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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. - PowerPoint PPT Presentation
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Unit 7Manufacturing Processes:Plastics and CompositesPROCESSING 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 moldingInjection moldingExtrusion
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=WaB-dsB1Kfk&NR=1
Processing of Plastics and Composites
OTHER MOLDING PROCESSES:Compression MoldingThermoformingTransfer MoldingRotational Molding
Plastic Thermoforming
http://www.youtube.com/watch?v=U60mdDW5Ulc
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-EI1IOr
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_TDd3bzDeM
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 MatrixPowder-Metallurgy
TechniquesLiquid-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=o0PGDRjoDUc
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 7Manufacturing Processes:Plastics and Composites
PROCESSING OF OTHER INDUSTRIAL MATERIALS
Other Important Industrial Materials
THE MORE IMPORTANT INDUSTRIAL MATERIALS USED IN MANUFACTURING INCLUDE:
GlassCeramicsWood, wood products, and paperFabricsRubberNatural materialsConstructions 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 economicalStrongerLighterEasier 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 7Manufacturing Processes:Plastics and CompositesCORROSION 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 OxidationGalvanic 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.