Mapa mental
DT
Contenido del mapa
DT
unit 1
unit 2
- 2.2
- synthetic polymers
- made through fractional distilation (crude oil broken down) to get naphta witch is the main component for polymers
- cracking
- the process of converting large hydrocarbons into smaller ones, done becasue large molicules dont flow well - done with heat and pressure
- polymerisation
- after cracking they get chemically processed, single compounds called monomers join with one another, atoms form end to end to form long chains (now known as polymers the base of Plastics)
- thermoplastics
- can be re heated, re-shaped under heat, long molicule chains (no fixed position, flexable and some shape memory
- Heated
- moulded
- cools
- hardens
- cools
- moulded
- Heated
- LDPE
- used in packageing where flex is needed tough
- HDPE
- 2
- High strenth to weight ratio (bottle caps, Buckets)
- PP
- 5
- flexable, food safe, solvent resistant, light, waterproof
- hips
- 6
- rigid, light high impact strenth, food safe, recyclable (cups, plastic cutlary)
- ABS
- 7
- hard, tough, great impact strenth, flexable, easily moulded
- PMMA
- 7
- (Acrylic) tough, light, large range of colars, shatter resistant, glass alternative, poor chemical resisstance
- nylon
- 7
- abrasion resistant, self lubricateing, good sternth to weight ratio, low coeficient of friction (seat belts
- PVC
- 3
- rigid, tough, hard, addatives to increase fire resistance, plasticisers added to alow for the pvc pipe to be extruded
- 3
- 7
- 7
- 7
- 6
- 5
- 2
- 4
- can be re heated, re-shaped under heat, long molicule chains (no fixed position, flexable and some shape memory
- thermoseting plastics
- long chains of cross linked molicules, rigid when curved, brittle, hard, waterproof, cant be reshaped, retains there shape
- heated
- sofend
- baked
- hardens
- baked
- sofend
- heated
- Urea Fermaldihide
- melamene fermaldihide
- Polyester resin
- apoxy resin
- carbon fibre, surface coating for led moitors, great at high temps
- most common, mixed with glass to make fibreglass, resin must be mixed with a catalist
- apoxy resin
- hard, scratch resistant, chemical and heat resistant (kitchen surfaces, toilet's)
- Polyester resin
- opaque resin, high tensile strenth, good heat resistance(sockets, plugs)
- melamene fermaldihide
- long chains of cross linked molicules, rigid when curved, brittle, hard, waterproof, cant be reshaped, retains there shape
- synthetic polymers
- 2.3
- 2.2
unit 3
- 3.2
- distortions
- wood is hydroscopic witch causes it to show ansetropic properties
- as water evaporated it shrinks the wood
- if done in an uneven way whe wood can warp
- shrink, get slide from ppt
- twist
- warp
- bow
- cup
- cups the opposite of the direction of the grain
- split
- cup
- bow
- warp
- increase depending on moisture content and sections of trunk
- seasoning
- timber must be seasoned to prevent distortion
- increases strenth, resistance to decay, obsorbs preservatives but can still distort
- makes wood more stable
- how to work with woods
- high oil content in wood can make them dificukt to glue
- acid content in oak can corrode ferrous metal fixing
- woods souch as ash, beetch, birch, glue well
- forming
- consists of both additive and wasteing processes as well as manipulation
- wasteing processes - carveing turning milling, routeing
- steam bending - changeing wood shape
- using heat and moisture to make wood pliable
- ash and beech have open pore structure so they bend well
- laminateing used to create bent surfaces
- combineing woods and adhesives. veneers can also be laminated to enhence surface orioerties
- machineing
- natrual timbers can be dificult to machine
- the natrual wood is less predictable and the oils can clog tools
- can be treated to increase resistance to decay throug funggal and insect attacks
- in a dry stable enviroment they dont decay
- many woods have high oil content so less prone to decay
- insect attacks - termites, attracted to starch in wood. larvai are borne inside wood, bore out. structual integrity down
- fungal attacks - feeds of nutrients. dry rot makes timber weak but wet rot visable
- moisture resistance - oily woods like teak and redwood have high resistance
- toxicity - wood dust can irratate skin, curtain species of cedar that can cause harm
- regulations
- COSHH
- controll of substances hazordous to health
- states that wood is limeted to 5mg per M cubed
- COSHH
- distortions
- 3.1
- natrual timbers
- sold as rough sawn and in dowls etc
- timbers avalable in a range of stock forms like, Rough sawn, planed square edge, planed all round
- once felled rough sawn timber is sold, others require extra machining- done by plainers and thickeners
- more machining = more money and smaller product
- pse timber has one square edge par is square on all sides
- rough sawn - used in construction, cheapest timber and rough surface from saws used to cut it
- once felled rough sawn timber is sold, others require extra machining- done by plainers and thickeners
- mouldings
- are machined profiles made for astetic and functional reasons
- used in: skirting boards picture frames beading
- manurfactured board
- full boards measure 1220x2440 and can have any thickness
- diy stores offer a cutting service where they can be cut to coustomer specs
- softwoods
- less time to season
- lightweight, fast growing, low cost, long and straight
- need to know abt: pine, cedar, larch, redwood, spruce, douglas fir
- redwood giant - softwoods grow fast, redwood species grow 3m a year, light, soft, good strenth to weight ratio, used in instrements
- pine - lightweight, streight grain, has knots, easy to work with, cheap, has to be treated to be used outdoors
- spruce - easy to work, uniform teaxture, light, good strenth to weight ratio, used in aircraft construction (ww1+ww2)
- cedar - high oil content- makes it resistant to decay, weathering, insects, lightweight, easy to work, knot free, toxic to an extent, used in boats/ outdoor paneling
- larch - hard timber, attractive colar, high resin content, an clog up cutting blades, used for veneer garden furnature and boats
- douglas fir - one of the toughest woods, cheap, strong, sutable for large scale projects (houseing frameworks), can be dificult to treat (high resin content, high density), stable as it holsd shape as it swells and shrinks
- hardwoods
- slow growing, need more space/land, dense, usally stronger and more durable
- need to know abt: Oak, Mahogony, birch, ash, teak, beech
- oak - main material for ship makeing and architexture, tough durable, hardwearing, rot resistant, contains tannic acid that corrodes steel
- ash - springy hardwood, larege pores (gives it elastic qualities),elasticity makes it shock absorbant, used in tool handles and sports stuff
- mahogony - great stability, workable, good grain, tall and stout trees, defect free, illigal logging means certain species are now protected
- teak, natrually high in oils, ideal for outdoor products, great dekay resistance, durability, high acid resistance
- birch - fine grain that gives a uniform even texture, low cost, used in boxes paper pulp and plywood, least resistant timbers in terms of insect attack, few noticable defects
- beech, hard, tough, odourless, abrasion resistant, noes not alter food taste, close straight grain so easy to work, ideal for steam bending
- natrual timbers
- 3.3
- testing wood for Tensile strenth, toughness, hardness, corrosion, mallebility
- charpy and izod test - to test tough - a peace with a notch in then a pengalum drops and you measure how far it travels
- none distructive test
- 3.2