External Gas-Assisted Mold Temperature Control Improves Weld Line Quality in the Injection Molding Process

Simulations and experiments were conducted with gas temperatures of 200–400 °C to investigate the impact of external gas-assisted mold temperature control (Ex-GMTC) on the quality of weld line of molding products. In the heating step, the heating rate was 19.6 °C/s from 30 to 128.5 °C in the first 5 s in a 400 °C gas environment. When applied to heating the weld line area of an injection mold, Ex-GMTC improved the appearance of the weld line when the cavity temperature was preheated to 150 °C. For the tensile strength test, a melt flow simulation comparing the packing pressure of different mesh thicknesses revealed that Ex-GMTC helped maintain a high pressure in the weld line area in different packing periods. This was verified by an experiment where Ex-GMTC was applied with 400 °C gas to change the mesh area temperature. The result indicated that an increase in the weld line area temperature from 60 to 180 °C improves the tensile strength of all mesh thicknesses, which was more pronounced with thinner parts, especially at 0.4 mm. The simulations revealed that high temperature is concentrated in the weld line area of the cavity surface, thus reducing the energy wasted during heating.

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

Materials ◽

10.3390/ma14040965 ◽

2021 ◽

Vol 14 (4) ◽

pp. 965 ◽

Cited By ~ 1

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.

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The simulation of the warpage rule of the thin-walled part of polypropylene composite based on the coupling effect of mold deformation and injection molding process

Science and Engineering of Composite Materials ◽

10.1515/secm-2015-0195 ◽

2018 ◽

Vol 25 (3) ◽

pp. 593-601 ◽

Cited By ~ 1

Author(s):

Jixiang Zhang ◽

Xiaoyi Yin ◽

Fengzhi Liu ◽

Pan Yang

Keyword(s):

Injection Molding ◽

Coupling Effect ◽

Mold Temperature ◽

Injection Molding Process ◽

Plastic Part ◽

Molding Process ◽

Melt Temperature ◽

Packing Pressure ◽

Thin Walled ◽

Packing Time

Abstract Aiming at the problem that a thin-walled plastic part easily produces warpage, an orthogonal experimental method was used for multiparameter coupling analysis, with mold structure parameters and injection molding process parameters considered synthetically. The plastic part deformation under different experiment schemes was comparatively studied, and the key factors affecting the plastic part warpage were analyzed. Then the injection molding process was optimized. The results showed that the important order of the influence factors for the plastic part warpage was packing pressure, packing time, cooling plan, mold temperature, and melt temperature. Among them, packing pressure was the most significant factor. The optimal injection molding process schemes reducing the plastic part warpage were melt temperature (260°C), mold temperature (60°C), packing pressure (150 MPa), packing time (2 s), and cooling plan 3. In this situation, the forming plate flatness was better.

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The Feasibility of an Internal Gas-Assisted Heating Method for Improving the Melt Filling Ability of Polyamide 6 Thermoplastic Composites in a Thin Wall Injection Molding Process

Polymers ◽

10.3390/polym13071004 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1004 ◽

Cited By ~ 1

Author(s):

Thanh Trung Do ◽

Tran Minh The Uyen ◽

Pham Son Minh

Keyword(s):

Injection Molding ◽

Heating Rate ◽

Temperature Control ◽

Cavity Surface ◽

Heating Process ◽

Injection Molding Process ◽

Thin Wall ◽

Molding Process ◽

Filling Ability ◽

Wall Injection

In thin wall injection molding, the filling of plastic material into the cavity will be restricted by the frozen layer due to the quick cooling of the hot melt when it contacts with the lower temperature surface of the cavity. This problem is heightened in composite material, which has a higher viscosity than pure plastic. In this paper, to reduce the frozen layer as well as improve the filling ability of polyamide 6 reinforced with 30 wt.% glass fiber (PA6/GF30%) in the thin wall injection molding process, a preheating step with the internal gas heating method was applied to heat the cavity surface to a high temperature, and then, the filling step was commenced. In this study, the filling ability of PA6/GF30% was studied with a melt flow thickness varying from 0.1 to 0.5 mm. To improve the filling ability, the mold temperature control technique was applied. In this study, an internal gas-assisted mold temperature control (In-GMTC) using different levels of mold insert thickness and gas temperatures to achieve rapid mold surface temperature control was established. The heating process was observed using an infrared camera and estimated by the temperature distribution and the heating rate. Then, the In-GMTC was employed to produce a thin product by an injection molding process with the In-GMTC system. The simulation results show that with agas temperature of 300 °C, the cavity surface could be heated under a heating rate that varied from 23.5 to 24.5 °C/s in the first 2 s. Then, the heating rate decreased. After the heating process was completed, the cavity temperature was varied from 83.8 to about 164.5 °C. In-GMTC was also used for the injection molding process with a part thickness that varied from 0.1 to 0.5 mm. The results show that with In-GMTC, the filling ability of composite material clearly increased from 2.8 to 18.6 mm with a flow thickness of 0.1 mm.

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Verification of External Gas-Assisted Mold Temperature Control for Injection Molding Process

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.752-753.949 ◽

2015 ◽

Vol 752-753 ◽

pp. 949-954

Author(s):

Pham Son Minh ◽

Thanh Trung Do

Keyword(s):

Heating Rate ◽

Plastic Material ◽

Mold Temperature ◽

Cavity Surface ◽

Injection Molding Process ◽

Molding Process ◽

Hot Gas ◽

Result Show ◽

Heating Uniformity ◽

The Common

In this study, a hot gas is used for heating the cavity surface of a mold. Different stamp thickness were designed and insert into the cavity plate. The stamp surface temperature was heated to above the glass transition temperature of the common plastic material. The heating result show that cavity surface can be heated to 196 °C after 20 s. The highest temperature appears at the center stamp surface. The stamp thickness strongly affects the heating speed and heating uniformity. When the stamp thickness is 0.5 mm the fastest heating rate can be reached with the value of 8.3oC/s. With the thicker stamp, the slower heating rate could be reached.

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Influence of Injection Molding Process Parameters on Sink Marks of Injection Parts Based on Moldflow

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.347-350.1163 ◽

2013 ◽

Vol 347-350 ◽

pp. 1163-1167

Author(s):

Ling Bai ◽

Hai Ying Zhang ◽

Wen Liu

Keyword(s):

Injection Molding ◽

Process Parameters ◽

Mold Temperature ◽

Processing Parameters ◽

Injection Molding Process ◽

Molding Process ◽

Melt Temperature ◽

Packing Pressure ◽

Sink Marks ◽

Research Show

Moldflow software was used to obtain the best gate location and count. Influence of injection molding processing parameters on sink marks of injection-piece was studied based on orthogonal test. The effects of different process parameters were analyzed and better process parameters were obtained. Results of research show that decreasing melt temperature, mold temperature, the increasing injection time and packing pressure can effectively reduce the sink marks index.

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Effects of dynamic mold temperature control on melt pressure, cellular structure, and mechanical properties of microcellular injection-molded parts: An experimental study

Cellular Polymers ◽

10.1177/0262489319871741 ◽

2019 ◽

Vol 38 (5-6) ◽

pp. 111-130

Author(s):

Guiwei Dong ◽

Guoqun Zhao ◽

Junji Hou ◽

Guilong Wang ◽

Yue Mu

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Flexural Strength ◽

Temperature Control ◽

Cellular Structure ◽

Weld Line ◽

Mold Temperature ◽

Cell Diameter ◽

Cooling Stage ◽

Molded Parts

In this work, the effects of dynamic mold temperature control (DMTC) on melt pressure, cellular structure, and mechanical properties of microcellular injection molding (MIM)-molded parts are investigated experimentally. It is found that with the increase of the mold temperature, the duration of foaming pressure in the cooling stage increases. Meanwhile, the average cell diameter and cell diameter dispersion increases as well as the cell density decreases in MIM molded parts. The turning point of mold temperature after which the foaming pressure in the cooling stage and the cellular structure in MIM molded parts generate a significant change is around the glass transition temperature of the used plastic material. Under DMTC conditions, with the increase of mold temperature, the tensile strength, flexural strength, and impact strength of MIM molded specimens of single gate without weld line change a little, while the tensile strength, flexural strength of MIM molded specimens of double gates with weld line increase obviously. When the mold temperature increases to 120°C and over, the tensile strength, flexural strength of MIM molded specimens of double gates with weld line reach an equivalent level of specimens of single gate without weld line.

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The Application of Moldflow in Injection Molding of the Helmet

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1096.366 ◽

2015 ◽

Vol 1096 ◽

pp. 366-370

Author(s):

Yong Cheng Huang ◽

Hong Bin Liu ◽

Hai Tao Wu

Keyword(s):

Injection Molding ◽

Process Parameters ◽

Hold Time ◽

Mold Temperature ◽

Appropriate Technology ◽

Injection Molding Process ◽

Injection Time ◽

Molding Process ◽

Melt Temperature ◽

Packing Pressure

Considering the importance of the reasonable injection molding technology.Based on the application of moldflow in injection molding of the helmet .By adjusting the mold temperature, melt temperature, injection time, packing pressure, hold time and so on the injection molding process parameters to develop appropriate technology methods to get the best injection molding parameters.

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

Advances in Polymer Technology ◽

10.1155/2019/5973403 ◽

2019 ◽

Vol 2019 ◽

pp. 1-17 ◽

Cited By ~ 5

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.

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Fill Time Optimization Analysis In Flow Simulation Of Injection Molding Using Response Surface Method

Malaysian Journal on Composites Science and Manufacturing ◽

10.37934/mjcsm.4.1.2839 ◽

2021 ◽

Vol 4 (1) ◽

pp. 28-39

Author(s):

Mohd Amran Md Ali ◽

Wan Nur Azrina ◽

Noorfa Idayu ◽

Zulkeflee Abdullah ◽

Mohd Sanusi Abdul Aziz ◽

...

Keyword(s):

Injection Molding ◽

Response Surface ◽

Response Surface Method ◽

Weld Line ◽

Mold Temperature ◽

Injection Molding Process ◽

Injection Time ◽

Molding Process ◽

Optimum Parameters ◽

Surface Method

This study focuses on the analysis of fill time by optimizing the injection molding parameters to reduce the defects that are always found on the plastics part such as poor weld line and part not completely filling which can contribute to mechanical properties of the plastic part. The parameters selected for this study are melting temperature, mold temperature, injection time, and the number of gate positions. Response Surface Method (RSM) was used to determine the most significant and optimum parameters on the fill time. From the result analysis, it is found that the injection time is the most significant parameter that affected the fill time with a 99% contribution. The result shows that there is no interaction between process parameters toward fill time which the injection time is the only major factor that affects the fill time. The improvement increases by 0.07% after the optimization process from 4.278s to 4.281s. The most optimum parameters to longer the injection time are mold temperature at 60°C, injection time at 4s, and the number of the gate with two gates position. Thus, the longer the injection time, it can reduce the defect of molded part in the injection molding process.

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The Study of Optimal Molding of a LED Lens with Grey Relational Analysis and Molding Simulation

Periodica Polytechnica Mechanical Engineering ◽

10.3311/ppme.13337 ◽

2019 ◽

Vol 63 (4) ◽

pp. 278-294 ◽

Cited By ~ 1

Author(s):

Min-Wen Wang ◽

Fatahul Arifin ◽

Van-Hanh Vu

Keyword(s):

Injection Molding ◽

Mold Temperature ◽

Injection Molding Process ◽

Molding Process ◽

Melt Temperature ◽

Injection Speed ◽

Relational Analysis ◽

Total Displacement ◽

Packing Pressure ◽

Grey Relational

Injection molding technology is known as the most widely used method in mass production of plastic products. To meet the quality requirements, a lot of methods were applied in optimization of injection molding process parameter. In this study the optimization based on Taguchi orthogonal array and Grey relational analysis (GRA) is used to optimize the injection molding process parameters on a LED lens. The four process parameters are: packing pressure, injection speed, melt temperature and mold temperature. The multi-response quality characteristics are total displacement, volumetric shrinkage, and thermal residual stress. The optimal molding parameters are packing pressure (90 MPa), injection speed (300 mm/sec), melt temperature (270 °C) and mold temperature (90 °C). The luminous uniformity of the LED is 92.61 % and the viewing angle of the LED is 124.76°. Among the four factors, packing pressure plays the key role in reducing total displacement, volumetric shrinkage, and thermal residual stress.

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