Flow Polishing Research Articles

Numerical simulation analysis of multi-physical coupling field with abrasive flow precision polishing variable-aperture tube

In the fields of aerospace, precision machinery and energy, there are variable-diameter tubes for many key components. Abrasive flow polishing technology is an effective precision polishing technology for finishing the workpiece with an internal cavity structure. This technology can improve the quality of part finishing, reduce stress concentration, and reduce the surface roughness of the workpiece, and ultimately can improve the performance of the workpiece. In this paper, variable-aperture tube is taken as the research object, and the characteristics of abrasive flow in the multi-physics coupling field are studied by numerical simulation, and the collision removal effect between the abrasive particle and the wall surface is analyzed. We also discussed the control law of the abrasive grain flow processing quality and provided theoretical guidance for abrasive grain flow polishing of this type of part.

CFD-based study of the abrasive flow characteristics within constrained flow passage in polishing of complex titanium alloy surfaces

Study on the constrained abrasive flow polishing of complex titanium alloy surfaces is discussed both numerically and experimentally. The numerical simulation using Computational Fluid Dynamics method and Discrete Phase Model is first conducted to model the particle-laden fluid through the constrained flow passage by considering four types of constrained plate, including chevron-type, golf ball-type, fork-type and triangle-type. The triangle-type constrained plate is found to be the most optimized design than the other types of pattern for the polishing purpose because of increasing the dynamic pressure of water flow and resulting in a relatively uniform distribution of water flow velocity near the bottom surface of the constrained flow passage, as well as increasing the number of collisions between particles and the target surface. A set of experiments, including the rough and precision polishing procedures, is then conducted to evaluate the polishing performance by using the original and triangle-type constrained plates, respectively. It is found that the average material removal rate obtained from the triangle-type constrained abrasive polishing process is larger than the corresponding data taken from the original passage, and the surface roughness is found to be reduced after the triangle-type constrained abrasive polishing process. These experimental results are in a good agreement with the corresponding simulated results. Thus, both the polishing efficiency and quality have been improved by using the abrasive flow polishing of complex titanium alloy surfaces with the triangle-type constrained plate.

Numerical Simulation Analysis of High-precision Dispensing Needles for Solid-liquid Two-phase Grinding

In order to investigate the effect of abrasive flow polishing surface variable diameter pipe parts, with high precision dispensing needles as the research object, the numerical simulation of the process of polishing high precision dispensing needle was carried out. Analysis of different volume fraction conditions, the distribution of the dynamic pressure and the turbulence viscosity of the abrasive flow field in the high precision dispensing needle, through comparative analysis, the effectiveness of the abrasive grain polishing high precision dispensing needle was studied, controlling the volume fraction of silicon carbide can change the viscosity characteristics of the abrasive flow during the polishing process, so that the polishing quality of the abrasive grains can be controlled.

Numerical Simulation Analysis of Five-Step Variable-Diameter Pipe with Solid-Liquid Two-Phase Abrasive Flow Polishing

In many areas of precision machining abrasive flow polishing technology has an important role. In order to study the influence of abrasive flow on the polishing effect of variable diameter parts, the fifth step variable diameter tube was taken as the research object to analyze the dynamic pressure and turbulent kinetic energy distribution of inlet velocity on the fifth-order variable diameter tube influences. Through comparative analysis, the abrasive flow polished variable diameter pipe parts have very effective and significant polishing effect and the higher the inlet speed, the more significant the polishing effect.

三相磨粒流抛光及其气泡溃灭分布特性

三相磨粒流抛光及其气泡溃灭分布特性

Numerical and experimental study on low-pressure abrasive flow polishing of rectangular microgroove

A low-pressure abrasive flow polishing (LAFP) technology is presented to address the issue of fabricating rectangular microgroove of Cu and SUS304 materials. The effects of abrasive flow on the polishing efficiency and uniformity are analyzed numerically and experimentally. The rectangular structure of polishing microchannel is designed and optimized by simulating the trajectory and erosion action of particles using computational fluid dynamics (CFD) model. The distributions of turbulence intensity and shear force in the polishing microchannel are analyzed. Polishing experiments are conducted to fabricate microgrooves on Cu and SUS304 materials. The experimental results reveal the increase of material removal with the increase in particle size, polishing pressure, and particle concentration. Surface roughness of Ra 4.8nm and Ra 12.7nm are respectively obtained when polishing the rectangular microgroove of Cu and SUS304 materials. Simulation and experimental results show that LAFP using polishing microchannel can fabricate microstructures with high-quality surface.

Numerical analysis of spiral curved tube of the solid liquid two phase abrasive flow polishing

In order to solve the problem that the inner surface of heterosexual surface parts is difficult to be machined, a solid-liquid two-phase abrasive flow machining method is proposed. The standard model and the pressure-coupled SIMPLEC algorithm are used. The dynamic characteristics of the dynamic pressure, turbulent kinetic energy and turbulence intensity of the polygonal spiral surface flow channel were obtained by numerical analysis of the solid-liquid two-phase abrasive grain polished polygonal spiral curved pipe under different outlet pressure conditions. The numerical simulation results show that the grinding effect is inversely proportional to the outlet pressure. We can achieve better polishing effect by appropriately reducing the outlet pressure.

Numerical simulation analysis of valve spool double-nozzle with abrasive flow

In order to study the numerical simulation of abrasive flow polishing small hole parts, the servo valve spool double nozzle parts were used as the research object, and the solid-liquid two-phase abrasive flow were used for numerical simulation, getting the dynamic pressure, velocity cloud and turbulent kinetic energy of the abrasive flow are obtained at different inlet velocities. Through the comparative analysis, the effect of the process parameters on the effect of the abrasive flow polishing small hole parts was obtained, which can provide a theoretical basis for the continuous improvement of the ultra-precision machining technology to promote the abrasive flow, so that the fatigue strength of the workpiece is improved, the reliability of the workpiece is enhanced and its service life is prolonged.

Numerical simulation analysis of large eddy simulation for T-tube based on solid-liquid two-phase abrasive flow

As a kind of nano machining technology, abrasive flow polishing technology plays an important role in precision machining region. As an important numerical simulation method in fluid mechanics, large eddy numerical simulation method has become an important method for many scholars to study abrasive grain polishing technology. In this paper, the use of fluid mechanics software FLUENT and selected Mixture mixed model. Based on the theory of solid-liquid two-phase flow dynamics, the large-eddy numerical simulation method was used to study the polishing process of T-tube abrasive flow, and the micro-machining mechanism of abrasive-polished workpiece was discussed. The influence of the different inlet velocities on the polishing effect of the abrasive grains was discussed by analyzing the numerical simulation results of the different inlet velocities of the abrasive grains during the processing of the T-tube.

Surface finish control of additively-manufactured Inconel 625 components using combined chemical-abrasive flow polishing

Little is understood about how to improve the interior surface quality of complex parts produced using additive manufacturing techniques, such as selective laser melting (SLM) and electron beam melting (EBM). Two surface-related problems can be highlighted in this context: the presence of semi-welded particles and a significant surface roughness and texture. Semi-welded particles could cause pollution in the fluid system of an engine part, while a significant surface roughness and texture could compromise fluid flow. This study aimed to design, manufacture and validate an innovative finishing technique combining chemical and abrasive flow polishing of interior surfaces of tubular IN625 components designed for the aerospace industry. The synergistic effect stemming from a combined use of the chemical and abrasive flows was investigated by studying: a) the flow of abrasive particles suspended in water, b) the flow of a chemical solution without abrasives, and c) the flow of abrasive particles suspended in a chemical solution. Considering the complexity of additively-manufactured components, the effect of the SLM build orientation on the internal surface finish was also characterized. The roughness and three-dimensional topography of the polished surface of IN625 parts for two SLM building orientations were assessed using the profilometry and confocal laser scanning microscopy techniques. The results obtained show that by employing the combined chemical-abrasive flow polishing technique, semi-welded particles on the interior surfaces of IN625 components can be completely removed and the surface roughness and texture, significantly improved.

Numerical analysis and experimental study on micro-holes in solid-liquid two-phase abrasive flow machining

In order to solve the problem that the aperture of the small hole part is too small and the irregular shape of the surface is difficult to be processed. A solid - liquid two - phase abrasive grain polishing method is proposed. Based on the standard model and SIMPLEC algorithm, the numerical simulation of the surface of the micro – holes were carried out under different inlet speed conditions. The change of the turbulence kinetic energy, dynamic pressure and turbulence intensity of the micro – holes flow channel with the inlet velocity is discussed. The quality control law of the inlet velocity on the sol-id-liquid two-phase abrasive flow polishing. In order to verify the accuracy of the numerical analysis, the necessary solid-liquid two-phase flow polishing test was carried out with the micro-hole parts. The surface roughness of the inner surface of the micro-holes before and after polishing was tested. The results show that the surface roughness is reduced from 1.702 before polishing to 0.303 after polishing. The solid - liquid two - phase abrasive flow machining can effectively improve the surface quality of micro – holes.

Numerical analysis in viscosity-temperature characteristics of solid-liquid two-phase abrasive flow polishing

The non-linear tube is widely used in military and civil fields and the general performance of the machine depends on the internal channel surface quality of it. The effective ways to improving the surface quality is solid-liquid two-phase abrasive flow polishing technology. So, the numerical analysis about the internal channel of non-linear tube polished by abrasive flow is implemented to analyze the effect of viscosity-temperature characteristics of abrasive flow polishing on the internal channel surface quality. Turbulent kinetic energy, intensity and viscosity, nephogram of the dynamic pressure distribution, and corresponding relation of temperature and turbulent kinetic energy, near the wall of non-linear tube, are received from the simulation in different initial turbulent kinetic energy and temperature which provides a theoretical basis for controlling the surface quality.

Study on the polishing of curved pipe parts by solid liquid two phase abrasive flow

In order to study the effect of abrasive flow on the polishing quality of the elbow parts, 90° elbow is used as the research object. The dynamic pressure and wall shear force of different incident angle flow is numerically simulated by setting the process parameters of elbow polishing, which shows that the properly increase entrance angle can improve the uniformity and reliability of abrasive flow polishing, and then, the numerical simulation analysis of turbulence viscosity and wall shear force for different incident pressures are also simulated. It indicates that the properly enhance inlet pressure is helpful to improve the polishing effect and polishing uniformity. Finally, the abrasive grain polishing test is carried out. After the measurement by Mahr stylus measuring instrument, the surface roughness decreases from 1.968 μm to 0.212 μm, which confirm the effectiveness of abrasive flow processing. The roughness value of the inside at the bend after the polishing of the abrasive grain is 0.274 μm by the measurement of the NT1100 Grating Surface Roughness Meter under the pressure condition of 7 MPa. By comparing the polishing effect of the pipe at different pressure and inflow angle, it is found that increase the pressure and inlet angle can improve the polishing effect of the abrasive flow on the curved pipe, but at the same time the uniformity of the polishing is decreased, in other words, the roughness gap at different positions of the elbow will increase. Therefore, it is exceedingly necessary to make some adjustments when in the actual operation.

Numerical and experimental study on the spiral-rotating abrasive flow in polishing of the internal surface of 6061 aluminium alloy cylinder

A spiral-rotating abrasive flow polishing technology was presented and discussed in this paper to address the issue of precision polishing of internal surface of the cylinder for 6061 aluminium alloy. The effect of the spiral-rotating abrasive flow on the polishing quality, i.e. polishing efficiency and uniformity, was analysed both numerically and experimentally. The relative equations involved in the spiral-rotating abrasive flow were first developed to simulate the particle trajectories by considering the centrifugal force, Coriolis force, Magnus force and Saffman force with Computational Fluid Dynamics method. Numerical simulation shows that the tangential velocity of the abrasive particles near the internal surface increases significantly with an increase of the rotation speed of the constraint module, and due to the spiral-rotating action the near-wall abrasive particles exhibits random direction and uniform magnitude at velocity, such that this technology is expected to enhance the polishing efficiency and uniformity. Experimental study indicates that the line roughness on the target surface decreases with an increase in the rotation speed due to the increased tangential velocity of impacting particles that enhance the micro-cutting action on the target surface, and hence, resulting in a better surface finish. While the material removal rate increases with an increase of the rotation speed due to the larger kinetic energy brought into the process by the rotation of the constraint module, so that the polishing efficiency could be significantly improved. These findings from the experiment are in a good agreement with the corresponding simulation results.

Optimization of abrasive flow polishing process parameters for static blade ring based on response surface methodology

Static blade ring process technology is a key part for gas turbine manufacturing, and the surface quality of the static blade ring has great influence on a gas turbine. To improve surface roughness of static blade ring, abrasive flow polishing process technology is studied. First, the range of extrusion pressure is obtained by using ANSYS software to analyze the blade deformation. Then a simplified model of surface roughness is estabalished according to experimental results and ANOVA’s results. At the same time, the optimal polishing parameters are confirmed through the response surface methodology. Finally, the polishing experiment is carried out by using the optimal polishing parameters. The experimental results demonstrate that the surface roughness of static blade ring decreased greatly (nearly 14.7%) compared with result using normal parameters.

Process parameters optimisation for Si3N4 in chemical-mechanical polishing via Taguchi technique

By applying chemical-mechanical polishing (CMP) technique to high precision processing of rotary curved surface workpieces of silicon nitride (Si3N4) ceramic, a CMP experimental device was established on a numerical control (NC) jig grinder. Using Taguchi robust design method, through signal to noise ratios (S/N ratios) and analysis of variance, the influence of slurry concentration, slurry flow rate and polishing wheel speed on surface roughness was analysed. With the increase of polishing wheel speed, the surface roughness Ra increased. The optimal process parameters of CMP on rotary curved surface workpieces of Si3N4 ceramic were selected: slurry concentration of 20%, polishing wheel speed of 6,000 r/min, and slurry flow rate of 0.6 L/min. The result showed that the descending order of selected process parameters impacting on surface roughness was polishing wheel speed, slurry flow rate and slurry concentration.

金型微細溝内面の砥粒流動研磨

金型微細溝内面の砥粒流動研磨

Experimental study on large size bearing ring raceways’ precision polishing with abrasive flowing machine (AFM) method

In some developing countries, the raceways of large bearing rings with outer diameters of 200 mm and above are ground and then are assembled and ready to leave the factory. While in the developed countries, they are superfinished with the high-frequency oscillation of whetstones, which is the only and conventional way and with a high cost. This paper presents a research on the precision polishing of large bearing ring raceways by an abrasive flow machine. This research adopts the ideas of forward design and reverse design in the design and manufacture of complex curved profile sections of the abrasive flow machine’s clamp and integrates the 3D scanning reverse and 3D printing technology into the design of the abrasive flow machine’s fixture, which reduce the bearing rings’ surface roughness from 0.4 μm after grinding to 0.1 μm after abrasive flow polishing, and change the surface microstructure and texture. This research provides new ideas and methods in bearing ring raceways’ superfinishing process and abrasive flow fixture design.

The Research of Extruded Pressure Auto-Adjustment Method in Abrasive Flow Polishing

Aiming at the quality problems of ‘over polishing’ and ‘insufficient polishing’ in the process of traditional extrusion abrasive flow machining,An abrasive flow polishing method at the constantly small pressure difference is developed, the hydraulic proportional control system is designed, and the mathematical modeling of the hydraulic proportional control system for small pressure difference constant extrusion polishing abrasive flow machining is set up. The simulation results show that the polishing pressure can be well controlled and the stability of polishing velocity is improved, which will improve the extrusion abrasive flow polishing quality.

Optimization of chemical mechanical polishing parameters on surface roughness of steel substrate with aluminum nanoparticles via Taguchi approach

Purpose – The purpose of this paper is to investigate the effects of abrasive contents, oxidizer contents, slurry flow rate and polishing time in achieving a mirror-like finish on polished surfaces. Chemical mechanical polishing (CMP) is now widely used in the aerospace industry for global planarization of large, high value-added components. Design/methodology/approach – Optimal parameters are applied in experimental trials performed to investigate the effects of abrasive contents, oxidizer contents, slurry flow rate and polishing time in achieving a mirror-like finish on polished surfaces. Taguchi design experiments are performed to optimize the parameters of CMP performed in steel specimens. Findings – Their optimization parameters were found out; the surface scratch, polishing fog and remaining particles were reduced; and the flatness of the steel substrate was guaranteed. The average roughness (Ra) of the surface was reduced to 6.7 nm under the following process parameters: abrasive content of 2 weight per cent, oxidizer content of 2 weight per cent, slurry flow rate of 100 ml/min and polishing time of 20 min. Originality/value – To meet the final process requirements, the CMP process must provide a good planarity, precise selectivity and a defect-free surface. Surface planarization of components used to fabricate aerospace devices is achieved by CMP process, which enables global planarization by combining chemical and mechanical interactions.