Edexcel AS Engineering Unit 1 - Materials

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Elastomers
Long-chain molecules that can be considered to be coils, when the material is distorted the molecules distort, and when force is released return to their original shape. Coiled molecules give the elastomers their properties.
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Thermoplastic Elastomers (TPE)
Used as they can be processed using conventional equipment associated with thermoplastic polymers, e.g. injection moulding and blow moulding. This reduces the production cycle as no wait for molecular cross-links to form.
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Liquid silicon rubber
Thermosetting elastomer made up of two components, one is a catalyst. The materials must be in liquid form and have to be mixed consistently before processing. Process is a bit like injection moulding.
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Rotational moulding
All rotationally moulded products are hollow, have no sprues however moulded halves must be joined together. Embossing can also be included.
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Thermoforming
Products are made from sheet materials. Stretching occurs making the sides thinner than the base. No sprue marks but marks where product has been removed from sheet. Thermoformed products contain more detail.
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Composites
Produced by mixing together two or more different materials. Properties from each material can be enhanced and utilised.
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Fibre-reinforced-polymers
Adding plasticisers makes it more easy to process. By adding fibres of glass, a tough, rigid, lightweight material is produced.
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Carbon fibre composites
Products are manufactured in a similar way to glass reinforced plastic. Good strength to weight, don't corrode, good fatigue and low thermal expansion.
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Annealing
Heat treatment that reverses internal stresses associated with work hardening. Heat material until crystals glow, making it softer and more ductile. Must be maintained until material soaks, cooled slowly.
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Hardening
Heat treatment changes the way the carbon within the steel affects the strength and hardness of the material. Medium carbon steel is heated to a specific temperature, the carbon moves out of its normal position. If quenched, carbon doesn't move back
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Tempering
Heat treatment that follows hardening of medium and high carbon steels. If left without tempering, the product will be brittle. Reduces amount of brittleness caused by hardening. Structure of materials 'relaxes'
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Normalising
Heat treatment where crystal structure is allowed to become uniform, the crystals become a similar size. Heating a piece of work to a temperature where the crystal structure begins to change. Temperature is maintained until all crystals refined.
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Case Hardening
Method of increasing the hardness of steels that do not have sufficient carbon to affect internal hardening. Involves the addition of carbon to outer skin. Outer surface is hardened leaving a tough core.
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Shape memory alloys
Metals designed to respond to stresses and strains placed on them. Heat treatment gives the alloy memory. When inserted into a blocked or collapsed artery, it will resume original shape when it reaches body temperature, opening up the artery.
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Piezoelectric actuators
When a voltage is applied to the quartz crystal, a small displacement is produced in the material which produces a mechanical force. The stack actuator can be used for micro-positioning applications for fast-acting values.
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Optical fibres
Work by transmitting light as a series of pulses. Significantly greater quantities of data can be transmitted using copper wires, each glass fibre in a cable can carry data.
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Boro-silicate glass
Glass containing boron and used generally for kitchen wear and lab equipment, due to its heat and chemical resistance.
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Heat shrink
Tubing is applied over electrical connections and held in place. Heat is applied and the tubing shrinks, permanently covering the connection, ensuring safety.
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Porcelain
Ceramic material that is often subject to further treatment and must be shaped.
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Other cards in this set

Card 2

Front

Used as they can be processed using conventional equipment associated with thermoplastic polymers, e.g. injection moulding and blow moulding. This reduces the production cycle as no wait for molecular cross-links to form.

Back

Thermoplastic Elastomers (TPE)

Card 3

Front

Thermosetting elastomer made up of two components, one is a catalyst. The materials must be in liquid form and have to be mixed consistently before processing. Process is a bit like injection moulding.

Back

Preview of the back of card 3

Card 4

Front

All rotationally moulded products are hollow, have no sprues however moulded halves must be joined together. Embossing can also be included.

Back

Preview of the back of card 4

Card 5

Front

Products are made from sheet materials. Stretching occurs making the sides thinner than the base. No sprue marks but marks where product has been removed from sheet. Thermoformed products contain more detail.

Back

Preview of the back of card 5
View more cards

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