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
What is soft soldering?
used when manufacturing electrical circuits and when plumbing with copper pipework.Ensure joint is clean. Soldering iron is used to heat the joint and soft solder is used as the bonding metal
What are the 8 factors that need to be considered when purchasing a material?
- functionality
- aesthetics
- enviromental factors
- availability
- cost
- social factors
- cultural factors
- ethical factors
What is hard soldering?
used for joininh precious metal together. Heat is applied using a blow torch or brazing torch and the solder is an alloy of silver, copper and zinc
Explain brazing?
Used for joining steel by melting a brass rod on the hot steel. As the brass melts, it forms a joint. Brazing is a slow and safe way to learn about joining metal with heat
WHat is welding?
very strong method of permanently joining metal. Uses same metal as joint
Explain oxyacetylene welding?
Oxygen and acetylene are used to produce a flame with a temperature of over 3,000°C. A filler rod is melted so that pieces of metal can be joined together. Gas welding/Oxyacetylene welding is faster than brazing and can also be used to cut metal
What is electric arc welding?
uses low voltage, high current of electricity down a faux coated filler rod, as electricity jumps across the gap produces high temp arc that instantly melts both sides of V-gap and filler rods
What are the three ways to shape metals?
- turning
- milling
- casting
What is turning?
uses a lathe. Stock forms held in chuck while it spins around. Cutting tool used to carry out variety of turning operations such as facing off parallel turning and taper turning
Explain milling?
machines used tk cut clots, grooves, machine edges and smooth large surface areas
WHat is casting?
method of producing complex shapes in metal by heating metal to a molten state and then pouring it into a pre-prepared mould
What are the 9 standard metal stock forms?
- flatstrip
- roundbar orrod
- square bar
- hexagon bar
- angle
- sheet
- round tube
- channel
- rectangular tube
What are extrusions?
long length of material with a standard cross section
What are componants used to join metals?
- rivets
- machine screws
- nuts
- bolts
What is riverting?
used for joinign metals, hole drilled through both sheets of metal to be joined and then pass a rivet with the same diameter through hole. head of rivet butts up against one side of sheets and the other side is hammered over to hold second sheet against first
What are the four types of rivet?
- countersunk
- flat head
- bifurcated rivets
- pop rivets
What are countersunk rivets used for?
neat finish
What are flat head rivets used for?
joining thin metals, too thin for countersink
What are bifurcated rivets for?
joining soft materials
What are pop rivets for?
used when cant access back of hole
What is a machine screw?
designed to fasten an object to an excisting tapped hole in a metal surface, no need for a nut
What are nuts and bolts used for?
- joining two materials together, hole is drilled through both
What are the 6 types of nut?
- wing nut
- hexagonal nut
- square nut
- locking nut
- castle nut and split pin
- nyloc nut
What are the four types of production?
- one- off production
- batch production
- mass production
- continuous production
Explain one-off production?
- just one complete product is produced
- cruise liners, power station, bridges
Explain batch production?
- limited number of the same product is made during a particular time
- jeweller, cakes, furniture
- will use jigs, patterns, moulds and formers so that they can be made again
- computer controlled machinery used with down time inbetween batches
Explain mass production?
- manufacturing in large quantities over a long period of time.
- typically uses a production line
- assembling small parts together
- machinery often used
Explain continuous production?
where item is made continuosely 24 hours a day, severn days a week.
- for items constantly being sold in high demand
- usually simpler products that can be easily produced
What is a scriber?
performs same function as a pencil but on metals, hard point will score fine line on metalm
What is marking out fluid?
- quick drying blue liquid that is applied to metal before marking out begins. produced clean and crisp lines
What are odd leg calipers?
mark a line parralel to edge
Outside calipers?
- used to measure/check the outside diameter of round bar or rod
inside calipers?
used to measure or check inside diameter of a hole
What are dividers ?
used to mark out a circle or arc on metal
What is a center punch?
when struck with a hammer produces small indentation in metal
What is a micrometer?
- very accurate tool for measuring small distances
What is a digital vernier calliper?
can measure to an accuracy of 1/100 millemeters
What is filling?
process of final shaping and smoothing a material once it has already been cut into shapre
What are the two types of filling?
cross filling and draw filling
What is milling used to do?
used to cut grooves, slots, edges and smooth large surface areas
Explain basics of casting?
metal is heated until in molten form and then poured into pre-prepared mould. Comple shapes can be formed
WHat is pewter casting?
using pewter and small amount of copper, heated in furnace with brazing torch, pewtwer can be pured in mould and then cooled
Explain sand casting?
done in school workshop and is used to produce larger metal castings, usually from aluminium. cast made from hardwood
What is a go-no-go gauge>
a preset value to measure a metal compinant to ensure that it is within a specific tolerence
What are the three types of go-no-go gauges?
plug guage - checking holes
gap gauge - check external dimensions
adjustable gap - versitle version of gap
What is a depth stop?
mechanical means of setting how deep a drill bit will be cut
What are the five metal finishes?
- painting
- dip coating
- powder coating
- galvonising
- anodising
explain painting?
- all dirt and grease removed before spraying with three coats
Explain dip coating?
provides a thin layer of polyethylene plastic over surface. metal cleaned then heated to 200 degrees and dipped in fluidised bath of polyethylene
What is powder coating?
item coated is electrostatically charged and paint is applied in powder form. podwer is attracted to object and then passed through oven where it sets and hardens
WHat is galvonising?
- item dipped in zinc so wont carrode
What is anodising?
-electrolysis process where aluminium parts are dipped in a chemical bath and an electrical current is passed through product. causes surface to oxidise forming a hard surface which is resistant to wear and scratches
