DT Year 11 Flashcards
Properties of coniferous trees/ soft woods
Mainly grow in cooler countries Looser grain structure Often used in building materials Grow faster and are relatively cheaper Usually softer and easier to work with Trees grow tall and straight to make them easier to cut long straight planks Evergreen, do not lose leaves
Common softwoods
Pine
Spruce
Redwoods
Properties of hardwoods/ deciduous
Usually quite hard Grow in temperate climates Broad leaved, produce seeds as fruit Slower growing trees ( can take 100s years ) Relatively more expensive
Common hardwoods
Ash Beech Mahogany Oak Balsa
Uses of common hardwoods
Ash: furniture Beech: furniture Mahogany: expensive furniture Oak: furniture Balsa: modelling
Why is timber considered sustainable
It is harvested responsibly and inly certain trees are cut. Trees can regrow whereas metals cannot. Timber can be recycled
What does the FSC do
Stands for: Forest Stewardship Council
Makes sure trees are harvested safely and responsibly
Cut down trees from certain areas and then leave to regrow for 30 years
Track timber to the buyer
About metals and where they come from
Ores are naturally formed rocks that contain metals
Metal takes millions of years to form and are extracted from the Earth
Will eventually run out
Mining is the process to extract metals
Mining disrupts surrounding environments and the atmospheres
Most metals can be recycled
What are the two categories can metals be sorted into?
Ferrous: contains iron, magnetic
Non ferrous: does not contain iron, not magnetic
Characteristics of ferrous metals
Contain iron
Magnetic, helps sort during recycline
Carbon content makes it prone to corrosion when exposed to moisture and oxygen e.g: rust
Properties: hardness, malleabel - more carbon less malleable
Characteristics of non ferrous metals
Doesn’t contain iron - Desirable due to malleability and resistance to corrosion
Majority are not magnetic, good for electronic devices and wiring
Aluminium is the most widely used metal
Exmples of ferrous metals
Cast iron
Low carbon steel
High carbon steel
Example of non ferrous metals
Aluminium- used for aircraft, window frames, saucepans, insulation, pistons and cranks
Copper - can be combine with tin to make bronze, bronze can be used for: ships’ propellers, musical instruments, bearings
Zinc: used in alloys, cosmetics, pharmaceuticals, batteries, electrical equipment
What are polymers
Made from refining crude oil
Frac
Chemical reactions produce a tionlarge number of identical molecules called monomers
Monomers can be combined together to form long strands called polymers
All plastics are types of polymers
Properties of polymers
Coloured: can be produced in any colour Self finishing Shaped: can be formed into unusual shaped Formed: formed in a number of ways Reasonable cost Versatile working properties
Properties of thermoforming plastics
Can be reheated and therefore shaped in various ways
Become mouldable after reheating as they do not undergo significant chemical changes
The bond is weak and and becomes weaker when reheated, allowing reshaping
These plastics can be reshaped
Pros of thermoforming plastics
Highly recyclables Aesthetically superior finishes High impact resistance Remoulding/ reshaping capabilities Chemically resistant Eco - friendly manufacturing
Cons of thermoforming plastics
Generally more expensive than thermosetting plastics
Can melt if heated
Examples of thermoforming plastics
HIPS: high impact polystyrene
HDPE: high density polythene
PP: polypropelene
PMMA: acrylic
What are thermosetting plastics
Once ‘ set ‘ these plastics cannot be reheated to soften, shape and mould. The molecules of these plastics are cross linked in 3 dimensions and this is why they cannot be reshaped or recycled. The bond between the molecules is very strong
Pros of thermosetting plastics
More resistant to high temperatures than thermoforming plastics Highly flexible design Thick to thin wall capabilities Excellent aesthetic appearence High levels of dimensional stability Cost affective
Cons of thermosetting plastics
Cannot be recycled
More difficult to surface finish
Cannot be remoulded of reshaped
Examples of thermosetting plastics
Polyester resin
Epoxy resin
What is tolerance
The acceptance range of difference from standard
Quality assurance definition
Procedures to manage all functions that effect quality
Quality control definitions
Check against the manufacturing specification
What is one off production
These products are expensive at cost price, sometimes bespoke, and often take a large time to make and cost of materials and labour are high. Many prototypes are “ one off products “
What is batch production
These products are identical and produced in small batchs, daily, weekly, monthly or when needed. They can range in cost price.
What is mass production
These products are produced in very high volume. They are are normally products that are in high demand and can range in expanse, cars are a good example
Continuous production
These items are normally very cheap to make and could be considered ‘ throwaway ‘. These factories are often found in developing countries where land for factories and equipment are cheaper
Example of one off products
Fitted shoes
Taylored suits
Example of batch production
Baked goods
Example of mass production
Lego
Example of continuous production
Toilet paper
Example of just in time production
Restaurants
What is just in time production ( JIT )
This scale of production relies on the product being manufactured to a time schedule. This allows raw materials to be delivered at an exact time for production, and then manufactured and are shipped straight to distribution/ retailers. Apple INC uses JIT production
What do the 6rs stand for
Reuse Recycle Rethink Reduce Refuse Repair
Name non renewable fuels
Coal
Oil
Natural gas
What greenhouse gas is produced when burning fossil fuels
Carbon dioxide 🚬
5 methods of renewable energy
Tidal Hydroelectric power Wind turbines Biofuels Solar power
What does fracking do?
Extract natural gas from shale rock
Benefits of nuclear energy
Losts of energy produced
Doesn’t produce greenhouse gases
Problems with nuclear energy
Produces nuclear waste which is environmentally damaging
Name common metal finishes
Anodising - colouring metal by adding dyes to solution
Electroplating: electrolysis to apply a different metal to a base metal
Galvanising: applying a zinc coating to prevent rusting
Plasting power coating : applying plastic powder then melting to provide coat
Brush on metal: painting metal with a brush
Plastic dip coating: dipping metal in plastic to provide simple surface finish
Name some wood finishes
Spray paint
Stain: retains wood grain
Teak oil: protects wood from UV rays
Polyurethane: makes the wood easily cleanable
Stages for injection moulding
Plastic granules fed into hopper
Screw in chamber below hopper sends granules forwards
Heated jackets around screw melt polymer
Screw winds back and hydraulic ram come forward into position
Mould closed and sealed as ram forces melted plastic into mould
Plastic allowed to cool and halves of mould released
“ Sprew “machined off
Stages of vacuum forming
Mould placed into former
Sheet of thermoplastic ( e.g HIPS ) clamped over mould
Plastic slowly heated to become soft
Former raised and air sucked out, drawing plastic over former to takes it’s shape
Plastic allowed to cool and then removed from mould
Edges trimmed and finished
Stages of line bending
Strip heater ( hot wire ) heats acrylic to 160 degrees Acrylic becomes soft and pliable and can be bent into shape Jigs and formers can be used to bend acrylic into desired shapes
Stages of blow moulding
Mould opened into two halves
Hollow tube of polymer ( known as parison ) is heated
Parison lowered into mould
Mould clamped shut, leaving small hole for air hose
Air is forced into mould at high pressure, plastic is forced to mould’s sides and cools
Stages of extrusion
Motor turns thread which feeds granules of plastic through heater
Granules melt into liquid, forced through a die forming long tube like shape
Extrusion then cooled and forms solid shape
Shape of die determines shape of tube
Ergonomics
The study of how well and comfortably people can interact with products and symbols
What are anthropometrics
The practice of taking measurements of the human body and provides categorised data that can be jsed by designer🍸
Eg: child head 4 cm
What is technology push
Develop in science and industry leads to new discoveries, these can be used to improve existing products or develop new ones. It happens before there is a user demand
What is market pull?
When product ideas are produced in response to customer needs.
