Soft Abrasive Flow Machining Research Articles

Magnetic-assisted soft abrasive flow machining studied with smoothed particle hydrodynamics

In many microsystem applications, a nanometric surface quality is crucial to the performance of a device. Soft abrasive flow machining (SAFM) is capable of finishing surfaces at very fine scale with complex geometries since, unlike traditional flow machining processes, abrasive grains are carried by a very low viscosity fluid. Several empirical studies have been done to ensure final high quality surfaces by enhancing the performance of SAFM. However, the present study aims to propose a consistent numerical approach which can handle the fluid-structure interface problems as well as surface erosion to model SAFM and help to gain deeper understanding of the process. Moreover, the approach is employed to investigate the effect of an external magnetic field on the performance of the machining process. All phases, namely carrier fluid, abrasive grains and workpiece, and their interactions are fully resolved by using smoothed particle hydrodynamics. The abrasive grains are modeled by particles that are rigidly moved together. The approach is used to study the surface finishing of a Polymethyl Methacrylate-based microchannel under external magnetic fields. Results show that a magnetic field of suitable strength can considerably improve the material removal rate and hence enhance the performance of SAFM.

Study on turbulence control method and surface quality analysis of softness abrasive flow machining

Study on turbulence control method and surface quality analysis of softness abrasive flow machining

Study on turbulence control method and surface quality analysis of softness abrasive flow machining

To improve mould structural surface quality, the softness abrasive flow (SAF) finishing method is proposed. By setting restrained component to the mould surface, restrained flow passage can be set up. In the flow passage, micro force and quantity cutting for the tiny scale structural surface is realised by using the turbulence wall effect of SAF. Dynamical model of SAF is established based on liquid-solid two-phase flow coupling theory. Semi-annular flow passage is taken as the research object, and turbulent parameters with different flow passages are analysed by using standard k-e turbulent model and discrete phase model (DPM), which is used for describing the influence to turbulent state caused by different boundary conditions, meanwhile, the optimisation design of finishing parameters can be obtained. Finishing platform is constructed, and finishing experiment results show that with the SAF method, the roughness machined is less than Ra 62 nm.

Soft Abrasive Flow Machining

Soft Abrasive Flow Machining (SAFM) was presented as a new finishing process about the existing problems that the irregular surface of plastic mould was polishing difficultly. The paper first introduced the working principle and feature of SAMF. Secondly, the main influences of SAFM were analyzed. The problem of technology and theory urgent to settle was discussed. At the last, the technology development of SAFM was expected.

Numerical Analysis and Processing Experiment of Double-inlet Restraint Flow Field in the Soft Abrasive Flow Machining

Uneven processing effect is conducted by the single-inlet processing device in soft abrasive flow machining,to overcome this problem,a novel double-inlet processing method is brought forward based on the liquid collision theory.Combining shear stress transport(SST) k-ω turbulence model with the mixture model in computational fluid dynamics software,the dynamics characteristics for two kinds of processing devices are studied.The results show that flow field distribution of single-inlet processing device is fixed;on the contrary,a cyclic swing occurs in double-inlet processing device,and there is an improvement of the disorderly movement of abrasive flow.Work piece surface roughness value Ra in single-inlet processing device is disperse after 35 h,and the processing effect is uneven,while the surface roughness of work piece in double-inlet processing device has a centralized distribution and a smaller value than that in single-inlet processing device,and the processing effect is better.The above results show that the flow filed in restraint channel is disturbed by two flows in the double-inlet processing device,disorderly movement of the abrasive flow is improved,and processing quality is better.

Analytical method of softness abrasive two-phase flow field based on 2D model of LSM

To solve the precision machining problem in the structural surface mould manufacturing process, a new no-tool precision machining method based on softness abrasive flow machining (SAFM) is proposed. The key technology of SAFM is the characteristic analysis of two-phase flow. To solve this problem, a two-dimensional model of the two-phase flow is established by the topological structure transformation of level set method. This mechanics model is used to simulate the motion of the turbulent flow and work out the characteristic parameters of abrasive two-phase flow. The simulation results show that this model can preferably simulate the motion of the two-phase flow and calculate velocity and pressure with k- model and Preston equation. Therefore the feasibility of SAFM can be confirmed and a good reference can be provided for the further research.

Research of Abrasive Injection Process to the Wall and Machining Characteristic of Soft Abrasive Flow Machining

Research of Abrasive Injection Process to the Wall and Machining Characteristic of Soft Abrasive Flow Machining

Analytical Method for Softness Abrasive Flow Field Based on Low Reynolds K-ε Model

As it was difficult to solve the near wall characteristics of flow field in softness abrasive flow machining (SAFM) on mould structural surface, a method for simulation the flow characteristics based on the low Re number k-ε model was proposed in this paper. The U-shaped tube was used as specific simulation object. The motion law of particles and related parameters were calculated and the precision machining mechanism of SAFM was discussed. Simulation results show that the micro cutting of abrasive flow mainly appears as the transposition of cutting location influenced by the particle pressure, and as the variation of machining efficiency influenced by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time, it is supposed to work out the machining process according with the machining requirements. By tracking near-wall particles, it can be confirm that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement, so the feasibility of SAFM method can be reaffirmed.

Analysis for Softness Abrasive Flow Field of the Greater Curvature of Small Size Tube

As it was difficult to solve the near wall characteristics of flow field in softness abrasive flow machining (SAFM) on mould structural surface, a method for simulation the flow characteristics based on the low Re number k-ε model was proposed in this paper. The greater curvature of small size tube was used as specific simulation object. The motion law of particles and related parameters were calculated and the precision machining mechanism of SAFM was discussed. Simulation results show that the micro cutting of abrasive flow mainly appears as the transposition of cutting location influenced by the particle pressure, and as the variation of machining efficiency influenced by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time, it is supposed to work out the machining process according with the machining requirements. By tracking near-wall particles, it can be confirm that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement, so the feasibility of SAFM method can be reaffirmed.

Numerical Simulation of Softness Abrasive Two-Phase Flow Field on Level Set Method

The soft abrasive flow machining was proposed for solving the problems of difficult contact finishing in course of mould manufacturing. It could reach the specular level and control turbulence abrasive flow. Based on the topological structure transformation of LSM, a two- dimensional model of the two-phase flow is established. This mechanics model with the SIMPLE (semi-implicit method for pressure-linked equations) algorithm incorporated is used to simulate the movement of the turbulent flow by using of k-ε model. The computed results show that this 2D model can preferably simulate the movement of the two-phase flow, and the characteristic parameters of abrasive two-phase flow are derived.

Analytical method for softness abrasive flow field based on discrete phase model

Aiming at the problem of difficult contact finishing for mini structural surface in course of mould manufacturing, a new no-tool precision machining method based on soft abrasive flow machining (SAFM) was proposed. It allocated restrained component near surface machined, constituted restrained abrasive flow passage, and made the surface become a segment of passage wall. It could control turbulence abrasive flow in restrained passage, realize micro cutting for passage wall, and utilize the irregular motion of abrasive flow to eliminate the mono-directional marks on machined surfaces, and the precision could reach the specular level. A two-phase dynamic model of abrasive flow oriented to SAFM combined with discrete phase model (DPM) was established, the law of two-phase flow motion and the related physical parameters was obtained by corresponding numerical simulation method, and the mechanism of precision machining in SAFM was discussed. Simulation results show that the abrasive flow machining process mainly appears as translation of ablating location with the influence by granular pressure, and as the variation of machining efficiency with the influence by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time, it is supposed to work out the machining process according to the machining requirements by using the Preston equation to seek the relationship among velocity, pressure and material removing rate. By tracking near-wall particles, it can be confirmed that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement, so the feasibility of the SAFM method can be reaffirmed.

A New Ultraprecision Machining Method with Softness Abrasive Flow Based on Discrete Phase Model

Considering the demand of precision in mould structural surface polishing method, a new method based on soft abrasive flow machining(SAFM) was proposed, which was supposed to achieve polydirectional and multi-angle cutting acting on the surface of the workpiece by utilizing the irregular motion of both wear particles and the media in turbulence flow. Thus as the monodirectional marks on the machined surfaces was eliminated, the disadvantage in machining precision in conventional abrasive flow machining(AFM) method would be overcome. According to the particle distribution characteristics of SAFM, a two-phase dynamic model of abrasive flow oriented to SAFM combined with Discrete Phase Model(DPM) was built to analog simulation with the software Fluent. Sequently the mechanism of ultraprecision machining towards mould structural surface was analyzed briefly. Simulation results show that the abrasive efficiency along the flow passage can be influenced by the development of turbulence and the distribution of dispersed phase. Thus there a specific region can be obtained in the passage in which the abrasive efficiency is relatively stable.