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.

3D printing is a promising digital manufacturing technique that manufactures product parts in a layer fashion. Fused deposition modeling (FDM) is a widely used 3D printing technique that produces components by heating, extruding, and depositing the filaments of thermoplastic polymers. Meanwhile, the properties of FDM-produced parts are significantly influenced by process parameters. These process parameters have different advantages that need to be investigated. This paper examines the effect of some process parameters on the tensile properties of some components produced using FDM technique. The study is performed on polylactic acid (PLA) material, using full factorial experimental design. Furthermore, three process parameter—material, infill density, and infill pattern—are considered. The results indicate that only the infill pattern significantly influences the tensile properties of the model.

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.

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.

This paper presents modeling and simulation of spring-mass damper system for quarter car in the Simulink environment. The simulations in this research have been carried out by using the Simulink of Matlab. The parameters in the simulation model for the suspension system under study include car body mass, wheel mass, spring and damping elements of shock absorber, and tire. A road disturbance profile comprising a combination of two sinusoidal curves is modeled. Controllers that are used in this study are the proposed fuzzy logic controller. The purpose of this research is to improve vehicle comfort using the Fuzzy Logic Controller (FLC). The simulation results of the system perform well fulfill the minimum percentage requirements and fast stability time, provide good leveling of stability and ride comfort.

Three-dimensional (3D) printing is a breakthrough technology that is being researched, developed and applied extensively in many areas of production around the world. One particular application is Selective Laser Sintering (SLS), in which a high-powered laser turns powdered material into a solid mass; however, in Vietnam the research and application of laser sintering is not very widespread, yet determining the durability, especially the tensile strength, of products made from this printing technology is necessary. The parameters during installation have a significant effect on the characteristics of the printing elements, so they need to they need to be studied. In this project, we focused on the influence of printing parameters to be able to optimize them to achieve the highest tensile strength in the products. The process consisted of producing specimens with 2 parameters to be tested: laser power and feed. The experimental results on the tensile strength were collected, and the influence of the printing parameters of the finished product were charted and analyzed. The result of the project is that laser power is the most important printing parameters that influences tensile strength.

The demand for vegetable consumption is essential issue to serve citizens. Excessive protective chemical elimination which is applied advanced solutions brings high effects being investigated by domestic and international scientists. In this report, research team conducted and designed the vegetable washing machine integrated with the ultrasonic power and Ozone microbubbles to wash out plentiful protective chemicals attaching to surfaces of leafy vegetables. Followingly, using Taguchi method for four kinds of vegetables including salad, water spinach, Chinese cabbage, and mustard greens verifies the effectiveness of solutions. Vegetable samples are treated soaking pool making ultrasonic wave and Ozone microbubbles raging from 1.0ppm to 2.0ppm. The practical results demonstrated that the method using the ultrasonic power and Ozone microbubbles has high effects on eradicating protective chemical on leafy vegetables.

The determination of side-core for plastic moldings plays an important part in design process. Numerous studies have been investigated for side-cores recognition in literature. However, most of the existing methods have been developed based on the side-core surfaces of one region are known. In fact, it is difficult to identify relevant surfaces of one region. This study proposes a new algorithm of relevant surface attribution (RSA) based on topological relationship and V-map to automatically identify relevant surfaces of a side-core region. Then, the proposed approach defines the shape of side-core region as bounding surfaces and side-core direction. Finally, case studies are used demonstrating the applicability and usage of proposed approach.