Page | 1
Injection Molding Simulation Analysis
of Car Rim Using SolidWorks® Plastics
Muhammad Sheharyar
Department of Poly...
Page | 2
in the real systems. Due to computer, as
more powerful, problems can be solved
before manufacturing it. [DOMINICK...
Page | 3
4. Results & Discussion
The processing parameters mold & melt
temperature, cooling time, packing pressure,
packin...
Page | 4
Figure 3: Weld Lines when two gates were used
So, it is clear from the figures that when one
gate was located, le...
Page | 5
Figure 5: Volumetric Shrinkage at Melt
Temperature 420°C
Figure 6 shows the shrinkage in the part at
melt tempera...
Page | 6
we give less time to part of complex
geometry then there will not be equal
distribution of material in mold which...
Page | 7
Table 5: Effect of Mold Temperature on Frozen Layer
Sr.No Melt
Temperature
Mold
Temperature
Injection
Pressure
Fr...
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Injection Molding Simulation Analysis of Car Rim Using SolidWorks® Plastics

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Injection Molding Simulation Analysis of Car Rim Using SolidWorks® Plastics

  1. 1. Page | 1 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
  2. 2. Page | 2 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
  3. 3. Page | 3 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.
  4. 4. Page | 4 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.
  5. 5. Page | 5 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
  6. 6. Page | 6 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]
  7. 7. Page | 7 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.

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