IN INJECTION MOLDING PROCESS BY USING A CAE PROGRAMME FOR CHOOSING SUITABLE THERMOPLASTIC COMPOSITE PART DESIGN Umit HUNER Trakya University, Engineering and Architecture Faculty, Mechanical Engineering Department, Edirne-Turkey Ertugrul S. ERDOGAN Trakya University, Engineering and Architecture Faculty, Mechanical Engineering Department, Edirne-Turkey Abstract Composite materials have been used in structures for a long time. In recent times composite parts have been used extensively in aircraft structures, automobiles, sporting goods, and many consumer products. Both thermoplastics and thermosets can reap the benefit of fibre reinforcement although they have developed in separate market sectors[3]. This situation has arisen due to fundamental differences in the nature of the two classes of materials, both in terms of properties and processing characteristics. In this study,there is an investigation about in a injection molding process, a thermoplastic composite part s design is how effective.parametres like shape of part,radius of corners or dimension of wall thickness were changed and these modifications were analyzied in a CAE programme.and results like clamp force,air traps,time to freeze etc. were compared.as a material %40 glass fiber reinforced PP was used. Introduction Computer technologies provide us a prediction about production or a process.so before the production,while in design phase, a product or a part can be analyzed for the process[4].if it is necessary some important points can be interfered.it save designer/engineer from unchangeable mistakes.also for industry waste of time and money occurs in optimum level. In this study a plastic matrix composite part was designed for a injection molding process.then two variation was investigated by changing some parameters(like dimensions) in design [1].And it was analyzed by the Moldflow programme.obtained results was compared for three different situations.composite part design and two different variation is shown in turn in order figure1.,figure2.,figure3.
Figure1.This part modelled in CAD programme.and dimensions was given in figure. Figure 2. Only one dimension was changed in design.one of the wall thickness was reduced 20mm to 10mm.
Figure 3. After changing wall thickness 2 mm radius was given to corners Analyzing Composite Parts For all designs material was choosen as a %40 glass fiber reinforced PP deatils of this material s properties is shown in table in below[2], Mechanical properties G12: 1724.39 MPa E1: 7630.42MPa E2: 3684.71 MPa V12: 0.4387 V23: 0.4723 Some of analysis result for all design variations are shown in figures in turn in order (Figure1,Figure 2.,Figure 3.) below; -Average fiber orientation -Clamp force XY plot -Fill time
Figure 4. Avg. Fiber orientation for design 1. Figure 5. Clamp force XY for design 1. Figure 6. Fill time for design 1.
Figure 7. Avg. Fiber orientation for design 2. Figure 8. Clamp force XY for design 2. Figure 9. Fill time for design 2.
Figure 10. Avg. Fiber orientation for design 3. Figure 11. Clamp force XY for design 3. Figure 12. Fill time for design 3.
In Table 1. results are shown numerically; DESIGN AVG. FIBER CLAMP FILL TIME ORIENTATION FORCE XY FIRST 0.9760 0.0077 40.38 SECOND 0.9759 0.0170 25.30 THIRD 0.9767 0.0058 25.21 Conclusion Fiber orientation is one of the major factors that determines the mechanical (elastic) strength as well as the stiffness of a molded part. Theories have been developed to predict the mechanical properties of short fiber composites once the fiber orientation distribution in the parts is known. [2] As seen in plot results(figure 4.,7. and 10.) fiber orientation is suitable for third design because of radius of corners. This provides homogeneous dispersion to the composite part. The Clamp force result is a time series result generated from a midplane, Fusion, and 3D flow analysis, and shows the force of the moldclamp over time. The clamp force is the resultant value of the pressure distribution over the entire part. It is a history of the force resultant from filling and packing pressure that acts to open the mold. [2] Because of radius of corners the third design s(figure 3.) clamp force is lower than the others. In Mold Flow program The Fill time result shows the position of the flow front at regular intervals as the cavity fills. Each color contour represents the parts of the mold which were being filled at the same time. At the start of injection, the result shows red, and the last places to fill are dark blue. If the part is a short shot, the section which did not fill has no color. As seen in Figure 6.,9. and 12. necessary clamp force is lowest in third design.
REFERENCES [1].Shephard,M. S. and Finnigan,P.M., 1988, Integrationof geometric modelling and advanced Finite Element preprocessing, Finite Elements in Analysis and Design, 4, 147±162 [2].MoldFlow V4.1 help notes [3].Zhai M., Automated Selection of Gate Location for Plastic Injection Molding Processing,, Singapore,2005 [4].Rosato D.,Rosato D., Reinforced Plastics Handbook, Elsevier Science & Technology Books,2004