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Injection Molding Simulation Analysis
of Car Rim Using SolidWorks® Plastics
Muhammad Sheharyar
Department of Polymer & Process Engineering,
University of Engineering & Technology Lahore, Pakistan.
Abstract
In this project the main purpose is to study the injection molding parameters of a car rim using
injection molding simulation software SolidWorks®
Plastics. The material used for simulation
was PEEK(Polyether ether ketone) with an addition of 30% carbon fibre. The investigations
were carried out on flowing, packing, cooling and costing of injection moulded car rim. At the
end of analysis the most feasible design can be selected for further stress or other analysis.
1. Introduction
In the past years, injection molding has
become very popular in designing the parts
of complex geometry. This technique is very
much efficient in decreasing labor cost and
to design the discrete parts. Now-a-days
more than one third of polymer products are
manufactured by injection molding.
Injection molding is a process in which
polymer in the form of powder or pellets is
injected into a mold cavity. Mold unit cools
down the polymer & heat is removed from
the polymer so that it becomes rigid. In an
injection molding process there are certain
parameters which ensure the efficient
molding process. These parameters are melt
temperature, mold temperature, injection
pressure, cooling rate & shear rate. The
insert material in an injection molding
process is made of polymer. Different insert
parts have variable effects on the injection
molding process. [AVRAAM, 1987] In this
project an analysis had been made to
analyze the different parameters of the
injection molded part. In this project the
study of car rim simulation had been carried
out using SolidWorks®
Plastics. The study
of injection molding simulation analysis
requires proper knowledge about its
parameters and thermal properties of
material. Simulation technique is very
important tool for the analysis and the
testing of the product before implementing

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in the real systems. Due to computer, as
more powerful, problems can be solved
before manufacturing it. [DOMINICK,
2000] Before going towards simulation by
SolidWorks®
Plastics the part was first
designed in SolidWorks®
Premium and then
imported in SolidWorks®
Plastics for
simulation. There are many other important
injection molding simulation softwares like
Autodesk®
Moldflow.
2. Part Selection
The car rim was selected as the desgin part
to study the injection molding simulation
analysis. The rim has great importance in
car. It is the outer part of the wheel on which
tyre is mounted. Basically, it provides the
base to tyre for mounting. It also provides
strength to the tyre and holds the car tyre
together. A car cannot operate without rims.
They come in different materials and sizes
to meet the specifications of cars. [JERRY,
2013] SolidWorks®
Premium was used to to
draw car rim geometrical layout as well as
SolidWorks®
Plastics software was used for
injection molding simulation analysis. The
design of car rim is shown in Figure 1.
Figure 1: Design Of Car Rim
The major dimensions are 215.53mm x
450.49mm x 446.71mm After making part
the simulation of injection molded part was
carried out.
3. Material Selection
Many types of materials are used to
manufacture the car rim. The most popular
and common materials are metal alloys and
polymer based composits. Out of these
materials polymers play an important role in
the energy saving design of car rim. In this
project the simulation was carried out using
PEEK(Polyether ether ketone) polymer with
30% addition of carbon fibre. The heat
transfer property of polymers helps to
decrese the heat losses in the tyre due to
road friction. The reason of selecting
PEEK+30% carbon fibre was that it has very
high modulus and is high impact polymer. It
provides excellent strength to the tyre and is
light weight. Due to light weight it provides
good acceleration and handeling to the car
[JERRY, 2013]. The material information is
shown in Table 1.
Table 1: Material Information
Melt Temperature 385°C
Glass Transition
Temperature
145°C
Thermal
Conductivity
13.5x 104
W/m.K
Young’s Modulus 24.5x 1010
Pa

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4. Results & Discussion
The processing parameters mold & melt
temperature, cooling time, packing pressure,
packing time, injection location, diameter of
gate have direct effect on volumetric
shrinkage, frozen layer, sink marks, weld
lines, residual stress. The simulation was
done using SolidWorks®
Plastics by varying
above parameters to study this model.
4.1 Number of Gates
Number of gates have major influence on
weld lines. Also by locating more gates
decrease the fill time. The gate should not be
located at sensitive location of part.
4.1.2 Effect of Number of
Gates on Weld Lines
Weld lines are formed when two or more
plastic melt flow fronts come together and
they can be caused by mold shut-off
surfaces, mold core features, multiple
injection locations or wall thickness
variations that cause flow front promotion or
hesitation. Weld lines are typically weaker
than areas without weld lines and they often
result in cosmetic defects. They can also act
as stress concentrators in the molded part.
Weld lines weaken the mechanical
properties [SHOEMAKER, 2006]. Weld
lines increase when greater number of gates
are used. In the first simulation single gate
was used while other processing parameters
were fixed. Table 2 shows the parameters to
study effect of number of gates on weld
lines when single gate was used.
Table 2: Parameters when single gate was used
Melt Temperature 385°C
Mold Temperature 190°C
Injection Pressure
Limit
100 MPa
Gate Diameter 5 mm
Number of Gates 1
Figure 2 shows the weld lines when single
gate was used.
Figure 2: Weld Lines when single gate was used
Table 3 shows the parameters to study effect
of number of gates on weld lines when two
gates were used.
Table 3: Parameters when two gates were used
Melt Temperature 385°C
Mold Temperature 190°C
Injection Pressure 100 MPa
Gate Diameter 5 mm
Number of Gates 2
Figure 3 shows the weld lines when two
gates were used.

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Figure 3: Weld Lines when two gates were used
So, it is clear from the figures that when one
gate was located, lesser number of weld
lines were formed and when two gates were
located, greater number of weld lines were
formed which is not a good thing for the part
as they decrease mechanical properties of
part.
4.2 Melt Temperature
Melt temperature is one of the most
important parameter that disturbed the
properties of end product. Shrinkage
increased at high melt temperature.
Shrinkage can be defined as an extreme
decreased in the dimensions of a molded
part after it had cooled to room temperature.
If the melt temperature is too high, the resin
absorbed an excessive amount of heat and
this in-creased the size of the voided area
between the plastic molecules. Upon
cooling, the skin of the material solidifies
first and the remaining resin closed up the
excessively large molecules and voids as it
cooled, pulling the solidified skin with it.
[FISCHER, 2013]
4.2.1 Effect of Melt
Temperature on Volumetric
Shrinkage
The volumetric shrinkage occurs in the thick
portions of the part. It means polymer
contracts when temperature is decreased
from high melt temperature to normal
cooling temperature. Also the high melt
temperature means that the part can be
packed with more pressure and part weight
is reduced as large increase in volumetric
shrinkage. [SHOEMAKER, 2006]
Three simulations were carried out at three
different melt temperatures that were 385°C,
420°C and 450°C when single gate was used
while other processing parameters were
fixed. Figure 4 shows the shrinkage in the
part at melt temperature of 385°C.
Figure 4: Volumetric Shrinkage at Melt
Temperature 385°C
Figure 5 shows the shrinkage in the part at
melt temperature of 420°C.

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Figure 5: Volumetric Shrinkage at Melt
Temperature 420°C
Figure 6 shows the shrinkage in the part at
melt temperature of 450°C.
Figure 6: Volumetric Shrinkage at Melt
Temperature 450°C
Table 4: Effect of Melt Temperature on Shrinkage
Sr.No Melt
Temperature
Mold
Temperature
Injection
Pressure
Shrinkage
1 385°C 190°C 100 MPa 11.1535%
2 420°C 190°C 100 MPa 12.4804%
3 450°C 190°C 100 MPa 13.6471%
4.3 Mold Temperature
Mold temperature had more effects on final
properties. Higher mold temperatures
produced lower levels of molded in stress
and consequently better impact resistance,
stress crack resistance and fatigue
performance. The mold temperature was the
dominant factor; however, the best results
were obtained when higher mold
temperatures were combined with lower
melt temperature. This behavior is
characteristic of all polymers. In general
optimal performance is produced by
combining low melt temperature and high
mold temperature. [SHEN, 2010]
4.3.1 Effect of Mold
Temperature on Frozen
Layer
When plastic melt makes contact with the
mold wall, a thin layer of the melt instantly
freezes along the cavity wall. This layer of
solidified plastic is called the frozen layer.
This frozen layer depends upon the
difference between melt temperature and
mold temperature. Frozen layer also depends
upon filling time because by giving more
filling there is a possiblity of freezing of
material in mold cavity. But the factor of
geometry of part is also important because if

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we give less time to part of complex
geometry then there will not be equal
distribution of material in mold which leads
the formation of more weld lines. [SHEN,
2010]
The three simulations were carried out at
three different mold temperature when
single gate was used while other processing
parameters were fixed.
Figure 7 shows the frozen layer in part at
mold temperature of 190°C.
Figure 7: Frozen Layer at Mold Temperature
190°C
Figure 8 shows the frozen layer in part at
mold temperature of 210°C.
Figure 8: Frozen Layer at Mold Temperature
210°C
Figure 9 shows the frozen layer in part at
mold temperature of 230°C.
Figure 9: Frozen Layer at Mold Temperature
230°C
It is clear from the figures that when the
difference between mold temperature and
melt temperature was decreased the frozen
layer also decreased. In other words when
mold temperature was increased the frozen
layer formed was decreased. Generally, a
hot mold will allow a material to stay molten
longer than a cold mold and cause the
molecules to flow farther before they
solidify. If the mold was too cold, the
molecules solidify before they were packed
and the weld lines will be more evident. So,
the solution is that Increase the mold
temperature to the point that the material has
the proper flow and packs out the mold with
maximum weld line strength. If the mold is
not cooling the plastic the molecules will
have varying cooling and shrinking
characteristics and this causes warpage.
[FISCHER,2013]

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Table 5: Effect of Mold Temperature on Frozen Layer
Sr.No Melt
Temperature
Mold
Temperature
Injection
Pressure
Frozen Layer
1 385°C 190°C 100 MPa 0.2500
2 385°C 210°C 100 MPa 0.2358
3 385°C 230°C 100 MPa 0.2279
Conclusions
This study shows that by changing the
different parameters in the SolidWorks®
Plastics, defects which are produced in the
product can be easily detected and by
adopting suitable parameters for the product,
these defects can be easily removed before
using the product for the practical
applications.
Acknowledgements
First of all, the author wants to say thanks to
Almighty Allah then thanks to Dr. Shafiq
Irfan and also the group members Umer and
Khizar for their guidance and advices on
injection molding simulation analysis.
References
AVRAAM, I. 1987. Injection and
Compression Molding Fundamentals, New
York, NY, USA, Marcel Dekker, Inc.
DOMINICK, R. 2000. Injection Molding
Handbook, Massachusetts, USA, Kluwer
Academic Publishers.
FISCHER, J. 2013. Handbook of Molded
Part, Warpage and Shrinkage. Intermediate
Technology Publication, UK
JERRY, F. 2013. Handbook of Molded Part
Shrinkage and Warpage, Oxford, UK,
Elsevier Publishers.
SHEN, J. 2010. Design and Molding
Simulation of the Plastic Part. John Wiley
and Sons Publications, USA
SHOEMAKER, J. 2006. Moldflow Design
Guide, Massachusetts, USA, Hanser
Publishers.