Additive manufacturing (AM) offers high-freedom in the design and processing of components with complex internal structures. In this work, a new injection mold with the self-supporting large cooling ...channel and tailored porous structures was designed to improve cooling efficiency and save AM build costs. The optimized internal supports suppressed the collapse and warpage of large channels, which improves the manufacturability and breaks the geometric constraints of laser powder bed fusion (LPBF). The formable diameter of self-supporting channels is significantly increased (≥20 mm). In comparison to the 8 mm normal-sized channel, the self-supporting 13 mm channel reduces the cooling time of more than 20%. Additionally, the porous diamond structure was designated in the assembly part of the mold to save the materials and build time. To tune the strength, a core-shell composite structure with solid shell surrounding inner porous structures is designed. The influence of the wall thickness on the mechanical property of the composite structure was explored, which guides the specific mold design. Finally, a mold with the above-mentioned novel design was successfully processed by LPBF, which substantiates the manufacturability of innovative design. This work also inspires other industrial applications of AM-processed components with improved performance and functionality.
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•Internal supports breaks the manufacturing constraints in LPBF large channel.•Self-supporting large cooling channels of mold increase cooling efficiency.•Tailored porous structures in the mold save build time and material costs.•A mold product with innovative design was produced by LPBF successfully.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Limited by the characteristics of drilling, the traditional straight cooling channel is difficult to provide the best cooling effect for the mold. The conformal cooling channel is more and more ...favored by the mold enterprises because of its excellent cooling performance. However, the current design of conformal cooling channels generally has the problems of complex, time-consuming, and error-prone design process. Inspired by the internal catheter structure of lotus root, this paper puts forward an automatic generation method of conformal cooling channel based on the basic requirements of conformal cooling channel design in engineering practice. The basic idea of this method is to slice the mold part that needs to be cooled and check the curve interference on each slice layer, so as to screen out the control points of the spline curve, and then formulate the connection strategy to obtain the spline curve, which is used as the trace line of pipe scanning, and finally form the conformal cooling channel through pipe scanning. Experimental results show that this method can significantly decrease the time of design and guide users to quickly complete the design while reducing design errors to improve working efficiency.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•A comprehensive and systematic review paper on conformal cooling channels.•Design methodology and layouts of conformal cooling channels are classified and reviewed.•Features and advantages of 8 ...types of conformal cooling channel layouts are discussed and evaluated.•Manufacturing techniques used to fabricate conformal cooling molds are discussed and compared.•Applications of conformal cooling channels are summarized.
Conformal cooling (CC) channels are a series of cooling channels that are equidistant from the mold cavity surfaces. CC systems show great promise to substitute conventional straight-drilled cooling systems as the former can provide more uniform and efficient cooling effects and thus improve the production quality and efficiency significantly. Although the design and manufacturing of CC systems are getting increasing attention, a comprehensive and systematic classification, comparison, and evaluation are still missing. The design, manufacturing, and applications of CC channels are reviewed and evaluated systematically and comprehensively in this review paper. To achieve a uniform and rapid cooling, some key design parameters of CC channels related to shape, size, and location of the channel have to be calculated and chosen carefully taking into account the cooling performance, mechanical strength, and coolant pressure drop. CC layouts are classified into eight types. The basic type, more complex types, and hybrid straight-drilled-CC molds are suitable for simply-shaped parts, complex-shaped parts, and locally complex parts, respectively. By using CC channels, the cycle time can be reduced up to 70%, and the shape deviations can be improved significantly. Epoxy casting and laser powder bed fusion (L-PBF) show the best applicability to aluminum (Al)-epoxy molds and metal molds, respectively, because of the high forming flexibility and fidelity. Meanwhile, laser powder deposition (LPD) has an exclusive advantage to fabricate multi-materials molds although it cannot print overhang regions directly. Hybrid L-PBF/computer-numerical-control (CNC) milling pointed out the future direction for the fabrication of high dimensional-accuracy CC molds, although there is still a long way to reduce the cost and raise efficiency. CC molds are expected to substitute straight-drilled cooling molds in the future, as it can significantly improve part quality, raise production rate and reduce production cost. In addition to this, the use of CC channels can be expanded to some advanced products that require high-performance self-cooling, such as gas turbine engines, photoinjectors and gears, improving working conditions and extending lifetime.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Injection molding is a cyclic process comprising of cooling phase as the largest part of this cycle. Providing efficient cooling in lesser cycle times is of significant importance in the ...molding industry. Conformal cooling is a proven technique for reduction in cycle times for injection molding. In this study, we have replaced a conventional cooling circuit with an optimized conformal cooling circuit in an injection molding tool (mold). The required heat transfer rate, coolant flow rate and diameter of channel was analytically calculated. Hybrid Laser powder bed fusion technique was used to manufacture this mold tool with conformal channels. The material used for manufacturing mold was maraging steel (M300). Thermal efficiency of the conformal channels was experimentally calculated using thermal imaging. Autodesk MoldFlow software was used to simulate and predict the cooling time required using conformal cooling channels. The results showed a decrease in cooling time and increase in cooling efficiency with the help of conformal cooling in additively manufactured mold insert.
It is quite challenging to control both quality and productivity of products produced using injection molding process. Although many previous researchers have used different types of optimisation ...approaches to obtain the best configuration of parameters setting to control the quality of the molded part, optimisation approaches in maximising the performance of cooling channels to enhance the process productivity by decreasing the mould cycle time remain lacking. In this study, optimisation approaches namely Response Surface Methodology (RSM), Genetic Algorithm (GA) and Glowworm Swarm Optimisation (GSO) were employed on front panel housing moulded using Acrylonitrile Butadiene Styrene (ABS). Each optimisation method was analysed for both straight drilled and Milled Groove Square Shape (MGSS) conformal cooling channel moulds. Results from experimental works showed that, the performance of MGSS conformal cooling channels could be enhanced by employing the optimisation approach. Therefore, this research provides useful scientific knowledge and an alternative solution for the plastic injection moulding industry to improve the quality of moulded parts in terms of deformation using the proposed optimisation approaches in the used of conformal cooling channels mould.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
According to the practical experiences in the injection molding, the knowledge about conformal cooling channel (CCC) is an essential factor that affects productivity and quality of the molded part ...greatly. In general, the CCC provides a reduction in the cooling time in series production. However, the distance between cooling channel edges of the circular conformal cooling channel (CCCC) and mold cavity edge is not constant. The profiled conformal cooling channel (PCCC) has flat surface of the cooling channel facing the profile of the cavity fully. The distance between cooling channel edges of the PCCC and mold cavity edge is constant. In this study, two maraging steel injection molding tools with two different CCC were designed and fabricated by the direct metal printing technology. The difference between injection mold with PCCC and CCCC on the cooling time of the molded wax pattern, part temperature difference, mold surface temperature difference, and part warpage were numerically investigated using Moldex3D simulation software. It was found that the PCCC seems to be a good candidate in the CCC design and provides a better alternative in the conventional cooling channels. The PCCC reduced the cooling time about 33.33% compared with CCCC under the coolant water temperature of 25 °C. The temperature of 26 °C is the optimal value for the coolant water based on the dimensional accuracy of the wax pattern and energy consumption of the cooling system.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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•Conformal cooling channels are designed for various of axisymmetric castings.•Two-dimensional simplification is performed inspired by origami technique.•Comprehensive design flow is ...proposed following theoretical analysis.•Topology optimization processes are customized within a unified framework.
To address the unacceptable computational burden in three-dimensional topology optimization, this paper presents an origami-inspired strategy that directly applies two-dimensional topology optimization to design three-dimensional conformal cooling channels. A comprehensive design flow incorporating theoretical analysis is proposed stepwise, aiming at axisymmetric castings. Various two-dimensional simplification styles are evaluated, following geometric configuration analysis on channel space. Multiple topology optimization processes are customized on the simplified domain, following thermal analysis of the casting and Reynolds number analysis on the bending transition. The objective is to design a conformal cooling channel with superior cooling performance at a steady state. Numerical simulations are performed to verify the cooling performance of optimized results. Two feasible designs are obtained for a given regular hexahedral casting, with one conducting two-dimensional simplification along the intersection axis of multiple planes exhibiting better steady-state cooling performance. It achieves a 6.7 K reduction in casting temperature and an 11.06 % decrease in pressure drop compared to the other design. In addition, the study explores the application of castings of increasing geometric complexity, including regular tetrahedron, octahedral, dodecahedral, and spherical shapes. For a given spherical casting, a trade-off analysis between average cooling spacing and optimization domain area is conducted as the number of segmentations increases. The optimal design, achieved with 12-part segmentations, results in a casting temperature of 308.05 K under a coolant inlet pressure of 400 Pa at a steady state. This study provides an efficient approach that circumvents the computationally intensive topology optimization process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Conformal cooling channels are designed via thermal fluid topology optimization.•Temperature difference and pressure drop be decreased up to 2.20 K and 25.40%.•Thermal-load-based ...design strategy reduce the average temperature up to 1.45 K.•Special-shaped cylindrical castings be studied via 2D topology optimization..
Conformal cooling technology is widely used in the thermal management for injection molding process. However, the overall design of cooling channel layout needs to be optimized due to non-uniform thermal load, limited design freedom and other factors. This paper presents a novel procedure for conformal cooling channel design by using thermal-load-based topology optimization. Unlike previous approaches that focused on optimizing the channel configuration or geometric parameters, the current work applies multiphysics topology optimization on the entire cooling area. The objective is to obtain the optimal channel layout with both low pressure drop and high heat transfer rate. A serious of optimized planar results are converted to three-dimensional channels that conform to the specific injection casting and are applied to injection molding process in a simulation software environment. For a given thin-plate casting, compared with the conventional parallel cooling process, the steady state average temperature and maximum temperature difference are decreased by 0.53 K and 2.20 K, respectively, and the pressure drop of coolant is decreased by 25.40%. For castings where non-uniform thermal loads are considered, the average temperature and pressure drop are decreased up to 1.45 K and 27.55%, respectively. The results for both sheet castings and cylindrical castings have demonstrated the stability, flexibility, and rationality of the proposed procedure. In addition, the conceptual design of cooling channels based on thermal load is expected to be applied to more potential thermal engineering fields.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study is a comment on “Numerical investigation on cooling performance of hot stamping tool with various channel designs” (Hu et al., Applied Thermal Engineering 96 (2016) 338-351, cited as Ref. ...1 in this study). Conformal cooling (CC) channels can significantly improve product quality and production efficiency, such as the reduction of differential shrinkage, warpage, and other surface defects and the shortening of the injection molding cycles. The Reynolds number is an important parameter to determine the cooling performance in CC molds. There is an optimal Reynolds number value below which the cooling is not sufficient and above which the cooling performance is not further improved but the pressure drop rises significantly. Ref. 1 proposed the optimal Reynolds number was 100,000 which is not convincing as such large a Reynolds number value will cause an unacceptable significant pressure drop in the channel. To verify and clarify this, numerical simulations were conducted using the same methods, conditions, and parameters as Ref. 1. The optimal Reynolds number was found as 20,000 rather than 100,000, which was approximately consistent with the results in other reliable references 2,3 rather than the result in Ref. 1.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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