Materials Science Forum Vols. 505-507

Abstract: The springback behavior of an invar sheet and its perforated form were examined in the present study. The mechanical properties for invar sheet and perforated invar-sheet at elevated temperatures were first obtained from tensile tests. The test results suggest that both invar sheet and perforated invar-sheet have favorable formability at temperature higher than 200oC. An analytical model was also established to predict the springback of the invar sheet and its perforated form under bending conditions at various elevated temperatures. In order to verify the predicted results, the V-bending tests were conducted for the invar sheet at various temperatures ranging from room temperature to 300
. The experimental data indicate that the springback decreases with the rise in temperature for both invar sheet and perforated invar-sheet. The good agreement between the experimental data and the predicted values confirms the validity of the proposed theoretical model as well.

Abstract: Grind-hardening was done on 65Mn steel with a conventional surface grinder and a corundum-grinding wheel. Research was conducted to probe into microstructures and properties of the hardened layer under varied depth of cut and cooling conditions. Results show that the hardened layer does not change noticeably in their martensitic structures and micro-hardness, which is ranged between 810-870HV. When the depth of cut increases or the dry grinding technique is adopted, the hardened layer becomes thicker accordingly. Under the condition of dry grinding with the depth of cut 1.0mm, the hardened layer depth reaches 2.0mm. It can find applications in grinding and metal surface modification field.

Abstract: This study investigates the possible ball burnishing and spherical polishing surface finish process of a freeform surface plastic injection mold on a machining center. The optimal plane polishing parameters were determined by utilizing the Taguchi’s orthogonal array method for plastic injection molding steel PDS5. Five polishing parameters, namely the speed of the polishing ball, abrasive material, feed, stepover distance and the depth of penetration were selected as the experimental factors of Taguchi’s Design of Experiment to determine the optimal plane polishing parameters, which have the dominant influence on surface roughness. The optimal plane polishing parameters have been determined after conducting the experiments of the Taguchi’s L18 orthogonal table. The optimal plane polishing parameters for the plastic injection mold steel PDS5 were the combination of the polishing speed 18,000 rpm, the abrasives of aluminum oxide (Al2O3) with grid no. 5000, the feed of 100 mm/min., stepover distance of 60μ m, and the depth of penetration of 240 μ m. The surface roughness Ra of the specimen can be improved from about 1.125μ m to 0.067μ m using the optimal ball burnishing parameters for plane burnishing. The surface roughness Ra of the burnished specimen can be further improved from about 0.067μ m to 0.023μ m using the optimal polishing parameters.

Abstract: Chemical Mechanical Polishing (CMP) is the key technique for wafer global planarization. However, the characteristic of abrasive particle, including particle size and grain/grain collision elasticity, plays an important role in CMP process. This investigation analyzes the slurry flow between the wafer and pad using a grain flow model with partial hydrodynamic lubrication theory. This model predicts the film thickness and remove rate of the slurry flow under a variety of the CMP parameters including load, rotation speed, pad roughness, grain/grain collision elasticity and grain size. The theoretical results compare well with the previous experiment data. This study elucidates the grain characteristics during CMP process. It also contributes to the understanding of abrasive particle effects in the chemical mechanical polishing mechanism.

Abstract: This paper presents an optimal cutting-parameter design of heavy cutting in side milling for SUS304 stainless steel. The orthogonal array with relational analysis is applied to optimize the side milling process with multiple performance characteristics. A grey relational grade obtained from the grey relational analysis is used as a performance index to determine the optimal cutting parameters. The selected cutting parameters are cutting speed, feed per tooth, axial depth of cut, and radial depth of cut, while the considered performance characteristics are tool life and metal removal rate. Experimental results have shown that cutting performance in the side milling process for heavy cutting can be significantly improved through this approach.

Abstract: This paper presents an optimal cutting-parameter design of heavy cutting in side milling for SUS304 stainless steel. The orthogonal array with relational analysis is applied to optimize the side milling process with multiple performance characteristics. A grey relational grade obtained from the grey relational analysis is used as a performance index to determine the optimal cutting parameters. The selected cutting parameters are cutting speed, feed per tooth, axial depth of cut, and radial depth of cut, while the considered performance characteristics are tool life and metal removal rate. Experimental results have shown that cutting performance in the side milling process for heavy cutting can be significantly improved through this approach.

Abstract: A microstructure assembled into another part using the mechanical elastic self-deformation assembly technology is proposed in the paper. To attain the self-deformation during assembling, the assembly joint on the microstructure is analytically designed as the feature with an appropriate taper and cross clearance. Take account of the accuracy, the whole process from micro-fabrication to micro-assembly is carefully planned and practiced under a micro-EDM machining center system which consists of vertical micro-EDM with dividing mechanism, and horizontal micro-machining mechanism, which is referred to as on-process micro-assembly. To illustrate the micro-assembly strategies and procedures, a micro-rotor production including assemble a tungsten carbide four-phase micro-rotor into an alumina base has been provided and discussed.

Abstract: This paper presents a new approach for the optimization of the high speed machining (HSM) process with multiple performance characteristics based on the orthogonal array with the grey relational analysis has been studied. Optimal machining parameters can then be determined by the grey relational grade as the performance index. In this study, the machining parameters such as cutting speed, feed rate and axial depth of cut are optimized under the multiple performance characteristics including, tool life, surface roughness, and material removal rate(MMR). As shown experimental results, machining performance in the HSM process can be improved effectively through this approach.