Conformal Cooling Channels Research Articles

Conformal cooling channels with composite layers

ABSTRACT Conformal cooling channels (CCCs) are a cooling method used in injection molding. According to the literature review, CCCs can reduce cooling time by 2%–70%, with the average reduction being 30%, and they can improve warpage by 5%–90%, with the average improvement being 37%. But the present study found that previous research has ignored the effect of the solidified skin layer in CCCs. This study posits that during the design of cooling channel positions, the plastic solidified layer exhibits distinct thermal properties. Heat transfer involves conduction thermal resistance, which affects the effectiveness of heat conduction. Ignoring the solidified layer can lead to inaccurate predictions of cooling channel positions. Accordingly, this study developed a novel calculation formula for determining the cooling channel positions while considering the existence of the solidified layer, leveraging the concept of steady one-dimensional conduction in composite layers. The results of this study indicated that in the uniform-thickness scenarios, optimal cooling efficiency and quality were obtained when the thickness of the solidified layer was 0.10 mm. However, in the variable-thickness scenario, the cooling efficiency decreased by approximately 2%. Regarding quality, higher deformation control in three dimensions but poorer warpage control in the z-dimension was observed.

Geometrical Parameter Optimization of Circular Cross-Section Conformal Cooling Channels in Injection Molds of Plastic Paving Block Molds

Geometrical Parameter Optimization of Circular Cross-Section Conformal Cooling Channels in Injection Molds of Plastic Paving Block Molds

Polymeric advancements in innovating wax injection molds using aluminum-filled epoxy resin with face-cooled waterfall cooling channels

Aluminum-filled epoxy resin is a polymer composite material formed by adding aluminum particles to epoxy resin, which is widely used to make a rapid tool for developing new prototypes in the research and development department. A conformal cooling channel (CCC) facilitates the swift and even cooling process in injection molding. Nevertheless, the considerable drawback of CCC lies in the notable pressure drop along the cooling channels. This study introduces an inventive solution known as the waterfall cooling channel (WCC), which was proposed and fine-tuned through optimization using Moldex3D simulation software. Two sets of aluminum-filled epoxy resin injection molds were designed and employed, featuring distinct cooling channels. The cooling time for the injection molded part was assessed using a low-pressure wax injection molding machine. Experimental results regarding the cooling time were then juxtaposed with simulation outcomes obtained from Moldex3D software. It was found that a mesh size of 1 mm is the optimal decision for molding simulation based on both the cooling time of the injection molded part and the total computation time. The maximum flow velocity of the cavity insert can be increased by 9.7 % using WCC. A reduction in the coolant flow length of the WCC is about 29–50 % compared to CCC. A reduction in the pressure drop of the WCC is about 58–61 % compared to CCC. The difference in cooling efficiency for CCC is 6 %, while the difference in cooling efficiency for CCC is 4 %. The heat flux of WCC is about 21 times larger than that of CCC. Taking a water cup as an example, the experimental results confirmed that an aluminum-filled epoxy resin injection mold embedded with WCC can increase cooling efficiency by about 16.4 % compared to an aluminum-filled epoxy resin injection mold embedded with CCC.

Optimization Design of Injection Mold Conformal Cooling Channel for Improving Cooling Rate

Optimizing the design of the conformal cooling channel can increase the cooling rate of injection mold. The aim of this study was the problem of low cooling efficiency of injection mold for deep-cavity plastic parts under the conventional cooling channel. Based on the analysis of the heat transfer principle of the injection mold, a mathematical description of the cooling time of the conformal cooling channel was made. By designing orthogonal experiments and using simulation methods in the Autodesk Moldflow 2019 software, with the minimum cooling time of the mold as the optimization goal, experimental optimization was carried out for the three design variables of the channel, thereby obtaining the optimal combination of design variables for the conformal cooling channel. The conformal cooling channel layout was innovatively designed, and through computer simulation experiments, it was concluded that the conformal cooling channel adopted a series flat-head layout, which has the shortest cooling time and the fastest cooling rate. Metal additive manufacturing technology was used to complete the manufacturing of the mold insert with the conformal cooling channel. After the trial production of the conformal cooling injection mold, the molding cycle was obviously shortened, and the injection molding production efficiency was significantly improved.

Line distributed pores in laser powder bed fusion manufactured dies: A critical factor in die failure for high pressure die casting

Additive manufacturing technologies, such as laser powder bed fusion (LPBF), have attracted a significant amount of attention for their capability in fabricating components of complex geometries with improved efficiency and design flexibility. However, the presence of pores in additively manufactured high pressure die casting dies has emerged as a critical issue affecting the performance and reliability of the dies. A numerical model for the formation of pores due to the instability of the keyhole and molten pool in a 18Ni300 steel is created. Computational fluid dynamic (CFD) simulation revealed that the keyhole in the molten pool undergoes inward ebbing and is wrapped by the liquid interface behind the laser beam, forming gas bubbles along the laser tracks. Some of the bubbles will either coalesce or breakup in remelting by the laser beam above in building the next layer forming a string of pores along the LPBF build direction, while others remain unchanged. The line distributed pores are the primary sites for cracking, and the cracks grow along the LPBF build direction. As a result, these longitudinal cracks cause the premature failure of dies with conformal cooling channels (CCC).

Generative design of conformal cooling channels for hybrid-manufactured injection moulding tools

Effective cooling systems for injection moulding (IM) tools are critical to reducing manufacturing costs and cycle time for the polymer parts produced. This work presents a novel automated methodology for designing conformal cooling channels (CCCs) for IM tools via interlinking commercial moulding simulation tools with custom scripts. These scripts adjust CCC design in response to the spatial variability in global and local temperatures at the mould tool-part interface (MTPI) via generative design (GD). Four tool designs for manufacturing a simplified part were analysed numerically simulation and experimentally, including tools with either straight-drilled (non-conformal) cooling channels (tool steel), a manually designed CCC system (stainless steel or bronze alloy), or an automatically designed CCC system (stainless steel). While both manually designed CCC tools cool the part faster than the non-conformal tool (3–5% predicted vs. 40% measured for stainless steel and 9–12% predicted vs. 40% measured for bronze alloy), the GD-optimised CCC tool outperformed both (15–30% predicted faster cooling vs. 70% measured). The predicted MTPI temperature feature achieves reductions to both maximum and spatial variability in MTPI temperatures, which lead directly to significant reductions in manufacturing cycle time and polymer part warpage. These findings could have a major impact on the IM industry by reducing tool design costs and raw material waste via improving moulded part quality.

The Impact of Surface Roughness on Conformal Cooling Channels for Injection Molding.

Injection molding technology is widely utilized across various industries for its ability to fabricate complex-shaped components with exceptional dimensional accuracy. However, challenges related to injection quality often arise, necessitating innovative approaches for improvement. This study investigates the influence of surface roughness on the efficiency of conformal cooling channels produced using additive manufacturing technologies, specifically Direct Metal Laser Sintering (DMLS) and Atomic Diffusion Additive Manufacturing (ADAM). Through a combination of experimental measurements, including surface roughness analysis, scanning electron microscopy, and cooling system flow analysis, this study elucidates the impact of surface roughness on coolant flow dynamics and pressure distribution within the cooling channels. The results reveal significant differences in surface roughness between DMLS and ADAM technologies, with corresponding effects on coolant flow behavior. Following that fact, this study shows that when cooling channels' surface roughness is lowered up to 90%, the reduction in coolant media pressure is lowered by 0.033 MPa. Regression models are developed to quantitatively describe the relationship between surface roughness and key parameters, such as coolant pressure, Reynolds number, and flow velocity. Practical implications for the optimization of injection molding cooling systems are discussed, highlighting the importance of informed decision making in technology selection and post-processing techniques. Overall, this research contributes to a deeper understanding of the role of surface roughness in injection molding processes and provides valuable insights for enhancing cooling system efficiency and product quality.

Towards sustainable injection moulding using 3D printed conformal cooling channels: a comparative simulation study

In recent years, studies have proven that conformal cooling channels (CCC) in an additively manufactured mould result in a more efficient and effective injection moulding process. This can be achieved since CCCs are designed to follow the contour of the part being moulded so that the surface of the part is equidistant from the channel at all points. However, no studies were found which explored the combined effect of mould material thermal conductivity and varying cooling channel designs on the cooling performance of the mould from a sustainability point of view. Within this context, a study was carried out to explore the effect of the tool material’s thermal conductivity on the performance of various CCC designs in comparison with conventional, straight drilled cooling channels. The performance of the cooling channels was analysed from a sustainability point of view by comparing the channel performances in terms of energy consumption, financial implications, and the resulting quality of the part. The results of this study showed that the higher conductivity alloys were especially effective at reducing the cycle time and improving the energy performance of the process in the conventional cooling channel designs. These materials were also capable of reducing the overall cost of the process which was calculated in terms of material costs and electricity consumption. For the CCC designs, however, the high conductivity alloys were less effective in all aspects of this analysis, namely cooling time, energy efficiency, and overall costs. However, it is worth noting that based on the melt flow simulations, the alternative materials had little to no effect on the resulting quality of the part.

Development of a Silicone Rubber Mold with an Innovative Waterfall Cooling Channel.

A conformal cooling channel (CCC) follows the mold core or cavity profile to carry out uniform cooling in the cooling stage. However, the significant pressure drop along the cooling channels is a distinct disadvantage of the CCC. In this study, an innovative waterfall cooling channel (WCC) was proposed and implemented. The WCC cools the injected products via surface contact, replacing the conventional line contact to cool the injected products. The WCC was optimized using numerical simulation software. Silicone rubber molds with two kinds of cooling channels were designed and implemented. The cooling time of the molded part was evaluated using a low-pressure wax injection molding machine. The experimental results of the cooling time of the molded part were compared with the simulation results from numerical simulation software. The results showed that the optimal mesh element count was about 1,550,000 with a mesh size of 1 mm. The simulation software predicted the filling time of the water cup injection-molded product to be approximately 2.008 s. The cooling efficiency for a silicone rubber mold with a WCC is better than that of the silicone rubber mold with a CCC since the core and cavity cooling efficiency is close to 50%. The pressure drop of the WCC is smaller than that of the CCC, which reduces the pressure drop by about 56%. Taking a water cup with a mouth diameter of 70 mm, a height of 60 mm, and a thickness of 2 mm as an example, the experimental results confirmed that the use of the WCC can save the cooling time of the product by about 265 s compared with the CCC. This shows how a WCC can increase cooling efficiency by approximately 17.47%.

Evaluating the Cooling Efficiency of Polymer Injection Molds by Computer Simulation Using Conformal Channels.

Injection molds are production tools that require detailed analysis based on the quality of the resulting part, the impact on cycle times, and the expected production volume. Cooling channels also play a critical role in mold performance and product quality as they largely determine cycle time. Designs that incorporate conformal cooling channel (CCC) geometries that conform to or align with the part contour are currently being explored as an alternative to conventional cooling channel designs in injection molds. In this study, a simulation of CCC geometries was performed and their effects on mold temperatures and warpage were investigated. Two cross-sectional geometries, circular and square, were selected for a three-factor level design of experiments (DOE) analysis. The response variables used were mold temperatures and part warpage. A cup-shaped part with upper and lower diameters of 54 and 48 mm, respectively, a height of 23 mm and a thickness of 3 mm was used for the injection molded part. A comparison was also made between two materials for the injection mold, steel and polycarbonate. The DOE results showed that the distance between the CCC and the injected part and the diameter or side of the square have significant effects on the response variables for both systems (steel and polycarbonate molds). In addition, a comparison between conventional and conformal cooling channels was analyzed using a cup-shaped part and a less rigid part geometry. The finite element simulation results show a 9.26% reduction in final warpage in the cup-shaped part using CCCs compared with the conventional cooling methods in steel. When using parts with lower geometry stiffness, the use of CCCs reduced final part warpage by 32.4% in metal molds and by 59.8% in polymer molds.

Development of an Injection Mold with High Energy Efficiency of Vulcanization for Liquid Silicone Rubber Injection Molding of the Fisheye Optical Lens

Liquid silicone rubber (LSR) techniques are experiencing exponential growth, particularly in the field of high technology due to the low-temperature flexibility, superior heat stability, chemical resistance, and aging resistance of LSR components. Enhancing the curing rate of LSR parts in liquid silicone rubber injection molding is an important research topic. In this study, an injection mold with high energy efficiency of vulcanization for the liquid silicone rubber injection molding of a fisheye lens was developed and implemented. The LSR injection mold has a conformal heating channel (CHC) and conformal cooling channel (CCC) simultaneously. The function of CHC is to enhance the curing rate of a fisheye lens in the LSR injection molding to meet the requirements of sustainable manufacturing. The curing rates of a fisheye lens were numerically examined using the Moldex3D molding simulation software. It was found that the curing rate of the fisheye optical lens cured by injection mold with CHC was better than that of the injection mold with a conventional heating channel. The curing efficiency could be increased by about 19.12% when the heating oil temperature of 180 °C was used to cure the fisheye optical lens. The simulation results showed that the equation y = −0.0026x3 + 1.3483x2 − 232.11x + 13,770 was the most suitable equation for predicting the curing time (y) through the heating oil temperature (x). It was found that the trend of the experimental results was consistent with the simulation results. In addition, the equation y = −0.0656x2 + 1.5827x − 0.894 with the correlation coefficient of 0.9974 was the most suitable equation for predicting the volumetric shrinkage of the fisheye optical lens (y) through the heating oil temperature (x). The volume shrinkage of the fisheye optical lens cured by injection mold with CHC was very similar to that of the injection mold with a conventional heating channel. The maximum volume shrinkage of the fisheye optical lens cured at 180 °C was about 8.5%.

Design and Optimization of Conformal Cooling Channels for Increasing Cooling Efficiency in Injection Molding

Injection molding is widely used in the manufacturing process of plastic products. The injection molding process aims to increase productivity, which is impacted by factors such as cooling time, the temperature distribution of plastic parts, thermal stress, warpage, etc. The cooling stage of the forming process is a critical factor that significantly influences the quality and cost-effectiveness of the final product in injection molding. With the development of additive manufacturing, the fabrication of conformal cooling channels becomes easier and more affordable compared to traditional machining techniques. Well-designed conformal cooling channels can substantially reduce cooling time, resulting in increased productivity and improved efficiency of the injection molding process. While conformal cooling channels offer improved cooling efficiency and part quality, their design process is more intricate than that of conventional channels due to the demand to account for the complex geometry of the part and to accommodate manufacturing constraints. In this paper, the conformal cooling channels are designed, and the variables for the channels are optimized to increase the cooling efficiency, and 3D printing technology is applied to produce the conformal cooling channel. A simplified finite element cooling analysis was used to compare traditional and hybrid solutions for designing cooling channels to reduce injection cycle time for plastic parts, and the design and simulation of the cooling system were based on UG and Moldflow. After comparing the simulation results of the cooling performance, we found that conformal cooling channels can reduce cooling time by 30% compared to conventional cooling channels. Additionally, they result in a more uniform temperature distribution throughout the plastic products.

Conformal Cooling Channel Design for Improving Temperature Distribution on the Cavity Surface in the Injection Molding Process

Mold heating is an essential process in plastic injection molding. Raising the temperature of the mold before injecting liquefied plastic can ease the mold-filling process. A cooling channel can be used to transport high-temperature fluids for this purpose, such as hot water or oil. This dual purpose is a cost-effective solution for heating the mold because the target temperature is easily achieved using this method. In addition, a conformal cooling channel (CCC) can provide more efficient mold heating than a straight cooling channel. This study used the response surface methodology to determine the optimum CCC shape for heat distribution in a mold, and the simulation results confirmed its optimization. The average temperature of the mold using a CCC was better than that using a straight cooling channel, and the heat zone was uniform across the mold surface.

Analysis of Phenomenon of Plasticity Loss of Steel Core Made by Selective Laser Melting Method in Zone of Pressure Mould Conformal Cooling Channel.

This paper presents the results of testing the mechanical properties of maraging steel 1.2709 that were obtained by the SLM method under uniaxial and triaxial states of stress. The triaxial state of stress was realised by making circumferential notches in the samples with different radii of rounding. The specimens were subjected to two types of heat treatment, which consisted of ageing at 490 °C and 540 °C for 8 h. The results of the tests that were conducted on the samples were considered as references and compared with the results of the strength tests that were conducted directly on the SLM-made core model. Differences were found between the results of these tests. Based on the experimental results, the relationship between the equivalent strain of the specimen in the bottom of notch εeq and triaxiality factor η was determined. Function εeq = f(η) was proposed as a criterion for the decrease in the plasticity of the material in the area of the pressure mould cooling channel. Using the FEM method, equivalent strain field εeq and triaxiality factor η were determined in the conformal channel cooled core model. Based on the proposed criterion of plasticity loss and the results of numerical calculations, it was shown that the values of equivalent strain εeq and triaxiality factor η in the core that was aged at 490 °C did not meet this criterion. On the other hand, the values of strain εeq and triaxiality factor η did not exceed the safety limit when ageing was carried out at 540 °C. The plasticity loss method presented in this paper assumes that the value of the triaxiality factor in the vicinity of the channel is influenced by the shape, cross-sectional dimensions and trajectory of the channel axis. Using the methodology proposed in this paper, it is possible to determine the value of allowable deformations in the cooling channel zone and to determine whether the heat treatment applied to the SLM steel does not cause an excessive reduction in the plastic properties.

Design optimization of conformal cooling channels for injection molds: 3D transient heat transfer analysis

This research aims to enhance the design of an injection mold in order to minimize ejection time and increase temperature uniformity by repositioning cooling channels. For 3D transient thermal simulations, the ANSYS finite element method (FEM) program was employed, while the MATLAB program was used for optimization. It was discovered that the method could be used successfully to optimize the design of Conformal Cooling Channels (CCCs) in injection molds. The objective function value of the optimized model represents a near 40% improvement in relation to the initial model. The combined parameterization, simulation, and optimization method has proven beneficial for enhancing the arrangement of channels in an injection machine mold. The methodology is generalizable. As such, it can be employed in any industrial applications involving injection molding machines, for the improvement of the quality of the manufactured part.

Hybrid Manufacturing of Conformal Cooling Channels for Tooling

Computer-aided manufacturing (CAM) techniques for hybrid manufacturing have led to new application areas in the manufacturing industry. In the tooling industry, cooling channels are used to enable specific heating and cooling cycles to improve the performance of the process. These internal cooling channels have been designed with limited manufacturing processes in mind, so, until recently, they were often straight in shape for cross-drilling operations and manufactured from a cast billet. To show a novel application of this common technology, a tool with integrated conformal cooling channels was manufactured using hybrid manufacturing (blown-powder DED and CNC machining) techniques. The computer-aided manufacturing strategy used, and the lessons learned are presented and discussed to enable future work in this industrial application space.

Automated Design of Honeycomb Conformal Cooling Channels for Improving Injection Molding Quality

Abstract The study of conformal cooling channel usually has adopted two assumptions in model design: the use of (1) a hot runner system and (2) a one-mold-one-cavity design. These assumptions substantially simplify the research. However, most molds are designed using a cold runner system and multiple cavities. These two assumptions may not apply to all commercial systems; hence, a design method for honeycomb CCCs for cold runner systems and multiple cavities is proposed in this study. Specifically, an algorithm was developed to automatically design CCCs for such systems. This algorithm can be used to reduce the cooling time, improve product quality, and ensure that the system temperature is relatively homogenous in practical situations. According to the result of this study, the honeycomb CCC models were more effective at maintaining a homogeneous temperature distribution, reducing shrinkage, and reducing warpage for both parts produced from the same two-cavity mold, thus ensuring consistent part quality.

Development of an Epoxy-Based Rapid Tool with Low Vulcanization Energy Consumption Channels for Liquid Silicone Rubber Injection Molding.

Liquid silicone rubber (LSR) parts have some distinct characteristics such as superior heat stability, low-temperature flexibility, aging resistance, and chemical resistance. From an industrial standpoint, the uniform vulcanization temperature of LSR is an important research point. However, the uniformity of the vulcanization temperature of LSR has been limited since the layout of the cartridge heater incorporated in the conventional steel mold does not follow the profile of the mold cavity. Metal additive manufacturing can be used to make LSR injection molds with conformal heating channels and conformal cooling channels simultaneously. However, this method is not suitable for a mold required to develop a new LSR product. In this study, a cost-effective approach was proposed to manufacture an LSR injection mold for the pilot run of a new optical lens. A rapid tool with low vulcanization energy consumption channels was proposed, which was incorporated with both a conformal heating channel (CHC) and conformal cooling channel (CCC) simultaneously. The function of the CHC was to vulcanize the LSR in the cavity uniformly, resulting in a shorter cycle time. The function of the CCC was to keep the LSR in a liquid state for reducing runner waste. It was found that the equation of y = -0.006x3 + 1.2114x2 - 83.221x + 1998.2 with the correlation coefficient of 0.9883 seemed to be an optimum trend equation for predicting the solidification time of a convex lens (y) using the vulcanizing hot water temperature (x). Additionally, the equation of y = -0.002x3 + 0.1329x2 - 1.0857x + 25.4 with the correlation coefficient of 0.9997 seemed to be an optimum prediction equation for the solidification time of a convex lens (y) using the LSR weight (x) since it had the highest correlation coefficient. The solidification time of a convex lens could be reduced by about 28% when a vulcanizing hot water temperature of 70 °C was used in the LSR injection mold with CHC.

Cooling Performance of an Additively Manufactured Lattice Structural Conformal Cooling Channel for Hot Stamping

Cooling Performance of an Additively Manufactured Lattice Structural Conformal Cooling Channel for Hot Stamping

The effect of conformal cooling channels on welding process in parts produced by additive manufacturing, laser powder bed fusion

Given the excellent performance in making lighter, customizable, strong, and aesthetically attractive components at a reduced time and cost, additive manufacturing (AM) presents an unparalleled approach to extending and developing industrial applications. A conformal cooling channel (CCC) is one application that is gaining traction in many vital industries, including mold production, aerospace, healthcare, automotive, and electronics. In this study, the laser powder bed fusion (LPBF) based AM approach is utilized experimentally and numerically to incorporate a CCC network to improve the performance of a weld joint of 316 L SS plates. The study demonstrates a substantial improvement in welding performance by expediting heat dissipation during the TIG welding process using a specifically constructed CCC network on weld plates. Furthermore, CCC-based computational models reported better hardness around the weld joint and lowered residual stress levels.