Papers by Keyword: Abrasive Particle

Abstract: The authors of the article analyzed the properties of the fluidized bed during the formation of the abrasive-polymer compound for waterjet cutting. It is noted that in the process of applying the polymer shell to the surface of the abrasive grain in the fluidized bed, the effect of slippage and the absence of the influence of the installation wall on the value of the longitudinal velocity of particles near it is observed, which allows to increase the productivity of creating an abrasive-polymer compound.

Abstract: Behaviors of both micrometer-size nonmagnetic abrasive particles and micrometer-size magnetic particles in a magnetic fluid are investigated by using the discrete particle method which is based on the simplified Stokes dynamics. Sheet-like clusters of nonmagnetic particles and sheet-like clusters of magnetic particles alternately appear one after another in the axis direction when the flow velocity is small.

Abstract: Shear thickening polishing (STP) method was newly developed to achieve high efficient and high quality finishing of complex curved surface. The shear thickening fluid based slurry is one of the key factors in STP process. Viscosity of different shear thickening polishing slurry (STPS) was tested by rheometer in this study. The influences of dispersed particle size and concentration, abrasive material, abrasive particle size and concentration on the rheological property of STPS were analyzed. The results show that smaller dispersed particle (5.5 or 13μm in this study) and relative higher concentration (50-55 wt.%) are better for shear thickening effect of the base fluid. The viscosity of base fluid increases from 0.15-0.3 Pa·s to 0.8-1.1 Pa·s under high shear rate. The participation of Al₂O₃ and diamond abrasive changes the rheological property little, and the viscosity of STPS reaches the highest value 1.8 Pa·s at shear rate 300 s^-1. But SiC abrasive obviously destroys the shear thickening effect. SPTS with different Al₂O₃ abrasive concentration in this study presents almost same viscosity curve. It is inferred that the number of the abrasive particle but not the weight ratio plays the role to effect the rheological property of STPS.

Abstract: Behavior of both suspended micrometer-size magnetic particles and micrometer-size nonmagnetic abrasive particles in a micro-tube filled with a magnetic compound fluid is investigated by using discrete particles method based on the simplified Stokesian dynamics in order to reveal the polishing process of inner surface of the tube with an axial flow. Giving the axial flow of the appropriate velocity is effective on performing uniform polishing of the surface in the magnetic compound fluid polishing.

Abstract: Tool wear and tool failure are critical problems in the industrial manufacturing field since they affect the quality of the machined workpiece and raises the production cost. Improving our knowledge of wear mechanisms and capabilities of wear prediction are therefore of great importance in machining. The three main wear modes usually identified at the tool/chip and the tool/workpiece interfaces are abrasion, adhesion and diffusion. Besides, because of their difficult experimental analysis and measurements of their friction interface features (such as temperature, pressure, particles embedded in the contact …), understanding mechanisms that govern these wear modes is still incomplete. The objective of this research work is to develop a new wear model in which abrasive particles are assumed embedded between the tool and the chip at the interface. These particles are considered with a conical shape and are characterized by two main geometric parameters: the corresponding apex angle and size. The wear particles can be seen as a non-metallic inclusions or wear debris generated during the machining process. A probability density function has been adopted to describe the fluctuation of the size and the apex angle of particles in the tool/chip contact area. The influence of the used statistical distribution has been analyzed depending on which law has been adopted: Gaussian or Weibull. The Volume of the removed material per unit of time was chosen, in this study as the main abrasive wear parameter and detailed on a parametric study. Finally, wear tests were carried out with an uncoated WC-Co carbide tool machining a Ti6Al4V titanium alloy to validate the proposed approach.

Abstract: In order to improve the surface quality of titanium alloy in electric discharge machining (EDM) milling, presents electrode ultrasonic vibration assisted EDM milling in the kerosene fluid which fills with 12g/L SiC abrasive particles. By the comparison test of surface roughness between EDM milling and abrasive particle ultrasonic vibration assisted EDM milling in short pulse(pulse width less than 1μs), it is found that ultrasonic vibration role of SiC particle could effectively improve surface roughness from Ra 0.5μm to 0.2μm. The recast layer and surface crack are analyzed by scanning electron microscope (SEM).Results show the thickness of recast layer reduced 20-30μm and surface crack decreased obviously under the role of abrasive particle ultrasonic vibration. It shows that the combined action of ultrasonic vibration and abrasive particle can dramatically improve the surface quality of titanium alloy in EDM milling.

Abstract: In advanced technological industries, like aerospace, missile, nuclear reactors, and automobile industries; the necessity of producing precise parts is clearly unavoidable. Further, conventional machining processes often face difficulties in producing these parts due to the big size of removed materials. Hence, kinds of machining named Non-Traditional Machining processes are developed since World War II largely in response to new industrial requirements. By the NTMs, precise parts can be produced thanks to molecular or atomic chip removal. Cavitation machining (CM) was lately proposed as a new non-traditional machining method. In this process, the released energy from collapsed bubbles is used to remove material from the workpieces surface. This energy is applied to abrasive particles and threshes them to the workpiece surface. There are some parameters affecting material removal rate (MRR) in CM process. One of the main parameters is the size of abrasive particles in conveyor liquid. Since it is a new process in machining sphere, there are no studies in this regard. This paper presents experimental results about influence of size of abrasive particles in conveyor liquid on Ultrasonic Cavitation Machining (UCM) process. The experimental results will be discussed, and the best size of the particles in which the MRR is maximized will be presented.

Abstract: The semi-fixed abrasive tool (SFAT) is a new tool used in the ultra-precision machining. Based on the theory of particle flow code (PFC), the abrasive particle motion characteristics of SFAT are studied in SFAT processing which is divided to workpiece pressing progress and workpiece tangential moving progress. It is conclusion that the particles are fallen out the tool surface due to the fracture of bonds under the normal force of workpiece point in the workpiece pressing progress; the particles contacting the workpiece are moved on every hand while some particles fall out the surface at the edge of abrasive tool in the workpiece tangential moving progress, and the maximum value of binding agent holding force is computed.

Abstract: Based on a three-body micro-contact mechanism and contact temperature theory, a micro-contact temperature model was developed to investigate the effect of particle size, particle density, and rotational speed on temperature rise between particles and workpieces. The experiments with different particle sizes and rotational speeds verified the feasibility of the micro-contact temperature analysis. The results indicate that contact temperature between particles and workpieces linear increases as particle size and rotational speed increase. The particle density has a negligible effect on maximum contact temperature between particles and workpieces.

Abstract: To improve the effect of magnetorheological finishing (MRF), it is necessary to control the behavior of abrasive particle effectively in machining process. This article described the machining principle of semi-bond abrasives under the MR effect, then, analyzed the magnetic field of the polishing tool. Based on the magnetic field theory, the constrained model of abrasive particle was established, consequently, the force and the machining behavior of abrasive particle were analyzed. And an experiment was carried out to analyze the effect of the abrasive behavior on the material removal. The results show that the experimental results are identical with the theoretical analysis. Therefore, the control of the particle behavior in process is proved to be available.