Comparison of Different Cooling Systems in Plastic Injection Molding

Abstract

Injection molding is preferred for plastic products due to its high efficiency. However, one of the most important factors after injection is the cooling of the part. Therefore, the cooling process considers being an essential part of the total molding time. Generally, the cooling process in plastic injection molds is done by circulating the cooling liquid through the holes opened in the radial and axial direction on the mold. However, in cases where the cooling is not at the wanted level, the efficiency is increased by placing high thermal conductivity coefficients materials in the molds. With the development of manufacturing methods, conformal cooling systems with cooling channels that follow the molded part geometry have emerged as an alternative to this method. However, this is an expensive method, and studies are ongoing. In this study, the mold cooling times were analyzed and compared with the help of the MoldFlow analysis program on a sample part with a conventional cooling system, as a result of placing a conformal cooling system and a material (insert) with a high thermal conductivity coefficient in the mold.

Keywords

• Plastic Injection
• Conformal Cooling Channels
• Cooling of Plastic Injection Molding
• Analysis of Mold Cooling Times

Plastik Enjeksiyon Kalıplamada Farklı Soğutma Sistemlerinin Karşılaştırılması

Abstract

Enjeksiyon kalıplama, plastik ürünler için yüksek verimlilik sebebiyle tercih edilmektedir. Enjeksiyon sonrasında en önemli unsurlardan birisi de parçanın soğutulmasıdır. Soğutma işlemi, toplam kalıplama süresinin önemli kısmını oluşturmaktadır. Genellikle plastik enjeksiyon kalıplarında soğutma işlemi kalıp üzerine radyal ve eksenel yönde açılan deliklerden soğutma sıvısı dolaştırılması ile yapılır fakat soğumanın istenilen düzeyde olmaması durumlarında kalıplara ısı iletkenlik kat sayısı yüksek olan malzemeler yerleştirilerek verim arttırılmaya çalışılır. İmalat yöntemlerinin gelişmesiyle bu metoda alternatif olarak kalıplanan parça geometrisini takip eden soğutma kanallarına sahip olan şekil uyumlu (konformal) soğutma sistemleri ortaya çıkmıştır. Ancak bu pahalı bir yöntemdir ve üzerinde çalışmalar devam etmektedir. Bu çalışmada, klasik soğutma sistemine sahip ve üretimi devam eden örnek bir parçada MoldFlow analiz programı yardımı ile klasik soğutma sistemi, şekil uyumlu (konformal) soğutma sistemi ve kalıba ısı iletkenlik katsayısı yüksek olan bir malzeme (insert) yerleştirilmesi sonucunda kalıp soğutma sürelerinin analizleri yapılarak karşılaştırılmıştır.

Keywords

• Plastik Enjeksiyon
• Konformal Soğutma Kanalları
• Plastik Enjeksiyonda Soğutma
• Kalıp Soğutma Sürelerinin Analizi

References

1. Reference1 Kim, H.K.; Sohn, J.S.; Ryu, Y.; Kim, S.W.; Cha, S.W. Warpage Reduction of Glass Fiber Reinforced Plastic Using Microcellular Foaming Process Applied Injection Molding. Polymers 2019, 11, 360.
2. Reference2 Shayfull, Z.; Sharif, S.; Zain, A.M.; Ghazali, M.F.; Saad, R.M. Potential of Conformal Cooling Channels in Rapid Heat Cycle Molding: A Review. Adv. Polym. Technol. 2014, 33.
3. Reference3 S.H.Masood and N.N.Trang, “Thermal analysis of conformal cooling channels in injection moulding,” in Proceedings of the 3rd BSME-ASME International Conference on Thermal Engineering, Dhaka, Bangladesh, (2006).
4. Reference4 J.Shoemaker, Moldflow Design Guide: A resource for plastics Engineers, vol.10, Hanser Publishers, (2006).
5. Reference5 J.Meckley and R. Edwards, “A Study on the design and effectiveness of corformal cooling channels in rapid tooling inserts,” The Technology Interface Journal, vol. 10, no.1, (2009).
6. Reference6 Y. Wang, K.-M. Yu, C. C. L. Wang, and Y. Zhang, “Automatic desing of conformal cooling circuits for raid tooling,” CAD Computer Aided Design vol.43, no. 8, pp. 1001-1010, (2011).
7. Reference7 Wang G. L., Zhao G. Q. and Wang X. X., "Heating/cooling channels design for an automotive interior part and its evaluation in rapid heat cycle molding", Materials & Design, 59: 310-322, (2014).
8. Reference8 Altaf K., Raghavan V. R. and Rani A. M. A., "Comparative thermal analysis of circular and profiled cooling channels for injection mold tools", Journal of Applied Sciences, 11(11): 2068-2071, (2011).

9. Reference9 Berger, G.R.; Zorn, D.; Friesenbichler, W.; Bevc, F.; Bodor, C.J. Efficient cooling of hot spots in injection molding. A biomimetic cooling channel versus a heat-conductive mold material and a heat conductive plastics. Polym. Eng. Sci. (2019), 59, E180–E188.
10. Reference10 Rajamani, P.K.; Ageyeva, T.; Kovács, J.G. Personalized Mass Production by Hybridization of Additive Manufacturing and Injection Molding. Polymers (2021), 13, 309.
11. Reference11 H. S. Park, N. H. Pham, Design of conformal cooling channels for an automotive part, International Journal of Automotive Technology 10 (1) (2009), 87-93.
12. Reference12 A.Safifullah, Sç Masood, and I. Sbarski “New cooling channel design for injection molding,” in Proceedings of the World Congress on Engineering, (2009).
13. Reference13 “Application of solidworks simulation for design of cooling system for injection molding,” International Virtual Journal, In press.
14. Reference14 Lin ZC, Chou MH (2002) Design of the cooling channelsin monrectangular plastic flat injection mold, J Manuf Sys 21(3): 167-186.
15. Reference15 Ahari H,Kajepuor A, Bedi S (2011) Manufacturing optimization of laminated tooling with conformal cooling channels, Rapid Prototype J 17(6): 429-440.
16. Reference16 Altaf K, Raghavab VR,Rani AMA (2001) Comparative thermal analysis of circular and profiled cooling channel for injection mold tools, J Appl Sci 11 (11): 2068-2071.
17. Reference17 Y. Wang, K.-M. Yu, C. C. L. Wang, Spiral and conformal cooling in plastic injection molding. Computer-Aided Design, vol. 63 (2015), 1-11.
18. Reference18 H. S. Park, N. H. Pham, Design of conformal cooling channels for an automotive part. International Journal of Automotive Technology, vol. 10, (2009), 87-93.
19. Reference19 Au, K. M. and K. M. Yu, A scaffolding architecture for conformal cooling design in rapid plastic injection moulding. The International Journal of Advanced Manufacturing Technology, vol. 34, (2007), 496-515.
20. Reference20 Y., Wang, K.-M. Yu, C. C. L. Wang, Y. Zhang, Automatic design of conformal cooling circuits for rapid tooling. Computer-Aided Design, vol. 43, (2011), 1001-1010.
21. Reference21 Jahan S. A., Wu T., Zhang Y., Zhang J., Tovar A. And Elmounayri H., "Thermo-mechanical design optimization of conformal cooling channels using design of experiments approach", Procedia Manufacturing, 10: 898-911, (2017).
22. Reference22 Göktaş M., Güldaş A. and Bayraktar Ö., “Cooling of plastic injection moulds using design adaptive cooling canals”, International Conference on Engineering and Natural Science s (ICENS 2016), Sarajevo, 1987-1993, (2016).
23. Reference23 J. M, Jauregui-Becker, G. Tosello, F. J. Van Houtena, H.N. Hansenb, Performance evaluation of a software engineering tool for automated design of cooling systems in injection moulding, Procedia CIRP 7, (2013), 270-275.
24. Reference24 Kuo, C.C.; Qiu, S.X.; Lee, G.Y. Characterizations of polymer injection molding tools with conformal cooling channels fabricated by direct and indirect rapid tooling technologies. Int. J. Adv. Manuf. Technol. (2021), 117, 343–360.
25. Reference25 Gibson, L.J.; Ashby, M.F. Cellular solids: Structure and properties. Cambridge Univ. Press (1997), 2, 510.