“parametric study of injection moulding using...
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“Parametric Study of Injection Moulding Using Polypropylene
H200mk Grade”
Subodh Singh Tomar1, Ashish Kumar Sinha
2, Ashish Shrivastava
3
PG Scholar
1, Assistant Professor
2, Assistant Professor
3
Department of Mechanical Engineering
Oriental Institute of Science & Technology, Bhopal
India
ABSTRACT: This paper deals with the mechanical and thermal properties of polypropylene material of grade
H200MK that is homopolymer from reliance polymer industry, where PP material is basically a thermoplastic
resin that is obtained by the polymerization of propylene. The monomer is propylene (CH2=CH-CH3)., and it is
a semi crystalline material that is easily manufactured by the injection moulding machine. Initially the raw
material of PP (H200MK) is taken as a filler material and fed into the feeder of injection moulding machine and
then it goes to the further process cycle of machining by varying different parameters of injection moulding
machine such as temperature , holding pressure , hold on time , cooling time, injection pressure , injection
speed and at each parameter specimens are ready. The mechanical and thermal properties of these specimens
are tested on INSTRON 3560 Universal Testing machine where the mechanical properties such as tensile
property is tested and these tests were carried out by taking ASTM methods of plastic material.
Keywords: Polypropylene, ASTM, Injection Moulding, H200MK, Hold on pressure.
INTRODUCTION
1.1. POLYPROPYLENE
Polypropylene (PP), also known as polypropylene,
is a thermoplastic polymer used in a wide variety of
applications including packaging and labeling,
textiles (e.g., ropes, thermal underwear and carpets),
stationery, plastic parts and reusable containers of
various types, laboratory equipment, loudspeakers,
automotive components, and polymer banknotes. An
addition polymer made from the monomer propylene,
it is rugged and unusually resistant to many chemical
solvents, bases and acids.
The global market for polypropylene had a volume of
45.1 million tonnes, which led to a turnover of about
$65 billion (~ €47.4 billion).
1.2. CHEMICAL AND PHYSICAL
PROPERTIES
Most commercial polypropylene is isotactic and has
an intermediate level of crystalline between that of
low-density polyethylene (LDPE) and high-density
polyethylene (HDPE). Polypropylene is normally
tough and flexible, especially when copolymerized
with ethylene. This allows polypropylene to be used
as an engineering plastic, competing with materials
such as ABS. Polypropylene is reasonably
economical, and can be made translucent when
uncolored but is not as readily made transparent as
polystyrene, acrylic, or certain other plastics. It is
often opaque or colored using pigments.
Polypropylene has good resistance to fatigue. The
melting point of polypropylene occurs at a range, so a
melting point is determined by finding the highest
temperature of a differential scanning calorimetry
chart. Perfectly isotactic PP has a melting point of
171 °C (340 °F). Commercial isotactic PP has a
melting point that ranges from 160 to 166 °C (320 to
331 °F), depending on atactic material and
crystallinity. Syndiotactic PP with a crystallinity of
30% has a melting point of 130 °C (266 °F).
The melt flow rate (MFR) or melt flow index (MFI)
is a measure of molecular weight of polypropylene.
The measure helps to determine how easily the
molten raw material will flow during processing.
Polypropylene with higher MFR will fill the plastic
mold more easily during the injection or blow-
molding production process. As the melt flow
increases, however, some physical properties, like
impact strength, will decrease.
There are three general types of polypropylene:
homopolymer, random copolymer, and block
copolymer. The comonomer is typically used with
ethylene. Ethylene-propylene rubber or EPDM added
to polypropylene homopolymer increases its low
temperature impact strength. Randomly polymerized
ethylene monomer added to polypropylene
homopolymer decreases the polymer crystallinity and
makes the polymer more transparent.
1.3. MECHANICAL PROPERTIES
The mechanical properties of semi‐crystalline
polymers strongly depend on the degree of
crystallinity, the crystallite size and the concentration
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of tie‐chains. The tie‐chains connect the adjacent
crystals (lamellae). In addition, the (average)
molecular weight and the molecular weight
distribution (MWD) also affect the mechanical
properties. Nucleating agents can reduce the cycle
time in the injection moulding process, increase the
stiffness, increase the tie‐chain concentration,
improve the clarity, promote the β phase etc. Single
crystals (lamellae) are highly anisotropic because of
the nature of bonding between atoms and molecules,
strong covalent bonds along the chain vs. weak
Vander Waals interaction etc between chains,
Random formations of spherulite structure in the 3D
space create an isotropic composition. Therefore,
even if the individual crystals are anisotropic, the
differences in the properties tend to average and,
overall, the material is isotropic. Note that the degree
of crystallinity and molecular orientation are affected
by the fabrication process that could lead to
anisotropic mechanical response in solid polymers.
Figure 1: Molecular Orientation of polypropylene
LITERATURE REVIEW
P. Postawa [1] The influence of thermal conditions
of the mould on properties of injection moulded parts.
Which give the Result of that the conditions of
cooling stage during injection moulding of
thermoplastics polymers for e.g. mould temperature
and cooling rate influence on structure properties.
Results shown that the same cooling channels in
different configurations can give another thermal
condition and in effect different structure. Presented
injection moulds that have been soundly designed
from the thermal point of view, help to bring down
the cost of production whilst ensuring greater
reliability. A large number of aids are currently
available to design engineers, together with the
results of theoretical and practical investigations,
which can be used in the thermal design of the mould.
In order to attain the specified aims of thermal mould
design, i.e precise maintenance of the target mean
cavity moulding surface temperature, uniform
distribution of the cavity temperature, short cycle
time for a high moulding quality.
T. Glomsakera [2] The response of mechanical
properties of injection-moulded parts at high strain
rates shows that mechanical loading of a
thermoplastic material like polypropylene at large
strains and different loadings rate may be reasonably
well simulated by use of a linear-elastic visco plastic
constitutive equation of von Mises type. However, it
is clear that these materials deviate from the von
Mises model, since their yield stress increases with
hydrostatic pressure and plastic dilatation occurs in
tension. Therefore a modified model with these
properties was implemented in LS-DYNA.
Simulations with this modified model, resulted in
improved agreement between simulations and
measurements for impact on a plate due to lower,
stiffness. For three-point bending the agreement was
poorer, possibly due to different strain hardening in,
compression and tension. In the unloading stage,
however, it is clear that the recoverable strain is non-
linear and at least one decade larger than predicted by
the linear elastic model.
Ranjusha J P [3] Effect Of Moulding Temperature
On The Properties Of Polypropylene/High Density
Polyethylene/Clay/Glass Fibre Composites are
analysis of moulding temperature on the properties of
composite based on PP/HDPE (80/20) was studied
which shows that the moulding temperature has
significant effect on the mechanical and thermal
properties of the composite. The optimum moulding
temperature depends on the desired
mechanical/thermal properties of the composite for its
application. The incorporation of nano clay and glass
fibres imp
roves the properties of PP/HDPE blends. The
enhancement in physical properties is well explained
by morphological characterization.
L.W. Seow, Y.C. Lam [4] Optimizing flow in plastic
injection molding The mold and part design of plastic
parts for injection molding is a complicated process,
considerations for producing a part ranging from cost
and speed of production to structural, ergonomics and
aesthetic requirements. One of the routines faced by a
designer when designing quality into a part is the
process of cavity balancing. This entails controlling
the plastic flow in the filling phase such that the melt
front reaches the boundaries of the mold at the same
time. This is done by adjusting the thicknesses of
various sections and can be a tedious trial and error
process. In this paper, a method is described whereby
the thickness-adjustment process can be automated.
An optimization routine is used to generate the
thicknesses necessary to balance the mold cavity. The
method is implemented on a PC through interfacing
of the Fortran code with the commercial software,
Moldflow ©. Using the method, good results have
been obtained for several basic geometric models
P.K. Bharti [5] Optimizing the plastic injection
moulding process in the determination of the process
parameters for injection molding. A number of
research works based on various approaches
including mathematical model, Taguchi technique
,Artificial Neural Networks (ANN),Fuzzy logic, Case
Based Reasoning (CBR), Genetic Algorithms (GA),
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Finite Element Method(FEM),Non Linear Modeling,
Response Surface Methodology, Linear Regression
Analysis ,Grey Rational Analysis and Principle
Component Analysis using cavity pressure signals
have been described. A review of literature on
optimization techniques has revealed that there are, in
particular, successful industrial applications of design
of experiment-based approaches for optimal settings
of process variables. Taguchi methods and response
surface methodology are robust design techniques
widely used in industries for making the
product/process insensitive to any uncontrollable
factors such as environmental variables. Taguchi
approach has potential for savings in experimental
time and cost on product or process development and
quality improvement. There is general agreement that
off-line experiments during product or process design
stage are of great value. Reducing quality loss by
designing the products and processes to be insensitive
to variation in noise variables is an ovel concept to
statisticians and quality engineers.ANN, GA, and
CBR are emerging as the new approaches in the
determination of the process parameters for injection
molding. A trained neural network system can
quickly provide a set of molding parameters
according to the results of the predicted quality of
molded parts. However, the time required in the
training and retraining for aneural network could be
very long. By using GA approach, the system can
locally optimize the molding parameter seven without
the knowledge about the process. In practical use, the
convergence rate to an optimal set of process
parameters could be very slow in some occasion.
CBR systems can determine a set of initial process
parameters for injection molding quickly based on the
similar case(s) without relying heavily on the expert
molding personnel.
Babur Ozcelik [6] Influence of injection parameters
and mold materials on mechanical properties of ABS
in plastic injection molding Are shows, changing of
mechanical properties of ABS material was optimized
by ANOVA and regression analysis with respect to
injection parameters and two mold materials. The
most important parameter affecting the elasticity
module, tensile strength and tensile strain at yield,
tensile strain at break was melt temperature and its
effect was determined for steel as 84.90%, 86.78%,
50.05% and 42.99%, respectively. The other
parameter affected by flexural module (73.26%) was
injection pressure. In case of aluminum mold
material, percentages of injection pressure were
found as 44.21% for elasticity module, 35.32% for
tensile strength at yield and 36.93% for izod impact
limit, and percentages of melt temperature were
89.39% for tensile strain at yield and 98.29%for
flexural module, respectively. The most important
parameter affecting tensile strain at break was
packing pressure by 52.48%.The elasticity module,
tensile strength at yield, flexural module and izod
impact strength for steel and flexural module for
aluminum mold materials gave linear relationships
(based on values of r2) with injection parameters
whereas other mechanical properties resulted in non
linear relationships. Values of elasticity module and
tensile stress at yield for Al mold were higher than
that of steel mold when melt temperature and cooling
time were high, there was hardly any difference
observed for values of tensile strain at yield and at
break. Value of flexural modules and izod impact
strength were found to be higher for Al mold when
melt temperature and cooling time were low.
OBJECTIVES
The huge applications of polymer material subjected
to the mechanical and thermal properties are evolving
at a rapid pace as these materials are having
widespread applications ,the response of polymer
material subjected to a tensile test in day to day uses
are vast generally in automotive industries that is an
excellent example for the application of Mechanical
and Thermal response , the automobile industry is
therefore rapidly growing in this field creating a
widespread demand for the polymer material.
The main topics of this thesis of the behavior of the
polypropylene under the mechanical properties,
specially this thesis deals with the following topics.
1. To produce the specimen by plastic injection
moulding by changing its different
parameters such as injection pressure,
cooling time, temperature, hold on time,
made different specimen and then compared
to obtain the specific mechanical and
thermal property such as tensile property.
2. To test the specimen of PP material for
comparing the improvement with the
existing material.
II. EXPERIMENTAL SETUP
2.1. POLYPROPYLENE GRADES
It is obvious from the points discussed so far that the
properties of end products are decided by various
parameters, viz.,
Temperature, pressure, speed and time set on
the machine
Moulds
Resin properties
In order to derive the properties of similar resins,
ASTM has devised standards, wherein they are
injection moulded under identical conditions and
tested.
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Figure 2: Universal Testing machine
2.2. TENSILE TESTING, ASTM D638
Tensile properties are most widely specified and are
used as an indication of strength of polymers. It
measures the ability of a with stand the force that
tends to pull it apart and the extent of deformation
before breaking. Tensile properties are also widely
used for defying the measures for quality of
production their designing and engineering behavior.
2.3. TENSILE STRENGTH
Tensile strength is defined as the maximum tensile
stress sustained by a test piece during the tension test
or ultimate strength of a material subjected to tensile
loading.
In other words, it is a measurement of the ability of a
material to withstand force that tends to pull it apart
and to determine to what extent the material stretches
before breaking. It is expressed in N/mm2.
Figure 3: Injection Moulding Machine
2.4. TENSILE MODULUS
The ratio of tensile stress to the corresponding strain
at maximum load within proportional limits is the
tensile modulus. It is an indication of the relative
stiffness of a material. It is expressed in N/mm2.
Tensile strength
Elongation at yield
The elongation produced in the gauge length of the
test piece up to the yield point called.
Elongation at yield= change in length (elongation)
Original length (gauge length)
Table 1shows the specification of test specimen used
in experiment purpose. Material used in this
experiment is Polypropylene.
Table 1: Sample Details
Sample details Parameters
Length 115 mm
Rate 1 100 mm/min
Standards ASTM D638
Temperature (deg
C) 25
Humidity (%) 55
Table 2 shows the different levels of experiment.
Injection speed, temperature, injection pressure,
cooling time, hold on pressure and hold on time are
the variable parameters taken on this experiment.
Table 2: All parameters at different level
Le
vel
Inject
ion
Spee
d (%)
Tem
perature
(0c)
Inject
ion
Press
ure
(%)
Cool
ing
Tim
e
(Sec)
Hold
On
Press
ure
(%)
Ho
ld
On
Ti
me
(Se
c)
1 37 205 30 20 25 3
2 40 210 40 40 40 5
3 50 215 50 60 50 9
III. RESULTS AND DISCUSSIONS
Table 3: Comparison table of mechanical
properties at different temperature Level
Temper
ature
level
Maxi
mum
load
(N)
Tensi
le
stren
gth
(N/m
m2)
Ten
sile
strai
n
(%)
Tensil
e
Exten
sion
(mm)
Mod
ulus
(N/m
m2)
Level-1 1410.3
2 34.73
10.6
5 17.04
1395.
07
Level-2 1429.0
9 35.19
10.3
8 16.61
1470.
48
Level-3 1460.3
1 35.96 9.21 14.74
1500.
96
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Figure 4: Tensile Strain at different level
Figure 5: Maximum load at different level
Figure 6: Tensile Strength at different level
Figure 7: Tensile Extrusion at different level
Figure 8: Modulus at different level
Tensile strain – According to varying the
temperature from 190oC-235
oC of injection moulding
the tensile strain is decreasing 10.65% to 9.21% by
decreasing the injection temperature because the
molecular bonding of polypropylene material is weak
due to high temperature so it shows less tensile strain
comparative to low temperature of pp material as
mentioned in figure 4.
Maximum load- It observe that by decreasing the
temperature 235oC to 190
oC the load bearing capacity
is increases 1410.32 N to 1460.31 N because at lower
temperature the density of polypropylene material is
high comparing to higher temperature as shown in
figure 5.
Tensile strength- As we seeing that by decreasing
the temperature 235oC to 190
oC at different level the
molecular structure of pp material become dense due
to which the tensile strength is increases 34.73
N/mm2 to 35.96 N/mm
2 because at low temperature
there is a dense material form in pp and at high
temperature, the molecular structure will changes
with minimizing the density due to which the strength
will goes down as shown in figure 6.
Tensile Extension – It indicates that as lowering the
injection temperature parameter 235oC to 190
oC the
density of pp will increases along with the tensile
extension will decreases 17.04 mm to 14.74 mm as
shown in figure 7.
Modulus – By decreasing the temperature at 235oC
to 190oC the modulus of elasticity is increases from
1395.07 N/mm2 to 1500.96 N/mm
2 which shows that
at lower temperature the higher elasticity of modulus
is formed and by increasing the temperature the value
of modulus is increases as shown in figure 8.
Table 4: Comparison table of mechanical
properties at different Injection Pressure Level
Pre
ssur
e
leve
l
Max
imu
m
load
(N)
Tensile
strengt
h(n/mm2)
Ten
sile
strai
n(%
)
Tensile
Extensi
on(mm
)
Modulu
s(N/mm2)
Lev
el-1
1439
.12 35.44
10.2
3 16.36 1351.99
Lev
el-2
1457
.06 35.88 8.97 15.33 1365.31
Lev
el-3
1472
.06 36.25 9.58 14.35 1387.92
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Figure 9: Maximum load at different level of
injection pressure
Figure 10: Tensile strength at different level of
injection pressure
Figure 11: Tensile Extension at different level of
injection pressure
Figure 12: Tensile strain at different level of
injection pressure
Figure 13: Modulus at different level of injection
pressure
Maximum load- By decreasing the injection pressure
at 50% to 25% we observe that the packing of pp
material is become dense due to which at higher
pressure level the load beating capacity increasing
from 1439.12 N to 1472.06 N of maximum
comparing to the lower pressure as mentioned in
figure 9.
Tensile Strength – The tensile strength is increasing
from 35.44 N/mm2 to 36.25 N/mm
2 by increasing the
injection pressure and is continuously decreases by
decreasing the injection pressure at 50% to 25%. As
mentioned in figure 10.
Tensile extension- The density of pp material is
increases at 235oC due to which the tensile extension
is 14.35 mm and a deformation is decreases but at
lower pressure 190oC the density of pp material is
also affected and it decreases at lower temperature
pressure level due to which the tensile extension is
16.36 mm also increases as shown in figure 11.
Modulus – It observe that the tensile modulus is
related to the load bearing capacity from 1439.12 N
to 1472.06 N which shows that the tensile modulus is
increases at 1351.99 N/mm2
to 1387.92 N/mm2 the
injection pressure at 50% to 25 % as shown in figure
12.
Tensile strain – The tensile strain from 8.97% to
10.23% indicates that there is some optimum value at
intermediate pressure level because we observe that
as we increases the injection pressure from 25% to
50% there is some decreasing slope is formed in
tensile strain but when it reaches to its intermediate
value which is the optimum value of tensile strain is
formed at that injection pressure level and as further
increasing the injection pressure from its optimum
value there is some changes is formed which shows
that beyond the intermediate pressure level the tensile
strain is also increases at the higher pressure level as
shown in figure 13.
Table 5: Comparison table of mechanical
properties at different Holding Pressure Level
Hold on
pressure
Maximum
Load
(N)
Tensile
stress at
Maximum
Load
(MPa)
Extension
at Break
(Standard)
(mm)
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Level-1 1461.59 35.1 13.02
Level-2 1465.3 36 13.11
Figure 14: Maximum load at different hold on
pressure
Figure 15: Tensile stress at different hold on
pressure
Figure 16: Extension at break at different hold on
pressure
Maximum load- It indicates that by increasing the
hold on pressure at 15% to 50% the packing of pp
material become dense due to which the maximum
load bearing capacity is increasing at1461.59 N to
1465.3 N higher holding pressure level as shown in
figure 14.
Tensile stress- The tensile stress is directly
proportional to the load bearing capacity so at higher
holding pressure there is a maximum load is beard
due to which the maximum tensile stress is
decreasing 36 N/mm2 to 35.1 N
//mm
2 and at
decreases the holding pressure at 50% to 15 % the
load as well as tensile stress is also decreases as
shown in figure 15.
Tensile extension- By increasing the holding
pressure at 15% to 50% the deformation and an
extension is goes down from 13.11 mm to 13.02 mm
comparing to the lower holding pressure as shown in
figure 16.
Table 6: Comparison Table of mechanical
property on different injection speed
Le
vel
Mech
anical
Load
(N)
Tensile
Strength(
N/mm^2)
Tensi
le
Strai
n(%)
Tensi
le
Exte
nsion
(mm)
Mod
ulus
(N/m
m^2)
1 1451.8
5 37.07 9.38 15.00
1502.
80
2 1461.5
2 37.35 9.65 15.44
1530.
88
Figure 17: Mechanical load at different injection
speed
Figure 18: Tensile strength at different injection
speed
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Figure 19: Tensile Strain at different injection
speed
Figure 20: Tensile Extension at different injection
speed
Figure 21: Modulus load at different injection
speed
Mechanical load – It observe that the load is
increasing from 1451.85 N to 1461.52 N by
increasing the injection speed at 20% to 50% because
when the injection speed is increases the molecular
structure of pp material become closely packed as
shown in figure 17.
Tensile strength - As we increases the injection
speed from 20% to 50% the high density polymer is
formed due to which there is a higher tensile strength
is increasing from 37.07 N/mm2 to 37.35 N/mm
2
occurs comparatively to the lower injection speed as
shown in figure 18.
Tensile strain – At different increasing level of
injection speed from 20% to 50% indicate that the
decreases in the tensile strain from 9.65 mm to 9.38
mm is formed because at higher injection speed the
denser pp material is formed , due to which the lower
strain is occurred as shown in figure 19.
Tensile extension- The tensile extension from 15.44
mm to 15 mm of pp material graph is continuously
decreases whole increasing the injection speed at
20% to 50% as shown in figure 20.
Tensile modulus- Modulus is a properly which
depend upon the stress and strain which acting on the
material and we have seen that the as increases the
injection speed at 20% to 50% the stress also increase
which show that by increasing the injection speed the
modulus also increases as shown in figure 21.
Table 7: Comparison Table of mechanical
property on different injection speed
Le
vel
Hold
on
Pres
sure
(N/m
m2)
Inject
ion
Spee
d
(mm/
min)
Ho
ld
on
Ti
me
(m
in)
Injec
tion
Press
ure
Coo
ling
Tim
e
(sec)
Tempe
rature
(0C)
1 101.
1 92.6
95.
7 88. 96.8 87.7
2 104.
6 88.8
90.
4 95.0 89.7 90.4
3 106.
4 94.3
89.
7 110
104.
3 90.1
Figure 22: HDT at different level of hold on
pressure
Figure 23: HDT at different level of injection
speed
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Figure 24: HDT at different level of hold on Time
Figure 25: HDT at different level of injection
pressure
Figure 26: HDT at different level of cooling time
Figure 27: HDT at different level of temperature
It observe that by testing the specimens, which is
produced by changing the different parameters of
injection moulding process as we identify that there is
some changes seen in Heat Deflection Temperature in
testing the specimens of different parametric values
of injection moulding by investing all the parameters
they are such as the hold on pressure by increasing it
the HDT temperature also increases which show in
fig.22, in injection speed we have seen that by
increasing it there is a continuous increasing curve is
formed which is shown in fig.23 , By taking holding
time parameter in this the HDT temperature is drop
for some time then it shows slightly constant curve it
means for a certain time the temperature fall than it
will be sustains by increasing the holding time as
shown in fig.24 as increasing the Injection pressure
the HDT is also increases because as the pressure
increases there is a densely closed packing pp
material formed as shown in the fig 25 if the cooling
time increases there is also the sudden drop of
temperature observe for the intermediate pressure
than the temperature also increases as increases in the
cooling time shown in fig.26 and finally by
increasing the moulding temperature the heat
deflection temperature also increases and when it
reaches at a certain temperature there is some
constant curve is shown which is indicated in the
'fig.27.
Figure 28: Comparison between maximum load at
different parameters
Figure 28 shows the comparison between maximum
loads at different parameters. In case of Temperature
maximum load in level 3 1460.31 N. in case of
injection pressure maximum load is 1472.06 in level
3. In case of hold on pressure 1465.3 N at level 2. In
case of injection speed maximum load is 1461.52 N
at Level 2.
Level-1
Level-2
Level-3
Maximum load (N) *Temp
1410.32 1429.09 1460.31
Maximum load (N)
*Injection Pressure
1439.12 1457.06 1472.06
Maximum Load (N) *Hold on Pressure
1461.59 1465.3
Mechanical
1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480
Max
imu
m L
oad
(N
) Maximum Load (N) v/s All Levels
www.ijoscience.com 27
Figure 29: Comparison between Tensile Strength
at different parameters
Figure 29 shows the comparison between Tensile
strength at different parameters. In case of
Temperature Tensile strength in level 3 35.96 N/mm2.
in case of injection pressure Tensile strength is 36.25
N/mm2 in level 3. In case of injection speed tensile
strength is 37.35 N/mm2 at Level 2.
Figure 30: Comparison between Tensile Strain at
different parameters
Figure 30 shows the comparison between Tensile
strain at different parameters. In case of Temperature
Tensile strain in level 3 9.21%. In case of injection
pressure Tensile strain is 8.97% in level 2. In case of
injection speed tensile strain is 9.38% at Level 1.
Level-1 Level-2 Level-3
Tensile strength (N/mm2)
*Temp
34.73 35.19 35.96
Tensile strength (N/mm2) *Injection Pressure
35.44 35.88 36.25
Tensile Strength(N/
mm2) * Injection
Speed
37.07 37.35
33 33.5
34 34.5
35 35.5
36 36.5
37 37.5
38 Te
nsi
le S
tre
ngt
h (
N/M
M^2
)
Tensile Strength v/s All Levels
Level-1
Level-2
Level-3
Tensile strain (%) *
Temp 10.65 10.38 9.21
Tensile strain (%) *
Injection Pressure
10.23 8.97 9.58
Tensile Strain(%) * Injection
Speed
9.38 9.65
8
8.5
9
9.5
10
10.5
11
Ten
sile
Str
ain
(%
)
Tensile Strain v/s All Levels
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Figure 31: Comparison between Tensile
Extensions at different parameters
Figure 31 shows the comparison between Tensile
Extension at different parameters. In case of
Temperature tensile extension is 14.74 mm at level 3.
In case of injection pressure tensile extension is 14.35
mm in level 3. In case of hold on pressure tensile
extension 13.02 mm at level 1. In case of injection
speed tensile extension is 15 mm at Level 1.
Figure 32: Comparison between Modulus at
different parameters
Figure 32 shows the comparison between Modulus at
different parameters. In case of Temperature Modulus
is 1500.98 N/mm2 at level 3. In case of injection
pressure Modulus is 1387.92 N/mm2 in level 3. In
case of injection speed Modulus is 1530.88 N/mm2 at
Level 2.
IV. CONCLUSION
The mechanical and thermal response of
polypropylene materials of grade H200MK was
investigated experimentally in this thesis. The
mechanical response of thermoplastic polymer
material is strongly related to its microstructure. The
microstructure is also affected by fabrication, e.g.
injection moulding, and the processing conditions.
The anisotropy and in- homogeneity of injection
moulded parts can be a challenge trying to predict
their mechanical response. Due to the complexity of
the molecular and composite structure of these
polypropylene compounds, making an accurate
simulation requires highly well‐defined material
models. It means the material model should be able to
describe the most important features of the material
behavior, e.g. mechanical strain rate, tensile strength,
extension and thermal heat deflection temperature. It
should be noted, however, that with this rather
complex material behavior it is often difficult to
separate the effects, but however experimental results
show the changes with respect to the variation in all
the parameters and these are concluded below-
1. It is observed that maximum load bearing
capacity is improved by the variation of injection
pressure as compared to other variable
parameters.
2. It is observed that the tensile strength is
increased by the variation of injection speed.
3. It is seen that the tensile strain depends upon the
temperature, the rate of strain suddenly changes
with the change in temperature.
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