Topic 4 Raw Materials To Final Production
Properties of materials
Properties of materials are categorized as follows.
Physical properties
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Density is important in relation to product weight and size (for
example, for portability). Pre-packaged food is sold by weight or
volume, and a particular consistency is required.
Electrical resistivity is particularly important in selecting
materials as conductors or insulators.
Thermal conductivity is important for objects that will be heated
or must conduct or be insulated against heat gain or loss.
Thermal expansion (expansivity) is important where two
dissimilar materials are joined. These may then experience large
temperature changes while staying joined.
Hardness is important where resistance to penetration or
scratching is required. Ceramic floor tiles are extremely hard and
resistant to scratching.
Task- Find a few products or context where a physical property is crucial to the design
and explain why.
Density
Electrical
Resistivity
Thermal
conductivity
Thermal
expansion
Hardness
Boat
Lighting rod
Resistor
Kettle
Pan
Bridge gap
Rail
Glass
Aircraft
Car
Mechanical properties
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Tensile strength is important in selecting materials for ropes and
cables, for example, for an elevator.
Stiffness is important when maintaining shape is crucial to
performance, for example, an aircraft wing.
Toughness is important where abrasion and cutting may take
place.
Ductility is important when metals are extruded (not to be
confused with malleability, the ability to be shaped plastically).
Task- Find some products or context where a mechanical
property is crucial to the design and explain
Tensile Strength
Stiffness
Toughness
Ductility
Cable
Rope
Aircraft wing
Chopping board Wire
Bullet proof glass Fence gate
Aesthetics
 Tensile strength- The ability of a material to withstand
pulling forces.
 Stiffness- The resistance of an elastic body to
deflection by an applied force.
 Toughness- The ability of a material to resist the
propagation of cracks
 Ductility- The ability of a material to be drawn or
extruded into a wire or other extended shape.
Aesthetic characteristics
Some aesthetic characteristics are only relevant to food, while others can be applied to more than one
material group. Although these properties activate people’s senses, responses to them vary from one
individual to another, and they are difficult to quantify scientifically, unlike the other properties.
Color is an important part of human expression.
This new lamp (led) changes the colours and moods in your home,
16.000 colours in one lamp it's a Philips innovation
Task- Watch this video Design 4 life 02 The Colour of Emotion - the importance of colour &
light
Smart materials
Piezoelectricity. When a piezoelectric material is deformed, it gives off a small electrical discharge. When
an electric current is passed through it, it increases in size (up to a 4% change in volume). These materials are
widely used as sensors in different environments. Specific details of crystalline structure are not required.
Piezoelectric materials can be used to measure the force of an impact, for example, in the airbag sensor on a
car. The material senses the force of an impact on the car and sends an electric charge to activate the airbag.
Piezoelectric material
develops an internal
electric field when
compressed (A) or
stretched (B). If electrical
contacts are attached to
material, a quantity of
electrical charge
proportional to the applied
force can be measured.
the
Shape memory alloys (SMA) are metals that exhibit pseudo-elasticity and shape memory effect due to
rearrangement of the molecules in the material. Pseudo-elasticity occurs without a change in temperature.
The load on the SMA causes molecular rearrangement, which reverses when the load is decreased and the
material springs back to its original shape. The shape memory effect allows severe deformation of a material,
which can then be returned to its original shape by heating it. Applications for pseudo-elasticity include
eyeglasses frames, medical tools and antennas for mobile phones. One application of shape memory effect is
for robotic limbs (hands, arms and legs). It is difficult to replicate even simple movements of the human
body, for example, the gripping force required to handle different objects (eggs, pens, tools). SMAs are
strong and compact and can be used to create smooth, lifelike movements. Computer control of timing and
size of an electric current running through the SMA can control the movement of an artificial joint. Other
design challenges for artificial joints include development of computer software to control artificial muscle
systems, being able to create large enough movements and replicating the speed and accuracy of human
reflexes.
Photochromicity refers to a material that can described as having a reversible change of colour when
exposed to light. One of the most popular applications is for colour-changing sunglass lenses, which can
darken as the sun brightens. 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.
Electro-rheostatic (ER) and magneto-rheostatic (MR) materials are fluids that can undergo dramatic
changes in their viscosity. They can change from a thick fluid to a solid in a fraction of a second when
exposed to a magnetic (for MR materials) or electric (for ER materials) field, and the effect is reversed when
the field is removed. MR fluids are being developed for use in car shock absorbers, damping washing
machine vibration, prosthetic limbs, exercise equipment and surface polishing of machine parts. ER fluids
have mainly been developed for use in clutches and valves, as well as engine mounts designed to reduce
noise and vibration in vehicles.
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. Thermoelectric circuits have been used in
remote areas and space probes to power radio transmitters and receivers.
Students are expected to be able to interpret stress/strain graphs and material selection charts to identify
appropriate materials depending on the context.
Stress/strain grahp
Plastic deformation relates to the “permanent deformation of a solid subjected to a stress”. This stress is
normally a force, whether it be, tensile, compressive, shear, bending or torsion.
Elastic deformation is the change in the state of the materials structure when force is applied. All materials have
an elastic limit, Yield point where they will return to their original shape once the force applied is removed.
Once a material passes this point the material enters a plastic region- material dislocation or defects cause the
material to harden and eventually fail/fracture.
http://en.wikipedia.org/wiki/Deformation
Plastic deformation occurs when a metal is stretched or bent beyond the elastic limit, so that it does not return to
its original length or shape when the force is removed. The ability of metals to be plastically deformed is widely
used in processing them (for example, the pressing of car panels into shape).
Material Selection Charts
In order to demonstrate the power of the material selection chart approach, a number of common property
combinations have been plotted:
 Allow you to view the selection charts.
 Enable you to interactively 'explode' particular classes of materials.
 Give brief definitions of the properties on the chart.
 Provide general information about each chart and some insights into the physical reasons
underlying it.
 Give examples of how each chart can be used in a design context.
 Set short easy questions involving each chart, with hints and brief answers
 Ask more involved questions about each chart that require greater 'lateral thinking' to solve - e.g.
considering other charts as well, processing issues etc.
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Young's modulus - Density
Young's Modulus - Cost
Strength - Density
Strength - Toughness
Strength - Elongation
Strength - Cost
Strength - Max service temperature
Specific stiffness - Specific strength
Electrical resistivity - Cost
Recycle Fraction - Cost
Energy content - Cost
Types of materials
Materials play a key role within the design, manufacture and use of all products. This topic considers the
historical development of materials not only in terms of the scientific advances made during the discovery of
a particular material but also in how various developments in unrelated fields later converge and lead to the
development of new manufacturing techniques and materials. These developments should not only be looked
at for their technological development but also for their social impact on the design and consumer industries.
Timber
Describe the structure of natural timber
Natural timber is timber that is used directly from the tree. Natural timber is a natural
composite material comprising cellulose fibres in a lignin matrix.
The tensile strength of timber is
greater along the grain (fibre) than
across the grain (matrix).
Wood is a fibrous material. The structure of wood similar to a bunch of parallel straws (the cellulose fibres),
which are bonded together with a glue (lignin matrix). The fibres are long and slender and are aligned with
the long axis of the trunk which gives it an interesting property behaviour.
When load is applied parallel to the axis of the fibres, they are very strong in tension and have reasonably
good compressive strength until they start to buckle.
When the load is applied perpendicular to the axis of the fibres, they will tend to crush under compression
and are weakest in tension, where the “glue” bond fails and the straws literally tear apart.
Outline that
timber can be
classified
according to the
conditions
needed for tree
growth
Study the
distribution of
forest map of the
world below.
Temperate
forests tend top
be in cooler regions and tropical forests tends to be between the Tropic of Cancer and Capricorn in
warmer climates.
Outline that conifer trees are referred to as softwoods and that these grow only in temperate regions
Conifers- Any of various mostly needle-leaved or scale-leaved, chiefly evergreen, cone-bearing trees or
shrubs such as pines, spruces, and firs.
Characteristics of softwood trees are:
 They take around 30 years to reach maturity
 The wood from these trees is generally softer
(That's where the name comes from) due to the faster
growth of the tree and therefore producing a less
dense cellulose fibres and lignin matrix
 Softwoods reproduce by cones
 Softwoods have needles
 They do not lose their needles in the fall They are
sometimes called evergreens because the needles are
green year round
 Examples included are pine, cedar, and cypress
Outline that deciduous trees are referred to as hardwoods and that these
grow in both temperate and tropical regions
Decidiouos- Hardwood trees shed their leaves and other characteristics
of hardwood trees are:
 The wood from these trees is generally harder. (That's where the
name comes from) as they take around 100 years to mature and
therefore ore have a much denser cell structure
 Hardwoods reproduce by flowers.
 Hardwoods have broad leaves and are fruit bearing
 Many lose their leaves every autumn and are dormant in the
winter
 Some examples of hardwood trees includes eucalyptus, elm, maple,
oak, and beech
Discuss the issues relating to the consideration of timber as a renewable resource
Issues should be placed in local, national and international contexts.
 time to reach maturity, e.g. Mahogany trees takes about 100
years to mature
 soil erosion ... the roots of the tree hold the soil in
 greenhouse effect ... less
trees to remove the greenhouse
gases
 extinction of species ...
destroying animal, insect and plant
life
http://www.youtube.com/watch?v=HfQgmlwzRXg
List two examples of composite timbers
Chipboard
Plywood
Compare the characteristics of particle board, laminated woods (for example, plywood), pine wood (a
softwood) and mahogany (a hardwood)
Consider composition, hardness, tensile strength, resistance to damp environments, longevity and the
aesthetic properties of grain, colour and texture. The ability to produce sketches showing cross-sectional
views of the structure of the materials is expected.
Task- Comparing particle board, plywood, pine and mahogany.
Resources needed: Testing timber samples of particle board, plywood, pine and mahogany
Chipboard
Plywood
Pine
Beech
Wood chips
Layers of wood
veneer
Original
original
Colour
Light
Dark and light
Light
dark
Texture
Rough
Smooth
Smooth
smooth
Hardness
4
2
3
1
Tensile
strength
Resistance to
dampness
4
2
3
1
4
3
2
1
Longevity
4
3
2
1
Composition
Grain
You will be given a sample of each material. Use the samples to make observational comparisons between
each material. Here are the categories that you need to use:
 Composition (show the structure of the material as a hand-drawn cross-sectional view)
 Grain
 Colour
 Texture
Now carry out some comparative testing to add to your sheet. In groups, devise and carry out a test to
compare the following properties of each material:
 Hardness

Tensile strength

Resistance to dampness
Moisture meter
https://www.youtube.com/watch?v=bQ5Lk8kRw6I
Longevity
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Outline criteria for the selection of timber for different structural and aesthetic design contexts
As a designer and manufacturer consideration of timber for buildings, bridges, furniture and children’s toys
must be carefully considered. This is mainly due to the various properties and characteristics of timber and
the product specifications.
E.g. Beech (Hardwood) is very hard and is therefore ideal for children’s toys. As it is quite expensive it
would not be suitable for building a house with and a different timber could be selected.
Task- Investigate the following products and identify a suitable timber for its use.
Children’s Toys
IKEA Flat pack
bookshelf unit
Modern Chair
Outdoor Garden
chair
Indoor Book Shelf
Timber choice
Hardwood
Softwood
Plywood
Hardwood
Chipboard
Reason
Hardness is high
Light weight
Cheap
Hardness is high
Tensile strength
is high
Hardness is high
Tensile strength
is high
Resistance of
dampness is high
Cheap
Describe the reasons for treating or finishing wood.
Consider reducing attack by organisms and chemicals, enhancing aesthetic properties and modifying other
properties.
Fungal attack are caused by parasitic plants which break down the wood cells and cause its collapse Fungus
causes timber to decay reducing its strength and weight and it structural integrity.
Types of attack on timber include:
Dry rot- reduces the timber to a sponge like consistency due
lack of circulated air
Wet rot- due to alternate wet and dry conditions
Insects- borers and weevils, in warmer climates these termites
each the cellulose of the timber
Dry rot in a house floor
Prevention and treatment for fungal and insect attack is quite straight forward. Most treatments are chemical
based, normally removing the damaged materials and spraying with a solution to prevent further rot or
infestation. Genetically modified (GM) timbers that have had their DNA modified provide opportunity to
reduce the amount of likely infections and defects that are associated with non-GM timbers. The issue of
whether plants, crops and trees are genetically modified is a contentious issue, one that stimulates debate
about the ethics of such action.
Explain three differences in the selection of timbers for flooring if it were made of a hardwood, a
softwood or a composite material.
Consider durability, ease of maintenance and aesthetics.
Timber flooring and the choice of materials depend very much on the ‘quality’ (fitness for purpose) that is
required.
Hardwood floors. This apartment has a hardwood wooden
floor- these have been chosen for:
Durability- hardwood is hard wearing and resistant to
compressive forces preventing indentation from furniture and
footwear.
Ease of Maintenanece- these floors can be easily sanded and
re-finished with a varnish.
Aesthetics- a wide variety of colours
and tones are available
Harwood flooring in an apartment
Softwood floors.
Durability -softwood floors are less durable than hardwood floors, that
is, compressive forces act more easily on their surface. This resistance
can be enhanced by the use of a finish such as varnish.
Ease of maintenance -like hardwoods floors softwoods can be sanded
and finished with varnish. Softwood floors can be stained which changes
the tones of the natural colour.
Aesthetics – softwood colours tend to be ‘warmer’ and lend themselves
to the older style of property ie cottages or Victorian style of interior
design – varieties of pine are often used.
Softwood flooring
Composite Flooring. These floor materials are varied
and can be composites based on wood chips and
adhesives such as chipboard or a composite of natural
wood fibres and plastics.
Durability – composites tend to very hard wearing and
have both industrial and residential applications. The
wood/plastic composites are suitable for heavy traffic
whereas chipboard, which is often used as a flooring
materials in attics & lofts tend to have a ‘softer’ surface
where heavy traffic is not common.
Ease of Maintenance- Both composites require little
maintenance- the plastic/wood composite required on
light cleaning where the chipboard surface required a
finish such as a sealer to repel any atmospheric moisture.
Aesthetics- for outdoor use a high aesthetic value is essential- it provides a realistic finish. Chipboard is often
used to create loft or attic flooring, mezzanine flooring. It is less important to consider the aesthetic value of
the surface finish in this case but it is essential that it is treated with a moisture repellent to prevent so as
retain its structural strength.
Metals
Draw and describe a metallic bond
Metals are often described as positively charged nuclei in a sea of electrons. The outer electrons of the metal
atom nuclei are free and can flow through the crystalline structure. The bonding is caused by attraction
between the positively charged metallic atom nuclei and the negatively charged cloud of free electrons.
Specific arrangements of metal atoms are not required.
Giant structures with free electrons
Metals form giant structures in which electrons in the outer shells of the metal atoms are free to move. The
metallic bond is the force of attraction between these free electrons and metal ions. Metallic bonds are strong,
so metals can maintain a regular structure and usually have high melting and boiling points.
Metals are good conductors of electricity and of heat because
the free electrons carry charge or heat energy through the
metal. The free electrons allow metal atoms to slide over each
other, so metals are malleable and ductile.
Metals are described as malleable (can be beaten into sheets)
and ductile (can be pulled out into wires). This is because of the
ability of the atoms to roll over each other into new positions
without breaking the metallic bond.
Metallic Bond
Explain how the movement of free electrons makes metals very good electrical and thermal conductors
Metals are materials that have a low value of resistivity allowing them to easily pass an electrical current due
to there being plenty of free electrons floating about within their basic atom structure. When a positive
voltage potential is applied to the material these "free electrons" leave their parent atom and travel together
through the material forming an electron or current flow.
When a metal is heated, the electrons closest to the heat source vibrate more rapidly. Electrons then collide
with these atoms and gain more kinetic energy (movement energy). The electrons therefore move around
faster and collide with other free electrons which then gain more kinetic energy. Kinetic energy is therefore
transferred between the electrons and through the metal from the point closest to the heat source towards
points further away. The electrons all travel very short distances but are very fast moving therefore
conduction of heat happens very quickly.
Electrical conductivity
Metals conduct electricity. The delocalised electrons are free to move throughout the structure in 3dimensions. They can cross grain boundaries. Even though the pattern may be disrupted at the boundary, as
long as atoms are touching each other, the metallic bond is still present.
Liquid metals also conduct electricity, showing that although the metal atoms may be free to move, the
delocalisation remains in force until the metal boils.
State that metals (pure or alloyed) exist as crystals
Crystals are regular arrangements of particles (atoms, ions or molecules). Details of types of crystals are not
required.
Minute nuclei (crystals) of a solid form when a pure, molten
metal is cooled to just below its freezing temperature.
Impurities in the molten material provide the centre for
growth for the nuclei.
 All metals (except mercury) are solid at room
temperature.
 A process of nucleation & growth achieves
solidification.
 ‘Dendrites’ grow out from the nuclei forming a
tree-like structure in the direction of the heat loss.
Task: The atoms arrange themselves in a regular pattern or lattice structure. Most metals form one of three
types of lattice structure. Draw the following:
Lattice Structure
Drawing of the structure
Close packaged hexagonal
(CPH)
Face-centered cubic (FCC)
Body centered cubic (BCC)
a= formation of nuclei. b- Dentrites form. c=dendritric growth. d=grain formation, grain boundries
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This crystalline structure gives metals their properties (strength, stiffness, ductility, conductivity &
toughness).
Each dendrite grows in a geometric pattern consistent with the lattice structure until each one touches
its neighbour. At this point the dendrites begin to thicken to form a totally solid grain of metal.
The grain boundaries between are visible under a microscope, each grain having the same structure but
a different orientation. This boundary is a narrow zone (perhaps three atoms) in which the atoms are not
properly spaced according to the lattice structure.
Draw and describe what is meant by grain size
The rate of cooling and the amount of impurities in the molten metal will affect grain size:
 Gradual cooling - a few nuclei are formed - large grain size
 Rapid cooling - many nuclei formed - small grain size.
 Reheating a solid metal / alloy allows the grain structure to re-align itself.
 Directional cooling in a structure is achieved by selectively cooling one area of a solid.
 The effect of impurities (or additives) in a molten metal can induce a large number of fine
grains that will give a stronger and harder metal. This addition must be carefully controlled as
too many impurities may cause an accumulation at the grain boundaries, which will weaken the
material.
Grain: A solid many-sided individual crystal consisting of groups of atoms bound together in
a regular geometric pattern (crystalline).
Grain Size: Average diameter of grains or alternatively, the number of grains per unit area.
Lower ductility and impact resistance accompanies increased grain size.
http://www.ami.ac.uk/courses/topics/0122_mos/index.html#7
Explain how grain size can be controlled and modified by the rate of cooling of the molten metal, or by
heat treatment after solidification
Reheating a solid metal or alloy allows material to diffuse between neighbouring grains and the grain
structure to change. Slow cooling allows larger grains to form; rapid cooling produces smaller grains.
Directional properties in the structure may be achieved by selectively cooling one area of the solid.
Task: Workshop demonstration and investigation: This will enable you to experience experience the
following processes: Hardening, tempering, normalising, planishing, annealing and case-hardening.
No.
Heat Treatment
Process
Hardening
(Mild Steel)
Equipment/Process
Grain Size
Hardening is a metallurgical and
metalworking process used to
increase the hardness of a metal.
Small
2
Tempering
(Mild Steel)
Heating the metal to some
temperature below the critical point
for a certain period of time, then
allowing it to cool in still air.
Large
3
Normalising
(Mild Steel)
Heating the suitable steel to a
temperature at or above the
hardening temperature of hardening
steels, and then cooling in air
Large
4
Planishing
(Copper)
Hammering with a planishing panel
hammer or slapper file against a
shaped surface called a planishing
stake
Small
1
5
Annealing
(Aluminium)
Heating the material (generally until
glowing) for a while and then slowly
letting it cool to room temperature in
still air.
Large
6
Case Hardening
(Mild Steel)
Hardening the surface of a metal
object while allowing the metal
deeper underneath to remain soft,
thus forming a thin layer of harder
metal (called the "case") at the
surface. The surface of the steel is
heated to high temperatures then
cooled rapidly, generally using water
Small on the surface
Summary: Reheating a solid metal or alloy allows material to diffuse between neighbouring grains and the
grain structure to change. Slow cooling allows larger grains to form; rapid cooling produces smaller grains.
Explain how metals work-harden after being plastically deformed
During the formation of the crystalline and grain structures,
flaws and faults occur. These interruptions in the patterns are
know as dislocations. When a force is applied to dislocation then
the metal resettle into more regular and stable forms, which make
the metal harder and stronger.
Dislocations at the grain boundries
Shaping of the metal by rolling, extrusion, pressing, hammering, and so on, and may be carried out at high
temperatures when the metal is soft (hot-working), or at normal temperatures (cold-working), when
deformation leads to progressive hardening of the metal (work-hardening).
Metal crystals yield plastically at stresses several orders of magnitude lower than the theoretical value for the
deformation of perfect crystals. This discrepancy is accounted for by the presence of linear imperfections
known as dislocation lines within the crystals. Plastic flow takes place by “slip” in definite crystallographic
directions on certain crystal planes, because of the movement of dislocation lines under the applied stress.
Dislocations multiply and entangle as deformation proceeds, thus making further flow increasingly difficult.
This is the process underlying work-hardening, mentioned above.
Describe how the tensile strength of a metal is increased by alloying
Alloying is the process of mixing or combining metals and or non-metals to enhance the mechanical or
physical properties of the original metal whether it be ferrous or a non-ferrous metal. The large numbers of
grain boundaries prevent defects progressing though the material. The effect of the impurities in a pure metal
can therefore induce a large number of fine grains which will give a stronger and harder metal than a large
grain structure. The introduction of impurities is, therefore, known as grain size strengthening. The addition
of certain metals affects grain size, e.g. vanadium and aluminum tend to give steel a fine grain.
Task: Complete the following table for ferrous and non-ferrous metals
Name
Composition
Properties
Uses
Stainless Steel
Made up of Iron, nickel and
chromium.
Resists staining and
corrosion
High Speed Steel
Made up of iron, tungsten
and vanadium
Withstand higher
temperatures without losing
its hardness
High Tensile Steel
Made up of nickel and
chromium and iron
Manganese Steel
Made up of manganese
Withstand great strain
without breaking or
becoming deformed
High impact strength and
resistance to abrasion
Casting Aluminum LM4
Made up of aluminum
Has fairly good machining
properties
Duralimin
Made up of aluminum and
copper
Titanium
Compounds with Ti-C
bonds
Brass
Made of copper and zinc
Improves strength, it also
makes these alloys
susceptible to corrosion.
Corrosion resistance and the
highest strength-to-density
ratio of any metallic
element.
Used for decoration for its
bright gold-like appearance
Used for the likes of cutlery
and surgical
instrumentation.
Used for form tools, slitter
knives, guillotine knives,
parting tools and many other
types of cutting tools.
Aircraft, automotive and
mechanical engineering
applications
Used in the mining industry,
cement mixers, rock
crushers, railway switches
and crossings, crawler treads
for tractors and other high
impact and abrasive
environments.
Cylinder-heads, crank-cases,
junction boxes, gearboxes,
clutch-cases, switch gear
covers, instrument cases,
tool-handles and household
fittings, office equipment
and electrical tools
Aircraft, screw machine
Industrial, aerospace,
recreational, and emerging
markets.
Low friction is required such
as locks, gears, bearings,
doorknobs, ammunition
casings and valves
Tensile strength of a material can be
enhanced by the addition of another
element
within
its
structure.
Their
introduction
affects
the
dislocations,
restricting the movement between the
grain boundaries and as a consequence
enhance the tensile strength of the original
material.
The red dot is carbon in iron- the distortion
that is caused impedes dislocation
Explain the effect of alloying on malleability and ductility
The presence of “foreign” atoms in the crystalline structure of the metal interferes with the
movement of atoms in the structure during plastic deformation.
Foreign atoms as show above 4.4.8 have the potential to
enhance the mechanical properties of materials. These
atoms such as carbon in iron or copper+manganese in
Duralumin will introduce a variety of grain size within the
newly formed alloy. A larger grain size enable ‘pile up’ to
occur at the grain boundary, where a smaller grain is
introduced as foreign atoms less pile up occurs increasing
or enhancing or decreasing properties such as malleability
and ductility.
Large grain- large pile up, lower plastic limits
Describe a superalloy
The strength of most metals decreases as the temperature is increased. Superalloys are
metallic alloys that can be used at high temperatures, often in excess of 0.7 of their absolute
melting temperature.
List two design criteria for superalloys
A superalloy is an alloy that is designed to be used at high temperatures that can resist creep
and oxidisation. Superalloys are based on iron, cobalt or nickel. Nickel based superalloys are
particularly suitable for use in aircraft engines and other applications that require high
performance at high temperatures.
Identify applications for superalloys
Superalloys can be based on iron, cobalt or nickel. Nickel-based superalloys are particularly
resistant to temperature and are appropriate materials for use in aircraft engines and other
applications that require high performance at high temperatures, for example, rocket
engines, chemical plants.
Plastics
Describe a covalent bond
In a covalent bond the outer electrons of some atoms
come close enough to overlap and are shared
between the nuclei, forming a covalent bond. Each
pair of electrons is called a covalent bond. Covalent
bonds are strong bonds and examples of primary
bonds (as are metallic and ionic bonds).
Describe secondary bonds as weak forces of attraction
between molecules
http://www.makingthemodernworld.org.uk/learning_m
odules/chemistry/03.TU.02/?section=7
Thermosetting
plastics
(or
thermosets, for short) can be
heated and set only once. They
cannot be remelted or reshaped.
When a thermoset is heated, it
undergoes a chemical reaction
called crosslinking, which binds its
polymer chains together. This reaction is similar to the hardening of an egg when it is boiled.
Once it has hardened, it cannot become a liquid again. Because thermosets cannot be
remelted, engineers use them in applications that require high resistance to heat. Products
made from thermosetting plastics include saucepan handles and trays for sterilizing medical
instruments.
Thermoplastics can be melted and re-formed. Their polymer chains do not form crosslinks.
Thus, the chains can move freely each time the plastics are heated.
http://www.azom.com/details.asp?ArticleID=506
Manufacturers use thermoplastics more than thermosets because thermoplastics are easier
to handle. They also require less time to set, as little as 10 seconds, compared to as long as 5
minutes for thermosets. Most thermoplastics can also be dispersed in liquids to produce
durable, high-gloss paints and lacquers. Because their molecules can slide slowly past one
another, some thermoplastics tend to lose their shape when exposed to constant pressure
over a long period. For this reason, manufacturers prefer to use thermosets for such products
as plastic seats.
Describe the structure and bonding of a thermoplastic
Thermoplastics are linear chain molecules, sometimes with side bonding of the molecules but
with weak secondary bonds between the chains.
Describe the effect of load on a
thermoplastic with reference to
orientation of the polymer chains
Deformation occurs in two ways:

elastic, in which initially
coiled chains are stretched and
the material returns to its original
size and shape when the load is removed
 plastic, when at higher loads the secondary bonds between the chains weaken
and allow the molecular chains to slide over each other, and the material does not
return to its original size and shape when the load is removed.
Explain the reversible effect of temperature on a thermoplastic, with reference to orientation
of the polymer chains
Increase in temperature causes plastic deformation and eventually will burn when heated
after the initial moulding.
Explain how the reversible effect of temperature on a thermoplastic contributes to the ease of
recycling of thermoplastics
Thermoplastics soften when heated and harden and strengthen after cooling.
Thermoplastics can be heated, shaped and cooled as often as necessary without causing a
chemical change, while thermosetting plastics will burn when heated after the initial
molding. Additionally, thermoplastics tend to be easier to mold than thermosetting plastics,
which also take a longer time to produce (due to the time it takes to cure the heated
material).
Draw and describe the structure and
bonding of a thermoset
Thermoplastics
are
linear
chain
molecules but with strong primary
bonds between adjacent polymer
chains. This gives thermosets a rigid 3D
structure.
Explain the non-reversible effect of
temperature on a thermoset
Heating increases the number of
permanent crosslinks and so hardens
the plastic.
Thermosetting plastics have a number
of advantages. Unlike thermoplastics,
they retain their strength and shape
even when heated. This makes
thermosetting plastics well-suited to the
production of permanent components
and large, solid shapes. Additionally,
these components have excellent
strength attributes (although they are brittle), and will not become weaker when the
temperature
increases.
Thermoset plastic products are typically produced by heating liquid or powder within a
mold, allowing the material to cure into its hardened form. These products can be removed
from the mold even without allowing it to cool. The reaction used to produce thermosetting
plastic products is not always the result of heating, and is sometimes performed by chemical
interaction between specialized materials. Typical types of thermosetting plastics are
epoxies, polyesters, silicones and phenolics. Vulcanized rubber is also an excellent example
of a thermosetting plastic; anyone who has ever driven an automobile can attest to the
properties of a superheated tire—it burns but does not mold into a new shape.
Discuss the properties and uses of polypropene and polyethene thermoplastic materials
Plastics can be defined by their SPI codes, and the numbers within the recycling arrows refer
to different types of plastic resins. There is no federal regulation governing the types of
symbols you see stamped to plastic, so you can not be certain of consistency from state to
state.
Task: Investigate the properties for each of the six plastics listed
Polymer Types
Examples of applications
Polyethylene
Terephthalate
Fizzy drink and water bottles. Salad trays.
High Density
Polyethylene
Milk bottles, bleach, cleaners and most shampoo
bottles.
Polyvinyl
Chloride
Pipes, fittings, window and door frames (rigid
PVC). Thermal insulation (PVC foam) and automotive
parts.
Low Density
Polyethylene
Carrier bags, bin liners and packaging films.
Polypropylene
Margarine tubs, microwaveable meal trays, also
produced as fibres and filaments for carpets, wall
coverings and vehicle upholstery.
Polystyrene
Yoghurt pots, foam hamburger boxes and egg
cartons, plastic cutlery, protective packaging for
electronic goods and toys. Insulating material in the
building and construction industry.
Unallocated
References
Any other plastics that do not fall into any of the
above categories - for example polycarbonate which
is often used in glazing for the aircraft industry
Symbol
Discuss the properties and uses of polyurethane and urea–formaldehyde (methanal)
thermoset materials
Polyurethane, commonly abbreviated PU, is any polymer consisting of a chain of organic
units joined by urethane links. Polyurethane formulations cover an extremely wide range of
stiffness, hardness, and densities. These materials include:
 low density flexible foam used in upholstery and bedding,
 low density rigid foam used for thermal insulation and e.g. automobile dashboards,
 soft solid elastomers used for gel pads and print rollers, and
 hard solid plastics used as electronic instrument bezels and structural parts.
Polyurethanes are widely used in high resiliency flexible foam seating, rigid foam insulation
panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, electrical
potting compounds, high performance adhesives and sealants, Spandex fibres, seals,
gaskets, carpet underlay, and hard plastic parts.
Urea-formaldehyde, also known as urea-methanal, named so for its common synthesis
pathway and overall structure, is a transparent thermosetting resin or plastic, made from urea
and formaldehyde heated in the presence of a mild base such as ammonia or pyridine.
These resins are used in adhesives, finishes, MDF, and molded objects. Urea-formaldehyde
resin's attributes include high tensile strength, flexural modulus and heat distortion
temperature, low water absorption, mould, high surface hardness, elongation at break, and
volume resistance.
Discuss the issues associated with the disposal of plastics, for example, polyvinyl chloride
(PVC)
Although PVC disposal is problematic, PVC is still widely used as a structural material, for
example, in windows and for guttering and drainpipes.
PVC has been at the centre of a controversial debate during much of the last two decades.
Despite its many alternatives, polyvinyl chloride (PVC) is one of the most widely used plastics.
Unfortunately, its production, use, and disposal create persistent toxic pollution, including
dioxin.
At low levels, dioxin can cause a range of health problems from learning disabilities to
cancer. The Environmental Protection Agency now estimates that the cancer risk from dioxin
for the average American is as high as 1 in 1000.
More than 14 billion pounds of PVC are currently produced per year in
North America alone. Approximately 75% of all PVC manufactured is used
in construction materials. There are also many PVC consumer products
such as toys, shower curtains, and window blinds.
Hospitals also use PVC medical devices such as intravenous bags and
tubing. DEHP, a phthalate used to soften PVC plastic, can leach from PVC
medical devices and is linked to reproductive birth defects and other
illnesses, according to animal studies.
PVC requires the use of many toxic chemical stabilizers, such as lead,
cadmium and organotins, and phthalate plasticizers. These chemicals
leach, flake, or outgas from the PVC over time, raising risks that include
asthma, lead poisoning, and cancer.
PVC poses a great risk in building fires. It releases deadly gases such as
hydrogen chloride long before it ignites, which turns to hydrochloric acid
when inhaled. Burning PVC, whether accidentally or in waste incineration, also results in
dioxin.
Because PVC products require many additives, recycling is nearly impossible for most
products and interferes with the recycling of other plastics. The Association of Postconsumer
Plastic Recyclers declared it a contaminant in 1998.
http://www.greenpeace.org/international/campaigns/toxics/polyvinyl-chloride
Ceramics
Describe the composition of glass
Glass is composed primarily of silicon dioxide
together with some sodium oxide and
calcium oxide and small quantities of a few
other chemicals.
Glass can be generally divided into two
groups: oxide glass and non-oxide glass. The
ingredients of oxide glasses include oxides
(chemical compounds that include oxygen).
Non-oxide
glasses
are
made
from
compounds that contain no oxides, and
which often instead contain sulfides or metals.
Oxide glasses are much more widely used
commercially.
Explain that glass is produced from sand,
limestone and sodium carbonate, and requires large quantities of energy for its manufacture
Scrap glass is added to new raw materials to make the process more economical.
Chemically glass is composed primarily of silicon dioxide together with some sodium dioxide
and calcium oxide and a small quantities of a few other chemicals.
Watch the video: http://manufacturing.stanford.edu/hetm.html and click on Glass Bottles
Glass is recyclable. It is produced from sand, limestone and sodium carbonate. The
manufacturing requires a large amount of energy because it is very heat intensive. Scrap
glass is added to raw materials to make the process of manufacture more economical.
Glass furnace temperatures reach up to 1675°C adding scrap glass
leads to savings not only in the raw materials, but also in the energy
consumption of the glass furnace.
Describe the characteristics of glass.
 brittleness,
 transparency,
 hardness,
 unreactivity
 high aesthetic properties
At the macroscopic scale, glass tends to be hard, brittle
and transparent. It is largely unreactive and so makes it
ideal for containers for things like food and certain
chemicals.
Glass is used extensively as a construction material. Plate
glass and glass bricks are often chosen both wall and floor
materials. Glass is generally transparent, has high
compressive strength and low thermal conductivity. It lets
in natural light and can trap heat.
Glass is increasingly used as a structural material to
increase the aesthetic and psychological benefits: allows
natural light into buildings and can visually link spaces, creating more interesting interiors. Use
examples of building from the 20th Century to show some examples that support this idea.
Explain that the desired characteristics of glass can be accurately determined by altering its
composition
Laminated glass
Laminated glass consists of two thin sheets of glass that have a sheet
of plastic glued between them.
When the glass is put under pressure and the glass fractures the plastic
bonded sheet retains the fragments.
Tempered glass- Pyrex®
Tempered glass has been heat treated – annealed which provides a low
stress uniform structure.
The cooling of the glass provides the strength as
the exterior which cools first is in compression and
the interior in tension.
Water Glass and Soda-Lime Glass
Glass of high soda content can be dissolved in water to form a syrupy fluid. Known as water
glass, it is used commercially for fireproofing and as a sealant. Most manufactured glass is a
soda-lime composition used to make bottles, tableware, lamp bulbs, and window and plate
glass.
Lead Glass
The fine-quality table glass known as crystal glass is made from potassium-silicate formulas
that include lead oxide. Lead glass is heavy and has an enhanced capacity to refract light,
which makes it suitable for lenses and prisms, as well as for imitation jewels. Because lead
absorbs high-energy radiation, lead glasses are used in shields to protect personnel in nuclear
installations.
Find out more about Glass
http://manufacturing.stanford.edu/hetm.html and click on Glass Bottles- Flash Video
Outline the differences between toughened and laminated
glass
Toughened Glass
Toughened or tempered glass is glass that has been
processed by controlled thermal or chemical treatments.
Toughened glass is made by heating glass almost to the
melting point. The surfaces are then cooled while the centre
remains hot and plastic. It will shatter into tiny fragments
when broken .
It has increased strength compared with normal glass and
will usually shatter into small fragments,
rather than sharp shards and therefore
is less likely to cause injury, when
broken (eg. windscreens of cars). In
toughened glass, the applied tensile
load must overcome the compressive stress at the surface before the surface can go into
tension and fail.
Laminated Glass
Laminated glass is a type of safety glass that holds together when shattered due to the thin
layer of material, usually plastic, between the layers.. In the event of breaking, it is held in
place by an interlayer between its two or more layers of glass. This prevents cracks from
growing and it can even be made bullet proof (eg windscreens or bank teller windows).
Explain why glass is increasingly used as a structural material
The use of plate glass and glass bricks as wall and flooring
materials is becoming very popular due to their material
properties, for example, resistance to tensile and
compressive forces, thermal conductivity and
transparency. The aesthetic properties and psychological
benefits: allows natural light into buildings and can visually
link spaces, creating more interesting interiors.
Glass Bricks
Plate Glass
Glass flooring
Glass flooring (bridge)
Plate glass, glass bricks and flooring are used as a structural material due to the:

Aesthetic properties Glass is can a transparent or translucent material, allowing
light to pass through, thus allowing users to see in or out. It will also allow light to it
can fill dark areas of building or office. Natural lighting has positive affects on
people and well as health reasons. In flooring can add appeal by having lights
shine through (dance floors) or over things of interest (aquariums).

Thermal Conductivity Glass can insulate a building thus keeping it cool/warm
which in turn is a benefit to the environment (reduced energy consumption) and
owner (reduced energy costs).

Hardness Compressive strength Resists scratching and indentation of peoples'
shoes or chairs etc etc. Easily maintained as well since it is non-reactive.
Composites
Describe composites
Composites are a combination of two or more materials that are bonded together to
improve their mechanical, physical, chemical or electrical properties.
Define fibre
A class of materials that are continuous filaments or are in discrete elongated pieces, similar
to lengths of thread with a length to thickness ratio of at least 80.
Describe the matrix composition of composites
Composite materials usually consist of synthetic fibres embedded within a matrix, a material
that surrounds and is tightly bound to the fibres. The most widely used type of composite
material is polymer matrix composites (PMCs). PMCs consist of fibres made of a ceramic
material such as carbon or glass embedded in a plastic matrix. Typically, the fibres make up
about 60 per cent of a polymer matrix composite by volume. Metal matrices or ceramic
matrices can be substituted for the plastic matrix to provide more specialized composite
systems called metal matrix composites (MMCs) and ceramic matrix composites (CMCs),
respectively.
carbon fibre
glass fibre
Explain that new materials can be designed by enhancing the properties of traditional
materials to develop new properties in the composite material.
Composite Materials are substances made up of a combination of two or more different
materials. A composite material can provide superior and unique mechanical and physical
properties because it combines the most desirable properties of its constituents while
suppressing their least desirable properties. For example, a glass-fibre reinforced plastic
combines the high strength of thin glass fibres with the ductility and chemical resistance of
plastic; the brittleness that the glass fibres have when isolated is not a characteristic of the
composite.
Task: Compare the differences between carbon fibre vs. steel bicycle frame
Designers sometimes engineer products in such a way that they are easy to manufacture. Design for
manufacture (DfM) exists in almost all engineering disciplines, but differs greatly depending on the
manufacturing technologies used. This practice not only focuses on the design of a product’s components,
but also on quality control and assurance.
Additive techniques: paper-based rapid prototyping, laminated object manufacture (LOM), stereolithography
Wasting/subtractive techniques: cutting, machining, turning and abrading
Shaping techniques: moulding, thermoforming, laminating, casting, knitting, weaving
Joining techniques: permanent and temporary, fastening, adhering, fusing
Manufacturing techniques
Define manufacturing technique
A specific manufacturing term,
sometimes relating to one material
group only. Manufacturing is the
making of goods by physical labour
and machinery. It generally involves
the conversion of raw materials into a
finished product. Raw materials can
include such items as fruit, cloth,
wood and plastic. They are supplied
from industries such as agriculture and
mining.
Cotton fields to Jeans
Trees to Books
Finished products include: Books,
jeans and compact discs and are
supplied to customers.
Outline the techniques of moulding,
casting, weaving, fusing, stitching,
cutting, machining, abrading, using adhesives and using fasteners
Injection Moulding
Injection moulding as its name suggests involves injecting molten thermoplastic into a mould under great
pressure. The moulds can be very intricate and are often made in several pieces. Radio housings, computer
casings, vacuum cleaners and watches are all made with injection moulding.
Injection moulding is widely used process for making products in volume. It would never be used for oneoff or small batch production. This is because the tooling cost for the machines is very expensive. However,
once set up, the products (or mouldings) can be produced very cheaply.
Casting
Casting is a method of shaping an object by pouring a liquid into a mould and letting it harden. The shaped
object is called either a cast or a casting.
Casting is used to make thousands of articles, including tools, machine parts,
toys, and art objects such as statuary. The Egyptians cast bronze in moulds
over 3,500 years ago. Today, plastics, aluminium, ceramics, and many other
materials are used in casting.
Weaving
Weaving is the process of making cloth, rugs, blankets, and other products
by crossing two sets of threads over and under each other. Weavers use threads spun from natural fibers like
cotton, silk, and wool and synthetic fibers such as nylon and Orlon. But thin, narrow strips of almost any
flexible material can be woven. People learned to weave thousands of years ago using natural grasses,
leafstalks, palm leaves, and thin strips of wood.
In general, weaving involves the interlacing of two sets of threads at right angles to each other: the warp and
the weft. The warp is held taut and in parallel order, typically by means of a loom, though some forms of
weaving may use other methods.
Task: Attempt a weave of your own using the above technique, how would you describe the process to a
year 6 using pictures alone.
Fusing
Fusing involves the melting of metal by the application of heat.
Gas Welding
Mixed gases in the proper Proportions, directed against
the parts to be welded. The molten edges of the parts
then literally flow together, after cooling, form one
solid piece.
Arc Welding
Arc welding electrode combines a central current
carrying "core wire", which acts also as the filler rod,
and a flux covering.
Spot Welding
Spot welding is used to weld various sheet metal
products. The process uses two shaped copper alloy
electrodes to concentrate welding current into a small
"spot" and to simultaneously clamp the sheets together.
Electron Beam
Electron Beam Welding (EBW) is a fusion joining
process that produces a weld by impinging a beam of
high energy electrons to heat the weld joint. Raising
electrons to a high energy state by accelerating them to
roughly 30 to 70 percent of the speed of light provides
the energy to heat the weld.
Laser
Laser Beam Welding (LBW) is a modern welding
process; it is a high energy beam process that continues
to expand into modern industries and new applications
because of its many advantages like deep weld
penetration and minimizing heat inputs.
Diffusion Bonding
Diffusion bonding involves holding pre-machined
components under load at an elevated temperature
usually in a protective atmosphere or vacuum. Times at
temperature can range from 1 to 60+ minutes, but this
depends upon the materials being bonded.
Friction Welding
Friction welding (FW) is a process that generates heat
through mechanical friction between a moving work
piece and a stationary component. Technically, because
no melt occurs, friction welding is not actually a
welding process in the traditional sense, but a forging
technique. Friction welding is used with metals and
thermoplastics in a wide variety of aviation and
automotive applications.
Ultrasonic Welding
Ultrasonic welding is an industrial technique whereby
high-frequency ultrasonic acoustic vibrations are
locally applied to work pieces being held together
under pressure to create a solid-state weld. It is
commonly used for plastics, and especially for joining
dissimilar materials. In ultrasonic welding, there are no
connective bolts, nails, soldering materials, or
adhesives necessary to bind the materials together.
Stitching
Joining of cloth, leather, furs, bark, or other materials, using needle and thread. Its use is nearly universal
among human populations and dates back to 30,000 BC. Stitching predates the weaving of cloth.
Cutting
Cutting is the separation of a physical object, or a portion of a physical object, into two portions, through the
application of an acutely directed force. For an object to be capable of cutting it must have a hardness
sufficiently larger than the object being cut, and should be applied with sufficient force. Cutting also
describes the action of a saw which removes material in the process of cutting.
Machining
Powered machines that shape metals and other materials through a variety of cutting or grinding processes,
machine tools operate on unfinished metal parts, such as rough metal castings o forgings, and perform
shaping and finishing operations that produce precisely dimensioned parts.
Most machine tools function in one or more of several basic categories: turning, shaping and planing, boring,
drilling, and milling and grinding.
Turning
The engine lathe is the oldest and most common turning
machine. It is used for shaping the external surface of a
cylindrical part by rotating the work piece against a cutting
tool. The turret lathe carries a number of cutting tools that
can be used in sequence to shape, drill, bore, ream, and cut
threads on both exterior and interior cylindrical surfaces.
Shaping
In shaper operations the cutting tool moves against a
stationary work piece, which is usually held on a horizontal
table.
Planing
These machines remove metal from flat surfaces. In the
planing machine the work piece moves beneath a stationary
cutting tool. Planers can shave even layers off a metal
surface or cut multiple grooves and channels.
Boring
Boring is the process of enlarging a hole that has already
been drilled (or cast), by means of a single-point cutting
tool, for example as in boring a cannon barrel. Boring is
used to achieve greater accuracy of the diameter of a hole,
and can be used to cut a tapered hole.
Drilling
Drilling is the process of using a drill bit in a drill to
produce cylindrical holes in solid materials.
Milling
The rotating cutting tool in a milling machine is usually
toothed and is used to cut a variety of shapes, from flatplaned surfaces to slots, grooves, shoulders, and dovetails.
Milling machines are used to cut gears.
Grinding
In grinding, metal is removed from the surface of a work
piece to make it smooth. A grinding machine has a grinding
wheel that spins at high speed against the work piece. This
wheel is made of an abrasive material similar to that on
sandpaper.
Abrading
To wear down or rub away by friction, also known as a wasting process because the piece that is removed is
usually referred to as 'waste'. Using this forming process you create a new form or component by removing
or cutting away any surplus material. This can be achieved by several means, such as:
Chemical (etching)
Mechanical
Adhesive
An adhesive is a compound that adheres or bonds two items together. Adhesives may come from either
natural or synthetic sources. Some modern adhesives are extremely strong, and are becoming increasingly
important in modern construction and industry. Advantage of adhesive: strong, cost-effective, hidden from
view and easy to join.
Identify a range of adhesives suitable for joining metals, woods and plastics PVA (polyvinyl acetate),
epoxy resin, contact adhesive, cascamite, tensol cement and superglue (cyanoacrylate)
PVA
PVA is sold as an adhesive for
porous materials, particularly wood,
paper, and cloth. It is the most
commonly use wood glue, both as
"white glue" and the yellow
"carpenter's glue." PVA is widely
used in book binding and book arts
due to its flexibility, and because it
is non-acidic, unlike many other
polymers.
Epoxy Resin
Epoxy or poly-epoxide is a
thermosetting epoxide polymer that
cures (polymerizes and cross-links)
when mixed with a catalyzing agent
or "hardener".
Contact
Adhesive
Cascamite
Contact adhesive is one which must
be applied to both surfaces and
allowed some time to dry before
the two surfaces are pushed
together.
Cascamite is a waterproof glue
and is probably
the most
effective glue of all and is suitable
for all furniture especially if used
outside as it resists rain water.
“Cascamite glue is a powder glue
that is mixed with water it creates a
bond stronger than the wood itself
as other contributor said
Cascamite is waterproof and
generally used in boatbuilding it is
also good to use on certain
hardwoods that have oil resin
present (teak, iroko afromosia
etc..)”
Tensol
Superglue
A single component cement
which hardens due to solvent
evaporation to produce a clear
bond in cast acrylic sheets.
Cyanoacrylate is a tenacious
adhesive, particularly when used to
bond non-porous materials or those
that contain minute traces of water.
It is also very good at bonding body
tissue, and while this can be a
bothersome (or even dangerous)
side effect during everyday use, it
has been exploited for the benefit of
suture-less surgery.
Cyanoacrylate glue has a low
shearing strength, thus its use as a
temporary adhesive in cases where
the piece can easily be sheared off at
a later time.
Describe how the techniques in 5.1.2 relate to different materials
Task: Using ticks or crosses (√ or x) complete the Materials/ Manufacturing Techniques below
For example, casting relates to metals, plastics, food, ceramics and some composites, but not to timber or
textiles.
Metals
Plastics
Food
Ceramics
Textiles
Timber
√
√
√
√
x
x
Moulding
Casting
Weaving
Stitching
Fusing
Cutting
Abrading
Fasteners
Adhesives
Machining
Discuss advantages and disadvantages of using the techniques to manufacture products
The manufacturing technique depends on the material to be processed, the amount of components needed and
the type of component required. Other factors contributing to the advantage or disadvantage of technique
selection would be production location and environmental issues concerned.
As a business grows in size and produces more units of output, then it will aim to experience falling average
costs of production—economies of scale. The business is becoming more efficient in its use of inputs to
produce a given level of output. Designers should incorporate internal and external economies of scale when
considering different production methods and systems for manufacture.










Craft production
Mechanized production
Automated production
Assembly line production
Mass production
Mass customization
Computer numerical control (CNC)
Production system selection criteria
Design for manufacture (DfM): design for materials, design for process, design for assembly, design
for disassembly
Adapting designs for DfM
Craft production
Define craft production and one-off
production.
Craft production (or One-off Production)
is the process of manufacturing by hand
with or without the aid of tools. The term
Craft production refers to a manufacturing
technique applied in the hobbies of
Handicraft but was also the common
method of manufacture in the preindustrialized world.
Describe why most products were
manufactured by craft techniques prior
to the Industrial Revolution
Prior to the Industrial Revolution most
products were manufactured by craft
techniques. The processes, techniques and
materials that were used were restricted by the technology and energy sources that were available at the time.
The development of skills were slow; sources of materials and energy were few and would depend on the
immediate surrounding areas; sales and distribution were workshop and market based; the craftsman was also
the designer as was the the client also the consumer.
Explain the advantages and disadvantages of craft production
Task: Which of the following are advantages and which are disadvantages?









Variable production costs are high, particularly labour costs, but fixed costs are low.
Expensive form of production.
Difficult to organise if production is technically complex.
Worker motivation enhanced. Each new job presents a different challenge, so they need to be adaptable.
Workers gain satisfaction from being responsible for the complete product.
Skilled workers needed with a high degree of technical expertise and the ability to adapt. Can be large
workforce if a technically complex project is involved.
Very flexible system, enables large variety of products to be manufactured, geared to customer
specification.
Manufacture of a single product or small quantity.
Selling aimed at particular customers or firms in specialised markets
Discuss the importance of craft production for developed and developing countries
In pre-industrial cities, craftsmen tended to form associations based on their trades, confraternities of textile
workers, masons, carpenters, carvers, glassworkers, each of whom controlled secrets of traditionally imparted
technology, the "arts" or "mysteries" of their crafts. Usually the founders were free independent master
craftsmen.
Before a new employee could rise to the level of mastery, he had to go through a schooling period during
which he was first called an apprentice. After this period he could rise to the level of journeyman.
Apprentices would typically not learn more than the most basic techniques until they were trusted by their
peers to keep the guild's or company's secrets.
In a developing country a guild can be said to some aspects of the modern corporation. They have control
over the materials and tools, needed to produce goods. They are early forms of small business associations.
Mechanization
Define mechanization
Watch this: Chocolates
http://www.youtube.com/watch?v=wQppu2jkIwE
Mechanization is defined as: “A volume production process involving machines controlled by humans”.
In other words, machinery is used to carry out some or all of the repetitive tasks in a production process.
Mechanization might involve the following elements:



Using jigs and templates to ensure quality control.
Using conveyor belts to control the rate of production and to keep components flowing from one
process to the next.
Using Robots to assemble complex machinery such as a car.
Task: Why is mechanization well suited to volume production and not to one-off or small batch production?
Describe how the availability of new sources of power in the Industrial Revolution led to the
introduction of mechanization
The only source of portable energy prior to the Industrial Revolution was human muscle power and
animal power. Tools were designed to be used only with these energy sources. Even though it was
possible to harness heat energy from fire (for example to forge metal), the limitation is that the
energy source (timber and coal) depended upon local availability.
The water wheel enabled the harnessing of energy for batch
production. However, the water wheel had a fixed location next to a
fast-flowing river and so lacked adaptability. However, the energy
from water could be harnessed at many points along the river, resulting
in the first batch and mass- manufacturing developments in textiles and
ironwork. Because the wheel creates rotary motion, the motion could
easily be converted into linear, oscillating and reciprocating forms to
carry out a variety of tasks. An oscillating hammer could be used to
forge metal for example.
Steam engines.
A real breakthrough came in 1712 with the manufacture of the
world’s first steam engine. The principle is very simple: Water is
heated until it boils and becomes steam. The steam is contained in a
cylinder and creates pressure. The pressure can be used to make a
cylinder reciprocate (move backwards and forwards in a straight
line). This motion is converted to rotary motion using mechanisms.
You can see this principle in action on a steam locomotive.
This meant that for the first time, power could be transported (you
did not need to be next to a river, timber or coal source to create
energy). This really was the beginning of the mass production age
and unfortunately, the source of many of today’s global energy and
environmental problems.
Define assembly-line production
Assembly-line production is defined as: “The mass-production of a product via a flow line based on the
interchangeability of parts, pre-processing of materials, standardization and work division.”
Put more simply, it means the following:



Each manufacturing task is divided up into basic stages.
Each stage is carried out using specialist labour and equipment (work division).
A flow line (like a conveyor belt) moves each part from one stage to the next. This controls the rate of
production (how fast it is made).
This makes each individual task repetitive. These repetitive tasks are increasingly carried out using control
technology (robots).
Charlie Chaplin made a great movie in 1936 about the impact of assembly line production on society called
‘Modern Times’. Watch this clip: Modern Times http://www.youtube.com/watch?v=qDnDaDYZ2AQ
Task: Was Charlie Chaplin’s vision of the future correct? Discuss.
Explain the relevance of assembly-line production to mechanization.
and
Outline two advantages and two disadvantages of mechanizing a production process
Hopefully you can see how assembly-line production and mechanization are related. You can’t have one
without the other! This table summarizes this relationship:
Which came first?
Why?
Economics
Design of products
Effect on the work force
Consumer choice
Summary:
Assembly line
First
This split tasks into stages
(work division)
More efficient. Products are
manufactured at a controlled
rate and with increased quality.
Less adaptable. Changes to
product design are harder to
implement.
Tasks are repetitive. Workers
Become skilled in a single process.
Labour is used more efficiently.
Health and safety issues arise
(repetitive strain etc.)
Reduced. Products become similar.
Advantage 1
Advantage 2
Disadvantage 1
Disadvantage 2
Mechanization
Second
Specialist machinery can then carry out the
repetitive tasks.
Even more efficient. Less labour
Intensive, production can be continuous.
Products become identical. Less
flexibility to adapt to new designs (this is now
changing with the development of ‘mass
customization’.
Minimal labour required. Labour is used mainly
to oversee automated processes.
Higher unemployment.
Minimal. Your products are identical.
Note that ‘mass customization’ is changing this.
Reduced cost of product for consumer.
Increased reliability and product quality.
Reduction in labour needed leading to
unemployment.
Re-skilling of workers needed to maintain
mechanized processes.
Define batch production and mass production.
Batch production: “Limited volume production (a set number of items to be produced)”
Mass production: “The production of large amounts of standardized products on production lines, permitting
very high rates of production per worker”
Compare batch production and mass production in a mechanized production system
Watch the following movie clips. Decide whether each is an example of batch production or mass
production. What evidence is there to support your choice?
Magnum
Shoelaces
T-shirt
Surfboard
http://www.youtube.com/watch?v=7hXfFfGMT_M
http://www.youtube.com/watch?v=8HHluPK9zWg
http://www.youtube.com:watch%3Fv=HVZh07CfJSw%0D
http://www.youtube.com/watch?v=FR8SndoR2RQ
Summary:
Task: Complete the following table to show how batch-production and mass-production compare:
Batch production
Market need (explain which types of
markets demand which scale of production).
Consumer choice (how does each system
affect consumer choice?)
Product differentiation (in what ways
Are products similar and different?)
Economies of scale (how does each
System affect costs for manufacturer and
consumer?)
Mass production
Automation
Define automation
The term automation refers to a wide variety of systems and processes that operate with little or no human
intervention. In most modern automation systems, control is exercised by the system itself, through control
devices that sense changes in such conditions as:
AC Temperature controls
Automatic water bowl for a Pet
Auto Volume Control
These devices then command the system to make adjustments to compensate for these changes. Most modern
industrial operations are too complex to be handled manually or even with simple machines under manual
control.
All automated systems depend on feedback to control their performance. The basic elements of feedback can
be illustrated by a home heating system.
Input
Fuel energy
and feedback
information
Process
The heating
system
Output
Heat energy
Feedback
Thermostat giving room
temperature information
to the boiler
Essential to all automatic-control mechanisms is the feedback principle, which enables a designer to endow a
machine with the capacity for self-correction. A feedback loop is a mechanical, pneumatic, or electronic
device that senses or measures a quantity such as position, temperature, size, or speed.
It compares the measurement with the previous measurement and takes whatever preprogrammed action is
necessary to maintain the measured. Using feedback devices, machines can start, stop, speed up, slow down,
count, inspect, test, compare, and measure.
Describe how the development of computer and information technology in the “technological
revolution” led to the introduction of automation
The development of computer and information technology in the Technological Revolution led to the
introduction of automation via computer controlled electrically powered assembly line procedures.
Automation has made a major contribution towards increases in both free time and real wages enjoyed by
most workers in industrialised nations.
Mechanised Assembly Line
Automated Assembly Line
Computers and feedback
loops have promoted the
development of numerically
controlled machines (the
motions of which are
controlled by punched paper
or magnetic tapes) and
machining centres (machine
tools that can perform several
different machining
operations).
A punch card reader and writer
Punch cards
Applications
 The chemical industries developed the technology of automation to regulate variables such as pressure
and temperature that are involved in the production of chemicals.
 The food industries found that packaging, bottling, and sealing operations, as well as the production of
food products, could be accomplished more efficiently by the use of automated systems.
 The methods of automation were refined with the development of aircraft guidance systems and
automatic pilots.
 The development of digital computers, which can monitor external conditions and make appropriate
adjustments to a system, added further impetus to the applications of automation.
 An entire oil refinery can be operated by just four persons.
 Industrial robots perform numerous functions on assembly lines, and automated spacecraft on deepspace probes are programmed automatically to make adjustments in operations.
 In our homes, thermostats control the temperature in automated heating and air-conditioning systems, in
refrigerators, and in water heaters.
 In medicine, cardiac pacemakers regulate the heart rate of people with heart disorders.
Define computer-aided manufacture (CAM) and computer numerical control (CNC)
When CAD systems are linked to manufacturing equipment which is also controlled by computer, they form
an integrated CAD/CAM (Computer-Aided Manufacture) system. CAM equipment relies on a series of
numeric codes, stored in computer files, to control manufacturing operations This Computer Numeric
Control (CNC) is provided by describing machine operations in terms of the special codes and component
shape geometry, and building specialised computer files or “part programs”. The development of these part
programs is a skilled task, now largely superseded by specialised computer software, which forms the link
between CAD and CAM systems.
Explain how CAD, CAM and CNC contribute to an automated production system
Consider the wide variety of systems available.
CAM offers significant advantages over more traditional approaches by controlling manufacturing equipment
with computers instead of human operators. CAM equipment is usually associated with the elimination of
operator error and the reduction of labour costs. However, the consistent accuracy and predicted optimum use
of the equipment lead to even more significant advantages. For example, cutting blades and tools will wear
more slowly and break less frequently, reducing manufacturing costs still further. Against these savings
should be set the higher costs of capital equipment or the possible social implications of maintaining
productivity with a reduced workforce.
Define mass customization
"producing goods and services to meet individual customer's needs with near mass production efficiency"
Tseng and Jiao (2001, p. 685)
A sophisticated CIM (Computer Integrated Manufacturing) system that manufactures products to individual
customer orders. The benefits of economy of scale are gained whether the order is for a single item or for
thousands.
Outline how mass customization is changing the relationship between the manufacturer and the
consumer
The relationship is akin to craft production, where the individual requirements of the consumer dominate.
Today’s turbulent markets and the internet Mass Customization is the new paradigm that replaces mass
production, which is no longer suitable growing product variety, and opportunities for e-commerce. Mass
customization proactively manages product variety in the environment of rapidly evolving markets and
products, many niche markets, and individually customized products sold through stores or over the internet. 1
Many industries have found that lengthy supply-chains, and the economics of configurability do not allow
them to economically offer mass customization.
Famously, some of the early businesses attempting mass
customization (e.g. in bicycle production) went out of business. In
1999 boosters of the mass customization trend proffered
Cannondale as the exemplar of the new model. "Cannondale [...]
for example can configure over 8 million different frame and
colour variations in its bicycles."
Although the company's subsequent bankruptcy in 2003 was
blamed on other causes (including a failed attempt to enter the
motorsports market) the mass customization "revolution" certainly
failed to save it, and it was dropped as a role model by some
business gurus
Discuss the impact of automation on working conditions
Consider nature and type of employment, health and safety issues, social interaction and job satisfaction.
Automation raises several important social issues. Among them is automation's impact on employment.
English textile workers in the early 1800s who protested against Jacquard's automated weaving looms
destroyed automated textile machines because they felt their jobs threatened.
Some argue automation leads to higher employment. One author made the following case. When automation
was first introduced, it caused widespread fear. It was thought that the displacement of human workers by
computerized systems would lead to severe unemployment. In fact, the opposite has often been true, e.g., the
freeing up of the labor force allowed more people to enter higher skilled jobs, which are typically higher
paying. One odd side effect of this shift is that "unskilled labor" now benefits in many "first-world" nations,
because fewer people are available to fill such jobs.
It appears that automation does devalue labour through its replacement with less-expensive machines;
however, the overall effect of this on the workforce as a whole remains unclear.
Advantages
 Automation has greatly increased production and lowered costs, thereby making cars, refrigerators,
televisions, telephones, and other goods available to more people.
 It has allowed production and wages to increase, and at the same time the working week has
decreased in most Western countries from 60 to 40 hours.
 In an automated system, health and safety can be monitored with more efficiency due to the
repetitive nature of the work process. The ‘human error’ is reduced.
 Provides opportunities for the “unskilled” labour force.
Disadvantages
 Workers will have little variety in their job and could result in low job satisfaction.
 Social interaction during work times will be cut, lunch and break may be at different times for each
worker so as to keep production at an efficient level.
Outline how automation has improved the type and range of products available to consumers
Many products require such precision in their manufacture that, without automation, it would not be possible
to produce them at an affordable price.
To meet increasing demands for productivity gains, manufacturers continually ask factory workers to do
more with less equipment, and in less factory floor space. The most automated assembly lines make factory
floors as efficient as possible, boosting the bottom line in highly competitive manufacturing markets.
Adding the latest in robotics and assembly line conveyor systems can help manufacturers meet the stiff
challenges they face. With smaller robotic cells, toploading robots mounted on gantries, new vision-based
robots, simulation software for visualizing robotic cells, and more efficient assembly line equipment,
manufacturers can boost productivity and remain competitive.
Manufacturing Engineering, Feb 2004 by Waurzyniak, Patrick
Automation has greatly increased production and lowered costs, thereby making cars, refrigerators,
televisions, telephones, and other goods available to more people.
Automation within society
Millions of human telephone operators and answerers, throughout the world, have been replaced wholly (or
almost wholly) by automated telephone switchboards and answering machines. Thousands of medical
researchers have been replaced in many medical tasks from 'primary' screeners in electrocardiography or
radiography, to laboratory analysis of human genes, sera, cells, and tissues by automated systems. Even
physicians have been partly replaced by remote, automated robots and by highly sophisticated surgical robots
that allow them to perform remotely and at levels of accuracy and precision otherwise not normally possible
for the average physician.
Robot
Designers should consider the benefits of increased efficiency and consistency when using robots in
production and be able to explore the latest advances in technology to ensure the optimum manufacturing
process is used. However, a good designer will also understand their responsibility to consider the moral and
ethical issues surrounding increased use of automation, and the historical impact of lost jobs.





Primary characteristics of robots:
work envelope and load capacity
Single-task robots
Multi-task robots
Teams of robots
Machine to machine (M2M)
https://www.youtube.com/watch?feature=player_embedded&v=fH4VwTgfyrQ
 Work envelope: The 3D space a robot can operate within, considering clearance and reach
 Load capacity: Within this context, the weight a robot can manipulate.
Single-task robots – can only carry out one task at a time
Multi-task robots – can carry out more than one task at a time
Teams of robots – groups of robots carry out similar tasks

Machine to machine (M2M) – where wireless and wired systems communicate between devices to
share information or send instructions. More information here.
Advantages of using robotic systems in production.
 Improve health and safety of workforce.
 High accuracy of work – reduced errors and waste ($$$). Quality of final product is up.
 Perform repetitive and dangerous tasks
 Work in confined spaces.
 Perform functions 24/7 leading to higher production
 Reprogrammability or flexible
Disadvantages of using robotic systems in production
 Expertise needed to operate such systems.
 Training of workers required in both operation and maintenance.
 High initial capital cost
Robot Generations
This robotee summaries it well
 First-generation robots are a simple mechanical arm that has the ability to make precise motions at
high speed. They need constant supervision by a human operator.
 Second-generation robots are equipped with sensors that can provide information about their
surroundings. They can synchronize with each other and do not require constant supervision by a
human; however, they are controlled by an external control unit.

Third-generation robots are autonomous and can operate largely without supervision from a
human. They have their own central control unit. Swarms of smaller autonomous robots also fit in
this category.
https://www.youtube.com/watch?feature=player_embedded&v=4ErEBkj_3PY
They are not industrial but it does illustrate the autonomous interactions with their environment.
When addressing robots in automated production, students are expected to understand the contexts that
different robots are used in.
https://www.youtube.com/watch?feature=player_embedded&v=HVLbtrlL5_E
International-mindedness:
The use of robots in automated production can depend on the local cost of manual labour.
Theory of knowledge:
Technology in the form of robots currently serves man. Is man’s place secure? Will the nature of man change
due to technological enhancement? Will he be superseded altogether by technological developments?