Materials and Manufacturing Process for Smart Phone Cases

This article discusses the different materials used for smart phone cases, including metal, polymer, and carbon fibre composite. It explains the justification for material usage, material grade, and the manufacturing process for each material. The article also covers cost considerations for each material. Course code, course name, and college/university are not mentioned.

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1. Introduction
The usages of smart phones have been able to increase a lot in the last five years. This has led
to the use of different materials for design of different parts. The phone casing is one of the
parts which have been able to experience the usage of different materials. Different materials
have different pros and cons when it comes to their design and usage (Nassos, & Avlonas,
2013). The usage of the metal casing, polymer and carbon fibre composite has been
employed in the design of the smart phone cases. Each material has its own justification for
their usage. In addition, different customers’ preferences are able to promote their usage.
Technological advancement in the mobile sector has led to the emergence of the different
materials for the different parts such as the cases.
Figure 1: phone case
2. Material selection
2.1. Justification of materials

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The different materials have different characteristics which make them be chosen to be used
for the smart phone casing. The justification for the material usage in the manufacture of the
casing depends on material properties and customer preferences. One of the most used
materials in the design of the smart phone case is the metal. Scratch free property is one of
the key characteristic which many designers are able to identify when choosing the metal
material (Röhrig, & Diebels, 2015). Aluminium is one of the most used metals in the design
of the phone cases. The lightweight property is identified as a key characteristic and
specification when making the preference for the metal material. In addition, customer
preference is another key characteristic which is considered when using metal for the case
design. The metal is considered classy and able to represent some section of the society.
Considering this section of people, the designers are able to move and use metal as part of the
materials for the casing. For the classy and wealthy show, the designers are able to use
diamond as part of metal for the design metal casing. In addition, the use of polymer is
another material which is used. The polymeric materials are able to combine different
materials in order to achieve the different specifications. In their design, the polymeric
materials key specifications which are considered during their design include their good
dimensional stability, high mechanical properties such as tensile and impact resistance. In
addition, good polish during painting is another specification which makes the polymeric
materials to be used for the phone casing. Lastly, the key polymeric materials can be
designed into different designs and characteristics as required. This makes it easy for the
designers to meet their customers’ preferences. The looks aspect and specification which the
designers look to meet while using the polymeric material in the design of the smart phone
cases. Additionally, another key material which is used is the carbon fibre composites. The
carbon fibre are able to weave and able to create a stronger material. This is ma key
specification which makes the casing much stronger. This is an important specification which

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is highly considered when choosing the carbon fibre composites for the material for the
phone cases. Additionally, the carbon fibre composites are light which is a key consideration
for the specification and consideration for the phone case materials. Lastly, carbon fibre
composite materials are attractive and this makes them more attractive. This attractiveness is
a key specification which is considered during the choice of the material as part of the phone
casing.
3. MATERIAL GRADE
Material grade is a key consideration in order to maintain the quality of the phone cases.
Different grades are usually produced but the metal grade for the phone cases must be able to
meet some key specification which will align with the use and purpose. The high strength of
the metal is one of the key characteristic which makes metal to be chosen as the casing
material. Aluminium is a key metal grade which is used and applied in phone cases. The
strength of the aluminium results from the strong electrostatic attraction between the positive
and negative electrons (Venturi, 2017). The grade of metal chosen must be able to have this
strong attract to move against the starching effects. The grade of metal must be able to
disperse the heat perfectly and ensure that device overheating is not easily felt. As a good
conductor of heat, the metal grader through the free electrons is able to carry the heat and
reduce device overheating.

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Figure 1: atomic structure of metal grade
Epoxy resin is an important grade for the polymers which is used in the manufacture of the
phone cases. Hydrocarbons, which are mixture of hydrogen and carbon structure, are able to
form the basic structure of the resin used for the phone cases. The hydrocarbon structure is
able to provide the key strength and scratch resistance properties which are needed in the
phone cases. This grade of the polymer is able to resist different scratching elements and even
electrical conductivity (Ho, 2014). This makes it an important part and grade to be used for
the manufacture of the phone cases. The internal arrangement of the hydrocarbons helps the
grade to achieve the required characteristics for the phone cases.
The carbon fibre composites consist of layers of carbon which are arranged in hexagonal;
patterns like graphite. The polyacrylonitrile (PAN) resin is a key grade of carbon fibre
composite which is used in the manufacture of the phone cases. The internal structure of this
material composes of carbon, hydrogen and nitrogen molecules (Delong, 2011). Monomers
are the main key inri9fdients which are used in order to attain the preferred characteristics for
the phone cases. The structure ensures that the temperature transition is only achieved under

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high temperatures. In the attaining of the high strength, the microstructure of the PAN resin
plays a critical role in achieving the desired characteristic.
4. Manufacturing process:
The material of the phone cases must be able to pass through a defined manufacturing
process. This ensures that the different desired qualities are achieved to meet the purpose of
the end user. The different materials have different manufacturing process due to their
differences in properties.
4.1. Manufacture process of aluminium
Aluminium is one of the key materials which are used for the manufacture of the phone
cases. This is due to its light weight nature. In addition, the specific characteristics are only
achieved through the proper manufacture and fabrication process. This ensures that the
specific characteristics which are required during the phone case manufacture are attained.
The strength and modern and sleek modern looking are some of the important aspects which
are attained during the manufacture process of the cases suing the aluminium materials
(Yasushi, Keijiro, Shinichi & Mitsutaka, 2012). In the manufacture process, first the material
is usually designed by cutting the blank into the specific shape under which the phone look
like. Drawing the shape and phone cases is done to ensure that the aluminium sheet is able to
emulate the shape of the phone case. Redrawing of the case is then done and the sleeves of
the phone case are ironed according to the required shape. Trimming is then done and this
ensures that the finest details of the phone shape are perfected. The trimming process ensures
that the crystal structure of the aluminium sheet is perfected (Guzman, Cugnoni, & Gmür,
2014). Cleaning and decoration to the required colour is lastly done. This ensures that the
tastes and preferences of the customers are taken into consideration.

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4.2. Manufacture of epoxy resin
The epoxy resins are able to consist of crosslinkable materials which help in production of
the key desired qualities. The epoxy resins are manufactured from the reactions of
epichlorohydrin (ECH) and bisphenol-A (BPA). At the first stage, the reactants, which are
ECH and BPA are charged with reactor. Additionally, in order to attain some key specific
characteristics, a solution of between 20 to 40% of caustic soda is added. The evaporation of
ECH is then carried out. After the evaporation stage, the two phases are separated through the
addition of inert solution of methylisobutylketone (MIBK). After that, the resin is washed
with water and the solvent is removed through vacuum distillation. Additives may be added
through a specific formula in order to enhance some key characteristics such as flexibility,
colour adhesiveness and fastercuring according to the application of the resin. Curing to
harden the resin and ensure the phone case application is achieved is usually carried out.
Temperature curing is usually applied between 5 and 1500C.

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Figure 1: manufacture process of epoxy resin
4.3. Polyacrylonitrile (PAN) resin manufacture process
As part of the carbon fibre composites, the PAN resin manufacture process helps to attain the
key required qualities. Polymerisation process is an important process, which is used in the
manufacture of the PAN resins. polyacrylonitrile resin, also known as Acrylic resin is
achieved after the polymerisation of vinyl cyanide. The manufacturing process helps to form
a strong PAN resin material which has the desired qualities such as synthetic, thermoplastic
and having high resistance to heat (Carpenter & Sanders, 2014). Thermal oxidising in air is
another key process which is applied during the manufacturing process. This ensures that the
material will be inert when reacting with key materials. Additionally, hot filtration process is
another key process which is involved in the manufacture of the PAN resins. This ensures
that the material and phone cases will be resistance to high temperatures. Also, this process
ensures that the end product will have high strength and resist any scratching elements.
Figure 1: polymerisation of PAN resin
The manufacturing process has two key processes. The first one, hydrogen cyanide is usually
added to the material in order to form the acrylonitrile. The process is shown below;

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The second step involves the following underlined processes.
5. Cost:
Cost preferences and consideration is one of the important aspects of any manufacturing
process. This ensures that the economics of every process are maintained and the used part
can be able to generate the required profits. Economies of scale are able to go hand in hand
with the amount of items which are being produced at each given moment. The cost of
production is able to reduce as more items are being manufactured. This happens units the
optimum amount of production are achieved (Wang, Wu, Ma, Sun, & Du, 2010). The sales
are able to produce the different parts which are manufactured and therefore determining the
optimum capacity at which the minimum cost will be achieved.
For each material, the following equation is used to determine the overall cost of the phone
case;
Cs=Cmaterial+ Cmarketing
n + ´Ccapital
´n
The Cs is the overall cost of the phone case while n is the amount of items which are
produced. The cost of the material, plus the cost of market and the capital; cost is able to form
the overall cost of the phone case. In order to attain the minimum amount of times to achieve
the economic production, each case is dividing by the number of items produced
(Kopeliovich, 2012). The cost per year is indicated below against the cost which will be
experienced in the production of each bracket.

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Material Cost of
each item
in 100
million
items
Cost of
each for
item
between
100 and 450
million
Cost of
each item
between
450 and 800
million
Cost of
each item
above
800
million
Cost of
each
item
above
1000
million
1 Aluminium
metal casing
3 2.8 2.5 2.4 2.3
2 Polymer
casing
1.5 1.3 0.8 0.8 0.8
3 Carbon fibre
composite
2.5 2.2 2.1 2.0 2.0
0
20
40
60
80
100
120
cost per alluminium casing Vs item
produced
Series1
number of items produced
cost per item produced
For the aluminium casing, they have the highest cost among the considered elements. Their
production is able to reduce with the increase of the amount of items which are produced.
The different groups are able to identify the costs of each item under the different groups.
The minimum amount of components under which the minimum cost of production is
achieved in this case is from the 1000 million items (Zhao & Gou, 2009). The cost of $2.3 is
the lowest cost of the item produced in this case. Therefore in order to achieve economies of
scale, more than 1000 million items must be produced. The highest profits will be achieved
when more than 1001 million components are produced. Any production below this amount
of components is able to attract more cost of production. The

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0
20
40
60
80
100
120
polymer cases production ciost Vs
items produced
Series1
amount of items produced
cost of production per item
The initial item produced in the use of polymer material is able to attract a cost of $1.5 per
item. In the same case as the aluminium, the cost of the items is able to reduce with the
increase of the production. The minimum amount of items required to achieve low cost of
production in this case is above 450 million (International Conference of Advanced
Materials, Mechanical and Structural Engineering, In Hong, In Seo, & In Moon, 2016). The
cost is able to reduce with the reduction of more items being produced. The minimum
amounts of items required are above 450 million and this will attract the lowest cost or
production. The consideration to have low items produced to achieve the highest profits is
viable for any business consideration. The increased yearly production is therefore good for
the business operation

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0
20
40
60
80
100
120
cost of production of carbon fibre
composite casing Vs item produced
Series1
number of items produced
cost of production per item
The carbon fibre composite casings are able to follow the same trend whereby increased
production is able to attract a low cost of production per item. Increasing production is able to
attract low cost and this leads to the economies of scale for the production. The minimum
amount of components required in this case to achieve the lowest cost is above 8000 million
components. This means that any production above this point will be done at the lowest cost
of production possible. These are productions which are viable per hour (International
Conference on Biomedical Engineering, & In Goh, 2013). Producing these items per year
will mean that the company will experience the minimum cost of production. For any
business, attaining the economies of scale is usually the goal to ensure that they are able to
generate the highest cost possible.
5.1. Waste factor
In each case, the cost of waste is usually attained in each case. The waste factor is able to
define the extra costs which will be experienced in each case and therefore affecting the
business operation for the casing production. Lean production is able to ensure that the least
wastage is usually achieved in each case. The manufacturing process is able to attract these

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wastage minimizing them is able to ensure that the manufacturing process is effective
(Kasper, Bernardes & Veit, 2011). The manufacturing process complexity and control is able
to determine the amount of wastes which will be produced. The metal manufacturing process
is complex and is able to attract a wastage production of 12%. The polymer process on the
other hand is able to produce wastage of 8%. The carbon fibre composites lastly produce a
wastage rate of 9.5%. These wastages are able to produce increased cost and therefore
reducing the effectiveness of business operation.
5.2. Manufacturing viability
For any business, reduction of cost and achieving the optimum production rate at the lowest
is level is desired. Therefore in order for the cases production to be viable, the business must
be able to attain the minimum wastage. The polymer manufacturing case has the lowest
amount of waste production (Idaho National Laboratory., United States., & United States,
2011). This is an effective process to carry out for business since it will mean more cost
reduction measures are achieved. In addition, for the business, the minimum cost must be
achieved with the lowest item produced. The polymer case has the lowest items which must
be produced in order to achieve the lowest cost of production. Therefore for business, the use
of polymeric material will be effective and viable to achieve business objective.
6. Process and structure/microstructure control
One of the materials which are good and viable for the smart phone case is the polymer
material. Their cost is low and their production and manufacturing process is easy to attain
(Chawla, 2013). This section will be able to look at the manufacturing process and
microstructure of the phone cases which are done using the polymer materials.

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The polymer, epoxy resin is affected by temperature variation during the manufacturing and
usage stages of the cases. Increasing the temperature during the manufacture process is able
to elongate the microstructure of the polymeric materials (Pike, Grabner, & Harkins, 2009).
The increase of temperature with time is able to affect the functionality of the epoxy resin
material. They become weak and their strength is reduced.
Exposing the epoxy resin to temperatures for long time is able to affect the strength as well.
The high temperatures and increased time of exposure are both able to reduce the
functionality and durability of the material (Serkov & Radishevskii, 2008). The structure
ability to hold on each other molecules is reduced and therefore reducing the strength.
Increasing the pressure is able to increase the compacting force and therefore bring the
microstructure together. This ensures that the molecules during the manufacturing process are
closer to one another. This is able to increase the ability of the material to resist other form of
destructing materials as well as scratched. The microstructure has more advantages when
done under high pressure and this improves the quality of material produced.

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In each stage of manufacture of epoxy resin time is of essence. In some key processes, taking
much time is able to reduce the durability of the final produce while in other increasing time
is able to the strength of the materials (Ho, 2014). For instance, increasing the time during the
heating process is able to reduce the durability and strength of the material. On the other
hand, increasing the time during the pressuring time is able to enhance the compacting of the
epoxy and thus increasing the strength of the casing.
7. Quality:
Due to the mechanical properties of the epoxy resin materials, temperature, pressure and time
factors are essential in the control of quality production. The control of these key elements
will ensure that the final product and case is of high quality to resist any external factors. The
following table is able to give the time exposure in each stage and the amount of pressure
required (Bajaj, Sreekumar, & Sen, 2001). This will ensure that quality and high strength
cases are produced. Observation on time exposures will be important to ensure that defective

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products are not produced. Inspection of the required qualities at each stage will be vital to
ensure that the quality required is achieved.
Process Temperature condition Pressure condition Time
Phase separation High temperature Low pressure 30 minutes
Wash process Medium temperature Medium pressure 1 hours
Evaporation stage High temperature High pressure 1 hr
Compressing stage High temperature High pressure 2 hours
Final production Low temperature High pressure 30 minutes

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