Key Engineering Materials Vols. 375-376

Abstract: Research on the mechanism of vibration cutting was carried out by analyzing the process of vibration cutting and comparing the model of vibration cutting and conventional cutting. Proper speed coefficient k can help to reduce the average cutting force while increase the cutting efficiency according to the velocity and acceleration equation of vibration tool. Dynamic model of conventional cutting and vibration cutting were built respectively. Compared with conventional cutting, it’s easier for vibration cutting to realize productivity gain, high machining accuracy and good surface finish.

Abstract: Multilayer ceramics based on the low-temperature co-fired ceramics (LTCC) are gaining increasing interests in the manufacturing of highly-integrated systems for microelectronic and micro-system applications. The polishing experiments of sintered LTCC using a custom-built precision polishing machine are reported in this paper. First, a micro-fluidic distributor was fabricated using LTCC. Then, the polishing of this meso-MEMS system was studied using several polishing parameters. By optimizing the polishing parameters, the surface roughness can be reduced to 4 nm.

Abstract: Hardness, elastic modulus and scratch resistance of single silicon wafer are measured by nanoindentation and nanoscratching using a nanoindenter. Fracture toughness is measured by indentation using a Vickers indenter. The results show that the hardness and elastic modulus at a peak indentation depth of 100 nm are 12.6 and 166.5 GPa respectively. These values reflect the properties of the silicon wafer, the bulk material. The fracture toughness value of the silicon wafer is 0.74 Mpa·m1/2. The material removal mechanisms are seen to be directly related to the normal force on the tip. The critical load and scratch depth estimated from the scratch depth profile after the scratching and the friction profile are 138.64 mN and 54.63 nm respectively. If the load and scratch depth are under the critical values, the silicon wafer will undergo plastic flow rather than fracture. The critical scratch depth is different from that calculated from the formula of critical-depth-of-cut described by Bifnao et al and some reasons are given.

Abstract: The laser peen forming (LPF) uses high-power pulsed laser beam replacing the tiny medium balls to peen the surface of plate and generate compressive stress near the surface, the metals respond to this residual stresses by elongating at the peened surface and effectively bend the overall shape. In this paper, the deforming process of metal plate induced by repetitive pulsed laser was discussed from theory firstly, and the bending mechanism of LPF was investigated. Then a mathematical model of bending curvature concerning the depth of residual stress was presented, the influence of residual stresses on the deformation of plate was analyzed. Lastly, the line-track-peening experiment for SUS 304 plate was carried out to evaluate the reasonability of the theoretical analysis model.

Abstract: The erosion process of abrasive waterjet (AWJ) on target material is very complicated and a complete clear understanding about material removal mechanisms in AWJ machining has not been obtained. In this paper, an experiment study on AWJ machining mechanisms of brittle materials is introduced so as to understand the actions of water jet and abrasive particle in material removal process and some experiment evidences of the change of material removal mechanisms have been obtained.

Abstract: A forming model of the feed-direction burr for drilling process is made in this paper. The feed-direction burr formation is studied by experiment. The related theories are analyzed. The influence factors of the feed-direction burrs are pointed out. Furthermore, a certain number of measures to prevent and decrease the burr in drilling process are advanced.

Abstract: Numerical Controlled Electrochemical Contour Evolution Machining (NC-ECCEM) is one of the most important development in Electrochemical Machining (ECM). In order to improve the machining accuracy of NC-ECCEM technology, the research works on precision NC-ECCEM technology are needed, and especially the study on its shaping law is significant for improving the machining accuracy of workpiece profile. In this paper, the shaping law of machining the planar surface by use of a kind of inner-spraying cathode with rectangle section was studied. First, the basic differential equations of shaping law in the case of cathode movement were established. Then, considering the structure of the cathode, the methods for calculating the side gap in machining the planar surface was given. Finally, the experiments of machining the planar surface were carried out. Experiments show that the calculated side gaps are bigger than the actual values, but the change trend of calculated side gaps with machining process parameters is coincident with the actual side gap change trend.

Abstract: In order to operate in narrow space, a novel miniaturized EDM (Electro Discharge Machining) mechanism has been developed. A prototype of miniaturized EDM device based on ultrasonic motor (UM) has been developed, which has its advantage of compact size (70×40×50 mm). The differential driving electrode has been presented, and coaxial forced vibration of electrode is benefit for the evacuation of debris, so it helps to achieve stable and efficient machining. Driving principle of ultrasonic motor is analyzed, and simulation using Finite Element Method (FEM) is accomplished. The auto-frequency tracking has been carried out, in order that the motor work on resonant or quasi-resonant frequency. Finally, EDM experiment has been finished, and holes with figures of circleΦ85μm and Y-typed have been machined.

Abstract: As a typical difficult-to-cut material, the nickel-based superalloy GH4169 has been used in many kinds of aeronautical key structures and turbine components because of its high yield stress and anti-fatigue performance even in high temperature. In this paper, finite element method (FEM) is introduced to study the saw-tooth chip formation in detail. By the way of Lagrange approach, adiabatic shear band (ASB) is simulated and the chip forming mechanism is interpreted by adiabatic shearing theory via the comparison of two models, one of which has a failure criterion and another not. The comprehensive comparison and analysis of chip morphology between simulation and experiment are also presented in this paper.

Abstract: Mechano-chemical modification (MCM) of nanodiamond was conducted with a stirring mill. A new type of silane coupling agent, GW was chosen as its modifier. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) were employed to study the surface properties of nanodiamond before and after treatments. Results showed that the peaks related to GW and the ball (for example, Fe, Si and Cl) appeared obviously after its MCM on their XPS spectra and mostly disappeared after its further purification with acid X or Y. A new peak located at 1382.48cm-1 was very strong after further purification. It was proven by their FT-IR spectra.