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Workshop Processes Engineering Materials
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PROPERTIES OF MATERIALS
What do you think the phrase
“a materials properties”
means?
“A MATERIALS INDIVIDUAL CHARACTERISTICS”
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MATERIAL PROPERTIES Mechanical Properties Electromagnetic
Properties Chemical and
Durability Properties Classification of
Materials Ferrous Materials Non Ferrous Materials
Non Metallic Thermoplastics Thermosetting Plastics Organic Materials Smart Materials Symbols/Abbreviations Forms of Supply Identification Coding
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This is the property of a metal, which enables the work to withstand a stretching load without breaking
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TENSILE STRENGTH
The ultimate Tensile Strength (UTS) of a material is the maximum load that each unit of a cross sectional area can carry before it fails. We call this the tensile stress at failure.
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TENSILE STRENGTH
This is greatly defined as the ability of a metal to resist indentation or abrasion. The measurement of hardness is usually based on a metals resistance to the indentation of either a hardened steel ball or a diamond.
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HARDNESS
MALLEABILITY A material is considered Malleable when it can be easily pressed or forged into shape. Most metals have a greater malleability when worked in the hot condition. Rivets used in engineering have to be Malleable so that they can be formed.
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DUCTILEThis term implies that a metal has the ability to be drawn into rod or wire. The ductility of a metal is determined by the amount it will stretch lengthways before it becomes brittle and fails. Because ductility reduces as the temperature of the metal is increased, metals are usually drawn in the cold state.
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BRITTLENESS
This is the opposite of plasticity. It refers to the tendency of metal to break suddenly when under load without any prior warnings. Many metals in their cast state will fracture when subjected to a large enough impact. In some metals an increase in temperature can reduce brittleness, while in others it can be caused to occur.
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This is the ability of a metal to withstand loads, which are not in the same line of force.
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SHEAR STRENGTH
COMPRESSIVE STRENGTH
This is the property that enables a metal to withstand compressive loading without fracture
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PLASTICITY
This measures the ability of a metal to be formed into a given shape without fracture. As very few metals are plastic in cold form state heat is used in most cases to increase plasticity
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ELECTRICAL CONDUCTIVITY
This is the ease with which a material conducts electricity. The most common material used for this is copper. Copper has a high electrical conductivity which allows current to flow, it is also cheaper than gold which also has a very high EC.
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This is the ability of a material to withstand an electrical current. Plastics have a very low EC and a high EI which will not allow a current to flow. This is why plastics can be used as a good insulator
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ELECTRICAL INSULATION
FERROMAGNETISM
Any metal that contains large amounts of Iron, Nickel or Colbalt can be made magnetic. Metals that contain these elements can be made to make permanent and electromagnets
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If you heat a magnet to approximately 800°C the metals magnetism will disappear. This point is known as the CURIE TEMPERATURE Of the material
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FERROMAGNETISM
This is the ability of a material to resist chemical attack
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CORROSION RESISTANCE
SOLVENT RESISTANCESome rubbers and plastics are attacked by certain chemicals. These chemicals are called solvents. Materials that are not effected by solvents are said to have a High Solvent Resistence
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If we are designing equipment that may use Petrol, Diesel or certain lubricating oils in its operation. We have to ensure that we chose materials that may contact these substances that have a HIGH SOLVENT RESISTANCE
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SOLVENT RESISTANCE
ENVIRONMENTAL DEGRADATION
If we leave certain materials out in the elements they will degrade.
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Wood will rot if exposed to moisture. Some plastics will turn brittle if exposed to UV light. Certain Rubbers will also degrade when exposed to UV light.We can overcome this by choosing the correct materials or protecting the materials we select for various applications
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ENVIRONMENTAL DEGRADATION
We can protect wood by painting or varnishing it before use.If we are using plastic for guttering, we could use one colored black as black plastic tends to stay more flexible for longer.
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ENVIRONMENTAL DEGRADATION
If the application requires metals to be used we can protect them from corrosion by using jointing compounds between mating surfaces, or we could clad the metal in another metal so that it acts as a barrier (Galvanized Zinc Plating). Or we could just simply paint the surface of the metal
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ENVIRONMENTAL DEGRADATION
WEAR RESISTANCE
As we know hardness is a property of Wear Resistance. However Wear Resistance can also be looked at as the durability of the property. Machine components that come into contact with each other need to have high Wear Resistance.
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WEAR RESISTANCE
Examples of components that require high Wear Resistance are:
Bearing Surfaces Gear Teeth Sealing/Forming plates Guillotine Blades
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CLASSIFICATION OF MATERIALS
Materials used in engineering are divided into 3 main groupsThese groups depend upon the properties which the materials have.The 3 classifications are:
Ferrous materialsNon-ferrous materialsNon-metallic materials
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Iron is the main constituent of FERROUS MATERIALS. They are called Ferrous as the Latin for iron is “Ferrum”
In its purest form Iron is a soft grey metal that has poor casting properties when molten and it will not give a good surface finish when machined.
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FERROUS MATERIALS
To overcome this and improve its properties we add small amounts of Carbon, this also gives us a wide range of Cast Irons and SteelsExamples are:
Cast ironLow carbon steelMedium carbon steelHigh carbon steelAlloy steel (stainless steel, high speed steel)
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FERROUS MATERIALS
Cast iron contains between 2-4% carbon
This means that it can be poured into complicated shapes easily when molten
The Carbon in Cast Iron is in the form of Graphite, this Graphite also makes the material easier to machine, when 2 pieces of Cast Iron rub together this Graphite acts as a lubricant. Because of this we can say that Cast Iron is self lubricating
Cast contains large voids in its make-up which adds to its brittleness (excess carbon)
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CAST IRON
Cast Iron does have a disadvantage, unless it is specially treated (ANNEALED developed in France in the 18th century) to make it more malleable. It is brittle and therefore should not be subjected to high tensile loading. It is however good at withstanding compressive loading
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CAST IRON
It is made by reducing iron ore in a blast furnace. The liquid iron is cast, or poured and hardened, into crude ingots called pigs, and the pigs are subsequently re-melted along with scrap and alloying elements in cupola furnaces and recast into molds for producing a variety of products.
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CAST IRON
Examples of uses are: Machine Beds Surface Tables/Angle Plates Extreme compression components Housings Crank Shafts/Cases Frames
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CAST IRON
STEEL
Steel is one of the most common ferrous metalsIt is available in many different forms and can be ordered in two different forms:
Black or
BrightSteel is dull grey in appearance until machined or treated
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Black Steel
Black steel is the cheaper of the twoIt has a black scaly surface that needs to be machined
Bright Steel
Bright steel is more expensiveIt is possible to leave the outer surface un-machined
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STEEL
PLAIN CARBON-STEEL
There are 3 main different varieties of steel and they are determined by the amount of iron and carbon present in each. They are:
Low-carbon steelMedium-carbon steelHigh-carbon steel
By adding different amounts of carbon to steel we can change its properties they are then called Plain Carbon-steel
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LOW CARBON STEEL
More commonly known as “mild steel”
It contains between 0.1% - 0.3% carbon
It has good Tensile Strength
It has a fair degree of malleability and ductility when cold worked
When heated to a bright red colour (1490°F 810°C it becomes more malleable and ductile which means it can be pressed or rolled easily into shape
It is cheap which makes it deal for low level engineering
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Mild Steel is one of the most widely used materials in engineering. Examples of its uses are:
Girders Ships Hulls Gates and Railings Pipes General Workshop purposes
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LOW CARBON STEEL
Contains between 0.3% - 0.8% carbon
Tougher and stronger than low-carbon steel, making them hard to cut or form
The higher carbon content means that it can be heat treated (using hardening and tempering) to gain improved properties
This make them more expensive
They are difficult to work in a cold state and could crack.
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MEDIUM CARBON STEEL
Properties: Strong Can be hardened by heat
treatment.
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MEDIUM CARBON STEEL
Examples of use are: Hammers Chisels Punches Gears/Couplings Components that require a high
degree of wear and impact resistance.
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MEDIUM CARBON STEEL
HIGH CARBON STEEL
High-carbon steels are the hardest steels and the most expensive to produce but they are less ductile
Contains between 0.8% - 1.4% carbon
They respond well to heat treatment.
Very poor at cold working and fracture easily in this state
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Properties: Strong Can be made very hard by heat
treatment
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HIGH CARBON STEEL
Examples of use are:Wood Cutting ChiselsFilesTaps and DiesCraft Knives
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HIGH CARBON STEEL
STAINLESS STEEL
In addition to the iron and carbon in steels, Stainless Steel has Chromium and Nickel in its make-up. It is part of the Ferrous Metal groups called ALLOY STEELS. The extra added constituents mean that Stainless Steel is more corrosion resistant than other Steels
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Properties: Corrosion Resistant. Strong
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STAINLESS STEEL
Examples of use are: Food Preparation Counters Medical Applications Pharmaceutical Applications Cutlery Automotive Trim
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STAINLESS STEEL
NON-FERROUS MATERIALS
Non-Ferrous materials DO NOT CONTAIN IRON
Examples are:
Aluminium
Copper
Brass
Tin
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ALUMINIUM
Aluminium is the most common non-ferrous material.
Aluminium is light grey in appearance, unless it has been treated or made into an alloy, silvery when polished.
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Properties:
Light weight
Good conductivity
Corrosion resistance
Malleable
High weight to strength ratio
In its natural state is weak and ductile
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ALUMINIUM
Examples of uses are: Cylinder Heads Small Machine parts Tools Utensils Castings/Housings
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ALUMINIUM
Copper Aluminum Alloy with only a 5-10% Aluminum content.
Strong Fluid when molten
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ALUMINIUM BRONZE
Examples of uses are: Boiler and Condenser components
in heating systems Chemical plant componnets Boat Propellers
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ALUMINIUM BRONZE
As Aluminum use has grown there has been a wide range of Aluminum Alloys developed. By adding small amounts Silicon, Copper, Magnesium and Manganese you can greatly increase the strength of Aluminum. Within Aviation the most widley used Aluminum Alloy is DURALUMIN. This 4% Copper and 1% Magnesium added to it
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ALUMINIUM ALLOYS
Properties: Ductile Malleable Good Strength Good Fluidity when molten
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ALUMINIUM ALLOYS
Examples of uses: Electrical powerlines Ladders Aircraft and Motor Vehicle
components Light sand and Die Casting
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ALUMINIUM ALLOYS
LEAD
Lead is a heavy grey metal that is very malleable, it has a low tensile strength but it is highly resistant to corrosion and chemical attack. It conducts both heat and electricity with ease.
When mixed with Tin it produces a range of alloys known as SOFT SOLDERS
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Properties: Extremely soft. Heavy Low tensile strength Highly resistant to corrosion Malleable
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LEAD
Examples of uses are: Roofing. Chemical Tank liners. Balance Weights. Jointing Compounds for electrical
joints.
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LEAD
COPPER
Copper has excellent conductivity
Lightweight & very malleable
Corrosion Resistant
Excellent conductor of heat and electricity
Average Tensile Strength (this can be improved by alloying with other metals)
Copper is the main ingredient in many alloys, such as brass
In its natural state it is orangey-red appearance
Polishes well and easily joined
More costly than Aluminium.
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Examples of use are: Cooking Utensils Water Pipes Electric Cables/Wires.
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COPPER
TIN
Tin is soft and malleable Highly corrosion resistant
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Examples of use are: Tin Cans Protective coating for Mild Steel this
is known as TINPLATE Used in the production of some
solders Used with Copper to produce
Bronzes
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TIN
ZINC
Zinc is a soft brittle metal It is highly corrosion resistant. When used to “coat” other metals
it has a feathery appearance
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ZINC
Examples of uses are: Acting as a protective coating for
Mild Steel (this is then said to be Galvanized)
Building Materials Buckets/Waste Bins
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STANDARD BRASS
Standard Brass is made up of 65% copper & 35% Zinc
Cheaper than most other brass alloys
Standard brass is gold/yellow in appearance
The High Copper content means that Brass is very Ductile
The High Zinc content means that it is more fluid when molten making it suitable for casting
It is only possible to harden brass alloy through cold working (work hardening).
Heating softens the brass (the annealing processes) 69
Examples of uses: Tubes Cartridge Cases Castings
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STANDARD BRASS
Bronze is an alloy of Copper an Tin the amounts of each vary from 96% Copper and 4% Tin to 78% Copper to 22% Tin
The high Copper content means that it is malleable, ductile and elastic when forming when cold.
The high Tin content means that it is more fluid when molten allowing it to pour easily
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BRONZE
Examples of uses are: High Copper content
Electrical contactsInstrument Parts
High Tin contentPump and Valve components
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BRONZE
NON-METALLIC MATERIALS
Non-Metallic materials contain NO METALS
Examples are:
Wood
Thermosetting plastics
Thermoplastics
Rubber
Ceramics
Glass
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PLASTICS
There are many different types available. They all fall into 1 of 2 different categories
Thermosetting plastics
Thermoplastics
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THERMOPLASTICS Thermoplastics do not undergo a chemical change when heated, this means they can be reheated and re-softened over and over again
These plastics are not as hard as thermosetting plastics but they do resist impact better and are tougher
Used for tubing, film, cable insulation
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Polychloroethene AKA Poly Vinyl Chloride (PVC).
PVC is a very good material, It can be made hard or soft and it can be used in a variety of ways dependent on its application.
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THERMOPLASTICS
PVC This material can be made solvent
resistant for use in manufacturing When made hard and tough it can
be used in the manufacture of window frames, guttering and drain pipes
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THERMOPLASTICS
PVC When soft it will age harden over
time. Used as cable and wire insulation, or as upholstery. Both types can be coloured to suit the use they are intended for.
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THERMOPLASTICS
Polyamide (AKA Nylon) Nylon has a multitude of uses. It is
a tough strong flexible material that is solvent resistant. The downside to this material is that is absorbs water and it will deteriorate when exposed to the elements
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THERMOPLASTICS
Examples of uses are: Bearings Gears Cams Brush Bristles Textiles
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THERMOPLASTICS
Methyl-2 methylpropenoate (AKA Perspex)
A strong rigid transparent material that is easily scratched, a material that is not resistant to petrol based solvent attack.Perspex can be easily softened and moulded into complex forms
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THERMOPLASTICS
Examples of uses are: Aircraft Canopies Aircraft transparencies Lenses Corrugated Roofing lights Machine guards
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THERMOPLASTICS
Polytetroflouroethane (AKA PTFE or Teflon)This material has a very smooth surface with a low coefficient of friction which means it is excellent bearing material.
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THERMOPLASTICS
Properties of PTFE Teflon. Tough Flexible Heat Resistant Solvent Resistant Low coefficient of friction
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THERMOPLASTICS
Examples of uses are: Bearings Seals and Gaskets in hydraulic
systems Tape Non stick coatings
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THERMOPLASTICS
Thermosetting plastics or thermo-sets as they are sometimes known start life as either a liquid OR a powder. They sometimes have fillers added to the mixture to improve the mechanical properties of the material. They are molded into shape using heat and pressure. It is whilst this process is happening that they undergo a chemical change.
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THERMOSETTING PLASTICS
The polymers within the material become cross-linked together once they are formed they cannot be broken.
This means that once we have shaped the Thermo-set we cann6t change it
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THERMOSETTING PLASTICS
THERMOSETTING PLASTICS Thermosetting plastics do undergo a chemical change when they are heated, and once this change takes place the plastic can never again be softened.
This means thermosetting plastics tend to be hard and brittle
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They are used mainly when heat is going to be present during operation.
Mainly used in resin base (Epoxy Resins) plastics like glass enforced plastic (fibre-glass), and for mouldings
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THERMOSETTING PLASTICS
Phenolic Resin (AKA Bakelite) Not that commonly used anymore
this was one of the first Thermo-sets. It has limited decorative value as its colors are limited to either brown or black
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THERMOSETTING PLASTICS
Properties of Bakelite: Hard Solvent resistant Good electrical insulator Machinable
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THERMOSETTING PLASTICS
Examples of uses are: Electrical fittings Electrical components Insulated handles Old radio outercases
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THERMOSETTING PLASTICS
Urea methanol resin (AKA Formica) This is very similar to Bakelite
however it is naturally transparent
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THERMOSETTING PLASTICS
Properties of Formica are: Can be coloured Hard Solvent resistant Good electrical insulator
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THERMOSETTING PLASTICS
Examples of uses of Formica are: Electrical fittings Kitchen fittings Bathroom fittings Kitchen hardware Laminates
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THERMOSETTING PLASTICS
Methanal- Melamine resin (AKA Melamine)
Again this material has similar properties to both Bakelite and Formica, however when moulded this material has a smooth finish
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THERMOSETTING PLASTICS
Properties of Melamine Harder than both Bakelite and
Formica More heat resistant than both
Bakelite and Formica Can be moulded and machined
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THERMOSETTING PLASTICS
Examples of uses are: Electrical equipment Tableware Control knobs Handles Laminates
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THERMOSETTING PLASTICS
EPOXY RESIN
Epoxy resins come in a variety of forms (SYSTEMS) and are made of:-
• EPOXY RESIN • HARDENER They can cure rapidly or slowly, permitting
the selection of any form designed for an application. Depending on the epoxy selected, cure can be achieved at any temperature range from 5°C to over 200°C. Epoxy resin systems
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They can be poured into moulds or applied to Glass Fibre, Carbon Fiber or Kevlar Fiber matting in /on moulds.
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EPOXY RESIN
GLASS FIBRE
Glass Fibre Reinforced Plastic (GFRP) has a much higher elasticity than metals, GFRP was only used structurally where this characteristic was beneficial, or of little consequence.
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Examples of uses for GFRP are: Radomes and aerials (as a result of its Radar transparency)
Helicopter rotor blades Skin of honeycomb structure
where stiffness is either unimportant or imparted sub-structurally.
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GLASS FIBRE
CARBON FIBRE
Carbon fibre is produced by a special burning process. The result of this process are fibres which are 8 to 10 microns in diameter, (a human hair is 60 microns in diameter,).
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Carbon, whilst possessing enormous tensile strength along the length of the fibre are relatively easily damaged in shear. They are formed into a ‘tow’ (twist free bundle fibres). And a size (epoxy based coating) is applied.
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CARBON FIBRE
This protects the fibres and also helps bonding to the relevant resin system at a later stage.
The tows can also be woven into matting's making them easier to handle and work with, the resin system being added later (after mixing) in a messy process known as wet lay-up.
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CARBON FIBRE
In addition to conventional dry fibres, carbon can be supplied in a form known as “pre-preg”. In this condition the manufacturer has already added the resin system. The advantages are that health and safety risks are lower, in so far as no resin mixing is required (fume extraction etc.)
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CARBON FIBRE
Disadvantages are that specialist storage facilities are required to prolong the life of the pre-preg (typically 30 days at 20° C; up to 1 year at -18° C.).
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CARBON FIBRE
When carbon fibre is used as a repair medium for metallic structures, galvanic corrosion can be a problem. Scrim cloths, adhesive films and Ballatine balls are the common barrier methods of alleviating this problem.
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CARBON FIBRE
Properties of Carbon Fibre are: High strength High stiffness Low density Good fatigue Good vibration resistance X-ray transparency an Chemical inertness Brittle
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CARBON FIBRE
Examples of uses of Carbon Fibre are:
Aircraft Wings Aircraft Structures Formula 1 Nosecones/Rear Wings
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CARBON FIBRE
Kevlar is a yellow coloured Aramid fibre (an organic polymer). The structural grade Kevlar fibre, Kevlar 49, is characterized by excellent tensile strength and toughness but significantly inferior compressive strength compared to carbon.
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KEVLAR
The stiffness, density and cost of Kevlar are all lower than carbon; hence Kevlar may be found in many secondary structures as a hybrid with fibreglass.
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KEVLAR
Advantages of Kevlar The primary reason Kevlar is
becoming widespread in the aircraft industry is the materials excellent impact resistance. Although damage will occur under impact, it is localised and will not spread, unlike laminates of carbon or glass.
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KEVLAR
The result of an impact test in which a panel of glass fibre and a panel of Kevlar of equal stiffness were repeatedly hit to a load of 907kg, using a hemispherical rod, were as follows:
5 ply GFRP failed after 836 hits 5 ply Kevlar survived 10,000 hits
with only minor damage
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KEVLAR
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A Kevlar composite will fail via a ‘NON-CATASTROPHIC YIELDING MECHANISM’, (similar to metal), rather than the fracture mechanism typical of glass or carbon composites. When impacted, Kevlar has an initial elastic phase, where the material stretches to absorb the “impact energy” rather than fracturing of the structure as occurs in carbon and glass.
KEVLAR
This ability of Kevlar to withstand impact and continuous static loads results in excellent fatigue resistance.
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KEVLAR
Examples of uses for Kevlar are: Aircraft applications. Ranging from
interior mouldings, wing and body fairings, access panels, leading and trailing edges, landing gear doors, instrument panels and radomes, propellers, cargo bay liners and containers, engine noise absorption pads and engine blade containment rings.
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KEVLAR
Properties of Kevlar are: fibres can deteriorate under ultra-
violet light. Excellent fatigue resistance. Impact resistant. Energy absorbent. Poor compressive strength. Good Tensile Strength
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KEVLAR
ORGANIC MATERIALS
When using the term Organic Materials we are referring to materials that have come from nature. Such as:
Leather Sinew Bone Timber
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HARDWOODS
We get our hardwoods from broad leafed trees. The term hardwood can be misleading. It does not mean that they are “harder” than softwoods but because of their relatively short fibres they tend to be denser than softwoods
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Hardwood Density (kg/m³)
Moisture content %
Uses
Elm 550 12 Lock Gates Piles Outdoor Cladding
Oak 720 12 Ship Building House Building Furniture
Mahogany 720 12 Furniture
Ash 810 12 Vehicle Bodies Tool Handles
Teak 900 11 Indoor/Outdoor Furniture
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HARDWOODS
SOFTWOODS
About 80% of the wood used today is Softwood. It comes from quick growing trees with long spikey leaves such as conifers. These woods tend to have long fibres making them less dense than hardwoods
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Softwood Density (kg/m³)
Moisture content %
Uses
Spruce 420 13 General Construction work Boxes Cases
Scots Pine 510 12 General Construction work Furniture Flooring
Douglas Fir 530 12 Heavy Construction work Plywood
Larch 810 12 Outdoor Purposes Mining General Purposes
SOFTWOODS
These composites fall into 3 catorgries Laminated Boards
Particle Boards Fibre Boards
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WOOD COMPOSITES
WOOD COMPOSITES
Plywood is the most commonly known Laminated Board. It consists of thin layers of wood bonded together. To prevent warping and to give strength these boards are layered in such a way that their grains run 90° to each other.
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Particle Board is made from recycled materials such as sawdust or shavings that have been bonded together to form Chip Board. This Chip Board is used in the manufacturer of Kitchen Units
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WOOD COMPOSITES
Fibre Board is made from compressed fibres of differing length that have been bonded together. They include both Hardboards and Medium Density Fibreboard (MDF)
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WOOD COMPOSITES
WHAT ARE SMART MATERIALS?
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SMART MATERIALS
Smart materials are materials that CAN undergo a change to their properties WHEN there is a change to its working environment
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SMART MATERIALS
What Smart Materials do you know of in common everyday use?
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Piezoelectric Materials When you apply a force to certain
materials such as quartz you are causing a potential difference to be set up across the faces of the material at 90° to the force. This effect is known as the PIEZOELECTRIC EFFECT
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SMART MATERIALS
This effect is used in pressure sensors on sealing machines used in pharmaceutical manufacture, vibration recorders used on Health Usage Monitoring Systems and microphones
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SMART MATERIALS
We can also use this effect in reverse if we apply a voltage. This produces a stress in the material which can cause it to twist or indeed bend by a controlled amount. Aircraft manufactures are using these smart materials in the manufacture of new aircraft.
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SMART MATERIALS
SHAPE MEMORY ALLOYS (AKA MEMORY ALLOYS)
When deformed these materials will return to their original shape when heated OR when the external force is removed.
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SMART MATERIALS
These alloys contain special combinations of Copper, Zinc, Nickel, Aluminium and Titanium. They are used in medical applications as VASCULAR STENTS that are place in blocked or narrowing blood vessels. They use your bodies temperature to enlarge which opens the vessels improving flow. They are also used in the manufacture of Dental braces where the bodies temperature causes them to contract and exert pressure on the teeth
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SMART MATERIALS
MAGNETO-RHEOSTATIC FLUIDS Within these fluids are microscopic
magnetic particles that are suspended in a type of oil. When we apply a magnetic force these particle align themselves along the magnetic flux lines. This greatly restricts the flow of the fluid. This can cause the fluids viscosity to rapidly change from a fluid to almost a solid
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SMART MATERIALS
These fluids have been used in fast acting clutches, shock absorbers and flow control systems.
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SMART MATERIALS
ELECTRO-RHEOSTATIC FLUIDS These are very similar to Magneto-
Rheostatic Fluids in that they will become viscous in the presence of a static electric field, again they line themselves up with the flux lines which opposes the flow of the fluid
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SMART MATERIALS
These liquids are extremely fast acting and can change from a fluid to a stiff gel and back again in milliseconds. They are used in similar applications to Magneto-Rheostatic Fluids
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SMART MATERIALS
Material Recognition Assessment
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HOW ARE MATERIALS IDENTIFIED
As engineers you will need to be able to interpret the material requirements given on engineering drawings, plans and processes . This information is often given in abbreviated form.
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There may be occasions that you will have to draw material from stores when the storekeeper is not present for these reasons you have to have an understanding of how to identify different materials used within engineering.
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HOW ARE MATERIALS IDENTIFIED
The constituents of the different metals and alloys in use are specified by the British Standards Institution (BSI),they will also state the most appropriate use and operating conditions (especially high temperatures/pressures) for the material
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IDENTIFICATION CODING
There is also the European BS EN 10277 standards for steels
Previous identification methods for steels include:
BS 970 issued in 1991 BS 970 issued in 1955
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IDENTIFICATION CODING
IDENTIFICATION CODING
Material BS EN 10277:1999
BS 970:1991 BS 970:1995
Mild Steel 1.7021 210M15 EN 23M
Medium Carbon Steel
1.0511 080M40 EN 8
Tool Steel 1.3505 534A99 EN 31
Free Cutting Steel
1.0715 230M07 EN 1A
High Tensile Steel
1.0407/1.1148 605M36T EN 16T
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Supplier Manufactures often have their own coding systems, metal bars are often painted on their ends so that they can be easily identified at a glance, some use tags that correlate to certain information. Whatever system is used in your work place YOU should familiarise yourself with it.
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IDENTIFICATION CODING
Material Colour Code
Mild Steel Red
Medium Carbon Steel Yellow
High Carbon Steel Purple/White
Free Cutting Steel Green
High Tensile Steel White
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IDENTIFICATION CODING
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Certificates of Conformity, (COCs) are issued by the Manufacture of the material and come in the form of a certificate, A-4 size, which should be attached to the material
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IDENTIFICATION CODING
The COC itself gives a range of information of which some examples are:
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IDENTIFICATION CODING
The Manufactures Name and address. The Manufactures QA Stamp. Dimensions and thickness of material. Composition of material. COC reference number. Batch number. Reference to which material conforms to, usually in the form of material specification.
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IDENTIFICATION CODING
Batch Numbers are similar to use as serial numbers of components but are no longer stamped/etched or painted onto materials such as sheet metals due to the fact that the process of stamping such numbers induces stress, and paint can easily be erased in transit. Batch numbers are now found on the COC.
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IDENTIFICATION CODING
SYMBOLS AND ABBREVIATIONS
The following is part of a typical title block used on an engineering drawing, containing the information on the material to be used
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TITLE BLOCK
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Title
Connector
Scale 1:1
Projection
Drawn: FB
Date: 25.10.13
Date: 25.10.13
Checked: MJ
Material:BDMS toBS070:040A.10
The material specified in this example is
BRIGHT DRAWN MILD STEEL BDMS The other information BS 070:040A.10
relates to it’s British Standards (BS) specification. This specifies the % of each of the ingredients of a material and its recommended uses
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TITLE BLOCK
The drawing itself may also give you some further information, such as the surface finish, heat treatment, surface hardness.
For Bar Stock, Sheet or wire it may also give you some dimensional information
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TITLE BLOCK
ABBREVILE TABLE FOR SOME COMMON METALS
Abbreviation Material
CI Cast Iron
SG Iron Spheroidal graphite Cast Iron
MS Mild Steel
BDMS Bright Drawn Mild Steel
CRMS Cold Rolled Mild Steel
SS Stainless Steel
Alum Aluminium
Dural Duralumin
Phos Bronze Phospher Bronze
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Abbreviation/Symbol Interpretation
ISO International Organisation for Standardisation
BS British Standard
BSI British Standard Institution
BH Brinell Hardness number
VPN Vickers pyramid hardness number
SWG Standard Wire Gauge
Ø 50 50 mm diameter
MS, Hex Hd Bolt-M8x1.25x50 Mild Steel Hexagonal headed, metric bolt 8mm diameter,1,25mm pitch,50mm long 158
ABBREVILE TABLE FOR SOME COMMON METALS
MEANINGS
Surface hardness is tested by pressing some form of indenter into the surface of the material and then using the dimensions of the indentation to calculate a hardness number
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Standard Wire Guage (SWG) is a means of classifiying a wires diameter or the thickness of sheet metal.
The higher the number the thinner the material.
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MEANINGS
FORMS OF SUPPLY
How do engineering materials begin their life?
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Metals begin their life as ores Plastics are derived from the by
products of oil distillation and from vegetable sources.
Timber is obtained from Forestry.
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FORMS OF SUPPLY
The ores for metals are smelted or otherwise extracted and produced into ingots. These then go on to secondary processing. This may occur at the same site.
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FORMS OF SUPPLY
Plastics are converted into powders, granules and resins
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FORMS OF SUPPLY
Timber is transported to mills for cutting and seasoning before use.
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FORMS OF SUPPLY
Once all of the manufacturing processes have been undertaken the materials are stored ready to be distributed to various engineering companies and merchants for use
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FORMS OF SUPPLY
METALS POLYMERS TIMBER
Ingots Powders Planks
Castings Granules Boards
Forgings Resins Composite Sheets
Pressings Sheet Rods
Bars Mouldings
Sheet Pipe/Tube
Plate Film
Pipe/Tube
Wire
Rolled Sections
Extrusions
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FORMS OF SUPPLY