Transcript DT1410 - Materials and Processes in Design

Unit 7
Manufacturing Processes:
Plastics and Composites
PROCESSING OF PLASTICS AND COMPOSITES
HTTP://WWW.YOUTUBE.COM/WATCH?V=PSXIHHBZCJK
Processing of Plastics and
Composites

Composites:

A materials category that
consists of a matrix or base
material reinforced by
another material.

The materials maintain
their original identification
but the properties of the
combination are
improved.
Processing of Plastics and
Composites
Composites:
 Matrix:

In composite materials the matrix is the
outer layer of material in which the
reinforcement is contained.

In metals, the background phase in
which another phase is contained;
steel is the matrix in which graphite
flakes are present in gray cast iron.
Processing of Plastics and Composites
Three Types of Composites:
•
•
•
PMCs – (Polymer Matrix Composites)
composite materials that have a
reinforcing material in a polymer matrix.
MMCs – (Metal Matrix Composites)
composite materials that have
reinforcing material in a metallic matrix.
CMCs – (Ceramic Matrix Composites)
composite materials that have
reinforcing material in a ceramic matrix.
Processing of Plastics and
Composites
Three Types of Composites:

Although the three types of
composites have some significant
differences, they are similar in their
general makeup.

Each has a polymer, metallic, or
ceramic matrix.

The reinforcements used inside these
matrices can vary.
Processing of Plastics and
Composites
Reinforcements:

The material added to
the matrix of a
composite to improve
its properties, usually
the strength or stiffness.
Processing of Plastics and
Composites

Composites differ from alloys,
polymers, and ceramic compounds
in that the matrix and reinforcement
are separate from each other.

A material may be added to a
metal, polymer, or ceramic for
strengthening purposes and the
material becomes part of the
original material; reinforcements do
not.
Processing of Plastics and
Composites




Reinforcements:
Vary from short or chopped fibers,
flakes, and particles to filaments
and wires to continuous woven
fibers and honeycombs.
Short, discontinuous reinforcements
increase mechanical strength
Better – continuous reinforcements
which can transfer or redistribute a
load throughout the composite.
Processing of
Plastics and
Composites
PROCESSING METHODS
FOR PLASTICS:
Blow molding
Injection molding
Extrusion
Processing of Plastics and
Composites
Blow Molding:
 Air is used to force a mass
of molten plastic against
the sides of a mold
shaped in the form of the
desired end product.
 Examples include: milk
bottles, soft drink bottles,
etc.

Extrusion Blow Molding
http://www.youtube.com/watch?v=ynsS2afrUzE
Processing of Plastics and
Composites

Injection Molding:
A process in which the material to is
heated sufficiently to become fluid
and then injected under pressure
into a mold cavity.
 There, it is cooled sufficiently to take
the shape of mold, and then
removed from the mold; polymers
and ceramics are processed in this
manner.
 Metal die casting is very similar to
injection molding.

Plastic Injection Molding
http://www.youtube.com/watch?v=jYkKBUFORco
&feature=related
Processing of Plastics and
Composites



Extrusion:
Usually under high pressure and
at elevated temperatures,
forcing materials through a die
containing the shape desired
so that a shaped product is
produced.
Metal and polymer shapes are
produced using this method.
Extrusion
http://www.youtube.com/watch?v=WaBdsB1Kfk&NR=1
Processing of
Plastics and
Composites
OTHER MOLDING
PROCESSES:
Compression Molding
Thermoforming
Transfer Molding
Rotational Molding
Plastic Thermoforming
http://www.youtube.com/watch?v=U60mdDW5Ul
c
Composites

Plastics and composites are fast
replacing metals in a vast array of
manufactured products

Why?

Because of the often high cost of
metals and the large energy
requirements in metal processing, and
the high strength and light weight of
plastics and composites.
Composites
NASA 360 Video
http://www.youtube.com/watch?v=tZhH2B-EI1I
Or
Composite Processing Methods
Methods to create and/or
form the three types of
composites:
 PMCs –





Prepregs
Sheet-molding compound
Molding
Hand layup
Methods for forming Composites

To form PMCs (Polymer Matrix
Composites)

Prepregs

Sheet-molding compound

Molding

Hand layup

Pultrusion

Filament Winding

Lamination
Methods for forming PMCs



Prepregs – an intermediate
preimpregnated product:
Continuous strands of fiber are
carefully aligned and then
coated with the appropriate
thermoplastic or thermoset resin
Made into sheets or tapes used
to form a laminated product
which is heated for curing
Pre-preg Materials
http://www.youtube.com/watch?v=IeST0vfDuhw
&feature=related
Methods for forming PMCs




Sheet-molding compound :
Made from chopped fibers that
are deposited, with random
orientation, on a resin-covered
carrier film, such as
polyethylene.
Another layer of resin covers
the fibers
Then a top sheet or film (e.g.
polyethylene) covers the resin.
Methods for forming PMCs

Sheet-molding compound :

The resulting sandwich is pressed
between rollers and coiled or kept as
flat sheets.

Kept in a controlled environment for
24 hours to cure.
Sheet Molding Compounds
http://www.youtube.com/watch?v=IxaTwSBWz14
Methods for forming PMCs



Molding:
Some molding methods previously
discussed take advantage of the
prepregs and molding compounds
are compression and transfer
molding.
In these cases the reinforcements
are placed into the mold cavities
before or during the application of
the polymer.
Methods for forming PMCs

Hand Layup:

The most common application of
Hand Layup is the use of fiberglass.

Alternating layers of glass fiber fabric
and resin are coated over a mold or
form built in the shape of the desired
end product.

Boat manufacturing is a popular
application.
Automated Composite Lay-up
http://www.youtube.com/watch?v=y_TDd3bzDe
M
Methods for forming PMCs

Pultrusion:

Fibers are pulled or drawn
through a liquid resin and then
through a heated die that
forms the desired shape.
Very much like extrusion except
for the pulling rather than
pushing of the material through
the extrusion die.

Pultrusion
http://www.youtube.com/watch?v=4MoHNZB5b_
Y
Methods for forming PMCs

Filament Winding:

Fiber is wound back and
forth on a cylindrical
form.
This method is used to
produce cylindrically
shaped products such as
tanks or other pressure
vessels.

Filament Winding
http://www.youtube.com/watch?v=iOZl3v4RC18
Methods for forming PMCs

Lamination:

Laminating alternating layers of
resin containing the structural
fiber.
Similar to the technique used
with fiberglass; however, here
the fibers are continuous
throughout the material (in
fiberglass, short pieces of glass
fiber are randomly distributed
throughout the resin).

Methods for
forming
Composites
TO FORM MMCS (METAL
MATRIX COMPOSITES)
Liquid Matrix
Powder-Metallurgy
Techniques
Liquid-Solid Processing
Methods for forming MMCs

Liquid Matrix – the typical MMC
methods involve casting the molten
matrix around solid reinforcements:

Using conventional casting techniques

Or, by using pressurized gas on the
liquid matrix to force it into and around
a preformed reinforcement

Reinforcements are often made of
metal sheet or wire, or a ceramic fiber.
Liquid Matrix Molding
http://www.youtube.com/watch?v=o0PGDRjoDU
c
Methods for forming MMCs




Powder-Metallurgy Techniques
The reinforcement fibers, whiskers,
or particles are carefully mixed
with the powdered metallic matrix
so that they are uniformly
distributed in the mixture.
The mixture is then compacted,
Then sintered
Methods for forming Composites

To form CMCs (Ceramic Matrix
Composites)

The most common process
used in producing CMCs is
slurry infiltration, in which the
slurry contains the ceramic
matrix powder.

A fiber pre-form of the desired
product is hot pressed and
impregnated with the slurry,
then sintered.
Tool and Die Making

Specialty tooling is required to hold
or form plastic materials until steps
are taken in the process that alter
the state of the material to make it
rigid.

Thus, Tool and Die Making – the
processes of building specialty
production tooling to support
manufacture of a product – is an
integral and indispensible part of
forming plastics and composites.
Unit 7
Manufacturing Processes:
Plastics and Composites
PROCESSING OF OTHER INDUSTRIAL MATERIALS
THE MORE IMPORTANT INDUSTRIAL MATERIALS USED
IN MANUFACTURING INCLUDE:
Other Important
Industrial
Materials
Glass
Ceramics
Wood, wood products, and paper
Fabrics
Rubber
Natural materials
Constructions materials
Other Important
Industrial
Materials
NONMETALLIC MATERIALS ARE USED IN
CONJUNCTION WITH METALS IN ALL TYPES OF
PRODUCTS.
IN MANY CASES THESE MATERIALS ARE REPLACING
METALS BECAUSE THEY ARE:
More economical
Stronger
Lighter
Easier to process
Other Important Industrial
Materials

Glass:

Consists primarily of fused silica
(SiO2), a major constituent of
beach sand.
Glass withstands chemical attack
and large variations in
temperature
Lead added to glass provides
shielding from ionizing radiation
Can be fashioned into optical
lenses



Other Important Industrial
Materials

Glass:
A relatively new/developing
technology in the use of glass
is fiber optics.
 Glass Manufacturing
Processes include:
 Pressing
 Blow and Blow Operations
 Press and Blow Operations

Other Important Industrial
Materials

Ceramics:

Ceramic engineering materials are
among the most researched and
developing technologies in
modern production.
Ceramics are made from the
metallic oxides of such metals as
silicon, aluminum, and magnesium.
Clay-based ceramics are
becoming increasingly popular.


Other Important Industrial
Materials

Ceramics:

Important properties of ceramics
include:





Resistance to high heat levels
High strength
Chemically inert
Heat reflective
Can be as hard as diamonds
and as light as aluminum.
Other Important Industrial
Materials

Wood, wood products,
paper:
Structural lumber for
construction
 Plywoods and other
laminates
 Hardwoods (furniture and
flooring)
 Paper

Other Important Industrial
Materials
Fabrics:
 Clothing and
upholstery
 Natural



Cotton, wool, flax, silk
Synthetic

Polyesters, nylons, other
plastic polymers
Other Important Industrial
Materials





Rubber:
Natural rubber or Latex
Derived from the natural
gum of the rubber tree.
Coatings, tubing, hose,
tires, etc.
Processing methods similar
to those of plastics
Other Important Industrial
Materials

Construction Materials:

Those from which structures are built

Engineering Materials:

Those from which products are
made.
Unit 7
Manufacturing Processes:
Plastics and Composites
CORROSION AND PROTECTION OF MATERIALS
Corrosion and Protection of
Materials

Because many materials,
especially metals, react
chemically with their
environments, it is often
necessary to provide
protective coatings and
coverings for them to
prevent or to slow surface
deterioration – corrosion.
Corrosion and
Protection of
Materials
METALS CORRODE BY
TWO MAJOR
PROCESSES:
Direct Oxidation
Galvanic Corrsion
Corrosion and Protection of
Materials

Metal Corrosion – Direct
Oxidation:

Most common metals exist in nature
chemically combined with other
elements as various oxides (ores).

There is a natural tendency for
refined metals to revert to their
natural state.

Because air and water are both
common agents, and since oxygen
makes up such a large percentage
of each …
Corrosion and Protection of
Materials

Metal Corrosion –
Direct Oxidation:

Metals react with the oxygen present
to revert back in varying degrees to
their original oxide (ore) state.

The oxidizing process, direct
oxidation, can occur slowly as
normal rusting, or quickly, as in the
case of steel heated to high
temperatures.
Corrosion and Protection of
Materials

Galvanic Corrosion:

A common type of
corrosion process in
which a potential
difference through an
electrolyte causes a
deplating (corroding)
of one of the metals.
Corrosion and Protection of
Materials

Metal Corrosion –
Galvanic Corrosion:

Galvanic Corrosion gets its name from
the galvanic effect – the electric
potential or voltage that results when
two different metals are connected
electrically in the presence of an
electrolyte.

Electrolyte – a medium, usually a liquid,
capable of conducting electric
current.
Protection of Metals:

There are two principal strategies for
protecting metals subject to direct
oxidation:
1.
Shielding the material from its
environment by coating it with
another material.
2.
Establishing the chemical makeup of
the parent material such that its
environment does not cause it to
degrade.
Protection of Metals:

Cladding:

Adding a layer of one metal to another metal:
To protect against
corrosion
 To improve mechanical
characteristics such as
hard facing
 In some cases to
improve appearance

Protection of Metals:


Plating:
The theory behind plating is that if a
thin layer of anticorrosive material
can be “plated” to a base metal,
then the material can be protected
from corrosion.
Protection of Metals:


Plating:
The process of depositing a layer of
one metal on another, often done
electrically, for the purpose corrosion
protection, appearance, improved
electrical conductivity, and other
engineering requirements.
Protection of Metals:


Plating:
Common plating techniques:
 Galvanizing
 Tin
plating
 Electroplating
 Coating
an object with a
thin layer of a metal
through electrolytic
deposition.