CFD Modeling and Optimization of Magneto-rheological Abrasive Flow Finishing (MRAFF) Process

A modern nano finishing technique called magnetorheological abrasive flow finishing (MRAFF), which is simply a combined hybrid form of abrasive flow machining (AFM) process and magnetorheological finishing (MRF) process, has been designed for micro finishing of parts even with difficult geometry for a broad range of industrial purposes. In the present work, a model for the prediction of removal of material and surface roughness has been estimated. An effort has been made to study the flow passing through the stainless steel workpiece by CFD modeling in ANSYS 15.0 FLUENT. By assuming the medium as Bingham plastic various parameters affecting the surface roughness has been calculated. Also a theoretical calculation is made for the model if no magnetic field is applied and then comparative study of the two models is proposed. An optimization of the process has also been carried out. With the help of SN Ratio plot and Means plot optimized value of input parameters has been found out to achieve better surface finish

CFD Modeling and Optimization of Magneto-rheological Abrasive Flow Finishing (MRAFF) Process

A modern nano finishing technique called magnetorheological abrasive flow finishing (MRAFF), which is simply a combined hybrid form of abrasive flow machining (AFM) process and magnetorheological finishing (MRF) process, has been designed for micro finishing of parts even with difficult geometry for a broad range of industrial purposes. In the present work, a model for the prediction of removal of material and surface roughness has been estimated. An effort has been made to study the flow passing through the stainless steel workpiece by CFD modeling in ANSYS 15.0 FLUENT. By assuming the medium as Bingham plastic various parameters affecting the surface roughness has been calculated. Also a theoretical calculation is made for the model if no magnetic field is applied and then comparative study of the two models is proposed. An optimization of the process has also been carried out. With the help of SN Ratio plot and Means plot optimized value of input parameters has been found out to achieve better surface finish

Experimental investigation on magnetorheological finishing process parameters

Magneto-rheological polishing (MRP) fluid was developed by MR fluid using a magnetic field, non-magnetic abrasives such as SiC and Al2O3, and carrier medium like oil. A magnetic polishing tool was developed using a super-strong permanent neodymium magnet (Nd2Fe14B) with 0.5-tesla magnetic intensity. This polishing tool was assembled to the vertical milling machine for the finishing workpieces. In the present research, magnetic materials (steel material) and non-ferromagnetic (copper) content were finishing using a developed MRP setup for experimental investigation. This research also investigated the parametric dependencies of different abrasives on the magneto-rheological finishing process. It determined the effect of magnetic particle concentration and abrasives on the surface roughness of ferromagnetic (stainless steel) and non-ferromagnetic material (copper). The final surface roughness value has reached 30 nm from its initial surface roughness of 800 nm for non-ferromagnetic (copper). For the magnetic material (stainless steel), the value is 50 nm from 1300 nm

Understanding the Mechanism of Abrasive-Based Finishing Processes Using Mathematical Modeling and Numerical Simulation

Recent advances in technology and refinement of available computational resources paved the way for the extensive use of computers to model and simulate complex real-world problems difficult to solve analytically. The appeal of simulations lies in the ability to predict the significance of a change to the system under study. The simulated results can be of great benefit in predicting various behaviors, such as the wind pattern in a particular region, the ability of a material to withstand a dynamic load, or even the behavior of a workpiece under a particular type of machining. This paper deals with the mathematical modeling and simulation techniques used in abrasive-based machining processes such as abrasive flow machining (AFM), magnetic-based finishing processes, i.e., magnetic abrasive finishing (MAF) process, magnetorheological finishing (MRF) process, and ball-end type magnetorheological finishing process (BEMRF). The paper also aims to highlight the advances and obstacles associated with these techniques and their applications in flow machining. This study contributes the better understanding by examining the available modeling and simulation techniques such as Molecular Dynamic Simulation (MDS), Computational Fluid Dynamics (CFD), Finite Element Method (FEM), Discrete Element Method (DEM), Multivariable Regression Analysis (MVRA), Artificial Neural Network (ANN), Response Surface Analysis (RSA), Stochastic Modeling and Simulation by Data Dependent System (DDS). Among these methods, CFD and FEM can be performed with the available commercial software, while DEM and MDS performed using the computer programming-based platform, i.e., "LAMMPS Molecular Dynamics Simulator," or C, C++, or Python programming, and these methods seem more promising techniques for modeling and simulation of loose abrasive-based machining processes. The other four methods (MVRA, ANN, RSA, and DDS) are experimental and based on statistical approaches that can be used for mathematical modeling of loose abrasive-based machining processes. Additionally, it suggests areas for further investigation and offers a priceless bibliography of earlier studies on the modeling and simulation techniques for abrasive-based machining processes. Researchers studying mathematical modeling of various micro- and nanofinishing techniques for different applications may find this review article to be of great help

Modeling of finishing force and torque in ultrasonic-assisted magnetic abrasive finishing process

A new finishing technique called ultrasonic-assisted magnetic abrasive finishing integrates ultrasonic vibration with magnetic abrasive finishing process for finishing of workpiece surface more efficiently as compared to magnetic abrasive finishing in the nanometer range. During finishing, two types of forces are generated in ultrasonic-assisted magnetic abrasive finishing, namely, a normal force (indentation force) and a tangential force (cutting force) that produces a torque. The finishing forces have direct control on the rate of change of surface roughness and material removal rate of the workpiece surface. This article deals with the theoretical modeling of the normal force and the finishing torque based on the process physics. In this work, finite element simulations of the electromagnet were performed to calculate a magnetic flux density in the working zone; they were also used to evaluate the normal force on the workpiece surface. The theory of friction for the abrasion of metals was applied together with the effect of ultrasonic vibration to calculate the finishing torque. The developed model predicts the normal force and finishing torque in ultrasonic-assisted magnetic abrasive finishing as functions of the supply voltage, working gap and concentration of abrasive particles in a flexible magnetic abrasive brush. A comparison of theoretical and experimental results is performed to validate the proposed model

Analysis of magnetic field assisted finishing (MFAF) process parameters for finishing brass workpiece using Soft-Computing Technique

Abstract Magnetic Field Assisted Finishing (MFAF) process is a precise nanofinishing process. Magnetorheological (MR) fluid is the main element in MFAF process. In these process two types of motion, rotational and reciprocation is provided to the MR fluid to get uniform smooth finished surface. Brass is used as the workpiece. The input process parameters are extrusion pressure, number of finishing cycles, rotational speed of the magnet, and volume ratio of carbonyl iron particle (CIP) and silicon carbide (SiC) in the medium. The output process parameter is percentage change in surface roughness. In this study the relationship between the input and output process parameters of MFAF is established using Backpropagation neural network technique. Also a close comparison has been made between the regression analysis model and neural network model of the process parameters. From the simulation results, it has been found that the neural network model yields a more accurate result than the regression analysis method. Further an optimization study has been carried out to optimize the input process parameters to get maximum output. Genetic algorithm (GA) technique is used as the optimization technique consideringregression equation model as the objective function. The optimized process parameters agree well with the experimental results

Precision Surface Processing and Software Modelling Using Shear-Thickening Polishing Slurries

Mid-spatial frequency surface error is a known manufacturing defect for aspherical and freeform precision surfaces. These surface ripples decrease imaging contrast and system signal-to-noise ratio. Existing sub-aperture polishing techniques are limited in their abilities to smooth mid-spatial frequency errors. Shear-thickening slurries have been hypothesised to reduce mid-spatial frequency errors on precision optical surfaces by increasing the viscosity at the tool-part interface. Currently, controlling the generation and mitigating existing mid-spatial frequency surface errors for aspherical and freeform surfaces requires extensive setup and the experience of seasoned workers. This thesis reports on the experimental trials of shear-thickening polishing slurries on glass surfaces. By incorporating shear-thickening slurries with the precessed bonnet technology, the aim is to enhance the ability of the precessions technology in mitigating mid-spatial frequency errors. The findings could facilitate a more streamlined manufacturing chain for precision optics for the versatile precessions technology from form correction and texture improvement, to MSF mitigation, without needing to rely on other polishing technologies. Such improvement on the existing bonnet polishing would provide a vital steppingstone towards building a fully autonomous manufacturing cell in a market of continual economic growth. The experiments in this thesis analysed the capabilities of two shear-thickening slurry systems: (1) polyethylene glycol with silica nanoparticle suspension, and (2) water and cornstarch suspension. Both slurry systems demonstrated the ability at mitigating existing surface ripples. Looking at power spectral density graphs, polyethylene glycol slurries reduced the power of the mid-spatial frequencies by ~50% and cornstarch suspension slurries by 60-90%. Experiments of a novel polishing approach are also reported in this thesis to rotate a precessed bonnet at a predetermined working distance above the workpiece surface. The rapidly rotating tool draws in the shear-thickening slurry through the gap to stiffen the fluid for polishing. This technique demonstrated material removal capabilities using cornstarch suspension slurries at a working distance of 1.0-1.5mm. The volumetric removal rate from this process is ~5% of that of contact bonnet polishing, so this aligns more as a finishing process. This polishing technique was given the term rheological bonnet finishing. The rheological properties of cornstarch suspension slurries were tested using a rheometer and modelled through CFD simulation. Using the empirical rheological data, polishing simulations of the rheological bonnet finishing process were modelled in Ansys to analyse the effects of various input parameters such as working distance, tool headspeed, precess angle, and slurry viscosity

A Fuzzy Logic based Model to Predict the Improvement in Surface Roughness in Magnetic Field Assisted Abrasive Finishing

AbstractIn this paper the effect of process parameters during Magnetic Field Assisted Abrasive Micro Finishing (MFAAF) of SS316L material is reported. Based on the experimental results obtained, S/N ratio and ANOVA analyses were made to identify the significant process parameters to improve the percentage improvement of surface roughness (%ΔRa). From the results it is observed that the process parameters like voltage applied to the electromagnet, machining gap, rotational speed of electromagnet followed by abrasive size are significant to improve the %ΔRa. Based on the process parameters selected from the S/N ratio analysis and ANOVA analysis, a fuzzy logic model has been developed to predict the %ΔRa. To develop the fuzzy model, four membership functions based on the four process parameters are assigned to be connected with each input of the model. The developed fuzzy model is tested using three different set of process parameters values that are not used in already existing experimental data set. It is found that the developed fuzzy model has a close relation with the experimental values with the maximum deviations of 7.16%

Development of Mathematical Model and Characterization of Internal Surface Obtained by Elasto-Abrasives Magneto-Spiral Finishing (EAMSF)

The implantation of stents and instruments with capillary action demands super-finished internal surfaces of the manufactured product. Elasto-abrasives magneto-spiral finishing (EAMSF) is the attempt made in this paper to enhance finishing productivity by incorporating the abrasive flow in spiral motion due to the presence of the magnetic field. Here, novel impregnated elasto-magnetic abrasive particles (IMPs) are used in a magnetic field-assisted environment to polish the inner walls of the workpiece. In EAMSF, magnetic force provides excess finishing pressure to the abrasives. In contrast, the high-impact polystyrene (HIPS) elasticity absorbs the extra force of the IMPs on the finishing surface. An Indigenous mathematical relation considering the physics of this superfinishing process indicating material removal shows a close resemblance to the experimental results with an error percentage of 1.03 has been developed. The results of the experimentation reveal that 50% concentration of abrasives and a magnetic field density of 18mT yield a superior surface finish with a Ra value equal to 0.053 μm and maximum material removal of 6.9 mg, while in the absence of a magnetic field, excellent surface finish with a Ra=0.266 μm and maximum material removal of 5.4 mg is achieved. In the presence of magnetic field density, significant enhancement of material removal, surface finish, and burr removal is observed. Finishing the surface at 50% abrasive concentration with a magnetic field represents regular finishing, and the trench marks on the original surface are removed after finishing

Fundamental Investigation on Nano-precision Surface Finishing Using MCF (Magnetic Compound Fluid) Slurry

秋田県立大学平成26年