study of the design of cooling channels for polymers injection molds.
The introduction of components made of plastic products and plastic injection processes has always been the driving force of modern industry. This requires a tool called a mold. The design and manufacture of molds is the most important task in the manufacturing chain of plastic products, which affects the cost of plastic products, Time and quality of final plastic parts. In the cycle of injection plastic parts, injection is one of the most important steps and usually requires 2/3 of [total Time]1] , At least 60% of visible defects recorded in the injection assembly, such as packaging, may be related to the inefficiency of the cooling system . Efficient cooling channels in plastic injection molds can shorten cycle time, improve product quality and reduce weld, warping, residual stress, sink marking and shrinkage [3-7] Traditionally, these cooling channels are manufactured through drilling. Linear and cylindrical channels can only be manufactured. Therefore, non-uniform heat transfer will occur in most cases, it will damage the process and the final product . Development of new processes for the manufacture of fully dense metal deposition additives such as selective laser melting and EBM ( Electric Beam Melting) The ability to change the way the mold is designed allows the manufacture of molds with cooling channels according to the product terrain (known as the shape-preserving cooling channel. Cooling efficiency can be greatly improved [4, 9] However, due to the high manufacturing cost of additives ,[9, 10] The real benefits of it are not yet clear. The guidelines in the cooling design literature are based on traditional channels, and due to the complexity and limitations of the part geometry, it is not necessary to obtain good results for the shape-preserving cooling channels. The work solved the problem. A new concept of shape-preserving cooling is proposed and analyzed by finite element simulation. Literature Review in very few specific cases, it is possible to improve the cooling system even if drilling is used. Introduce a device called a baffle in a cylindrical hole that divides the hole into incoming and outgoing water flow . Nevertheless, infree shape, in the case of most plastic injection molds, it would be very convenient to establish a channel inside the mold that follows the free shape geometry. Ordinary processing processes cannot make such a channel. In general, shape-preserving cooling follows the cylindrical channel on the surface of the product with different strategies [9-18] There is no single standard for shaped cooling design . Cooling channels are usually connected in series or in parallel. The designer\'s expertise and mathematical formula in the existing literature are the basis of mold design [8, 19]. Computer-aided engineering (CAE) Important role of software in mold development13-15] , Which is critical for validation and validation of models by flow and heat transfer formulas including conduction convection and radiation . It is an important tool to reduce development and manufacturing time, avoiding [rework]4] , Even if the simulation results may be different from the real one, it is a very important tool to evaluate different design options, especially if the real assessment becomes not feasible, this work is due to the high cost of additive manufacturing. Park and Pham (2009) The series of shape-preserving cooling and the use of zig- Zag and spiral pattern. In zig- Before the other parts, the coolant reaches some parts so that the temperature increases as the flow length increases and the uniformity in the mold is the worst. With a series of spiral cooling modes, coolant flow can be configured from end to center and Vice Depending on the mode of the fuse flow and vice versa, this will result in a more uniform cooling. In parallel cooling systems, each channel starts at the same temperature, increasing uniformity, however, a large amount of fluid is required and the pressure drop is expected to be greater. Wang et al. (2015) A spiral shape-preserving cooling (series) For high surfaces. The results show that the productivity is higher compared to the shape-preserving cooling generated by conformal onodialis using parallel circuits- Probably because the flow behavior is improved using tandem mode. Marques et al.  The series and parallel strategies of shape-preserving cooling are studied. This work shows better results for the series circuit with 10,000 closing, while in the parallel circuit, the flow problem and the area with poor heat exchange will haveRao et al.  An Analytical thermal model of cylindrical shape-preserving cooling was developed to optimize the cycle time according to the surface and thickness of the product. Dang and Park  Adopt the host. Thermalanalysis defines the parameters to optimize the process. Park and Pham(2009), Mayer  Based on the design expertise, case and engineering analysis are studied to provide parameter suggestions for shape-preserving cooling design. Table 1 summarizes their suggestions. Rannar et al. (2007) The cooling of the h13 mold made with byEBM was studied. The cycle time and product quality of products injected with the baffle cooling system using a series of shape-preserving cooling plug-ins are analyzed. Shape-preserving cooling shows less warping in the product. Wang et al. (2011), Au and Yu (2011) And Agazzi. (2013) The heat transfer of complex cooling channels based on product geometry is studied. According to the better temperature distribution of the simulation, defects such as cycle time and warping are expected to decrease compared with traditional cooling channels. Li (2001) An automatic channel generation method based on feature recognition is proposed. the algorithm divides the product into a simple structure for channel generation and unifies the results. Au et al. (2011) Automate the shape-preserving cooling design using a multi-angle body composition to check the surface visibility of the shape-preserving cooling. Later,Jauregui-Becker et al.  An automated method for cooling channel design was developed. However, due to the variability of product shapes and cooling solutions, these methods are limited to parts with few limitations, low complexity, and simple section shape-preserving cooling. Au and Yu  Compared with traditional design, studying shape-preserving cooling in the bracket format has better results in terms of thermal uniformity, as surface geometry is followed. This will lead to reduced shrinkage, warping and thermal stress. However, there is a lot of pressure on this cooling loop. This study promotes the development of shape-preserving cooling expertise, but does not minimize the cooling efficiency of parallel circuits. Eiamsa- Ard and Wannissom (2015) The use of the baffle near the surface of the cooling loop was studied and it was verified that the cooling was more uniform. Park and Dang (2010) Design a mold with a baffle array on the surface of the product, which combines improvements in heat transfer at a lower manufacturing cost. However, the performance of this solution is limited to product geometry. Works found in the literature contribute to the development of a series of shape-preserving cooling to assess the benefits of the development of polymer injection tools. However, it still lacks knowledge about shape-preserving cooling series and/or parallel design. To solve this problem, a new shape-preserving cooling scheme is proposed in this paper. It mixes the system of string and parallel flow. The entrances and exits are continuous and only some of the internal areas use parallel modes. The commercial automobile plastic parts are used as the workpiece, and the simulation is carried out through finite element analysis. To evaluate the design of the shape-preserving cooling proposed. In this paper, a new design scheme of shape-preserving cooling channel is proposed, which is mixed in series and parallel. This method combines the better cooling law of the parallel mode with the high efficiency of the series mode. Auto parts used as work pieces (Fig. la). This part of the selection is due to the fact that it has a complex cooling area, and in addition to the possibility of using a shape-preserving cooling channel, its geometry allows the use of a baffle cooling system manufactured by simple drilling. Therefore, the shape-preserving cooling channel can be evaluated according to baffle cooling, which is the most effective cooling possibility made by traditional methods ( But only for a few cases, it can be geometrically fitted). The small tower as shown in the figure. 1 maintain greater heat compared to other parts of the mold. Therefore, an efficient cooling system is convenient in that area. The part of the mold was investigated. Using 3D CAD software, three cooling channel design schemes are developed, named I. Design 1: conventional baffle system made by drilling; II. Design 2: The shape-preserving cooling of the series pattern can only be made through additive manufacturing technology. According to the literature, the series pattern is selected because it provides better results than the parallel pattern; III. Design 3: Proposed shape-preserving cooling, mixed parallel mode to achieve better temperature uniformity in key areas and in series mode to ensure better coolant flow. Cae sigmasoft [evaluation of cooling design]R]5. 0. Cycle time was determined in previous studies. It is fixed to evaluate the temperature distribution on the mold surface and product as well as the life of the part according to the cooling channel design. Table 2 shows the general process parameters used to perform the simulation. According to the material to be injected, the influence of the cooling system was also studied. The simulation was carried out Two different plastic materials are used :(i)polymer PA6 ( Engineering polymer) With high Poly point and rapid solidification and (ii) PPcopolymer with lower curing rate and temperature process. This material is widely used in manufacturing goods. Results and Discussion Figure 2 show the three cooling Channel designs developed in this work. Figure 2a, the method of baffle is given (Design 1); Fig. 2 B shape-preserving cooling in serial method (Design 2); and Fig. A serial and parallel design is proposed for 2c consistent cooling (Design 3). Figure 3 and Figure 4 respectively show the surface temperature obtained by CAEsimulation on movable and fixed mold cavities using nylon 6 and PP polymer materials; The three designs of the cooling channel are studied. Two materials (Figs. 3 and 4) , The temperature concentration of the Tower of the insert can be observed. However, it is worth noting that this concentration is low for design 3. Figure 5 shows the average temperature of the two materials on the surface of each mold. It is important to emphasize that temperature uniformity is more important to shorten the quality of the product than the cycle time. Design 3 gives better temperature uniformity to the surface of the mold. The uniformity of mold temperature can not only shorten the production cycle, but also directly improve the product quality. Observe the situation of nylon 6 material, the temperature uniformity is about 5. 1% and 11. Design 2 reduced by 2% ( Corner cooling seriesandDesign 3 ( Parallel mixing of shaped cooling series) Respectively than the ordinary baffle channel. Similar results are available for PP materials. Therefore, it is worth noting that the proposed shape-preserving cooling, hybrid tandem and parallel partners achieved the best results. Since the process temperature of PP solidification is low and the cooling time is long, the improvement in the process is small compared with nylon 6, which is 3 respectively. 1 and 8. 0% it was also observed that nylon 6 has the highest temperature reduction than PP polymer. The nylon 6 material has a stronger van der huali and requires more energy ( Temperature gain) Fast solidification changes state. Otherwise, the PP polymer has a lower intermolecular force, resulting in less sudden solidification. In this way, integrated cooling has a greater impact on materials with strong molecular interaction such as pa6. Figure 6 shows the setting time of the two materials. These times are important for cycle time and product quality. When the solidification process reaches 3%, there is no significant change in the design of the cooling system, about 45%. Optimizing the temperature distribution on the mold and closing the cooling channel does not guarantee a better cycle time for the product. However, the material has an effect on the setting time. Figure 7 shows the use of three cooling Channel designs using pp polymer materials ( More sensitive material than nylon 6). Sleep time was assessed in 12 different regions. This result shows the time of the material. flow. The homogenization temperature of the part directly affects the cycle time. The product can only be extracted if the hot test area reaches a no-flow temperature, which means that poor homogenization increases the cycle time. Shape-preserving cooling gives better temperature uniformity, especially on the surface of the part. Therefore, extracting parts at a time when the surface is complete can reduce the cycle time. Angle-saving cooling design 3 and angle-saving cooling design 2 need 22 respectively. 3% and 18. Curing time is 3% lower than design 1 (baffle). Homogenization of product temperature is an important limitation of the use of the baffle. Conclusion The current work proposes a new method to design the cooling channel that meets the requirements, the mixed series and parallel mode can be realized by additive manufacturing technology. In addition to the proposed design scheme, CAE simulation was carried out on the traditional series shape-preserving cooling and baffle cooling system. The main conclusions of this study are: * even if the literature shows better results for the series mode in the angle-saving cooling design than the parallel mode, the current work shows that the combination of the two modes can achieve better It can recommend appropriate hybrid series circuits to maintain turbulence and parallel circuits to improve the temperature uniformity in key areas. * In the case studied, with a restricted geometry of the mass accumulation area, the shape-preserving cooling does not significantly improve the cooling cycle compared to the baffle. For drilling, using only expensive processes is a very important product format and accessibility. * A more uniform temperature is observed for shape-preserving cooling compared to the baffle on the mold and part surfaces. The mold opening time is limited by the hottest area of the part, in addition to improving the quality of the product, it is possible to reduce the cycle time with the increase of temperature uniformity. * Plastic material display is also one of the variables to be analyzed before investing in shaped cooling molds. The material has stronger intermolecular bonding and shows better results than the insensitive PP polymer. Thanks to the authors for the support of BMW Brazil, MAGMASigmasoft, Polimold industries. REFERENCES [1. ]Z. L. Ching and M. H. Chou, J. Manuf. Syst. , 21, 107 (2002). [2. ]Z. Huamin, Y. Bo, and Z. Yun, J. Mater. Process. Technol. ,204, 475 (2008). [3. ]H. S. Park and N. H. Pham, Int. J. Automot. Technol. , 10, 1(2009). [4. ]L. E. Rannar, A. Glad, and C. G. Gustav Sen, rapid PrototypingJ. , 13, 128 (2007). [5. ]S. Marques, A. F. Souza, J. R. Miranda, and R. F. F. Santos, \"evaluating the shape-preserving cooling system in plastic injection molds through CAE simulation\", in the minutes of the International Conference on industrial tools and material processing technology in Ljubljana, Slovenian tool and mold development center2014). [6. ]A. Agazzi, V. Sobotka, R. LeGoff, and Y. Jamy, Appl. Therm. Eng. , 52, 170 (2013). [7. ]H. S. Park and X. P. Dang, Int. J. Precision Eng. Manuf. , 11,879 (2010). [8. ]K. M. Au, K. M. Yu, and W. K. Chiu, Comput. -Aid. Des. , 43, 356(2011). [9. ]A. Armillotta, R. Baraggi, and S. Fasoli, Int. J. Adv. Manuf. Technol. , 71, 1 (2014). [10. ]D. G. Ahn, Int. J. Precision Eng. Manufacturing, month, 925 (2011). [11. ]X. Xu, E. Sachs, and S. Allen, Polym. Eng. Sci. , 41, 1265(2001). [12. ]F. H. Hsu, K. Wang, C. T. Huang, and R. Chang, Adv. Prod. Eng. Manage. , 8, 107 (2013). [13. ]J. G. Kovacs, F. Szabo, N. K. Kovacs, A. Suplicz, B. Zink, T. Tabi, and H. Hargitai, Appl. Therm. Eng. , 85, 44 (2015). [14. ]D. E. Dimla, M. Camilo and F. Miani, J. Mater. Process. Technol. , 164-165, 1294 (2005). [15. ]U. Vietri, A. Sorrentino, V. Speranza and R. Pantani, Polym. Eng. Sci. , 51, 2542 (2011). [16. ]C. L. Li, Comput. -Aid. Des. , 33, 1073 (2001). [17. ]Y. Wang, K. -M. Yu, C. C. L. Wang, and Y. Zhang, Comput. Aid. Des. , 43, 1001 (2011). [18. ]Y. Wang, K. M. Yu, and C. C. L. Wang, Comput. -Aid. Des. , 63, 1(2015). [19. ]K. Eiamsa-ard, and K. Wannissom, computer. -Aid. Des. , 69, 126(2015). [20. ]S. Mayer, optimize the mold temperature control program using dmls. EOS white paper EOS Limited, 1 (2005). Available in dmls. pdf [21. ]S. Marques, A. F. Souza, J. Miranda, and I. 564,25 ,(2015). [22. ]N. S. Rao, G. Schumacher, N. R. Schott, and K. T. O\'Brien,J. Reinf. Plast. Compos. , 21, 451 (2002). [23. ]X. P. Dang and H. S. Park, Int. J. Precision Eng. Manuf. , 12,73 (2011). [24. ]J. M. Jauregui-Becker, G. Tosello, F. J. Van Houghton and H. N. Hansen dia CIRP Hansen, 270 (2013). [25. ]K. Au and K. Yu, Int. J. Adv. Manuf. Technol. , 34, 496(2007). Felipe Marin (iD), (1) Jackson Roberto de Miranda2) De Sousa (1)(1) GPCAM, Universidade Federal de Santa Catarina, Joinvlle, santacarina 89218-035, Brazil (2) Jackson R. de Miranda, Santa Catalina, Brazil my mailing address: FMarin; e-mail: felipe. marin@posgrad. ufsc. Sponsor: FAPESC; Sponsor of contract award: CNPQ; Sponsor: CAPES. Committee of the conference on polymer and mold innovation (PMI-2016) Held in Ghent (Belgium)21- By submitting instructions to PES Journal, 2016 ofSeptember ,( Special issue of polymer and mold innovation). To better understand, maintain the numbers, meaning, and results, the work was polished and renamed. DOI 10. 1002/pen. 24769 description: Figure1. Study products with active and fixed cavity. [ You can see the color picture in wileyonlinelibrary. com]Caption: FIG. 2. Cooling channel :(a)Design 1--Baffle, (b)Design2-- Shaped cooling series ,(c)Design 3-- Put forward shape-preserving cooling ,(d) Wireframe view of the plug-in with a shaped cooling channel. [ You can see the color picture in wileyonlinelibrary. com]Caption: FIG. 3. Temperature of blade surface after 10 cycles of 6 (a)movable baffle--Design 1. (b)Fixed baffle--Design, (c) Shaped cooling of activity series--Design 2. (d) Fixed series conformalcooling--Design 2. (e) Active shaped cooling--Design 3. (f) Shaped cooling--Design 3. [ You can see the color picture in wileyonlinelibrary. com]Caption: FIG. 4. Temperature of insert surface after 10 cyclesa)Movable baffle--Design 1. (b)Fixedbaffle--Design, (c) Shaped cooling of activity series--Design 2. (d) Shaped cooling-fixed series-Design 2. (e) Active Cooling--Design 3. (f) Fixed shaped cooling--Design 3. [ You can see the color picture in wileyonlinelibrary. com]Caption: FIG. 5. Temperature observed during each mold design. Caption: FIG. 6. Percentage of solidification time for each material. [ You can see the color picture in wileyonlinelibrary. com]Caption: FIG. 7. Curing surface time of PP polymer (a)baffle--Design 1. (b) Shaped cooling series--Design 2. (c) Conformaloring--Design 3. [ You can see the color picture in wileyonlinelibrary. com]