Temperature Distribution In Mold Research Articles

Influence of Mold and Heat Transfer Fluid Materials on the Temperature Distribution of Large Framed Molds in Autoclave Process.

Massive composite components manufactured by autoclave curing in large framed molds are extensively used in the aerospace industry. The high temperature performance of the large framed mold is the key to achieving the desired composite part quality. This paper explores and summarizes the important thermal properties of metal and heat transfer fluid materials influencing the heating performance of large framed molds, with the aim of improving the mold temperature distribution. Considering the fluid–thermal–solid interaction inside the autoclave, a reliable computational fluid dynamics (CFD) simulation model was developed and verified by a temperature monitoring experiment to achieve the prediction of the temperature distribution of the large framed mold. Then, numerical simulations were designed on the basis of the CFD model, and the single-variable method was used to study the effects of the material thermal properties on the temperature performance of large framed molds. Our simulation predicts that when copper is used as the mold material, the temperature difference decreases by 30.63% relative to that for steel, and the heating rate increases by 3.45%. Further, when helium is used as the heat transfer medium, the temperature difference decreases by 68.27% relative to that for air, and the heating rate increases by 32.76%. This paper provides a reference for improvement of large framed mold manufacturing and autoclave process in terms of heating rate and temperature uniformity.

Hot tearing behavior of NZ30K Mg alloy under progressive solidification

Progressive solidification is usually considered an effective strategy to reduce the hot tearing susceptibility of a cast component. In this study, special constrained plate castings with progressive changes in cross-section were designed, which enabled progressive solidification. The hot tearing behavior of a newly developed NZ30K Mg alloy (Mg-3.0Nd-0.2Zn-Zr, wt.%) was studied under progressive solidification using various mold temperature distributions and constraint lengths. Of these, a homogeneous mold temperature distribution is found to be the best option to avoid hot tearing, followed by a local low mold temperature distribution (with a chiller), then a gradient mold temperature distribution. Unexpectedly, compared with the homogeneous mold temperature distribution, adding a chiller does not provide any further reduction in the hot tearing susceptibility of the NZ30K Mg alloy. A high mold temperature and a short constraint length increase the hot tearing resistance of cast Mg alloys. Progressive solidification is not a sufficient and necessary condition to avoid the formation of hot tearing. The two key factors that determine the occurrence of hot tearing under progressive solidification are the maximum cooling rate and the constraint length. Decreasing these values can reduce the incidence of hot tearing.

A physical model and data-driven hybrid prediction method towards quality assurance for composite components

Since composite components have been used in many fields with high-performance requirements, their quality is always of great concern. During production, improving temperature uniformity of the mold, which has close contact with the composites, is critical for reducing component deformation. However, the bottleneck is realizing the rapid and accurate prediction for the mold temperature distribution. Therefore, this paper designs a new hybrid modeling method for mold temperature prediction, which is driven by both physical and data models. The proposed method is applied in a case study of quality assurance for a plate component. Its advantages are also validated.

유도가열 기반 콘크리트 양생용 거푸집 온도분포 분석

유도가열 기반 콘크리트 양생용 거푸집 온도분포 분석

Characterization of Stereolithography Printed Soft Tooling for Micro Injection Molding

The use of microfeature-enabled devices, such as microfluidic platforms and anti-fouling surfaces, has grown in both potential and application in recent years. Injection molding is an attractive method of manufacturing these devices due to its excellent process throughput and commodity-priced raw materials. Still, the manufacture of micro-structured tooling remains a slow and expensive endeavor. This work investigated the feasibility of utilizing additive manufacturing, specifically a Digital Light Processing (DLP)-based inverted stereolithography process, to produce thermoset polymer-based tooling for micro injection molding. Inserts were created with an array of 100-μm wide micro-features, having different heights and thus aspect ratios. These inserts were molded with high flow polypropylene to investigate print process resolution capabilities, channel replication abilities, and insert wear and longevity. Samples were characterized using contact profilometry as well as optical and scanning electron microscopies. Overall, the inserts exhibited a maximum lifetime of 78 molding cycles and failed by cracking of the entire insert. Damage was observed for the higher aspect ratio features but not the lower aspect ratio features. The effect of the tool material on mold temperature distribution was modeled to analyze the impact of processing and mold design.

Temperature optimization of mold for autoclave process of large composite manufacturing

In autoclave processing, the temperature distribution of mold is important to the curing quality and performance of composite. The scale and complex structure of the mold have a great influence on heat transfer efficiency, which result in no uniform temperature field of the mold. Therefore, a method of heat transfer compensation is proposed, in which a “heat conducting fin” with high heat conductivity is installed in the section with slower heating process of the mold to improve the heat transfer efficiency of the mold and hot air, and to determine the structural size, quantity and reasonable installation position of “heat conducting fins” by combining CFD with heat transfer calculation. The results show that, combined with the typical panel mold, the heat transfer efficiency of the local section of the mold can be effectively improved by optimizing “heat conducting fin”, the maximum temperature difference of the mold surface is reduced by 15.1%, and the temperature gradient along the axial direction of the mold is decreased.

A Numerical Study on the Temperature Distribution of Mold according to the Heat Flux and Heat Transfer Time at the Surface of Tire Mold

A Numerical Study on the Temperature Distribution of Mold according to the Heat Flux and Heat Transfer Time at the Surface of Tire Mold

Simulation of mold temperature distribution in a running process autoclave

Composite materials have become increasingly more popular in aviation because of their good characteristics. One of the ways to fabricate composite products is through autoclave process. Due to the fact that in the molding process of the thermosets the performance and quality of composite products depend on mold temperature distributions, it would be necessary to analyze the heat transfer behavior on large size molds. A simulation was performed using finite element softwares to obtain temperature distributions on mold surfaces. The measured values were basically in good agreement with the simulated results. The simulation on the temperature stability was also studied and the simulated results of the temperature distribution, in the stabilized stage, were analyzed. The increases in temperature and simulation of the results of stabilization could provide guidance for the mold design. The novelty of the research is taking into account the influence of gravity and the real atmosphere considered as the environment of simulation. The K-epsilon turbulence model, which corresponds more exactly with the real conditions, was selected. Besides that, unstructured mesh was applied, because it accommodated well to complex geometrical shapes and generated suitable boundary layer.

Analysis of optical properties in injection-molded and compression-molded optical lenses.

Numerical mold-flow simulations and experimental measurements for injection-molded lenses have been investigated in form accuracy on a two-cavity mold with various process conditions. First, form profiles of the molded lenses have been measured together with the corresponding simulated mold-temperature distribution and displacement distribution of the lens in the z direction. A flow-through type layout of cooling channels has been devised for balance of mold-temperature distribution in mold cavities with various parametric distances for assessments in uniformity of temperature distribution. Finally, a compression-molding process is proposed for the post-process of birefringence relaxation as well as adequate form accuracy of lenses. In conclusion, optimization of process parameters to achieve good form accuracy in a multicavity mold with symmetric geometry but nonuniform cooling conditions is difficult. A good design of cooling channels plus optimized process conditions could provide uniform mold-temperature distribution so that molded lenses of good quality would be possible. Then, the profile deviation of lenses could be further compensated by profile geometry corrections. In conclusion, the post-compression-molding process could make birefringence-free plastic lenses with good form accuracy.

Determination of Thermal Contact Conductance of an Injection Mold Assembly for the Prediction of Mold Surface Temperature

Injection molds are fabricated by assembling a number of plates in which mold core and cavity components are inserted. The assembled structure causes a number of contact interfaces between each component where the heat transfer is affected by the thermal contact resistance. However, the mold assembly has been treated as a one body in numerical analyses of injection molding, which has a limitation in predicting the mold temperature distribution during the molding cycle. In this study, a numerical approach that considers the thermal contact effect is proposed to predict the heat transfer characteristics of an injection mold assembly. To find the thermal contact conductance between the mold core and plate, a number of finite element (FE) simulations were performed with the design of experiment (DOE) and statistical analysis. Thus, the heat transfer analyses using the obtained conductance values can provide more reliable results than conventional one-body simulations.

Finite Element Analysis of Flow Field and Temperature Field in Continuous Casting Mold

Researching on continuous casting mold at a domestic steel slab, the coupled models of flow field and temperature field inside of mold were established in finite element analysis software ANSYS, and the flow field and temperature field of liquid steel in mold was simulated. The effect on flow field and temperature field in continuous casting mold caused by change of the withdrawal speed was mainly discussed in this paper. The simulation results show that the change of withdrawal speed has little effect on flow field and much effect on temperature distribution in mold. The simulation results are good agreed with the practical produce data, verifying the accuracy of the numerical simulation analysis, which provide theoretical basis and effective guidance for improving process and increasing yield in practical production.

열접촉 저항을 고려한 사출금형의 온도분포특성 고찰

In the design of the injection molding process, various parameters including mold design parameters and molding conditions should be investigated to improve part quality. The mold temperature is one of important processing parameters that affect the flow characteristics, surface appearance, part deformation, mechanical properties, etc. Numerical analyses have been used to predict the temperature distribution of the mold under the given cooling or heating conditions. However, conventional analyses have been performed by assuming that the mold material is a single solid even though a number of plates are assembled to construct an injection mold. In the present study, a numerical approach considering the thermal contact resistance is proposed to provide more reliable prediction of the mold temperature distribution by reflecting the heat-resistance between assembled mold plates.

Numerical Simulations and Verifications of Cyclic and Transient Temperature Variations in Injection Molding Process

Cooling analysis of fully 3D simulation including multi-cycle time span and heat resource was completed. To test the numerical accuracy, different numerical models and algorithms were applied to simulate the mold temperature profile. Simulation accuracy of different numerical methods was compared and verified by experimental measurements. Mold temperature distribution was measured by an infrared radiation thermal imaging (IRTI) system from which the temperature variations at special interested locations can be obtained. As for heated mold with electric heater resource, fully 3D simulations of mold temperature variation based on both standard finite element method (FEM) in single CPU and finite volume method (FVM) implemented in parallel computation scheme were executed. All simulations show reasonable predictions in accordance with experimental results. However, predicted results of the fully 3D model for FEM and FVM exhibit are more accurate than that of the 2.5D model for BEM. The fully 3D simulated results show the minimum difference of 0.2°C, and the 2.5D model results show a minimum value of 2.4°C. Moreover, the fully 3D model not only can simulate the cyclic, transient mold temperature field but also can obtain polymer temperature simultaneously.

Reduction in Injection Cycle Time Using a Milling-Combined Laser Metal Sintered Mold

By composing a cooling channel just near the mold surface using the milling-combined laser metal sintering method, cooling during injection is promoted and the cooling time is reduced. In order to evaluate this effect, a cone with ribs inside the upper part is picked up. A spiral-cooling channel is fabricated along the side surface of the mold core and also between the ribs in the upper part. To compare with this, a steel mold with machined baffle channels was made. The diameter of the upper part of the molded cone was chosen as an evaluation dimension. The temperature on the upper surface of the core is kept low at around the cooling water temperature in the case of sintered mold during the cycle of the injection. On the other hand, the temperature on the upper surface of the steel mold increases far higher than the cooling water temperature. Cycle time for the same shrink ratio in the upper part of the molded cone was 25 s in the sintered mold and 40 s in the steel mold. Owing to the cooling time reduction, cycle time of the injection molding was reduced 35% by using the sintered mold with cooling channels. Simulation is available to evaluate the mold temperature distribution and is useful for improving the arrangement of cooling channels in the process of mold design.

3D numerical simulation of transient temperature field for lens mold embedded with heaters

In injection mold, cooling process has important effects on parts quality and production cost. Traditional cooling simulation is conducted in a decoupled way by a cycle-averaged approach plus one-dimensional transient variation for computational efficiency concern. In the present study, fully 3D simulations of mold temperature variation based on FEM and FVM implemented in parallel computation scheme were executed for lens mold embedded with heaters. With the fully 3D simulation, mold temperature and melt temperature are solved in coupled manner and obtained simultaneously. Also the time when mold temperature distribution reaches the cyclic-average steady state can be determined. The simulation results were verified with measured cavity temperatures using infrared thermal image system at interest locations. The numerical results for cyclic, transient with heat source problem show reasonable consistency with measured values. The computing time with multi-CPU and parallel scheme is much less than that of single CPU.

Simulations of cyclic, transient variations of mold temperatures in the SMC compression molding process

AbstractThe dual reciprocity boundary element technique is used to simulate the cyclic SMC compression molding process, taking into account the heat transfer within the whole mold. The cyclic, transient variations in mold temperatures at different mold locations are illustrated through the analysis of a plate mold. The transient temperature fluctuation near the mold cavity surface is much larger than that away from it. It was also found that owing to the high heating fluid temperature (compared with the ambient air temperature), the heat transfer at the mold exterior surface shows a significant effect on the mold temperature distribution, especially when the mold is a small or medium size. The present method provides a complete and more accurate description of the mold temperature variation during the whole cycle history by including the mold as the analysis domain, meanwhile minimizing the computation time. Other analysis methods, including the constant mold wall temperature approach, the hybrid shape‐factor/finite element method, as well as the cycle‐averaged boundary element technique imposed with 1‐D transient analysis, basically overestimate mold wall temperatures and the associated charge conversion rate.