Unit 4 Flashcards
Piezoelectricity meaning
The ability to release an electric charge when deformed. When an electric current is passed through a piezoelectric material its volume will increase or it will vibrate.
Magneto-rheostatic & Electro-rheostatic meaning
Electro-rheostatic (ER) and magneto-rheostatic (MR) materials are fluids that can undergo dramatic changes in their viscosity.
viscosity meaning
the state of being thick, sticky, and semi-fluid in consistency, due to internal friction
what are MR fluids used for?
use in car shock absorbers, damping washing machine vibration, prosthetic limbs, exercise equipment and surface polishing of machine parts.
what are ER fluids used for?
use in clutches and valves, as well as engine mounts designed to reduce noise and vibration in vehicles.
Thermoelectricity meaning
Thermoelectricity is, at its simplest, electricity produced directly from heat. It involves the joining of two dissimilar conductors that, when heated, produce a direct current.
What is thermoelectricity used for?
used in remote areas and space probes to power radio transmitters and receivers.
Photochromicity meaning
Photochromicity refers to a material that can described as having a reversible change of colour when exposed to light.
How does photochromicity work?
A chemical either on the surface of the lens or embedded within the glass reacts to ultraviolet light, which causes it to change form and therefore its light absorption spectra.
Example of photochromicity?
One of the most popular applications is for colour-changing sunglass lenses, which can darken as the sun brightens.
Shape memory Alloys meaning
have a pseudo-elastic property that allows them body to return to its original shape after deforming. Their shape changing property can be stimulated by either a change in temperature or the application of an electrical current. When the load is released, the body returns to its original shape.
What are SMAs used for?
- The frames of some eyeglasses use SMAs to create a flexible frame
- Medical devices such as Nitinol stents use SMAs to repair damaged blood vessels. to allow a thin device to be inserted into a vein. As the device heats up because of the body heat, it changes shape and keeps the blood vessel open.
modern plastics are derived from?
-derived from non-renewable petroleum resource, such as crude oil, coal or natural gas.
All plastics are a type of ___?
polymer
What determines the physical and mechanical properties of plastic?
the different types of bonds.
Which plastics are made from biomass?
PLA and Bioplastic
what is biomass?
plant or animal material used as fuel to produce electricity or heat.
plastic production’s impact on our environment?
The social, environmental, and economic impacts of plastic production and disposal are of increasing concern for our global community.
Which plastic can be reheated and molded?
Thermoplastics
Characteristics of thermoplastics
low production cost
easily injected into a mold
low stiffness, making them ideal for uses requiring flexibility
can be reshaped after heating
Types of thermoplastics?
- PP (Polypropylene)
- PE (Polyethylene)
- HIPS (High Impact Polystyrene)
- ABS
- PVC (Polyvinyl Chloride)
Properties and applications of polypropylene?
Polymer resin
Low cost
Stiff
Production Process: Injection molding
Application:bottles such as cleaning materials
Properties and applications of Polyethylene?
- Available in a variety of density levels (low, medium, high)
- Density determines properties:
LDPE: low cost, translucent
HDPE: Flexible, transparent to opaque, low temperature toughness, waterproof, Very common
Applications: plastic bags, water bottles
Properties and applications of High Impact Polystyrene?
Easy to machine and shape
Low cost
impact resistant
Applications: Lunch trays
Properties and applications of ABS?
Low cost
heat resistant
dimensional stability
Applications: lego bricks, keyboards
Properties and applications of Polyvinyl Chloride?
High hardness; Can be flexible when exposed to a plasticizer
Applications: Pipes, windows
plasticizer meaning?
a substance (typically a solvent) added to a synthetic resin to produce or promote plasticity and flexibility and to reduce brittleness.
Thermoplastics have a ____ chain
Linear
Thermosetting plastics have a ____ chain
Cross-linked
What are thermosetting plastics?
linear chain molecules with strong primary bonds between adjacent polymer chains. Gives a rigid 3D structure.
Characteristics of thermosets?
high stiffness
higher strength than thermoplastics
cannot be reheated and re-moulded – it will usually char and burn
Types of Thermosets?
- Polyurethane
- Urea-formaldehyde
- Epoxy Resin
Properties and application of polyurethane?
Very effective electrical insulator
High tensile and compressive strength
easily bonded
flexible
applications: glove coatings, rubber boots, wheels, shoe soles, varnish
Properties and application of Urea-formaldehyde?
High heat distortion temperature
high tensile strength
applications: decorative laminates, textiles, paper, foundry sand molds, wrinkle-resistant fabrics, cotton blends, rayon, corduroy, etc.
Properties and application of Epoxy Resin?
Resistant to chemicals and water
Adhesive form can bond to metal.
High mechanical strength
Applications:used in the construction of vehicles, snowboards, aircrafts and bicycles and adhesive purposes
Is plastic recyclable?
Plastic is recyclable, however the degree to which it can be recycled depends on the type, economic factors, logistics, and technology.
As it is a non-renewable resource, it is quite valuable. However, its low cost combined with a throwaway society and poor collection mean that much plastic ends up in the environment.
How is plastic recycled?
Plastic needs to be separated by type in order for it to be recycled. Mixing different types of plastics, or allowing contaminants can reduce the overall quality of the recycled plastic.
Disposal of thermosets and thermoplastics
Thermoplastics are easier to recycle than thermoset plastics. In many cases, Thermoset plastics are sent to the landfill or incineration (destruction of something).
Strategies when it comes to the use of plastic
Designing for Disassembly strategies can include the labelling of plastic parts with the type of plastic to ensure proper recycling.
Light-weighting or reducing the amount of material required in a product and its packaging
Promoting and using recycled plastics can encourage user acceptance of the unique aesthetic properties.
Selecting other materials when appropriate (glass, metal, or wood)
What are bioplastics?
Bioplastics are plastic materials produced from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, woodchips, sawdust, recycled food waste, etc.
Applications: bags for compost, agricultural foils, horticultural products, nursery products, toys and textiles. They are also often used for disposable cups, salad bowls, plates, clingfilm and food containers.
Disposal of bioplastics
Plant based polymers are able to fully compost at the end of their useful life
What are composite materials?
A MIXTURE COMPOSED OF TWO OR MORE MATERIALS WITH ONE ACTING AS THE MATRIX (GLUE) THE OTHER ACTS AS A REINFORCEMENT (FIBRES/SHEET/PARTICLES).
characteristics of composites?
It takes the form of fibres/sheets/particles (reinforcement) in a matrix (glue).
The fibres/sheets/particles can be made from textiles, glass, plastics, wood and carbon.
The matrix can be made from thermoplastics, thermosetting plastics, ceramics (e.g. concrete), metals.
It is made via the process of weaving, moulding, pultrusion or lamination
Composition and structure of composites
- concrete
- engineered wood-also called composite wood, man-made wood, or manufactured board.
- fiberglass
- carbon
- laminated veneer lumber
- kevlar
composition of concrete?
water, Portland cement, and aggregates (gravel etc)
composition of engineered wood
Gluing sheets (veneer), particles or stands of wood together.
composition of fiberglass
stands of glass, formed into a matt and then covered in resin (polymer/thermoset plastic).
composition of carbon
reinforced plastic – carbon fibres formed into a matt (see above image) then covered in resin
composition of LVL
uses multiple layers of thin wood assembled with adhesives
composition of kevlar
para-aramid synthetic fiber covered in a resin
Advantages of composites
Excellent strength-to-weight and stiffness-to-weight
Laminate patterns and ply buildup in a part can be tailored to give the required mechanical properties in various directions.
It is easier to achieve smooth aerodynamic profiles for drag reduction.
Complex double-curvature parts with a smooth surface finish can be made in one manufacturing operation.
Composites offer excellent resistance to corrosion, chemical attack, and outdoor weathering;
disAdvantages of composites
- Composites are more brittle than wrought metals and thus are more easily damaged
- Repair introduces new problems, for the following reasons:
Materials require refrigerated transport and storage and have limited shelf lives. .
Hot curing is necessary in many cases, requiring special equipment. Curing either hot or cold takes time.
Repair at the original cure temperature requires tooling and pressure
design context of concrete
skyscrapers, bridges, sidewalks, highways, houses and dams.
design context of plywood
a wide range of uses from construction, internal (furniture, flooring, etc) and exterior uses (such as marine ply for boats).
design context of particle wood
used in furniture (such wardrobes, wall units, TV cabinets), shelving, toys, and wall linings
design context of fiberglass
boats, pools, pipes, bathtubs, motor industry (vehicle bodies)
design context of kevlar
armour, high performance canoes or sports equipment, ropes, military applications, tyres, sails,
design context of carbon re-inforced plastics
high performance car racing, sports equipment (golf clubs, etc), aviation (the Boeing Dreamliner)
design context of LVL
structural applications such as in buildings.
what are natural fibres?
Materials produced by plants or animals that can be spun into a thread, rope or filament.
examples of natural fibres
wool, cotton, silk, leather
properties of natural fibres
Absorbency – is very high
Strength – low tensile strength
Elasticity – not very elastic
Effect of temperature – will burn but does not melt.
what are synthetic fibres
Fibres made from a man-made material that are spun into a thread; the joining of monomers into polymers by the process of polymerisation.
what is polymerisation?
is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks
examples of synthetic fibres
acrylic, nylon, polyester, lycra
properties of synthetic fibres
Absorbency – is very low
Strength – high tensile strength
Elasticity – highly elastic (like stockings, socks etc)
Effect of temperature – will burn and melt.
characteristic of non-ferrous metals.
Contain No Iron
Non Magnetic
Will Not Rust
characteristics of ferrous metals.
Contain Iron
Will Rust
Are Magnetic
what are pure metals?
These are metals that once have been taken from the ground and processed contain NO OTHER ELEMENTS or METALS.
characteristics of pure mentals?
Pure metals tend to be soft and lack PROPERTIES that would make them useful.
This means most metals are ALLOYS to improve their purpose.
what are alloys
alloy, metallic substance composed of two or more elements, as either a compound or a solution
-Alloys can also be mixtures of NON-METALS
Aluminum:
- non-ferrous
- silver gray metallic
- soft, durable, lightweight, ductile, malleable and is a good conductor
- one of the most commonly recycled metals in the world.
- used for tin foil, soda cans, bikes
copper:
- non-ferrous
- reddish orange colour
- soft, ductile, malleable and is a VERY good conductor
- When copper is exposed to the elements it turns GREEN naturally. This is how the copper protects itself
- Copper is an Expensive metal because of its high demand in Electrical and Plumbing.
- Its is commonly found in the ground with Zinc and Silver
- coins, cables, heat exchangers
gold:
- non-ferrous
- yellow and shiny
- The GLOBAL price for gold is at a all time high. This is because of its use in COMMUNICATION TECHNOLOGY.
GOLD is in Ireland but would take a huge investment to extract it from the ground
- dense, soft, shiny, malleable, ductile metal. Gold is also one of the BEST CONDUCTORS of all metals
- jewelry, coins, grills, conductor for electricity (used in electronics)
Iron:
- ferrous
- It can RUST easily when exposed to air or water.
- dark grey and dull
- soft, tough, very hard to machine and work with
- Since the Iron age- Iron has very little use in its PURE state.
It is REFINED to make STEEL by adding CARBON
lead:
- non-ferrous
- bluish white but can change to a dull grey.
- Lead is used with NUCLEAR power.
Lead has a NATURAL shield against RADIATION
- Very Soft, Malleable, and is Corrosion resistant.
- paint, ceramics, pipes and plumbing materials, solders, gasoline, batteries, ammunition and cosmetics
Tin:
- non-ferrous
- White Metal with
a shiny surface
- Malleable and has excellent resistance to Corrosion.
- used for cans,
zinc:
- non-ferrous
- bluish white, lustrous
- hard, brittle
- After ALLOYING- ZINCS greatest use is GALVANISING
this is when another metal (STEEL) is dipped in MOLTEN ZINC to create a RUST PROOF COAT.
-fence, roofing, nails
tungsten:
- hard steel grey
- non-ferrous
- widley use for alloys
- HARD, BRITTLE MATERIAL, Can Be difficult to work with
- x-rays,lightbults
Brass:
- copper + zinc
- gold in colours, very lustrous
- MALLEABLE , TOUGH,
GOOD CONDUCTOR,
GREAT ACOUSTIC PROPERTIES
-instruments, bolts, locks, door hinges
bronze:
- copper+tin
- hard, brittle
- coins, medals,
- brownish orange, dull
steel:
- iron+carbon
- either bright or black
- MALLEABLE, HARD,HIGH TEMPERATURE, TOUGH (depending on carbon content), Ductility, TENSILE STRENTH,
- bolts, buildings, boots,
solder:
- lead+tin
- dull silver
- MALLEABLE, SOFT, CONDUCTOR, LOW MELTING TEMPERATURE
- SOLDERS MAIN USE is to JOIN other METALS
eg
COPPER
BRASS
STEEL (sheet)
TIN
-clasps, clips, or cuffs, used in. metal working
what is a conductor:
A conductor is something that allows heat or electricity flow easily through it.
Metal ore
when metals occur naturally
Metal must be extracted from their ore before they can be used; this is done through extraction from the earths core, mining, removal of rocks and other compounds
What is timer?
Timber is a major building material that is renewable and uses the Sun’s energy to renew itself in a continuous cycle.
timer’s effects on the environment
While timber manufacture uses less energy and results in less air and water pollution than steel or concrete, consideration needs to be given to deforestation and the potential negative environmental impact the use of timber can have on communities and wildlife.
natural timber
Is timber that is sawn from the tree and is used as is. This includes hardwood and softwood trees.
softwood trees
Softwood trees are coniferous trees that have cones and needle-like leaves.
Pine, Cedar, and Fir are commonly used examples of softwood.
characteristics of softwoods
Environmental considerations: Relatively fast growing and thus considered a renewable resource
Physical properties: less dense;
Aesthetic properties: generally lighter colored; can have very strong aroma (cedar, for example)
Design Contexts: low-cost furniture;
natural timber- hardwoods
Is timber that is sawn from the tree and is used as is. This includes hardwood and softwood trees.
hardwood trees
Hardwood trees are deciduous trees that bear fruit, seeds or nuts and broud leaves.
Maple, beech, birch, and oak are examples of commonly used hardwoods
characteristics of hardwoods
Environmental considerations: hardwoods can take longer to reach maturity. (~100ys) This longer growth period is reflected in their higher cost. Because of this, they are also considered to not be a renewable resource.
Physical properties: Comparable density, strength, hardness and durability.
characteristics of natural timber
Tensile Strength: The tensile strength of natural timber is greater along the grain than across the grain.
Resistance to damp environments: is very resistant.
Longevity: Hardwoods very good. Softwoods good.
Aesthetic properties: natural colours range (red, purple, cream and brown). The grain can add to its aesthetics
Moisture content of natural timber
When living trees are cut down the timber is of very little use. This is due to the moisture (or greenness) of the wood. Most of this moisture needs to be removed and a equilibrium moisture content achieved. In order to achieve this timber needs to be seasoned.
Equilibrium Moisture content (EMC): This is when the moisture content of wood is at equilibrium (same as) the local environment. This can be affected by humidity and temperature changes
what is seasoning
Seasoning is the commercial drying of timber which reduces the moisture content of wood
Thus making the timber highly useable.
types of seasoning
Air-drying: Air- drying are stacks of sawn Timber in the open or in large sheds. There is little control over the drying process as the weather elements have affects.
Kiln-drying are stacks of sawn timber in a kiln, to reduce the moisture content in wood, where the heat, air circulation, and humidity is closely controlled.
timber defects
Warping is the distortion in wood caused by uneven drying, which results in the material bending or twisting.
Bowing is the warping along the length of the face of the wood.
Cupping is the warping across the width of the face of wood, in which the edges are higher or lower than the centre.
Twisting is the warping where the two ends of a material do not lie on the same plane.
Knots are imperfections in timber, caused by the growth of branches in the tree that reduces its strength
what causes defects
While the moisture content of ‘wet’ timber is being removed defects may occur. Controlled seasoning can avoid this. However, once the EMC is achieved and timber goes from high humidity to low humidity (uncontrolled) then the defects will occur.
man-made timbers
Plywood (Laminated boards) are layers of veneers (very thin slices of wood) glued together perpendicularly.
Particle board (Chipboard) which is made from different sizes of wood chips, joined with glue and pressed.
characteristics of man made timbers
Tensile strength: depends on the man-made timber
Plywood – high tensile strength in all directions
Particle board and MDF – very low
Resistance to damp environments: depends on the man-made timber.
Exterior plywood – excellent.
Interior plywoods very low
Particle board and MDF – very low
Longevity:
Plywood is high
Particle board and MDF is low to medium
Aesthetic properties:
Plywood if the top layer is of a nice timber like Beech will be good
Particle board and MDF requires finishing or a sheet of lamination (see previous section)
treatment and finishing of timbers
Treatment of wood can involve using solutions. The reasons for treating or finishing wood include:
Reducing attack by insects, fungus and marine borers by making the wood poisonous
Creosote: A material that penetrates the timber fibres protecting the integrity of the wood from attack from borer, wood lice and fungal attack.
Protection from the weather
Protection from Dry rot.
Where timber is subjected to decay and attack by fungus.
Improving chemical resistance
Enhancing aesthetic properties
Modifying other properties
recovery and disposal of timbers
Wood recycling is the process of turning waste timber into usable products.
Recycling timber is a practice that was popularized as deforestation and climate change prompted both timber suppliers and consumers to turn to a more sustainable timber source.
Reforestation is the process of restoring tree cover to areas where woodlands or forest once existed. If this area never returns to its original state of vegetative cover the destructive process is called deforestation.
one off production
- made once at a time
- continuous flow- constantly manufactured
- mass customization-
- batch production- make in batches when needed
one off production advantages
- highly customizable to consumer needs
- flexibility for the designer and consumer
- allows for testing of prototypes before continuous flow production
one off production disadvantages
- time consuming
- high production cost
- possible that there are no interchangeable parts
batch production
-limited production run ( specific number of items to be produced).Made in batches
batch production advantages
- lower cost
- less time consuming
- still can be customizable
- easily adjustable to market’s demands
- greater customer choice
- good process for smaller companied that can’t afford a continuous flow production
batch production disadvantages
- down time between productions run when retooling
- products must be stored raisins the costs per item
craft production
- small scale production –> Manuel skills
- custom items
- expensive
- very time consuming
- highly skilled and specialized
- typically higher quality materials in lower quantity
mechanized production
- high volume production where machines are controlled by humans
- machines assist workers in productivity, quality, and safety
mechanized advantages
Advantages:
- less labour
- smaller chance of human error
- repetitive tasked carried out by machines
- increased productivity
mechanized disadvantages
- high maintenance by technicians
- less opportunity for workers
- repetitive work
- limits customization
- increased pollution
- health and safety issues
automated production
- machines do it themselves
- controlled by computers
- use CAD, CAM, and CNC to link computers to manufacturing equipment
advantages automated
- less human error involved
- produce products at a fast rate
- lower amount waste due to higher precision and less faults
- less labour
- higher quality
- blueprint and final product are similar
- work 24/7
- improve health and safety due to less workers
- less waste produced as the production system can be optimized
disadvantages automated
- less jobs
- high initial cost
- reduce work force
- high pollution
- less customization
- lower labour cost
- workers need to be highly trained and skilled
CNC
- computer control of machines for manufacturing complex parts in metals and diff materials
- controlled by “G code”. Codes assigned specifically for a certain proceed. The control x,y,z movement and feed speeds
- CNC n CAD work together. CAD file contains info about the product, dimension etc. later interpreted by the CNC machine to produce the final product
- eg: 3d printers, laser cutters,
cnc advantages
- machine is more accurate
- less time consuming
- cheaper
- more reliable
- more customizable
- reduces waste
cnc dis
-high initial cost
-
assembly line production
-continous flow of products
-dont build all in one go
Goes thru a step by step in a line
-high volume — predicted snd comp0onents moved continuous along a conveyor
advantages assembly line production
-economy of scale
High production volume of is miller products Is possible
disadvantages assembly line production
-increased pollution Limitied customization Can be expensive to retool Depend on reliable supply -discrease in jib staisfication due to repetition
design for manufacture
- design for materials- designing in relation to materials
- design for process-designing to enable the product to be manufactured using a specific manufacturing process.
- design for assembly-
robotics advantages
- robots are doing more dangerous jobs
- more accurate
- less labour
- increased productivity
- work in confined spaces
- perform 24/7
- re-programmability or flexible
robotics disadvantages
- high initial cost
- reduction in employment
- high maintenance
- costs more energy
- need expertise to operate such systems
1st gen robots
- do one thing
- cannot adapt to their environment
- no sensors
- a simple mechanical arm- work at high speeds for a long time. Used in single task assembly lines, no variables walking or around
2nd gen robots
Sensors: -camera sensor -radar -unltrasound -force Lidar -multitask
- use sensors such as light, distance, temp, pressure, radar, etc. they can sense their environment
- complex code uses these snore to guide the robots to operate autonomously
- synchronize with each other and done require constant supervision
- controlled by external control unit
3rd gen robots
- no human interaction needed
- fully autonomous
- self controlling
- no need for human super vision
- have their own central control unit
- use of artificial intelligence to process the world around them and to accomplish tasks
load capacity
-how much the robot arm can lift — max weight it can hold
-includes the weight of the end arm tooling
-
work envolope
-the 3d space a robot can operate within considering clearance and reach
cartesian robots
3 axis X-Y-Z
- 3d printer, laser cutter, pick and place
- work envelope almost like a rectangular prism
cylindrical robots
- cylindrical work space
- have at least on rotary joint at the base and at least one prismatic joint connecting the links
- the robots have a cylindrical workspace with a pivoting shaft an
polar robots
- works in a sphere
- twisting joint connecting arm
- combination of 2 rotary joins and one linear joint connecting the links
- aka spherical robots
- axes form a polar co-ordinate system
- centrally pivoting shaft and extendable arm
machine 2 machine
- networking of robots to =gether to share info and instructions
- common application include remote monitoring of worksites and product restocking.
