Materials Flashcards
Strength
Ability to withstand forces such as pulling, squashing and twisting.
Toughness/Brittleness
Ability to withstand sudden impacts.
Hardness
Ability to resist scratches or wear.
Ductility
Ability to be deformed by stretching or bending.
Malleability
Ability to be compresses and squeezed into shape.
Chemical Resistance
Ability to resist corrosion or attack by chemicals.
Conductor
Material can carry electrical current and/or heat.
Insulator
Material blocks or inhibits electrical current and/or heat.
Physical Properties
Size, Density, Surface texture, Friction/slipperiness.
Durability
Withstands wear and tear.
Flexibility
Bends and twists easily.
Strength-to-weight Ratio
A measure of a material’s strength compared to its lightness.
Identifying Materials - Tests
Materials can be subjected to scientific tests:
Weight/density,
Strain and stress,
Chemical composition,
Heating
Identifying Materials - Symbols
Some materials carry identifying symbols.
Float Test - Weight and Density
Materials have different densities which can be tested by floating or sinking the material in liquid such as oil or water.
Scratch Test - Hardness
Since materials have different hardness, their exact nature can be determined by scratching the surface and noticing how easy/difficult it is.
Flame Test - Material Type
When burned, metals create different coloured flames.
Magnetic Test - Ferromagnetic Metals
Some metals can be identified by using magnets. Iron, Cobalt, Nickel, etc.
Advantages of Wood
Non-toxic,
Very versatile,
Strong,
Inexpensive,
Sustainable if grown properly,
Easy to shape and machine
Disadvantages of Wood
Some aren’t durable,
Weatherproofing requires a coating,
Some woods are running out
Hardwoods
From deciduous trees (they have leaves). Generally tougher and more durable than softwoods, less sustainable.
Beech (Hardwood)
Properties: Hard, Strong, Tough. Bends-well. Mid-brown colour.
Uses: High quality furniture, toys, handles, veneers.
Ash (Hardwood)
Properties: Flexible, Tough, Bends well. Yellow colour.
Uses: Tool handles, cricket bats, snooker cues.
Mahogany (Hardwood)
Properties: Medium weight, quite strong, easy to work with and durable. Wraps easily. Dark brown colour.
Uses: High-quality furniture, shop fittings, veneers.
Oak (Hardwood)
Properties: Hard, tough, heavy and durable. Hardens with age. Mid to dark brown.
Uses: High-quality furniture, garden furniture, boat fitting and decks.
Softwoods
From coniferous trees (they have needles). Generally less expensive than hardwoods. Quick-growing trees means that softwoods are usually more sustainable.
Red Pine (Softwood)
Properties: Straight grained but knotty. Quite strong, easy to work with. Red-orange in colour.
Uses: Building, construction, requires protection for outdoor work.
Spruce (Softwood)
Properties: Straight grained with few knots. Quite strong, easy to work with. Not durable. Pale yellow colour.
Uses: Internal furniture - cupboards, kitchen cabinets.
Manufactured Boards
Made in factories from wood and glue. Flat sheets.
Plywood (Manufactured Board)
Properties: Very strong and stable, easy to machine and work. Light/white-yellow colour.
Uses: Furniture, construction and joinery.
Flexi-Ply (Manufactured Board)
Properties: Same as plywood but flexible. Can be bent and curved.
Uses: Curved furniture, high quality cabinets.
Veneered Boards (Manufactured Board)
Properties: Property will be as core material typically chipboard, blockboard or MDF.
Uses: Furniture, worktops, desks, kitchen cupboards
Blockboard (Manufactured Board)
Properties: Heavy and strong board made from blocks of wood glued together. Usually veneered.
Uses: Worktops, fire door
MDF (Manufactured Board)
Properties: High strength, easily machined. Takes paint well. Not water proof.
Uses: Furniture, construction and joinery.
Chipboard (Manufactured Board)
Properties: Heavy, and strength is dependent on the density of wood chip.
Uses: Kitchen cabinets, worktops and carcasses for furniture.
Hardboard (Manufactured Board)
Properties: Like hard cardboard. Weak and brittle.
Uses: Low-cost furniture parts: drawer bottoms, cupboard backings.
Advantages of Plastics
They are low cost,
Very versatile,
Able to be coloured,
Able to be transparent,
Have a range of properties,
Easy to shape and machine
Disadvantages of Plastics
They are polluting,
Manufacture is also polluting,
They can’t be recycled,
Can degrade over time
Thermoplastics
Plastics which can be heated and shaped many times.
ABS (Thermoplastic)
Properties: Strong, light, durable, scratch-resistant, chemical-resistant.
Uses: Toys, kitchenware, furniture, crash helmets, flight cases.
Acrylic (Thermoplastic)
Properties: Stiff, hard, durable, easily scratched and brittle. Coloured or clear.
Uses: Substitute for glass, lenses, signs, cases and jewellery.
Nylon (Thermoplastic)
Properties: Durable, tough, easily machined, self-lubricating.
Uses: Bearings, bristles, clothing, gears.
Polypropylene (Thermoplastic)
Properties: Tough, semi-rigid, chemical-resistant, can be formed into hinges, electrical resistance.
Uses: Shampoo lids, cases, bottle caps.
High-Density Polythene (Thermoplastic)
Properties: Tough, chemical resistant.
Uses: Rigid - buckets, bowls, containers
Low-Density Polythene (Thermoplastic)
Properties: Soft, pliable, electrical insulator.
Uses: Flexible - bags (“poly bags”), bottles, cable sheaths.
Plasticised PVC (Thermoplastic)
Properties: Soft, flexible, electrical insulator.
Uses: Hoses, cable insulation.
uPVC (Thermoplastic)
Properties: Rigid, weatherproof, abrasive resistance.
Uses: Bottles, gutters, window frames.
Polystyrene (Thermoplastic)
Properties: Light, stiff, water resistant, thermal insulator.
Uses: Food packaging, containers, DVD cases, protective packaging.
Thermosets
Plastic which can be heated and shaped only once.
Urea Formaldehyde (Thermosets)
Properties: Stiff, strong, hard, brittle. Excellent electrical insulator.
Uses: Electrical fittings (sockets and plugs), handles, door knobs.
Melamine Formaldehyde (Thermosets)
Properties: Waterproof, chemical resistance, hard, scratch resistant.
Uses: Laminated worktops, chopping boards, tableware (plates, cups).
Elastomers
Plastics which are ‘rubbery’ and springy. Can be thermoplastics or thermosets.
Rubber/Silicone (Elastomers)
Properties: Flexible, water resistant, chemical resistant, impact resistant.
Uses: Seals, cooking utensils (silicone), toys.
Additives
Mixed with plastics to improve their properties. For example, last longer, easier to work, more colourful.
Common Additives
Colourings,
UV stabilisers,
Lubricants,
Flame retardants
Fillers
Added to plastics to ‘bulk’ them out and reduce the amount of polymer being used. Can also increase hardness.
Common Fillers
Glass bends,
Metal powder,
Sawdust,
Ceramic powder
Metals
Can be ferrous or non-ferrous,
Shiny when polished,
Excellent conductors of heat and electricity,
Malleable - can be squeezed or hammered flat,
Ductile - can be drawn into thin wires,
Easy to recycle
Metals (Types)
Ferrous - Contains iron.
Non-Ferrous - Contains no iron.
Alloys
An alloy is a mixture of two or more metals.
Often have more desirable or better properties than pure metals.
Better corrosion resistance, greater strength, improved conductivity.
Alloy Examples
Brass - Copper & Zinc
Mild Steel - Iron & Carbon
Stainless Steel - Iron, Chromium & Carbon
Advantages of Metals
Some are low cost,
They are abundant,
Malleable and ductile,
Resistant to heat,
Great strength,
Excellent conductors of heat and electricity
Disadvantages of Metals
Can be heavy,
Some metals corrode badly,
Finite resource,
Not chemical resistant
Zinc (Non-Ferrous Metal)
Properties: Soft, ductile and malleable over 100 Degrees Celsius. High resistance to corrosion.
Uses: Galvanising other metals to weather-proof them.
Tin (Non-Ferrous Metal)
Properties: Soft, ductile and heavy. High resistance to corrosion.
Uses: Coating steel food cans, solder.
Aluminium (Non-Ferrous Metal)
Properties: Strong and lightweight, corrosion resistant. Can be dyed and coloured.
Uses: Ladders, drinks cans, aircraft bodies, car structure.
Copper (Non-Ferrous Metal)
Properties: Tough, ductile and malleable, Excellent electrical conductor. Expensive. Bronze colour.
Uses: Coins, pipes for plumbing, electrical wires.
Brass (Non-Ferrous Alloy)
Properties: Hard, casts well, easily joined, polishes well, corrosion resistant.
Uses: Hinges, door handles, furniture hardware, decorative fittings.
Iron/Cast Iron (Ferrous Metal)
Properties: Relatively inexpensive, brittle and casts well. Strong but prone to rust.
Uses: Engine parts, vices, machine tools.
Mild Steel (Ferrous Alloy)
Properties: Malleable and ductile, easy to work with.
Uses: Car bodies, nuts, bolts, screws, tubes, springs, small tools.
High Speed Steel (Ferrous Alloy)
Properties: Malleable and ductile. Can be hardened and tempered.
Uses: Cutting tools, files, blades, knives, drill bits.
Stainless Steel (Ferrous Alloy)
Properties: Hard and tough. Corrosion resistant.
Uses: Outdoor frames, cutlery, boat fittings, sinks.
Composites
Mixture of two separate materials. They combine to give a material with properties that are different from the original components.
Glass Reinforced Polymer
Matrix: Thermoset,
Reinforcer: Loose or woven glass fibres,
Uses: Sculptures, amusement rides, boat hulls, aircraft bodies
Properties: Lightweight, very strong and corrosion resistant. Able to form many shapes. Smooth outer surface.
Carbon Fibre Reinforced Polymer
Matrix: Thermoset,
Reinforcer: Woven carbon fibres,
Uses: Car parts, aircraft parts, fishing rods, body armour
Properties: Very light, very strong and corrosion resistant. Resists high temperatures.
Advantages of Composites
Mega strong,
Mega lightweight,
Corrosion resistant,
Very stable,
Can be made into almost any shape
Disadvantages of Composites
They are not recyclable,
Hazardous to manufacture,
Difficult to repair
Selecting and Justifying Materials
Design Factors: Function, performance, ergonomics, aesthetics, market, safety.
Material Factors: Properties, costs, availability, production volume, product complexity, environmental.
Justification: Choose a material, be specific, full sentences, explain.
