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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.

Three-dimensional (3D) printing is a method of additive manufacturing that involves creating objects by serial deposition for pre-production or production. After designing a 3D model with a CAD program, a processable file is customized to create a layered design, which is then printed. Although this technique costs more than traditional techniques, such as metal injection molding, metal 3D printing can significantly improve the production times of lightweight parts produced in small numbers. Furthermore, is improves flexibility, and is more able to produce complicated geometries that would not be possible with common methods, such as turning, milling or drilling. The fused deposition modeling technique uses a metal powder filament, which is pulled through a high-temperature extrusion nozzle, thus melting the material; after that, the printed parts are placed in the debinding station with a solvent to remove the wax from the powder. Finally, completed products are taken from the sinter furnace with inert gases. Depending on the material, different characteristics arise in the production process, and the produced parts manifest different mechanical properties. This paper describes some experiments performed on the fused deposition modeling method using stainless steel filaments, debinding Opeteon and a sinter furnace.

Ultrasonic Vibration-Assisted Machining (UVA) is a machining process that adds a micro-scale high frequency vibration to the motion of a cutting tooltip to interrupt the continuous interaction of tool - workpiece surface. A good point of machining with UVA is more effective than conventional processes such as lower machining forces, higher machining stability, less tool wear and better surface finishes. In molds fabrication with some narrow cavities having a conversion space diameter of less than 3mm will face many difficulties while low surface roughness is required. Low stiffness of technological system in these cases of finishing machining is the reason of a weak machining in high-speed cutting. The ability to achieve cutting speeds for surface finishing of this type in tight spaces is also an interesting application for UVA tools. This paper discusses the finishing machining tool design with UVA for milling machine in such as analyze of the main parameters, adding diagonal split and simulation of the generated vibration effects to evaluate the achieved results before fabrication by using the help of ANSYS.

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.

In this paper, an induction heating system was applied to the heating stage in the injection molding process. Through simulation and experiment, the heating process was estimated by the temperature distribution and the heating rate. In the simulation, the mold temperature was increased from 30°C to 180°C in 9 s. Therefore, the heating rate was higher than 16°C/s, which represents a positive result in the field of mold heating. Additionally, the temperature distribution revealed that the higher temperature is concentrated on the gate area, while the outside of the mold cavity is at a lower temperature. The same parameters were applied to both the experiment and the simulation, and the results were in good agreement.

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.

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.

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.

In these days, the troubles in overpopulation seem to be an urgent message. Like human, robots exist in real-world not only one but also a group of them. The control of multi-robots becomes a key factor to actuate the whole system which scheduling period must be taken place initially. In this paper, a modified scheduler scheme to manage mobile robots is proposed simultaneously. The planner algorithm dynamically generates to update global states whenever robot tracks the reference trajectory. Moreover, the traveling distance could be chosen better in concerning with the movement of other robots. To verify the proposed method, a multi-agent system was built in hardware model. The physical experiments proved that our approach is valuable, feasible and extendible in large scale system of logistics, manufacturing and factory automation. &nbsp

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.

The effects of cutting fluids to health, environment, productivity, and quality in machining operations have been discussed. MQL is a green technology that is gradually applied in mechanical processing. The article has introduced about MQL cooling lubrication method in mechanical processing. Some previous research results have been made to clarify the meaning of this method. In addition, the comparison of the outputs of MQL, dry, and wet methods has also been shown to show the effectiveness of the MQL method. Then, based on the MQL equipment being used at Tran Dai Nghia University, the authors designed the experiment to evaluate the impact of MQL parameters on the process outputs. Machining and optimization of that parameter. This paper presents the MQL parameters optimization approach in which the multi-response outputs based on Taguchi's L9 orthogonal array method is used. During the turning AISI-1045 steel, the cutting temperature, the maximum of tool wear, and the surface roughness were measured. The MQL parameters, which are the ratio of soluble lubricant and water, pressure of spray head, the flow volume of the emulsion was simultaneously optimized by taking the multi-response outputs using Taguchi based grey relational analysis (GRA) into consideration. In turning experiments, three different flow volume of emulsion Q (40, 60, 80 ml/h), three different levels pressure of spray head P (3, 5, 7 bar) and three different levels ratio of soluble lubricant and water R (4, 6, 8%) were used. Here, three mathematical models were created using response surface regression methodology. The experiments had been done to investigate the effect of the MQL parameters to the turning process. As a result, the set of optimal MQL parameters had been pointed out to simultaneously minimize the cutting temperature, the tool wear, and surface roughness. The Flow volume of emulsion 80 ml/h, Pressure of spray head 7 bar, Ratio of soluble lubricant, and water 6% was observed to be the most effective.

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.

The last few decades have seen a large number of methods for ranking fuzzy numbers; centroid-index based approaches are the most commonly used among them. However, there are some weaknesses associated with these centroid-indices. Therefore, this paper reviews several fuzzy numbers ranking methods based on centroid-indices and proposes a new centroid-index ranking method that is capable of effectively ranking various types of fuzzy numbers. The proposed centroid-index ranking method uses fuzzy TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) to solve multi-criteria decision making (MCDM) problems, where triangular fuzzy numbers express the ratings of each alternative and importance weight of each criterion. To avoid complicated calculations of fuzzy numbers, the normalized weighted ratings are defuzzified into crisp values to simplify the calculations of distances from each alternative to the ideal and to the negative ideal solutions. A closeness coefficient is defined to determine the ranking order of alternatives. The proposed method is applied to a parting surface evaluation and selection problem in plastic mold design, demonstrating its applicability and computational process. Key words: Ranking fuzzy numbers, centroid index, fuzzy TOPSIS, parting surface.