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The manufacturing technique known as investment casting has found extensive application in producing metal components featuring intricate geometries. The production efficiency of the wax patterns is an essential issue in the investment casting industry, especially for the mass production of wax patterns. A conformal cooling channel (CCC) performs the rapid uniform cooling process for injection molding. However, the significant pressure drop along the cooling channels is a distinct disadvantage of CCC. In this study, an innovative waterfall cooling channel (WCC) was proposed and implemented. The WCC cools the injected products by surface contact, replacing the conventional line contact to cool the injected products. The WCC was optimized using Moldex3D simulation software. Rapid tools with two kinds of cooling channels were designed and implemented. The cooling time of the molded part was investigated using a low-pressure wax injection molding machine. Considering a water cup characterized by a mouth diameter of 70 mm, a height of 60 mm, and a thickness of 2 mm, the experimental results confirmed that the use of WCC can save the cooling time of the product by about 265 s compared with the CCC. This result shows that the WCC can increase cooling efficiency by approximately 17.47% compared with conventional CCC. [ABSTRACT FROM AUTHOR]

Fused filament fabrication (FFF) is an additive manufacturing process that uses a continuous filament of a thermoplastic material. The FFF is able to fabricate physical models with sophisticated geometries. Unfortunately, the mechanical property of the fabricated physical models is limited. Therefore, this drawback will limit the application of the fabricated physical models made by FFF. To improve this drawback, this work demonstrates a simple method to increase the tensile strength of printed parts. This method combines filament preheating and ultraviolet (UV) resin reinforcement methods. The tensile strength of the printed tensile test piece with a filling density of 100% was soaked in UV resin and then cured with a wavelength of 405 nm for 30 min. The tensile strength was increased from 35.08 to 37.5 MPa with an improvement rate of about 6.9%. The tensile strength was increased from 35.08 to 43.97 MPa when the filling density was 100% and the filament was preheated at 50 °C with an improvement rate of about 25.34%. Combining filament preheating and UV resin reinforcement methods, the tensile strength was increased from 35.08 to 46.75 MPa. The improvement rate in tensile strength is up to 33.26%. The failure mechanism of the tensile test sample made by combining UV resin reinforcement and filament preheating method is also investigated. [ABSTRACT FROM AUTHOR]

In practice, the fused deposition modeling technique is widely used for producing various plastic functional components in the research and development stage. In particular, adhesive bonding is capable of bonding dissimilar materials quickly. However, the bonding strength is affected by human factors. In addition, bolts are also used to bond small 3D printed parts for making a large 3D physical model. However, this locking method is not resistant to vibration. The feature of fusion bonding of thermoplastic materials is known for its weldability. Rotary friction welding (RFRW) has low energy consumption in the welding field. In general, the weld quality is affected by the process parameters of RFRW significantly. The Taguchi method was used to optimize the process parameters of RFRW of dissimilar polymeric rods to reduce random efforts by the trial-and-error method. The most critical control factor is the weld time. The contribution percentage for the weld time, feed rate, rotational speed, and preheating temperature is 35.21%, 27.85%, 24.84%, and 12.10%, respectively. The optimal process parameters of the frictionally welded parts with better bending strength are the feed rate of 0.05 mm/s, preheating temperature of 50 ℃, rotational speed of 950 rpm, and weld time of 20 s. The bending strength of the frictionally welded parts can be enhanced by about 1.29 to 1.538 times. [ABSTRACT FROM AUTHOR]

This research established half of the finite element model to investigate the thermal and stress field evolution of single track cladding deposited by the wide-beam laser. The proposed FE model is validated by the molten pool temperature measured by a pyrometer. And the characteristic of the cladding shows good agreement with the temperature profile. Based on the temperature data, the molten pool length, width, and depth are calculated. Meanwhile, the effect of process parameters including laser power and scanning speed on the molten pool dimensions, temperature gradient G, cooling rate ε, solidification rate R, and G/R are discussed. Three experiments under different process parameters are conducted to verify the simulation results. Furthermore, the thermal stress distribution of the cladding in different direction and different path are discussed. The results indicate that laser power and scanning speed have a significant influence on the thermal and stress field evolution. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the temperature field evolution of the single track clad in wide-beam laser cladding. By using the birth and death element technique, a 3D transient finite element (FE) model was established to study the temperature field evolution, temperature gradient (G), cooling rate (ε), and solidifying rate (R) of the molten pool. The temperature field results of the molten pool were also validated by the temperature measurement and characteristics of the clad. Meanwhile, the effect of main parameters namely as laser power, scanning speed, laser absorptivity, laser power efficiency, and preheat temperature on the peak temperature of the molten pool and temperature variation rate were discussed in detail. Then, the effect of laser power and scanning speed on G, ε, R, and G/R were also investigated and the corresponding microstructure was analyzed. The results show that from the top surface of the clad to the interface between the clad and substrate, G/R decreases slightly at first and then increases sharply while the cooling rate continues to decrease. Moreover, the peak temperature of the molten pool increases with an increase of laser power, laser absorptivity, laser power efficiency, and preheat temperature, while with the increasing of scanning speed, the peak temperature decreases. [ABSTRACT FROM AUTHOR]

In order to achieve the restoration of the sprocket, it is significant to repair or modify the damaged sprocket by using an advanced surface treatment technique, such as the laser cladding process. In this paper, the Taguchi method was applied to conduct the experiment to optimize the process parameters for repairing a sprocket in the laser cladding process. The dilution was chosen to evaluate the quality of the cladding layer and the effect of the process parameters, such as the laser power, scanning speed, and powder feeding rate, with respect to the cladding layer geometry, and the dilution was investigated systematically. Then, using the optimized parameters, the sprocket was remanufactured and its surface profile characteristics, microstructure, and microhardness of the repaired sprocket were analyzed. The results show that the optimal process parameters (1000 W, 2.81 g/min, 1200 mm/min) obtained by the Taguchi method could realize the lower dilution. With the optimal parameters, the repair accuracy of the sprocket could reach 2.973 mm, which offers the machining allowance for machining of the sprocket. A white bright band observed at the interface shows that the metallurgical bonding was realized between the cladding zone and base metal. The microhardness of the cladding zone is higher than that of the heat-affected zone and base metal. Furthermore, the results reveal that the Taguchi method can effectively acquire the optimal combination of process parameters, and the laser cladding process exhibits good feasibility and effectiveness for repairing the machinery components with complex shapes. [ABSTRACT FROM AUTHOR]

This study involves the investigation of the mechanical properties of the extruded tube products with reinforced silicon carbide particulates (SiCp). Finite element analyses are firstly conducted to analyze the plastic flow of the magnesium alloy AZ61 within the die and to investigate the effects of initial billet temperatures on the extrusion loads and final product temperatures. AZ61/SiCp composite ingots reinforced with different weight fractions of SiCp are fabricated by a melt stirring technique. A specially designed die set is used in the extrusion experiments to obtain tubes with uniform thickness distribution in the circumferential direction. The extruded tubes are also heat treated to obtain even better mechanical properties. Finally, tensile tests, Vickers microhardness, tests and microstructure observation are performed on the billets and extruded tubes of AZ61 monolithic alloys and AZ61/SiCp composites. A much smaller grain size and higher tensile strength and hardness are achieved for the extruded AZ61/SiCp composite tubes. [ABSTRACT FROM AUTHOR]

Product disassembly is a basic period of life cycle design. This paper first introduces the modelling method and basic concepts of the disassembly activity logic network, then establishes the optimal model of the minimum disassembly cost. According to the characteristics of the model, the solution for the single disassembly object is acquired by constructing the orthogonal list storage structure and the reverse search algorithm which follows the depth-first policy. A complete example is illustrated. [ABSTRACT FROM AUTHOR]