Hot happens a poor surface condition can happen.

Hot working processes involves taking slabs
of metal that are thicker width than the roller, then are rolled through the
rollers to achieve a thinner slab of metal. This occurs by using compressive
stresses through the rollers which compresses the metal to the desired
thickness. The hot rolling uses heat so the metal becomes ductile and soft so
it can be compresses easier, this process usually uses high temperatures of
950-1000 degrees. However the hardness of the material cannot be controlled, as
it depends on the rate of cooling and chemical composition. The surface of hot
working metal depends on the surface oxidation as this can result in scale
formation and poorly finished surface. However if this happens the hot rolled
material s further treated and cold rolled to ensure a better surface finish.

 

Cold working processes involves the
material being rolled through rollers to reduce the material thickness, when
this happens the material gets compressed and the metal grains are deformed.
The benefits of the cold working processes the dimensional accuracy is much
better, better surface finish obtained, and there is no costs involved with
heating the metal. The disadvantage of this process high forces are required
for deformation.

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70-30

Hot
working processes on the properties and behaviour of 70/30 brass. The
properties of 70/30 hot working process are stated in the image below. The
heated brass is fed through a series of opposing steel rollers which reduce
thickness of the brass step by step to about 0.5 inches or less and this will
increase the width.          60-4060-40 brass is an economical alloy with a
high content of a zinc and copper. This is commonly used for bathroom fixtures,
brass brand instruments, and tooling. The properties of 60-40 it has good
forming properties, when hot rolling the microstructure is maintained, and has
a medium strength. But when oxidation happens a poor surface condition can
happen. Usually cold rolling occurs for 60-40 brass as it achieves a better
surface finish than hot rolling and the 60-40 brass becomes up to 20% stronger.
  

Describe
the effects on properties and behaviour of uni-axial orientation in
thermoplastic polymers drawn into fibres. Thermoplastic polymer is a type of plastic
which changes properties when heated and cooled. When thermoplastic are heated
they become soft, and have a hard finish when cooled. A property of
thermoplastic polymer is that they can be heated and shaped many times. The
uni-axial orientation in thermoplastic polymers, the polymer chain are
orientated in one direction. This occurs by heating the polymers by doing this
an extensional strain when melted, then a force is applied so they flow through
a die to align the polymers in the same direction, then the material is
stretched In one direction so that all the chains line up.  A property of having uni-axial orientation in
thermoplastic polymers is the material becomes tougher and stiffer. When
thermoplastic polymers drawn into fibres the material is cut into pellets so
they are at fibre length, by doing this it makes fibre length shorter than
other composites fibres. This happens as the cost of material is lower so it’s
a cheaper alternative to metal components.  Describe
the effects on the properties and behaviour of biaxial orientation in film
sheets.Biaxial orientation is the procedure of
stretching a hot plastic film in two directions, which causes a molecular
redirection. As a result of doing this it tends to be much stronger and
balanced in both directions.  The
properties of the biaxial orientation in film sheets is they are transparent
and can be made reflective, good gas and aroma barrier properties are achieved,
good chemical levels happen during the process, 
and good electrical insulation. The dimensional stability can be improved
by controlling the crystallization by changing certain processing parameters.
The biaxial orientation can be used for food packaging and wrapping crates.  Describe
how, in an engineering context, the water content of clay affects the
properties and behaviour of the material during processing.The water content of clay can affect the
properties and behaviour of the material during processing however it can
differ with different types of clay. The first type of clay is raw clay this
type of clay contains no water content and this is extracted in its natural
state, the properties and behaviours are dry and crumbly this is due to the no
water content.  The second type of clay
is slip, which is a mixture of water and clay, and this clay is extracted. The
properties and behaviours of this clay is it cannot be moulded and it has a
slime like texture. The third type is plastic, the properties and behaviours
are the clay can be joined to other objects, the clay weight can be supported
when moulded, and has workable properties. The next type is leather the water
content will have reduced compared to plastic and slip at this point the clay
is viably damp, the properties and behaviours are it can be handled without
deformation, and is still joinable to other pieces of clay. The last stage is
green ware where there is water content before toughening, the properties and
behaviours of the clay at this point the clay will hold the shape, wetter clay
can be joined to the green ware clay, and green ware can be broken easily.  Describe
how the strength of concrete is improved during processing with the addition of
reinforcement.Concrete is made by mixing together cement,
gravel, sand, and water. This sets hard by a chemical reaction taking place.
Before concrete is reinforced it is strong in compression, but weak in tension
so this makes it not very useful for many things. However concrete is
reinforced with metal to make it stronger in tension, the metal used to
reinforce concrete usually is steel. The steel support is made by joining steel
bars or cables together and is surrounded by a mould. Then concrete is poured
around the mould and is left to set hard. Reinforced concrete is used for
building foundations or building.  Write
a brief outline of so called ‘Smart’ materials and the special properties they
possess for particular applications, quoting examples of applications you may
find.A smart material is a material that has one
or more properties that can be changed by an external condition. The external
condition can be temperature, light, pressure, or electricity. This change can
be repeated many times and is reversible so it can return to its original
state. A smart material is piezoelectric materials when this material is
compressed an electric voltage is produced for moment, and when a voltage I put
across the material it makes a tiny change in shape. An example of the
application you may find this is contact sensors for alarm systems. Another
smart material is shape memory alloys when bent out of shape they will stay
that way until heated above a certain temperature, and will return to original
shape. Quantum tunnelling composite is a flexible polymer, when squeezed it
becomes a conductor. Electroluminescent materials produces light when current
passes through it. Thermochromic materials changes colour as the temperature
changes. Photochromic materials changes colour according to different
lightening conditions.     Task2
(M1):

Compare
and contrast the properties of low and medium carbon steel to aluminium alloy
in relation to their behaviour in the manufacture of a motor vehicle frame,
chassis and panels.Aluminium alloy properties are they are
lightweight as it has a low density, at low temperatures aluminium doesn’t
become brittle and its strength increases, but at high temperatures aluminium
strength decreases, but to make aluminium stronger, you can create aluminium
alloys with Si, Mg, Cu, Zn or heat treatment. Aluminium is easily worked with
most machining methods such as milling, drilling, cutting, punching, bending,
etc. This is useful for motor vehicle frame, chassis, and panels as aluminium
can be machined into parts. Aluminium has a good conductivity this is useful
when manufacturing motor vehicle frame, chassis and panels as the aluminium can
be easily shaped. Aluminium reacts with oxygen in the air which forms a thin
layer of oxide which is dense and protects the aluminium from corrosion. The
properties of aluminium alloys means there is huge benefits in manufacturing,
for example as aluminium is lightweight this enables a good fuel economy and
low emissions which is desired for motor vehicles. A disadvantage of using
aluminium is that it’s difficult to arc weld on this material. Low carbon steel has properties such as
good formability so it easy to form into different shapes, by pouring,
moulding, and pressing, and low carbon steel has good weld ability. Low carbon
steel is significantly cheaper than aluminium, but low carbon steel has a poor
resistance to corrosion.  When comparing
both low carbon steel and aluminium the similarity is they both are easy to
shape. Medium carbon steel is made up of composition
of 0.29%-0.54% carbon, with 0.60%-1.65% manganese. The properties of medium
carbon steel is ductile, strong, and has long wearing properties. When
comparing aluminium and medium carbon steel they both have strong properties,
are readily available, both materials can be recycled, and can easily shaped,
but medium carbon steel has long wearing properties, this could be a benefit in
the manufacture of a motor vehicle frame, chassis and panels as the parts will
have a long lasting life.

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