Dynamic Mold Temperature Control Using Gas-Assisted Heating and Its Effect on the Molding Replication Qualities of Micro Channels

2008 ◽  
Author(s):  
Shia-Chung Chen ◽  
Yaw-Jen Chang ◽  
Jen-An Chang ◽  
Hsin-Shu Peng ◽  
Ying-Chieh Wang
Keyword(s):  
Injection Molding ◽  
Surface Temperature ◽  
Temperature Control ◽  
Heating System ◽  
Mold Temperature ◽  
Mold Surface ◽  
Water Heating ◽  
Molded Part ◽  
Micro Channels ◽  
Gas Heating

Dynamic mold surface temperature control (DMTC) has the advantage of improving molded part qualities without significant increases in cycle time. A gas-assisted heating system combined with water cooling was developed to achieve DMTC for injection molding. With gas-assisted heating, it takes 2s for the mold surface temperature to vary from 60 °C to 120 °C whereas it requires 186s using water heating. Further, it takes 21s and 84s for the mold surface to cool to 60 °C under gas heating and water heating, respectively. The gas-assisted heating system also shows excellent efficiency for micro injection molding of biochips to achieve high replication accuracy of the micro channels.

scholarly journals Study on External Gas-Assisted Mold Temperature Control for Improving the Melt Flow Length of Thin Rib Products in the Injection Molding Process

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Phan The Nhan ◽  
Thanh Trung Do ◽  
Tran Anh Son ◽  
Pham Son Minh
Keyword(s):  
Injection Molding ◽  
Temperature Control ◽  
High Efficiency ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Thin Wall ◽  
Mold Surface ◽  
Melt Flow ◽  
Molding Process ◽  
Flow Length

In the injection molding process, mold temperature control is one of the most efficient methods for improving product quality. In this research, an external gas-assisted mold temperature control (Ex-GMTC) with gas temperature variation from 200°C to 400°C was applied to thin wall injection molding at melt thicknesses from 0.2 to 0.6 mm. The melt flow length was evaluated through the application of this system to the mold of a thin rib product. The results show that the heating process achieves high efficiency in the initial 20 s, with a maximum heating rate of 6.4°C/s. In this case, the mold surface reached 158.4°C. By applying Ex-GMTC to a 0.2 mm flow thickness, the flow length increased from 37.85 to 41.32 mm with polypropylene (PP) material and from 14.54 to 15.8 mm with acrylonitrile butadiene styrene (ABS) material. With the thin rib mold and use of Ex-GMTC, the mold temperature varied from 112.0°C to 140.8°C and the thin rib height reached 7.0 mm.

scholarly journals The feasibility of external gas-assisted mold-temperature control for thin-wall injection molding

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401880610 ◽  
Author(s):  
Pham Son Minh ◽  
Thanh Trung Do ◽  
Tran Minh The Uyen
Keyword(s):  
Temperature Distribution ◽  
Injection Molding ◽  
Heating Rate ◽  
Temperature Control ◽  
Mold Temperature ◽  
Cavity Surface ◽  
Thin Wall ◽  
Mold Surface ◽  
Hot Gas ◽  
Wall Injection

Simulation and experimental testing were conducted on an external gas-assisted mold-temperature control combined with a pulsed cooling system used for thin-wall injection molding to determine its effect on the heating rate and temperature distribution of a mold surface. For mold heating via external gas-assisted mold-temperature control, a hot gas was directly discharged on the cavity surface. Based on the heat convection between the hot gas and the cavity surface, the cavity temperature rose to the target value. Practically, the gap between the heating surface and the gas gate is an important parameter as it strongly influences the heating process. Therefore, this parameter was analyzed under different values of plate-insert thickness herein. Heating was elucidated by the temperature distribution and heating-rate data detected by the infrared camera and sensors. Then, external gas-assisted mold-temperature control was applied for the thin-wall injection-molding part of 0.5 mm thickness with the local-gate-temperature control. The results show that with 300°C gas temperature, the heating rate could reach 9°C/s with a 0.5-mm stamp thickness and a 4-mm gas gap. The results show that with local heating at the melt-entrance area of the mold plate, the cavity was filled with a 20-s heating cycle.

scholarly journals Study on External Gas-Assisted Mold Temperature Control with the Assistance of a Flow Focusing Device in the Injection Molding Process

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 965 ◽  
Author(s):  
Nguyen Truong Giang ◽  
Pham Son Minh ◽  
Tran Anh Son ◽  
Tran Minh The Uyen ◽  
Thanh-Hai Nguyen ◽  
...  
Keyword(s):  
Injection Molding ◽  
Temperature Control ◽  
Mold Temperature ◽  
Injection Molding Process ◽  
Melt Flow ◽  
Flow Focusing ◽  
Molding Process ◽  
Heating Efficiency ◽  
Flow Length ◽  
Insert Plate

In the injection molding field, the flow of plastic material is one of the most important issues, especially regarding the ability of melted plastic to fill the thin walls of products. To improve the melt flow length, a high mold temperature was applied with pre-heating of the cavity surface. In this paper, we present our research on the injection molding process with pre-heating by external gas-assisted mold temperature control. After this, we observed an improvement in the melt flow length into thin-walled products due to the high mold temperature during the filling step. In addition, to develop the heating efficiency, a flow focusing device (FFD) was applied and verified. The simulations and experiments were carried out within an air temperature of 400 °C and heating time of 20 s to investigate a flow focusing device to assist with external gas-assisted mold temperature control (Ex-GMTC), with the application of various FFD types for the temperature distribution of the insert plate. The heating process was applied for a simple insert model with dimensions of 50 mm × 50 mm × 2 mm, in order to verify the influence of the FFD geometry on the heating result. After that, Ex-GMTC with the assistance of FFD was carried out for a mold-reading process, and the FFD influence was estimated by the mold heating result and the improvement of the melt flow length using acrylonitrile butadiene styrene (ABS). The results show that the air sprue gap (h) significantly affects the temperature of the insert and an air sprue gap of 3 mm gives the best heating rate, with the highest temperature being 321.2 °C. Likewise, the actual results show that the height of the flow focusing device (V) also influences the temperature of the insert plate and that a 5 mm high FFD gives the best results with a maximum temperature of 332.3 °C. Moreover, the heating efficiency when using FFD is always higher than without FFD. After examining the effect of FFD, its application was considered, in order to improve the melt flow length in injection molding, which increased from 38.6 to 170 mm, while the balance of the melt filling was also clearly improved.

scholarly journals Prediction of the maximum flow length of a thin injection molded part

2020 ◽  
Vol 40 (9) ◽  
pp. 783-795
Author(s):  
Sara Liparoti ◽  
Vito Speranza ◽  
Annarita De Meo ◽  
Felice De Santis ◽  
Roberto Pantani
Keyword(s):  
Injection Molding ◽  
Maximum Flow ◽  
Mold Temperature ◽  
Complete Characterization ◽  
Rheological Parameters ◽  
Injection Molding Process ◽  
Spiral Flow ◽  
Molding Process ◽  
Molded Part ◽  
Flow Length

AbstractOne of the most significant issues, when thin parts have to be obtained by injection molding (i.e. in micro-injection molding), is the determination of the conditions of pressure, mold temperature, and injection temperature to adopt to completely fill the cavity. Obviously, modern computational methods allow the simulation of the injection molding process for any material and any cavity geometry. However, this simulation requires a complete characterization of the material for what concerns the rheological and thermal parameters, and also a suitable criterion for solidification. These parameters are not always easily reachable. A simple test aimed at obtaining the required parameters is then highly advantageous. The so-called spiral flow test, consisting of measuring the length reached by a polymer in a long cavity under different molding conditions, is a method of this kind. In this work, with reference to an isotactic polypropylene, some spiral flow tests obtained with different mold temperatures and injection pressures are analyzed with a twofold goal: on one side, to obtain from a few simple tests the basic rheological parameters of the material; on the other side, to suggest a method for a quick prediction of the final flow length.

Fast mold surface temperature evolution: relevance of asymmetric surface heating for morphology of iPP molded samples

RSC Advances ◽  
2015 ◽  
Vol 5 (46) ◽  
pp. 36434-36448 ◽  
Author(s):  
S. Liparoti ◽  
A. Sorrentino ◽  
G. Guzman ◽  
M. Cakmak ◽  
G. Titomanlio
Keyword(s):  
Surface Temperature ◽  
Molecular Orientation ◽  
Mold Temperature ◽  
Surface Heating ◽  
Temperature Evolution ◽  
Mold Surface

It is widely accepted that mold temperature has a strong effect on the amount of molecular orientation and morphology developed in a non-isothermal flowing melt.

scholarly journals Optimization and application of temperature field in rapid heat cycling molding

2021 ◽  
pp. 291-291
Author(s):  
Mingliang Hao ◽  
Haimei Li
Keyword(s):  
Injection Molding ◽  
Electric Heating ◽  
Heating System ◽  
Mold Temperature ◽  
Temperature Control System ◽  
Cavity Surface ◽  
Injection Mold ◽  
Molding Process ◽  
Molded Parts ◽  
Automotive Part

The rapid thermal cycle molding (RHCM) belongs to the injection mold temperature control system which is helpful to improve mold ability and enhance part quality. Despite many available literatures, RHCM does not represent a well-developed area of practice. The challenge is the uneven distribution of temperature in the cavity after heating, which mostly leads to defects on the surface of the products. In order to obtain uniform cavity surface temperature distribution of RHCM, the power of heating rods of the electric-heating system in an injection mold was optimized by the response surface method(RSM) in this work. The proposed optimization result was applied to design a complex RHCM injection mold with side core-pulling, holes and different thickness of an automotive part to verify its effectiveness by injection molding. Compared with initial design, the mold temperature uniformity was remarkably improvedby79%. Based on the optimization and injection molding numerical simulation results, the workable molding process to weaken the weld-lines effects on the quality was suggested and the practical injection molded parts were well produced.

Experimental Investigation of Plastic Injection Molding Heating System Using Hydrogen Absorbing Alloys

2020 ◽  
Author(s):  
Yoshio Fukushima ◽  
Masataka Kosaka
Keyword(s):  
Injection Molding ◽  
Temperature Difference ◽  
Alternative Energy ◽  
Heating System ◽  
Plastic Injection Molding ◽  
Maximum Temperature ◽  
Hydrogen Energy ◽  
Mold Surface ◽  
Maximum Temperature Difference ◽  
Plastic Injection

Abstract Much focus from various fields is being placed on the hydrogen and utilizing the technique. Nowadays, the applied researches of hydrogen energy have been trying as one of an alternative energy source for fossil fuel. And, since we could not think lightly of consumed energy by machine tools and industrial machinery, Eco-friendly manufacturing is going to be achieved by hydrogen energy. In this study, to prevent the weldline that is a representative defect in the field of plastic injection molding, heat & cool technology using hydrogen energy, LmNi4.90Mn0.10 hydride, is applied to the mold. This method can achieve heat & cool technology by using only hydrogen energy. So, since electricity and warm/cool water that are for heating/cooling the mold are not necessary, this method should thus be at an engineering advantage in terms of eco-friendly manufacturing. After manufacturing the hydrogen-used-prototype-mold that is dedicated to preventing the weldline, the comparison between the experimental data and numerical simulation was carried out. As result, using this approach, the mold surface temperature difference from initial temperature was rapidly increasing to 40 K, in 18 seconds from the beginning of hydrogen-absorbing and the maximum temperature difference ΔT in this experiment has become 48 K.

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