible parting lines.
No scrap, No trimming and No waste.
Not much auxiliary equipment required.
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IBM-Disadvantages
The process is more expensive than extrusion blow
molding.
There is a compromise between preform wall
thickness and blow up ratio.
The process is not suitable for manufacturing of
bottles with handles.
Prior design is required before any process can
begin. 46
IBM-Application
Medical devices such as surgical syringes.
Open container like buckets.
Plastic housing of different tools.
Daily use products such as tooth brushes.
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