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Mild Steel
Tough, ductile, high tensile strength, rusts easily
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Carbon Steel
Tough, can be hardened and tempered
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Stainless Steel
Tough, resistant to rust and stains
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Cast Iron
Strong in compression, brittle, very high compressive strength
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Wrought Iron
Fibrous, tough, ductile, resistant to rusting
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Aluminium
Ductile, sort, malleable, machines well, very light, corrosion resistant
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Copper
Ductile, malleable, conducts electricity and heat
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Brass
Hard, brittle, conducts electricity
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Silver
Ductile, malleable, resists corrosion
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Lead
Soft, heavy, malleable, loses it shape under pressure
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Zinc
Hard, brittle at most temperatures, malleable between 100-150C, low melting point
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Tin
Malleable, ductile, anti-corrosive
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Tungsten
Extremely hard, brittle, tough
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Thermoplastic Polymer
More flexible, soften when heated, can be reshaped
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Acrylic (PMMA)
Brittle, rigid, easily scratched, softens under heat and can be moulded, susceptible to chemical attack
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Poly vinyl chloride
Can be made tough and hard or soft and flexible, solvent resistant, age hardens
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Polyamide (Nylon)
Tough, flexible, self lubrication and very strong, good solvent resistance
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ABS
Tough, flexible, good impact strength, good insulator, low softening temperature, good mouldability
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Thermosetting polymer
Rigid, brittle, not softened by heating, cannot be reshaped
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Urea Formaldehyde
High tensile strength, low water absorption, non-conductive, good heat resistance
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Epoxy resins
Tough, good chemical and thermal stability, good electrical insulator, good adhesive
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Urea formaldehyde (UF)
Rigid, hard, good strength, brittle, heat resistance, good electrical insulator, used for electrial fittings and adhesives - thermosets
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Rubber
Tough, flexible, good solvent resistance, good elasticity
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Neoprene
Good resistance to UV light, performs well with oils and chemicals, very tough, high resistance to burning, high resistance to damage by bending or twisting, stable over a range of temperatures.
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Shape memory alloys (SMA)
Metal alloys specially developed to remember their shape under specific conditions
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Piezoelectric actuator
When a voltage is applied to quartz crystals a small displacement is produced in the material, this produces a high mechanical force.
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Optical fibres
Optical fibres work by transmitting light as a series of pulses.
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Ductility
The ductility of a material is a measure of the amount by which it can be drawn out in tension before it fractures, drawn into wire.
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Elasticity
The elasticity of a material is a measure of its ability to withstand elastic deformation.
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Malleability
Ability to be bent and worked into shape.
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Hardness
Hardness is the ability to withstand wear, scratching or abrasion.
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Toughness
Ability to withstand impact without fracturing.
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Pressure Die Casting - Cold chamber
Two halves of die brought together. Metal placed in shot sleeve. Hydraulic cylinder forces plunger rod to push metal into cavity. Shape forms in mould. Half of mould opens. Ejector pins release product
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Soft soldering
Stripe cable end, tin cable end, apply flux, fit lug to cable end, apply heat, apply solder
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Hard soldering
Used for products requiring additional strength and in the constructino of products requiring the soldering of a number of mating components - melt between +600 - +800
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Spot welding - Process
Copper electrodes come together, to clamp material in place. Circuit completed, electricity flows. Heat generated, to fuse material together. Electrodes removed, and ‘nugget’ of molten material solidifies forming the joint
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Solid phase welding - ultrasonic
The use of very high frequency vibrations to generate heat within the area to be joined, thereby allowing the materials to fuse together.
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Crimping
***** cable end, position sleeve of lug on cable end, set crimping tool to correct size, apply pressure
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Contact adhesives
Evo-stick. Used for bonding sheet material on contact
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Epoxy resin
Araldite Two. - Joins most materials
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Drop forging
Used where larger numbers of similarly shaped objects are needed. One half of the die is attached to a verticle hammer, large forces are put onto the material being forged, forcing it into the shape of the die.
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Gravity die casting
In this process the molten metal is poured into the dies through runners
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Injection moulding
1. Plastic granules are placed in hopper. 2. Archimedean screw rotates forcing the pastic to the heaters where it melts. 3. hydraulic ram forcers softened polymer theough into the mould. 4. left to cool, mould opened.
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Extrusion
1. Thermoplastic powder is placed in the hopper. 2. The heaters doften the plastic which is forced through the die by the archimedean screw. 3. the plastic is cooled as it exits the die. 4. the product is cut to the required length.
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Blow moulding
1. A tube of heated and softened polymer is extruded vertically downwards. 2. The mould halves close trapped the upper end of the parison. 3. Hot air is then blown into the parison forcing it into the mould. 4. the mould cools the polymer. 5. opened
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Compression moulding
1. slug power material is placed between the mould. 2. the mould is heated. 3. The mould is closed onto the preform and the pressure used will forceout any excess material. 4. the mould is opened and the product can be ejected
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Anodising
Natural barriers. Produced in an electrochemical cell where sulphuric acid solution is the electrolyte
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Plastic coating
the component is heated to above the softening point of the polymer, which is in the form of a fine powder, then dipped into the polymer. The polymer adheres to the heated metal which begins to cool and so the polyer solidifes into a protective layer
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Self-finishing
Plastics are known as self-finishing materials. This means that the quality of the material is very high to ensure that any trimming of flash or excess material is kept to a minimun
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Pressure Die Casting - Hot chamber - 1
Two halves of die brought together. The supply of molten metal is attached to the die casting machine. Shot cylinder provides the power for the injection stroke
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Pressure Die Casting - Hot chamber - 2
Plunger rod goes from shot cylinder down the plunger, and which is in contact with the molten metal. Intake ports allow chamber to fill with liquid metal. Plunger travels past intake ports, cutting off flow of molten liquid to hot chamber
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Pressure Die Casting - Hot chamber - 3
Correct amount of molten material in the chamber, for the ‘shot’ that will be used to fill the mould. Shape forms in mould. Mould opens and releases shaped product
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Pressure Die Casting - Advantages
Can produce intricate shapes. Less waste material produced. Fast production process. Good surface finish
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Pressure Die Casting - Disadvantages
Expensive machine set-up costs. Expensive tooling costs. Only certain materials can be used. Die casting is only suitable for materials with low melting points
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Normalising Carbon Steel - Purpose
Relieve internal stress
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Normalising Carbon Steel - Process
Heated to cherry red temperature (800-900C). Allow to cool. At room temperature/air
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Case hardening low carbon steel - Purpose
Harden the other layer or skin
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Case hardening low carbon steel - Process
Heated to cherry red temperature. Plunged into case hardening compound. Steel heated again to cherry red. Plunged into cold clean water or brine
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Hardening Carbon Steel - Purpose
Increase resistance to wear
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Hardening Carbon Steel - Process
Heat. Until it is red/critical temperature. Quench. Quick cooling process
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Tempering carbon steel - Purpose
To increase toughness/reduce brittleness
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Tempering carbon steel - Process
Heat. Until oxides form. Quench when appropriate oxide colour is visible
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Annealing Carbon Steel - Purpose
To soften/remove internal stresses
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Annealing Carbon Steel - Process
Heat. Until it is red/critical temperature. Allow to cool
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Temporary joining methods
Screw/bolt through each piece of material, with a spring washer, and nylock nut for secure fastening to avoid vibration
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Electroplating - Materials
Tin, Zinc, Nickel, Silver, Gold, Chromium
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Electroplating - Process - 1
Component chemically cleaned. Part to be plated is cathode. Anode to be made of metal to be plated. Electrolyte solution that permits flow of electricity
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Electroplating - Process - 2
DC power supply required. DC power supply oxidises metal atoms from anode. Dissolved metal ions in electrolyte solution attract to cathode
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Sand Casting - Process - 1
Pattern appropriately placed in cope and drag. Sprinkled with parting powder. Sprue pins to create runner and riser. Filled the flask with sand
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Sand Casting - Process - 2
Create gates. Remove pattern and sprue pins. Pour metal and allow to cool. Remove casting and fettle
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Vacuum Forming - Process
Platen placed into vacuum chamber. Plastic sheet clamped into position. Heated. Platen is raised. Switch on compressor/vacuum applied. Moulding cooled. Removed and trimmed
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Galvanising - Advantages
Durable, can be painted, seals cut edges. Prevents corrosion/rusting
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Galvanising - Disadvantages
Only suitable for low carbon steel, expensive
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Galvanising - Process
Work chemically cleaned. Heated to a suitable temperature. Fluxed. Molten zinc. Aluminium added for bright finish. Work dipped. Work cooled. Precautions against heat/PPE. Ventilation
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Painting - Advantages
East to apply, relatively cheap, east to clean, comes in a variety of colours
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Painting - Disadvantages
Can be chipped or cracked, flammable process
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Plastic Coating - Advantages
Corrosion resistance, decorative, non-stick
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Plastic Coating - Disadvantages
Expensive, relatively high thickness
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Hardness Test - Brinell Test
Steel/tungsten carbide ball indenter. Downward load. Test specimen. Indentation
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Other cards in this set

Card 2

Front

Tough, can be hardened and tempered

Back

Carbon Steel

Card 3

Front

Tough, resistant to rust and stains

Back

Preview of the back of card 3

Card 4

Front

Strong in compression, brittle, very high compressive strength

Back

Preview of the back of card 4

Card 5

Front

Fibrous, tough, ductile, resistant to rusting

Back

Preview of the back of card 5
View more cards

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