How as being economical. This is reinforced

How the process has been applied to a product

Engine
blocks are normally sand casted, as the external final surface finish is not
required to be precise. This is because they are the housing for the inner
aspects of the engine such as coolant passages, exhaust gases, crankshaft
housing & cam shafts. These elements do not require close tolerances, as
they are not essential for the function of the engine itself. The engine bores
however; require precise tolerances as this affects the overall performance of
the engine, which therefore means that machining will require to be completed.

 

 Due to the fact that sand casting results in
excess flash to be created, machining would be necessary to eradicate any
unwanted material. As the engine block is a very complex shape, sand casting is
the ideal procedure to create them. (Paul Jeter, 2013)

 

Due to
the economical aspects of sand casting, it is widely used across the world to
create engine blocks by companies such as Ford, Chrysler & JLR. This is
because there is minimal waste from this process and the required components
including tooling, are relatively cheap; especially for small production runs.

 

“Alternatively, there are automotive
components that are produced using this process, so it may also be used in high
volume applications.”
(Dave Olsen , 2013)

 

Sand
casting is used within the supply base and at JLR due to the versatility of the
products that sand casting can produce.

How the process has been used and illustrates
key points from the record

The
sand casting process has been used for the creation of the engine block as the
process itself is  “Versatile – Size, Weight, Shape: 
Sand castings can be produced in
weights from ounces to 200+ tons.  Through the use of cores, internal
structures can be cast in place. “(Dave Olsen , 2013)

 

As
well as being economical. This is reinforced by the ability to be able to sand
cast any type of ferrous or non-ferrous alloy.

Product
& function

The
product of this case study is of an engine block. An engine block is the
external housing that is comprised of all of the components that ensure that
internal combustion processes occur. The engine block contains all of the
essential parts of the engine such as; engine cylinders, cooling systems &
crankcases.  Due to the fact that engine
blocks are created from metal, the internal combustion process can easily
dissipate heat energy to the cooling system efficiently.

What material it is made from

The
component itself is normally made from aluminium “more fuel efficient, more and more engine blocks are being cast from
aluminium.” (Balfour, 2011)

 

As
cylinder blocks are made out of aluminium, they have a higher power to weight
ratio when compared to cast iron. This is because of the current political
strive to ensure more effectiveness for combustion engines and the smaller
output of exhaust emissions.

 

The
lower overall cost (due to heating the material and machining process) of
aluminium also means that it is the optimal choice when compared to cast iron.

How it is made

Cylinder
blocks are made from sand casting, the process of which can be seen in Appendix
I.

How design, material and manufacturing processes
are linked

When
initially designing a component, both the material and manufacturing process
are taken into consideration and are constrained by each other. Engineers often
create a prototype of a component in order to perfect the manufacturing process
that will be used.

 

All of
the design, material and manufacturing processes are linked as they are
detrimental factors in order to produce a effective component. An example of
this is that the design of the component needs to account for the shrinkage
that occurs during the manufacturing process. The shrinkage that occurs is
dependent on what material is used; an example of this is that if the component
is made out of aluminium, the shrinkage occurred could be up to 6%. (Hawworth
Castings, 2015)

 

Furthermore,
as for projects; companies receive a set amount for a budget; if the
manufacturing process is expensive then the ideal material may not be feasible
due to its cost.

 

In
addition, if a material that is unsustainable or recyclable is initially
suggested, then the finished component will not be ideal for mass production,
requiring different manufacturing processes. Moreover to this, if for example,
a graphene material is required for a component then more intuitive manufacturing
processes will be required to be coined.

 

Lastly,
the design of the component is linked to the material chosen as depending on
the requirements of the market or improvements in current material technology;
a different material may be required to be used therefore changing the design.

Image of part and geometry

Please
refer to Appendix F,G & H.

Alternatives

Alternatively,
the materials that are used for sand casting could be changed from Aluminium to
cast iron, steel, brass, or any metal that is required as sand casting is a
viable option for all metal casting. Depending on the design of the component
and the future application / environment that the component will operate in,
will determine what material should be used.

 

Engine
blocks have been created by cast iron alloys in history due to the benefits of
using cast iron, such as strength, low cost & fatigue resistance as well as
lower thermal expansion. This is now being outdated as new materials such as
aluminium alloys have been found to have greater strength with lower weight,
therefore increasing the efficiency of the engine.  (Mechanical Engineering, 2016)

Processes

Die casting

An
alternate process to create the engine block would be through die casting as
this process is much less time consuming meaning a lower cycle time to create
effective parts. This process could also be used if geometrical precision is
required. (Premier Die Casting, 2015)

Forging

Forging
will not be suitable for the creation of an engine block as it is more time
laborious and requires greater amounts of money and time to create a sufficient
component.

Why
do we not use them?

Material

The
materials that are currently used to create engine blocks are used as they have
been found to be the lighter and more fuel-efficient than their cast iron
counterpart, however, the cost of a aluminium engine block could be up to three
times more expensive. (Richard Rowe, 2012)

 

In
addition, if aluminium is used for both the gasket and engine block, their thermal
expansion coefficient is the same meaning less chance of fracture when compared
to a cast iron block. (Richard Rowe, 2012)

 

Aluminium
is also used for cylinder blocks as the machining cost and heating cost
required to treat / machine aluminium is much lower than the same manufacturing
process of cast iron. (Stack Exchange, 2016)

Process

The
alternate process to create engine blocks is stated above as die casting, this
would not be a feasible option as geometrical precision is not required.
Furthermore, for JLR the amount of engines that are produced do not warrant the
initial high cost of paying for die cast tooling. In addition, die casting will
not be able to create the complex geometry required for the engine block as a
component. (Accuform, 2003)

 

Process cost comparison

(Kinetic Die Casting, 2016)

Improvements

The
only improvements that can be found from this process is to ensure that the
design of the component is fully succinct as well as making adequate attention
to the gate system, as this is the main cause of failure for casts. The second
improvement is to ensure that the chemical composition of the sand &
material are accurate.

 

Conclusion

To
conclude, sand casting is the ideal manufacturing process to produce an engine
block; this is because of the economical benefits when producing the molten
aluminium as well as the ability to produce a complex array of components even
with hollow aspects. Aluminium is the most suitable metal to create the engine
block, as its power to weight ratio is greater than that of cast iron and is
widely available. Moreover, other materials do not produce the same strength
properties.