A Hybrid Cooling Model Based on the Use of Newly Designed Fluted Conformal Cooling Channels and Fastcool Inserts for Green Molds

The paper presents a hybrid cooling model based on the use of newly designed fluted conformal cooling channels in combination with inserts manufactured with Fastcool material. The hybrid cooling design was applied to an industrial part with complex geometry, high rates of thickness, and deep internal concavities. The geometry of the industrial part, besides the ejection system requirements of the mold, makes it impossible to cool it adequately using traditional or conformal standard methods. The addition of helical flutes in the circular conformal cooling channel surfaces generates a high number of vortexes and turbulences in the coolant flow, fostering the thermal exchange between the flow and the plastic part. The use of a Fastcool insert allows an optimal transfer of the heat flow in the slender core of the plastic part. An additional conformal cooling channel layout was required, not for the cooling of the plastic part, but for cooling the Fastcool insert, improving the thermal exchange between the Fastcool insert and the coolant flow. In this way, it is possible to maintain a constant heat exchange throughout the manufacturing cycle of the plastic part. A transient numerical analysis validated the improvements of the hybrid design presented, obtaining reductions in cycle time for the analyzed part by 27.442% in comparison with traditional cooling systems. The design of the 1 mm helical fluted conformal cooling channels and the use of the Fastcool insert cooled by a conformal cooling channel improves by 4334.9% the thermal exchange between the cooling elements and the plastic part. Additionally, it improves by 51.666% the uniformity and the gradient of the temperature map in comparison with the traditional cooling solution. The results obtained in this paper are in line with the sustainability criteria of green molds, centered on reducing the cycle time and improving the quality of the complex molded parts.

Evaluation of Cooling Performance of an Additive Manufactured Gravity Die Casting Mold with Conformal Cooling Channel

A cooling channel with an optimized design provides not only high throughput with gravity die casting, but also guarantees product quality. A conformal cooling channel (CC) whose structure follows the shapes or surfaces of the mold cavity has attracted great attention in the die casting industry, because it allows rapid and uniform cooling. However, implementing conformal cooling remains highly challenging, because the complicated geometries of CC are difficult to form using conventional fabrication methods such as drilling and milling. In recent years, advances in additive manufacturing (AM) technology have made it possible to fabricate products with complex and elaborate structures. In this paper, a gravity die casting mold with CC was designed and built using AM technology. The cooling channel performance was estimated and evaluated using an Al-Si-Cu alloy casting simulation and die casting experiments, respectively. The casting simulation results showed that the cooling performance of the CC was enhanced by ca. 10% compared with that of a conventional cooling channel. The experimental cooling performance of the CC improved by ca. 8% compared to that of a conventional cooling channel, and the increment in performance was consistent with the simulation results. In addition, microstructural evidence clarified that the effective cooling performance of CC could be attributed to the decrement (ca. 17%) of the secondary dendrite arm spacing (SDAS) of the Al-Si-Cu alloy. In this research, AM technology provides a novel way to fabricate functionally superior CC molds that are hardly producible with traditional methods.

Improving Cooling Performance of Injection Molding Tool with Conformal Cooling Channel by Adding Hybrid Fillers

Silicone rubber mold (SRM) is capable of reducing the cost and time in a new product development phase and has many applications for the pilot runs. Unfortunately, the SRM after injection molding has a poor cooling efficiency due to its low thermal conductivity. To improve the cooling efficiency, the thermal conductivity of the SRM was improved by adding fillers into the SRM. An optimal recipe for fabricating a high cooling efficiency low-pressure injection mold with conformal cooling channel fabricated by fused deposition modeling technology was proposed and implemented. This study proposes a recipe combining 52.6 wt.% aluminum powder, 5.3 wt.% graphite powder, and 42.1 wt.% liquid silicon rubber can be used to make SRM with excellent cooling efficiency. The price–performance ratio of this SRM made by the proposed recipe is around 55. The thermal conductivity of the SRM made by the proposed recipe can be increased by up to 77.6% compared with convention SRM. In addition, the actual cooling time of the injection molded product can be shortened up to 69.1% compared with the conventional SRM. The actual cooling time obtained by the experiment is in good agreement with the simulation results with the relative error rate about 20%.

Enhancing the Structural Strength for Injection Molding Tooling With Conformal Cooling Channels Using ANSYS Software

Injection molding of wax patterns faces increasing demands for production rate. Proper thermal management of the injection molding tooling is capable of improving the production rate. Precise temperature control is a key to shorten the cooling time using the conformal cooling channels which are conformal to the molding cavity. However, the service life of the injection molding tooling with cooling channels will reduce significantly because the structural strength will reduce obviously. In this study, the feasibility of applying the increase in the mold thickness to maintain the structural strength of the injection molding tooling with cooling channels was verified through simulation and experiments conducted. It was found that the average variation between the results of simulation and the experiment is about 24.9%. The approximately amount of the increase in the thickness required for different diameters of cooling channels can be determined according to the trend equation of y=1.3429x-2.3429. The results can provide a reference for the conformal cooling channel design.

Fabrication of circular cooling channels by cold metal transfer based wire and arc additive manufacturing

Additive manufacturing has been proven to be a promising technology for fabricating high-performance dies, molds, and conformal cooling channels. As one of the manufacturing methods, wire and arc additive manufacturing displays unique advantages of low cost and high deposition rate that are better than other high energy beam-based ones. This paper presents a preliminary study of fabricating integrated cooling channels by CMT-based wire and arc additive manufacturing process. The deposition strategies for fabricating circular cross-sectional cooling channels both in conformal and straight-line patterns have been investigated. It included optimizing the welding torch angle, fabricating the enclosed semicircle structure and predicting the collision between the torch and constructed part. The cooling effect test was also conducted on both the conformal cooling channel and straight-line cooling channel. The results affirmed a higher cooling efficiency and better uniform cooling effect of the conformal cooling channel than straight-line cooling channel.

COOLING UNIFORMITY ANALYSIS of INJECTION MOLDING PLASTIC PRODUCTS WITH COOLING SYSTEM VARIATIONS USING CFD METHOD

The cooling system design selection plays an important role in a product cooling process in injection molding. This study presents an analysis of the uniform cooling of plastic products with a variety of cooling systems using the CFD method. Good cooling design, able to uniform the temperature drop in plastic products. There are two types of cooling system variations used, namely the conformal cooling channel system and the straight cooling channel system using the volume of fluid model with the k-epsilon turbulent model. The mold material used is steel and the plastic material used is polypropylene. The simulation results using the CFD method show that the variations in the conformal cooling channel system resulting from a decrease in temperature for each product are more uniform, as evidenced by the color of the contour experiencing light green degradation on all sides of the product, the maximum temperature value is 422, 44 ° K and the minimum temperature value is 338. , 00 ° K, while the straight cooling channel system has a non-uniform temperature reduction, as evidenced by the value with the contour color that is still orange, the maximum temperature value is 473.11 ° K.