Key Engineering Materials Vol. 693

Abstract: In this paper, finite element model of SiCp /Al single cell body and single diamond particles were established by cross-scale modeling method. The results shows that the extent of damage of SiC particles increased with the increase of amplitude and frequency; The integrity of SiC particles are still better under the ultrasonic frequency 20000 Hz and the maximum amplitude 5um,so the optimal frequency range of ultrasonic scratch is (20000-30000)Hz. As for 22000 Hz, the integrity of SiC particles was better under the amplitude 4um,while the SiC particles have a significant damage in the border area under the amplitude 5um,so the best frequency and amplitude for ultrasonic scratches are: 22000 Hz and 4 um.

Abstract: The purpose of this paper is to investigate the variation of temperature field of ultrasonic vibration assisted milling compared with that of conventional milling by FEM method. An equivalent two-dimensional finite element model was built to simplify the complexity of calculation. As results, the temperature field distribution, the variation of tool tip temperature and the change of heat generation rate in ultrasonic vibration assisted milling were analyzed compared with that in conventional milling process. According to analytical results, the application of ultrasonic vibration in milling process can significantly improve the distribution of cutting temperature, and reduce the impacts of thermal deformation and various thermal effects to cutting process.

Abstract: In this study the influence of tool inclination angle on deformation of thin wall cantilever shape part has been analyzed using finite element numerical simulations. Polycrystalline diamond, PCD tool has been chosen as a tool material in this study because PCD tool has given better results in terms of surface roughness, tool life and productivity in end milling of titanium alloy Ti-6Al-4V. Firstly, in this study, the effect of tool inclination angle on tool contact geometry, cutting speed and cutting forces has been discussed. Then, finite element numerical simulations (FEM) have been carried out in AdvantEdge® for the prediction of cutting forces with PCD tool at four different tilt angles viz. 70°, 75°, 80° and 85° and the results have been compared to the coated carbide tool. Then the maximum magnitude of the forces which occurred in tangential direction (F_Y) were input in the Abaqus® software as a load acting on the thin long cantilever part and deformation results were analyzed. Results show that PCD tool due to its high hardness, strength and better wear resistance produce lower cutting forces at all angles studied and at an angle near the perpendicular to the surface being machined both tools have lower values of the deformation. The FEM simulation results match well with the theoretical study as theoretical analysis also shows that at angles nearer to perpendicular to the surface being machined, the tool will have lower effective cutting speed & forces and hence proved as the key to achieving better accuracies for long thin wall parts.

Abstract: Inconel 718 alloy is a typical difficult-to-cut material and widely used in the aerospace industry. Finite element simulation is an efficient method to investigate the cutting process, whereby a work material constitutive model plays an important role. In this paper, finite element simulation of the cutting process for Inconel 718 alloy using a new material constitutive model for high strain rates is presented. The effect of tool cutting edge radius on the cutting forces and temperature is then investigated with a view to facilitate cutting tool design. It is found that as the cutting edge radius increases, the characteristics of tool-work friction and the material removal mechanisms change, resulting in variation in cutting forces and temperature. It is shown that a smaller cutting edge radius is preferred to reduce the cutting forces and cutting temperature.

Abstract: The graft polymerization in radio frequency hollow cathode plasma (RFHCP) is suitable for the surface modification of large-area thin film materials. The homogeneity of plasma surface modification of large-area thin film materials has always been paid close attention, and it is also the key factor affecting the industrialized applications of the technique. However, the homogeneity of plasma surface modification is thought to depend greatly on the distribution of discharge gas. In this paper, a finite element model is proposed to discuss the flow of discharge gas in hollow cathode plasma. The concentration distribution of the discharge gas has been discussed by the combination of numerical simulation of fluid distribution and pipe flow theory based on the investigation of the transport property of gas under vacuum. Comparisons between available experiments have also been performed to validate the applicability and practicability of the proposed model.

Abstract: Cutting tool temperature which mainly depended on the tool-chip interface temperature has crucial effect on the tool service performance and its life. It is essential to investigate the heat conduction in the cutting tool in order to define the temperature distribution on the cutting tool during machining. Advanced coating materials are adopted to deposit on the carbide substrate to enhance the tools’ cutting performance. Thus, the influence of coating layers on the heat transfer during the cutting process has been an important research topic. Advantage software was employed to simulate the cutting process in this paper. The influences of coating materials on the temperature distribution in the cutting tools were investigated. The study results show that KCU10 cutting tool with TiAlN/TiN coating layers shows good thermal properties than that of KT315 cutting tool with TiN/TiC/TiN coating layers. The cutting temperature along the tool-chip contact length shows increasing trend first with the distance from the tool tip point and then decreasing after the tool-chip separation point. Under the same coating thickness, TiAlN coating material presents better thermal properties than TiN coating material.

Abstract: Tool edge preparation can eliminate defects and realize hone cutting edge, which can improve the quality of the workpiece surface, elevate the stability of cutting process and the tool life. In order to better investigate the edge preparation mechanism, the influence law of the edge preparation process parameters on the cutting edge is analyzed. The paper presents the single factor experiments and orthogonal experiments with the cemented carbide milling tool spindle rotation rate, edge preparation time, abrasive size and abrasive ratio in drag finishing. The edge preparation mechanism is revealed in the paper, which provides basis for the structure optimization of cutting edge contour.

Abstract: This paper investigated the fabrication and design of embedded Ni-chrome thin-film strain gauges as micro-sensors in tool holders to measure the cutting force in machining operations. A Ni-chrome thin film as piezoresistive material sensor device is embedded within a substrate structure through brazing bonding process, which consists of a Ti6Al4V substrate, a Nickel-chromium thin film sensor and an Alumina insulating layer. The thin-films were characterized by 3D Super Depth Digital Microscope, SEM/EDS, Stylus profiler, to study microstructure, material composition, thickness and sheet resistance respectively. The thin-film strain gauges are calibrated in a cantilever beam setup. Accordingly, in-process cutting force measurement systems are established. The results showed that the thin-film sensor had good linearity and more elaborate structure and superior properties.

Abstract: The heavy belt-grinding is a new machining method, which combined the characters of heavy-duty grinding and belt-grinding together, with high efficiency and low cost. In the present paper the removal rate model of heavy belt-grinding in manufacturing of U71Mn steel is established. It is assumed that the distribution of the abrasive particles protrusion height of the abrasive belt surface closes to Gaussian distribution. The model is presented by calculating the removal volumes of all abrasive grains contributing to cutting action based on the probability theory, elastic-plastic mechanics and abrasive cutting theory. It is analysis that the material removal rate depends essentially on the mechanical properties of the workpiece and the belt and the grinding conditions. It is proportional to the average pressure, belt velocity and the indentation depth and is inverse proportion to the grain size.

Abstract: The production cost of the sapphire substrate was restricted by the efficiency of processing and the surface quality. A proposed level orthogonal experiment was conducted to reveal the effect of workbench speed, lapping pressure, the Concentration of triethanolamine and abrasive pad types on the material removal rate and surface roughness and morphology of sapphire substrate when lapped with a diamond fixed-abrasive pad. The results showed that the average material removal rate of sapphire is about 24μm/min, and the surface roughness Ra achieves 0.36μm when the 200/230 mesh diamond fixed-abrasive pad was used. The material removal rate and the surface roughness as the optimization goal, the optimal lapping parameters were as follows: the lapping pad with raised, lapping pressure 0.075MPa, workbench speed 120rpm and the Concentration of triethanolamine 1%. Under these optimal machining parameters, the material removal rate reached 42μm /min and the surface roughness Ra reached 0.37μm.