Applied Mechanics and Materials Vols. 217-219

Abstract: Dry or clean cutting without the hazards of cooling liquid, and the ability to monitor thermal impact on cutting tools in real time have been very appealing to the manufacturing industries. This paper presents the FEM-based design and analysis of a smart cutting tool which possess dual functions of cooling the cutting tool with the internal cooling structure and estimating temperature at the tool tip by measurement of the cooling liquid’s temperature at the inlet and outlet of the cooling structure. To evaluate the performance and feasibility of the smart cutting tool, thermal modelling is carried out by commercial software - ANSYS and FLUENT. The numerical simulation results demonstrate that the novel tooling design concept can effectively reduce tool temperature away from the tool wear critical temperature zone and sensing the cutting temperature at the cutting tip.

Abstract: This paper is to experimentally investigate the mechanical micro machining properties of AL6061-T6 using tungsten-carbide micro end mills. The cutting simulation based on Finite Element Analysis (FEA) method is also conducted to estimate cutting forces, cutting temperature, and minimum chip thicknesses. The simulation results are used for the determination of experimental machining conditions such as depth of cut, feed rates and cutting speeds. A number of slot micro-milling experiments were performed using 400um diameter micro end mills on a 3 Axis CNC machining center attached with a high precision and high speed spindle unit. The machined surface quality, geometric feature shape, cutting burr generation as well as build-up edges are observed in the cutting experiments. Optimum cutting parameters for a better surface quality and smaller burr sizes are suggested.

Abstract: According to the limitations of conventional method of optimization design for the process parameters in the hydroforming process, a new simulation method has been proposed for the optimization of the process parameters, which is the integration of the neighborhood cultivation genetic algorithm (NCGA) and the dynamic explicit algorithm based on finite element method (FEM). The new method has been adopted for the optimization of the hydroforming loading path of an instrument panel beam and the process parameters are the internal pressure vs. time and the axial feeding displacement vs. time. It is concluded that the acquired loading path through the new method is more optimal than the one through the trial and error method. In addition, the new method can simultaneously generate multiple Pareto-optimum solutions in one computation and provide more freedom for the designer's decision making of the process parameters.

Abstract: This paper described the effect of hollow jet atomization technology, under charge action, according to the spray forming process, to improve the quality of atomization. In order to deeply study the charge action on the annular molten metal of spray forming process, this paper analyzed theoretically quantity of electric charge of the annular molten metal and the surface tension of atomization droplets. The results show that the quantity of electric charge increases with the increasing of charging voltage. Under the same conditions, the hollow annular metal liquid charge is always greater than the solid cylindrical molten metal charge, but the surface tension is less than the solid molten metal. As the quantity of electric charge reduce the surface tension of the droplet, the power of atomization increases relatively. It means that the atomization quality of annular molten metal will be better than the solid cylindrical molten metal. By comparison, the structure under charge action is fine and homogeneous after experiment.

Abstract: In this paper, gelatin was selected as binder, sodium alginate as dispersant. The slurries with low viscosity and high solid loading were prepared by mixing two types of 316L stainless steel powders with different particle sizes in proper mass ratios. The freeze drying process was adopted to treat the wet green body. The results show that the slurry with a solid loading as high as 58 vol.% can be obtained by mixing 316L stainless steel powders with mass ratio of fine particles to coarse as 4:6, which has better fluidity and densification. The viscosity of the slurry is less than 1Pa•s. After the freeze drying process, the bending strength of green body reaches 11.15MPa, the drying shrinkage is decreased to 0.44%, and the generation of crack can be prevented. The study results provide some helpful references for further research in rapid manufacturing of complex metal part.

Abstract: Conventional methods for preparing ceramic bodies, such as cold isostatic pressing, gypsum-mold slip casting, and filter pressing are not completely suitable for fabricating large and thick ceramic plates, because of disadvantages such as the high cost of equipment, formation of density gradient, and differential shrinkage during drying. These problems could be avoided by employing step pressure-vacuum hybrid slip casting in which consolidation occurs not only by the compression of the slip in casting room, but also by vacuum sucking of the dispersion medium (water) around the mold. This method enabled us to fabricate a 110 × 110 × 20 mm alumina plate without cracks and with homogenous density, and the possibility of extending the method to fabricate other ceramic products appears to be promising.

Abstract: A case study of the comparison of the properties of conventional foundry sand and light weight cenosphere/microsphere particles has been undertaken. This analysis was initiated by the preparation of their respective specimens, followed by the actual testing of these samples. Properties such as Compression strength, Shear strength, Permeability and Hardness were determined. In addition the grain form and microstructure of the specimens prepared was also analyzed. This analysis clearly indicates the possibility of the usage of cenospheres as a replacement of foundry sand.

Abstract: A gear meshing mathematical model was set up according to the tooth profile normal line method. The influence of the gear cutter-workpiece center distance on the tooth profile accuracy was discussed in spur gear cutting using a new type of gear cutter, with the center distance errors being ±0.005, ±0.01, ±0.02 and ±0.04 respectively. The results show that the machined tooth profile errors at the root circle is less than 1μm, while errors at other parts of the tooth profile are even smaller.

Abstract: Surface roughness plays a critical role in evaluating and measuring the surface quality of a machined product. Two workpiece materials have been investigated by experimental approach in order to gain a better understanding of their influence on the obtained surface roughness in the micro-milling processes. The experimental results show that: surface topography is completely different for different materials at the same cutting speed and feed rate; surface roughness increases with an increase of material grain size. Surface roughness decreases to a lowest value, and then increases with an increase of the feed rate. A new surface model to illustrate the influence of material and uncut chip thickness was developed. The model has been experimentally validated and shows more promising results than Weule’s model.

Abstract: An aluminum base interlayer was used for transient liquid phase bonding of pure aluminum under argon flux. The bonding was carried out at 595°C for 2 minutes under 7MPa. Microstructure of the joint was studied with SEM and EDX, and the mechanical properties were analyzed by tensile test and bending test. A homogenous bonding zone is observed in the joint. The defects in the joint are silicon oxides and voids. The tensile strength of the joint is 190MPa, and no failure occurs when the joint is bent to 180°. This indicates that TLP bonding can produce a strong and ductile Aluminum joint, which is equivalent to the base metal.