engineering theory 2 COPY Flashcards
why are aesthetic approaches important
colour psychology is all about how colour make people feel. different colours stimulate different parts of the brain
it contains important visible information about an abject and, at a basic level, allows us to distinguish between animals, plants, foods and fabrics
this makes the texture a significant part of the sensory input that we receive every day.
our senses respond to texture in two ways
physical texture can be felt by touch
visual texture is the illusion of physical texture we see
what are thermoset polymers
thermoset polymers are obtained by irreversibly hardening a soft solid or viscous liquid prepolymer. curing is induced by heat or suitable radiation and may be promoted by, high pressure, or mixing with a catalyst .
define epoxy resin and its properties
epoxy resin is a thermoset polymer. it has good heat resistance and hardwearing, formed by mixing together liquid resin and hardener to trigger cross linking. it is used in adhesives ad the production of laminates and reinforced plastic composites
define and describe urea formaldehyde
. it has a high tensile strength, low water absorption, high surface hardness used when producing electrical appliances casing also desk lamps, used in resins form to manufacture MDF sheets
define polyester resin
another thermoset polymer is polyester resin. it is similar to epoxy resins with good heat resistance and hardwearing surface. it is used in the production of reinforced plastic composites
define thermoplastics and describe them
thermoplastics polymer have a low density, lightweight and very flexible, high impact resistance, heat resistance, chemical inertness, transparent. it is used in automotive applications, household goods, containers, appliances, packaging
define and describe acrylic
it is transparent, has good impact and chemical resistance, scratch-resistant, good thermal insulator, uv resistant. it is used for aircraft windows, point of sales displays, medical components, lenses and furniture
define and describe polystyrene
high impact polystyrene is easy to mould. light and strong. high impact strength, good machinability. it is used in vacuum-formed packaging and casings appliance components, toy, tv, and audio-visual equipment parts, recording tape cassettes, bicycle trailer, toys. automotive instrument panels and fittings, petrol tanks. hot and cold drinking cups
what is an elastomer
An elastomer is a polymer with viscoelasticity and with weak intermolecular forces, generally low Young’s modulus and high failure strain compared with other materials.
define and describe rubber
rubber is a type of elastomer. it is abrasion-resistant, tear-resistant, it has high tensile strength, hardness, durability, flexibility
it is used in tyres tubes, hoses, belts, matting, flooring, medical gloves, adhesives
what is a title block and where is it found
a title block on a drawing is usually located in the bottom right hand corner and contains all the information necessary to identify the drawing. the title block is separated into different sections
the author, title, date of production, system of measurement, scale, projection, drawing number, sheet number, surface finish
- what are the two main systems for measuring in engineering drawings
metric and imperial
what are metric units
millimeters, centimeters, meters, kilometers
what are imperial units
inches feet yard and miles
what do most countries use
most countries use metric system as their preferred system of measurement, with the exception of America, liberia and Myanmar
what are the benefits of using metric
metric is the worldwide standard. it is used by 96% of the owrlds population
set by international agreement an advantage for international trade
A decimal system
base 10 easy to convert units x by 10, 100, 1000
avoids errors
less errors for international trade when communicating drawings or manufacturing products
Future proof
the metric system is likely to previal as the only system of measurement internationally and non- metric units could be left behind the global economy
what are the disadvantages of metric
not well studied for working with fractions
1/6 metre is approximately equivilant to 167 millimetres and 1/3 kilogram is approximately equal to 333 grams
what are the benefits of using imperial
visualisation
easier to visualise in imperial than in metric
easilt divisible
base 12 divisible by 1, 2, 3, 4, 6 and 12
pre 1965
engineering drawings which pre-date 12965 will still be in imperial system
america, liberia and myanmar still use this system
america being in the top ten of the worlds largest global innovators for engineering.
what are the disadvantages of imperial
conversion tables
imperial is not an easy measurement to convert into metric meaning they have to use conversion tables to assist in the process
smae name for different measurements
ton which can have several differet weights as there is a short ton and a long ton
what is scaling
a drawing that shows a real object with accurate sizes reduced or enlarged by a certain amount is called scaling.
why would we apply scales in drawings
the object may need to be scaled up or down so that it can fit onto the page
accurate use of scale will provide a clearly defined and accurate measurements so that the objects can be manufactures
accurate use of scale will ensure ease of communicating the design
what are visible lines
a visible line is represented by a thick dark line, used to show the outline an objects visible edges and surfaces
what are hidden lines
a hidden line is represented by a series of short dashes and is used to represent the lines or features which are not visible from the direction of view in a drawing
the hidden line should begin with a dash in contact with the line from which it starts
what are centre lines
centre lines are represented by a series of alternate short and long dashes
this is usually used to indicate the centre of holes, circles, fillets or circular edges in a drawing, Although it can also used to indicate the cenre line of symmetry
a centre line should always ectend beyond the edges of a drawing
