material and components 1 Flashcards
functional performance
- how materials actually work and perform e.g. strength, weight, durability
aesthetics
- shape form and colour
- links to a customers reaction and response when selecting a product to purchase
Cost and availability
- increased availability, decreases cost
- increased cost increases quality
- cost involves transportation and processing materials
properties and characteristics
- properties can be measured, characteristics can’t
- mechanical properties: strength, ductility, hardness
- physical properties: density, melting point
- chemical properties: corrosion resistant, hygroscopy
- manufacturing properties: formability, machinability, fusibility
environmental considerations
6 R’s
- rethink, what materials and energy we use
- reduce, the materials we use
- reuse, materials and products
- repair, existing products
- recycle
- refuse, to use certain materials
social, cultural and ethical factors
- there is a responsibility to ensure that other peoples quality of life and human rights are not compromised e.g. fair pay and decent working conditions and qol for residents nearby.
- inclusivity
different physical properties of natural timber
- weather resistant
- chemical resistant
- impact resistant
- stiffness
- density
different working properties of natural timber
- ease of machining
- ability to be glued
- ease of finishing
advantages of manufacture boards
- available in large sheets
- relatively dimensionally stable - don’t twist/warp
- consistent properties across the board
- available pre-finished (laminated, foil or veneer)
- treated with flame retardant chemicals
what are laminated boards
- > layers of wood glued using a synthetic resin
e. g. plywood, blockboard and laminboard
what are compressed boards
- > made form chips and glued together
e. g. chipboard, MDF, HDF
Developments in timber
- Neatflex -> flexible board for furniture
- cement-bonded particle board (overcomes durability problems)
- glulam -> strips of solid timber glued together
- engineered timber -> considerably stronger and more stable
what is a ferrous metal
contains iron
types of steels
- alloys of iron and carbon
> mild steel: up to 0.25%
medium carbon steel: 0.25-0.5%
high carbon steel: 0.5-1.5%
cast iron
used for machine beds and vices
> cost effective but heavy
> rigid and strong in compression
> casts well and is easily machined
Mild-steel, description, properties, uses
- 1.65% manganese, 0.6% silicone copper
- tough, ductile, malleable, poor resistance to corrosion
- uses: case hardening, structural material
High-carbon steels, description, properties, uses
- 0.3-0.9% manganese
- High resistance to wear, brittle, poor resistance to corrosion
- uses: cutting tools and blades
stainless steel, description, properties, uses
- 10.5% chromium (which produces a thin layer of oxide) preventing corrosion
- corrosion resistant, ductile, work hardening makes it magnetic
- cutlery, sinks, surgical instruments
what are non-ferrous metals
they do not contain iron
describe Aluminium
- low density, corrosion resistant
- soft with low strength and high ductility
- strengthened by alloying with silicon, manganese, magnesium, tin
- good thermal and electrical conductor
- uses: car bodies, ladders, windows, door handles
describe Zinc
- galvanising
- corrosion resistant
- uses: watering cams etc.
describe Copper
- soft and can be beaten into shape
- corrosion resistant and has great thermal/electrical conductivity
- uses: wires, heating application, plumbing
describe Tin
- rarely used by itself
- coats tin cans
describe Tungsten
- one of the toughest materials found in nature
- very dense, durable, resistant to corrosion and impossible to melt (3400 degrees c)
- highest tensile strength
- uses: drill bits, cutting tools, blades
define non-ferrous metal alloys
they are metals mixed with other metals/substances to improve properties
describe Brass
- Alloy of copper and zinc
- Its bright gold-like appearance makes it suitable for decorative metalwork
- melting point: 900-940 degrees C, density 8.4-8.73 c/cm3
- uses: locks, door handles, taps, musical instruments
describe Bronze
- alloy of copper and tin (and aluminium, manganese)
- tough and low coefficient of friction, tin content increases corrosion resistance/tensile strength
- uses: electrical products, bearings
describe aluminium alloys
- 99% aluminium, 0.1% mangenese and 0.5% silicon
- gives a strength-to-weight ratio of five times that of pure aluminium
mechanical properties of metals
strength, hardness, toughness, elasticity, plasticity, brittleness, ductility and malleability
- they are used as measurements of how metals behave under a load
what is normalised steel
it has been softened by heating and cooling in air
define polymer
many simple single units from which thermopolymers are made
how polymers are made
- the units are joined together in long chains
- the chains become entangled during a chemical reaction
- a solid is formed that is both strong and rigid
- Re-heated -> the forces of attraction between the molecules decrease, making material less rigid - ‘thermo”
Polymers have……
- excellent electrical and thermal insulators
- good strength to weigh ratio, flexibility, impact resistance
thermo polymers
deform when heated, remoulded many times
suitable for vacuum forming, injection/blow moulding, recycling
polystyrene (PS): safe working temp., characteristics, uses
- 80°C
- stiff, hard, brittle
- disposable cups
- polystyrene: high impact/expanded (98% air)
polyethylene (LDPE): safe working temp., characteristics, uses
- 75°C
- flexible, soft, waxy
- squeeze bottles, bin liners
polyethylene (HDPE): safe working temp., characteristics, uses
- 75°C
- fairly stiff, hard
- bleach bottles, milk crates
polymethyl methacrylate (PMMA): safe working temp., characteristics, uses
- 95°C
- crystal clear, glossy, tougher than glass but sunlight degrades it over the years
- car rear light units, illuminated signs
polypropylene (PP): safe working temp., characteristics, uses
- 100°C
- thin, stiff, hard, flexible, lightweight
- carpets, banknotes
polyvinyl chloride (PVC): safe working temp., characteristics, uses
- 95°C
- plasticised: flexible, hosepipes
- unplasticised: rigid, guttering/pipes
acrylonitrile-butadiene-styrene (ABS): safe working temp., characteristics, uses
- 80°C
- opaque, impact resistant, heavy
- plug for vacuum, casing for cameras
Polyethylene terephthalate (PET): safe working temp., characteristics, uses
- one of the strongest plastics
- translucent, hard
- fizzy drink bottles (can withstand the gas), containers
polyamide (PA):
- heat resistant e.g. cooking utensils
- natural: wool and silk
- artificial: nylons
- washers, cable ties
thermosetting polymers
once the polymers have been shaped and hardened, they cannot be reshaped
urea formaldehyde (UF): safe working temp., characteristics, uses
- 80°C
- opaque, light in colour, hard/brittle
- resin is inexpensive and heat resistant: used in plywood/chipboard
- electrical fittings
phenol formaldehyde (PF): safe working temp., characteristics, uses
- 120°C
- opaque, dark in colour
- heat and water resistant
- laminant sheets, iron/saucepan handles
melamine formaldehyde (MF): safe working temp., characteristics, uses
- 130°C
- opaque, multi-coloured
- cups, plates
polyester resin: safe working temp., characteristics, uses
- 95°C
- clear liquid resin, brittle, ease of handling, low cost, dimensionally stable
- boats and vehicles
epoxy resin: safe working temp., characteristics, uses
- 200°C, 2 resins in tubes/ 80°C, one tube has activator (adhesives)
- high mechanical properties, temp an chemical resistance
- hardwearing, durable finish and is an excellent insulator
- ‘potting’ of electronic circuits
mechanical properties and physical properties of metal
mechanical:
- hardness -resistant to scratching
- toughness -will not shatter
- malleability -can be press formed into a shape
physical:
- resistant to corrosion
- chemical resistant -will not degrade with detergents
- electrical conductivity
