Section 2 - Intro to Materials + Systems Flashcards
Overview of different properties of materials
- The properties of a material determine what is useful for. Thinking about these properties are super important when it comes to designing a new project product
- Materials have working properties
- They also have physical properties
What are some examples of working properties of materials?
- strength
- hardness
- toughness
- elasticity
- malleability
- ductility
What is strength of a material?
Strength is the ability to withstand forces without breaking. For example:
- The rope in a tug-of-war resists pulling forces
- Bridge supports resist compression forces
- A surfboard resists forces trying to bend it
- Fabrics that contain Kevlar fibres are really strong and resistant to abrasion - so they’re used in motorcycle clothing
What is hardness of a material?
- This is the ability to resign scratching, abrasion or denting.
- It’s very important for tools that cut, like files and drills.
What is toughness of a material?
- If a material is tough, it is hard to break or snap – the material changes shape a bit instead.
- Armour and bullet-proof vests need to be tough.
What is elasticity of a material?
- Elastic materials can stretch and bend and return to their original shape.
- A spring has good elasticity
What is malleability of a material?
- Materials that are malleable can be bent and shaped.
- Most metals are malleable – they can be hammered into thin sheets without breaking.
What is ductility of a material?
Ductile materials can be drawn into a wire
What are some examples of physical properties of materials?
- Electrical conductivity
- Thermal conductivity
- Fusibility
- Density
- Absorbency
What is electrical conductivity of a material?
- Electrical conductors let electricity travel through them easily. Electrical insulators don’t.
- Electrical wires need to be conductors, but the coating around the wires must be insulating.
- Metals are good electrical conductors. Plastics tend to be good insulators.
- Some fabrics are blended or coated with an electrical conductor material (e.g. a metal) – gloves can have electrically conductive fingertips so you can still operate touch screens with them on.
What is electrical conductivity of a material?
- Thermal conductors let heat travel through them easily. Thermal insulators don’t.
- Metals are good thermal conductors. Plastic, board and wood are good thermal insulators.
- Pans must be made from good thermal conductors, but the handles are often made from thermal insulators.
What is fusibility of a material?
- Materials with a high fusibility have low melting points – only a small amount of heating is required to convert these materials to liquids.
- For example, solder has a high fusibility – this allows it to melt before the metals that are being soldered together (which have a lower fusibility).
What is density of a material?
- The density of a material is a measure of its mass per unit volume.
- A table made of solid metal would likely be heavier to carry than an identical table made of plastic. This is because metal tends to be denser.
- Density often has units of kg/m^3
What is absorbency of a material?
- Fibres and fabrics that are absorbent are good at soaking up moisture. Paper towels are a good example.
- Absorbent materials can be dyed easily, but they also dry slower and are vulnerable to stains.
- Natural fibres (e.g. wool, cotton and cellulose fibres that make up paper) are absorbent.
- Synthetic fibres (e.g. polyester and lycra) are not absorbent.
What are properties of non-metals?
Nonmetals tend to have a very different set of physical properties to metals.
Compared to metals, they are generally:
- More brittle
- Not always solid at room temperature
- Poor electrical conductors
- Dull looking
- Less dense
What are properties of metals?
Metals tend to have similar basic physical properties to one another. They’re usually:
- Strong
- Malleable
- Good conductors of heat electricity
- Not very fusible (have high melting and boiling points)
What is an alloy?
- Alloys are a mixture of two or more metals, or a metal mix with one or more elements.
- The alloy is a new material – it has different properties to the individual metal it’s made of.
- Alloys are developed to have a specific set of properties. This is often done with future products in mind.
What are the 5 types of paper?
- cartridge paper
- layout paper
- tracing paper
- grid paper
- bleed-proof paper
What is cartridge paper?
It is high-quality and has a textured surface – it is great for sketching with different drawing materials like pencils, crayons and inks.
What is layout paper?
It is thin and translucent (you can see light through it) and is used for general design work – particularly sketching ideas.
What is tracing paper?
It is semi transparent, and is used to copy images.
What is grid paper?
It may have a square or isometric pattern printed on it. Square grid paper is useful for orthographic and scale drawings and isometric paper is good for isometric drawings.
What is bleed-proof paper?
It is used by designers when drawing with felt tip and a marker pens. The ink doesn’t spread out (bleed) – it stays put.
What is the weight of paper and board measured in?
The weight of paper and board is measured in gsm (grams per square metre).
Above 200 gsm, it’s not paper anymore – it’s board (also known as card or cardboard).
Why is board often used in packaging?
Because of its low cost compared to other packaging materials, and it’s high strength-to-weight ratio
What are the 6 types of boards?
- solid white board
- ink jet card
- corrugated card
- duplex board
- foam core board
- foil-lined board
What is solid white board?
It has a high quality bleach surface, which is ideal for printing. It’s used loads for primary packaging – packaging for individual items.
What is ink jet card?
It is card used for ink jet printing. It’s designed so that the ink doesn’t bleed – this allows the printed image to be sharply defined and have a high quality.
What is corrugated card?
It is made up of a fluted inner core sandwiched between two outer layers (the liner), which can be printed on. The flutes add strength and rigidity – this is useful in a lot of secondary packaging to protect products during transit.
What is duplex board?
It has a different colour and texture on each side. It’s often used where only one surface is seen, so that only one side needs to be smooth for printing. This board is often used for food packaging.
What is foam core board?
It is made by sandwiching expanded polystyrene foam between 2 thin layers of card. It’s stiff, lightweight and the thin outer card layer can be scored. It’s good for making models and mounting posters.
What is foil-lined board?
It is a board with an aluminium foil lining. It is often used to package food – the foil keeps flavours in, and air and moisture out.
What is primary packaging?
packaging for individual items
What is secondary packaging?
it is used to contain lots of the same item
What are the 2 types of wood?
hardwood and softwood
What is timber?
It is sawn chunks of solid wood that are used as building materials.
What are softwoods?
Softwoods grow in colder climates and are fast-growing – this makes them fairly cheap and readily accessible. The trees have leaves like needles, are usually evergreen and have cones (e.g. pine).
What are examples of softwoods?
Pine, spruce, larch
What are pine trees like?
Pine is yellow with brown streaks. It’s quite strong and cheap – but knotty, which makes it harder to work with. It’s used for telegraph poles, fences and cheap furniture.