Section 2 Flashcards
WHy can materials be enhanced?
to resist and work with forces and stresses to improve functionality.
How can concrete be enhanced?
adding steel bars which are embedded in concrete
How can materials be stiffened?
having strips of other materials inserted in them
How is a collar stiffened?
adding horn or nylom rounded at one end and pointed at the other to sitffen and prevent bending
How can timber be stiffened?
laminating
WHat is timber laminating?
thin layers of timber are glued together to shape and stiffen materual for furniture
How is fabric given tensile strength?
when it is woven
What are the four ways of getting resources?
mining, drilling, farming, deforestation
What are the 6rs?
reduce, reuse, recycle, rethink, refuse, repair
What is mining?
removal of minerals and metals from the earth - gold silver diamonds
What are the advantages of mining?
- huge employment
- income for countries
What are the disadvantages of mining?
- contaminates water supplies threatening communities
- deforestation
- separate metals from ore - cyanide and mercury used poisonous marine life
- land mining and river dredging can cause increase of malaria and other diseases due to waste collected in pools
What is drilling used for?
extracting liquids or gas from underneath the earth’s surface, on land or sea
disadvantages of drilling?
- disruption as roads created and space needed for machinery
- as roads been made encourages other companies like logging as can use access
- dangerous chemicals used to extract, hard to dispose of and some dump chemicals causing harm
- oil can harm wildlife if touches or inhaled/ digested - stops birds flying and then die
- oil spills can have economic effect as has to be cleaned up people hired
- leads to global warming as carbon dioxide produced - called flaring
Disadvantages of farming?
- felling of native trees and other vegetation necercerry for specific breeds of animals
- soil erosion due to lack of tree roots, lead to silting up of rivers
- pesticides have effect on animals
- use of fertilisers and and the eutrophication of streams and rivers
What is eutrophication?
excessive nutrients in a body of water often caused by fertilisers
WHat is farming?
the use of land for growing crops or keeping animals for food
Disadvantages of deforestation?
- reduction in hunting areas
- carbon produced
What guidelines do designers have to ensure are met?
- employment is a choice
- safe and hygenic working conditions
- workers can join and form trade unions
- paid living wage
- no child labour
- non excessive working hours
- no discrimination
How is atmospheric pollution created?
- sulphur dioxide is often released when coal is burned in power stations
- carbon monoxide is released from cars or when boiler is not working properly
- carbon dioxide produced when burning fuels
how do designers have to consider all aspects of life in their product?
- extraction of raw materials
- manufacturing processes used
- treatment of workers
- transportation
- effect of product on user and environment
- how easy to repair
- disposal of product
What are ores?
naturally occuring rocks that contain metal or metal compounds in sufficient amounts to make it worthwhile extracting them
How is iron ore made>
iron and steel
What happens when the ore has been extracted?
process known as smelting
What are the two types of smelting?
blast furnace and reduction cell
Explain blast furnace smelting?
iron is extratced from haematite in blast furnace. Crushed haemitite limestone and coke are loaded into the main section and heated to very high temperature. iron is melted out of rock and runs out of furnace into ingots known as pig iron. Product formed is called slag as impurities removed
Explain reduction cell smelting?
- load crushed bauxite that been chemically processed to form alumia into a chamber filled with molten cryolite. . …….
What are the four processes of modifying metals?
- heat treatment
- annealing
- annealing process ( steel)
- annealing process ( aluminium )
Explain heat treatment for metals?
- properties can be changed by heating and cooling, they can be hardened, softened, made brittle or toughened simply by heating to certain temp or cooling in certain way
Explain annealing?
- if metal is intensely worked on by constant bending or being hammered it can become hard or brittle and is likely to split or fracture. - work hardening. annealing removes this making the metal soft
Explain steel annealing?
- steel placed on firebricks
- brazing torch to heat steel to 700 degrees
- steel soaks for short while
- steel cools very slowing ( burying in sand)
Explain aluminium annealing?
- same as steel but to control temperature the surface is marked with soap. when soap turns black aluminium is at correct temperature for annealing
What are the 4 ways to join metals?
soft soldering, hard soldering, brazing, welding
What are the two types of welding?
oxyacetylene welding and electric arc welding