technology of a toaster _ materials
Post on 04-Jul-2015
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Judith Lievens
What kind of materialsare there?
POLYMERS
Acrylonitrile Butadiene Styrene
ABS = Acrylonitrile Butadiene Styrene (C8H8)x· (C4H6)y·(C3H3N)z)
• thermoplastic melting point 105°C
• ABS can be used between -25 and +60°C
• stronger than pure polystyrene
• styrene gives it a shiny, impervious surface
• butadiene (rubbery) provides resilience even at low temperatures
• can be recycled
• !! Hardness, gloss, toughness, electrical insulation, light weight, injection
molding & extrusion possible
• dissolves in acetone
• Examples: car bumper, lego, golf club heads, canoes, luggage, small
kitchen appliances, toys,…
PolypropylenePP = polyprop(yl)ene
• thermoplastic polymer
• applications: packaging, textiles, plastic parts, chairs, loudspeakers, …
• unusally resistant to chemical solvents, bases and acids
• The MOST used polymer
• good resistance to fatigue
• Tough and flexible
• melting temperature 171°C
• extrusion and injection molding
• recyclable
• Very cheap
Polybutylene TerephthalatePBT = Polybutylene terephthalate
• thermoplastic engineering polymer for special applications
• Good chemical, thermical and mecanical properties
• injection molding possible
• type of polyester
• mechanically strong
• Heat-resistant up tot 150°C (or 200°C with glass-fibre reinforcement)
• when treated with flame retardants non combustible
• can be made out of PET
METALS
NichromeNichrome = alloy of 80% nickel and 20% chromium
• non-magnetic
• resistance wire current is passed through to produce heat
• corrosion-resistant
• high melting point 1400°C
• used in electric heating elements eg hair dryers, ovens, toasters
• expensive due to its high nickel content
• in toaster the reached temperature is 154°C (requiered temperature for
toasting)
• temperature varies when alloy/current/voltage differs
Aluminium• most abundant metal in the Earth’s crust
• low density
• resistant to corrosion
• soft – durable – lightweight – ductile – malleable metal
• nonmagnetic and nonsparking
• density & stiffness (Al)=1/3 density & stiffness (steel)
• easily machined – cast – drawn – extruded
• silvery reflection
• thermal and electrical conductor
• 100% recyclable
• applications: packaging foil, lightning poles, cases for equipment, paint,…
OTHER
Mica Heater PlateMica sheet is composed of muscovite mica paper and a small amount of heat
resistant silicon binder.
• electrical and thermal insulation
• retains properties even after being exposed to heat
• resistant up to temperatures of 500°C
• application: toasters, hair dryers, electric rice cookers, electric ovens,…
Nichrome wires are wound around it
Muscovite
• the most common mica
• a phyllosilicate mineral of aluminium and potassium
• found in sheets
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