Magnetic Abrasive Particles Research Articles

Multiobjective optimization of magnetic abrasive finishing process with periodic re-distribution of magnetic abrasive particles on 17-4PH stainless steel

Magnetic abrasive finishing (MAF) exhibits considerable potential as a promising process for enhancing surface finish quality for softer as well as harder materials. This work proposes a novel approach to harness the potential of MAF for obtaining superior surface quality of precipitation-hardening martensitic steel (17-4PH steel) while performing periodic re-distribution of magnetic abrasive particles. The experiments were conducted using the Box-Behnken design of experiments and response surface methodology (RSM). RSM-based desirability function approach and genetic algorithms were used for multiobjective optimization. The set of pareto-optimal solutions obtained through multiobjective optimization were ranked using the Technique for Order of Preference by Similarity to an Ideal Solution (TOPSIS) by assigning equal importance to the selected performance parameters (percentage change in surface roughness (PCSR) and material removal rate (MRR)). The optimized values of PCSR and MRR obtained through the desirability function of RSM and genetic algorithm were validated experimentally and compared with the predicted values obtained through the regression model. Results showed that the desirability function of RSM provided better results than the genetic algorithm for the selected conditions and confirmed the effectiveness of the proposed approach.

Fabrication of a new core–shell structured magnetic abrasive particles with good performance

The traditional Fe-based magnetic abrasive powders (MAPs) are prone to degrade by corrosion and oxidation. The extremely low stability to some extent limits the development of magnetic finishing. In this study, a new kind of 410 stainless steel-based spherical MAPs with core–shell structure was synthesized by gas nitriding. The nitride layer shows the dendrite structure containing (Fe, Cr)4N phase and lath-like CrN phase. The Zirconium tube roughness can be reduced from 0.280 to 0.153 μm. The origin of the good finishing performance was investigated through the Vickers hardness and nanoindentation tests.

Simulation and experimental study of tool passivation based on magnetic elastic abrasive particles

The presence of micro-cracks and serrations on the tool often leads to its premature failure. However, these microscopic defects can be mitigated through passivation treatment of the tool. Magnetoelastic abrasive particles are new composite particles formed by using abrasive phase particles, magnetic media phase particles and polymer matrix according to a certain ratio, the abrasive particles have both viscoelasticity and magnetic conductivity. The introduction of magnetoelastic abrasive grains into the dual-disk tool passivation equipment can effectively improve the surface quality of the tool and increase the passivation efficiency. At the outset, a model for tool passivation was crafted employing the ABAQUS simulation software. This model aimed to evaluate the effects of diverse passivation variables on the stress levels, the shape of the impact, and the depth of the impact experienced by the tool. Subsequently, by applying statistical theory combined with fitting function techniques, a mathematical model was constructed to determine the passivation volume of the tool subjected to multiple magnetic elastic abrasive particles. This model was then used to examine the impact count and passivation volume associated with each passivation factor. Finally, a tool passivation experiment was conducted using a dual-disk magnetic tool passivation device. The results showed that the smaller the impact velocity of magnetic elastic abrasive particles, the stress and impact depth of the cutting tool are decreasing, and the deformation of the cutting edge is caused by compressive stress. The error of impact depth calculated by simulation and mathematical model is within 20 %, which proves that the mathematical model can better calculate the impact depth of magnetic elastic abrasive particles on the cutting edge of the tool.

Processing Optimization for Halbach Array Magnetic Field-Assisted Magnetic Abrasive Particles Polishing of Titanium Alloy.

To extend the working life of products made of titanium alloy, it is necessary to improve the polishing method to diminish the remaining defects on the workpiece surface. The Halbach array-assisted magnetic abrasive particle polishing method for titanium alloy was employed in this work. The distribution of magnetic field strength was simulated and verified at first to learn the characteristics of the Halbach array used in this work. Then, the polishing performance of the polishing tool was studied by conducting the polishing test, which aimed to display the relationship between shear force and surface roughness with polishing time, and the surface morphology during polishing was also analyzed. Following the establishment of the response surface model, a study on the optimal polishing parameters was conducted to obtain the suitable parameters for maximum shear force and minimum surface roughness. The results show that the maximum shear force 6.11 N and minimum surface roughness Sa 88 nm can be attained, respectively, under the conditions of (1) polishing tool speed of 724.254 r·min-1, working gap of 0.5 mm, and abrasive particle size of 200 μm; and (2) polishing tool speed of 897.87 r·min-1, working gap of 0.52 mm, and abrasive particle size of 160 μm.

Achieving in-situ Fe-based spherical particles for magnetic abrasive finishing process of Zirconium tube via gas nitriding method

The magnetic abrasive powders have great influence on the magnetic abrasive finishing accuracy and efficiency. A new kind of Fe-based spherical magnetic abrasive particles with Fe2N precipitates and Fe4N matrix was successfully synthesized by gas nitriding. The results show that the prepared Fe-based magnetic abrasive particles can reduce the roughness of the Zirconium tube from 0.325 to 0.154 μm by four MAF passes. The high hardness and wear resistance of the Fe-based magnetic abrasive particles are assessed based on the Vickers hardness and nanoindentation results. This study can provide theoretical and experimental support for fabricating high-performance magnetic abrasive particles.

A Comparative Study of Machining Property in Inconel 718 Superalloy Grinding with Al2O3- and CBN/Fe-Based Spherical Magnetic Abrasives

A comparative analysis was studied on the finishing performance of spherical CBN/Fe-based magnetic abrasive particles (MAPs) and Al2O3/Fe-based magnetic abrasive particles (MAPs) prepared by the gas atomization method in the magnetic abrasive finishing (MAF) of the Inconel 718 superalloy. In the MAF, it was found that compared with Al2O3/Fe-based MAPs, CBN/Fe-based MAPs have a lower grinding temperature and generate less heat during the grinding of the Inconel 718 superalloy. The grinding pressure generated on the workpiece is relatively stable (Al2O3/Fe-based MAPs have a larger fluctuation range of grinding pressure on the workpiece surface during the grinding process). The surface roughness of the workpiece rapidly drops from Ra 0.57 μm to Ra 0.039 μm, and the material removal reaches 42 mg within 20 min. After finishing, the scratches on the surface of the workpiece basically disappear, the contour curve is relatively flat, and there is almost no adhesion on the surface of the workpiece. The mirror effect of the superalloy surface is good, and ultimately a better surface quality can be obtained.

Investigation of Synthesis, Characterization, and Finishing Applications of Spherical Al2O3 Magnetic Abrasives via Plasma Molten Metal Powder and Powder Jetting.

Magnetic abrasive finishing (MAF) is an efficient finishing process method using magnetic abrasive particles (MAPs) as finishing tools. In this study, two iron-based alumina magnetic abrasives with different particle size ranges were synthesized by the plasma molten metal powder and powder jetting method. Characterization of the magnetic abrasives in terms of microscopic morphology, phase composition, magnetic permeability, particle size distribution, and abrasive ability shows that the magnetic abrasives are spherical in shape, that the hard abrasives are combined in the surface layer of the iron matrix and remain sharp, and that the hard abrasives combined in the surface layer of the magnetic abrasives with smaller particle sizes are sparser than those of the magnetic abrasives with larger particle sizes. The magnetic abrasives are composed of α-Fe and Al2O3; the magnetic permeability of the magnetic abrasives having smaller particle sizes is slightly higher than that of the magnetic abrasives having larger particle sizes; the two magnetic abrasives are distributed in a range of different particle sizes; the magnetic abrasives have different magnetic permeabilities, which are higher than those of the larger ones; both magnetic abrasives are distributed in the range of smaller particle sizes; and AZ31B alloy can obtain smaller surface roughness of the workpiece after the grinding process of the magnetic abrasives with a small particle size.

Experimental Investigation on Magnetic Abrasive Finishing for Internal Surfaces of Waveguides Produced by Selective Laser Melting.

To enhance the surface quality of metal 3D-printed components, magnetic abrasive finishing (MAF) technology was employed for post-processing polishing. Experimental investigation employing response surface methodology was conducted to explore the impact of processing gap, rotational speed of the magnetic field, auxiliary vibration, and magnetic abrasive particle (MAP) size on the quality enhancement of internal surfaces. A regression model correlating roughness with crucial process parameters was established, followed by parameter optimization. Ultimately, the internal surface finishing of waveguides with blind cavities was achieved, and the finishing quality was comprehensively evaluated. Results indicate that under optimal process conditions, the roughness of the specimens decreased from Ra 2.5 μm to Ra 0.65 μm, reflecting a reduction rate of 74%. Following sequential rough and fine processing, the roughnesses of the cavity bottom, side wall, and convex surface inside the waveguide reduced to 0.59 μm, 0.61 μm, and 1.9 μm, respectively, from the original Ra above 12 μm. The findings of this study provide valuable technical insights into the surface finishing of metal 3D-printed components.

Characteristics of magnetic elastic abrasive particles and their effect on tool passivation

Characteristics of magnetic elastic abrasive particles and their effect on tool passivation

A new magnetic enhanced chemical mechanical polishing method for quartz glass slender holes

Due to the limitations of tool size, field assisted polishing methods are often employed for polishing the internal surfaces of slender holes with large aspect ratios. However, in existing polishing methods, fields are often applied in isolation, which limits the ability to obtain high surface quality. Furthermore, it is rare for polishing method studies to fully leverage the advantages of multiple fields to create a synergistic effect. Therefore, developing a polishing method that harnesses the synergistic interaction of multiple fields, and revealing the polishing mechanism, is crucial for achieving high-quality internal surfaces of quartz slender holes. To address this problem, a novel magnetic enhanced chemical mechanical polishing method was proposed in this paper and a systematic process study was carried out to analyze the synergistic effects of magnetic and chemical fields. To evaluate the effects of process parameters on material removal and forecast MRR, the material removal process was modeled and validated based on the consistency between experimental and theoretical values. Suitable process parameters are determined through experiments and analysis on magnetic field distribution and process parameters. By conducting EDS mapping and XPS analyses on the reaction product, the enhancement mechanism of magnetic field on material removal in the chemical mechanical polishing process was identified. Under the assistance of a magnetic field, the magnetic abrasive particles encircle the CeO2 particles to fully contact the workpiece surface. The contact force between the polishing tool and the workpiece surface increase. Both of the effects promote the chemical reaction and enable the reaction layer on the surface to be removed in time to obtain higher surface quality. As a result, this method achieves high-efficiency and high-quality polishing, significantly reducing the surface roughness Sa of slender holes from 0.3 μm to 77 nm, with a material removal rate of 141 μm/h.

Modelling and simulation of tool passivation by magnetic elastic abrasive particles

Magnetic elastic abrasive particles possess magnetism, low elasticity, and excellent grinding performance. Utilizing a double magnetic disk magnetic force tool for passivation can significantly enhance the efficiency and quality of passivation. Firstly, a mathematical model for the impact depth and volume on the tool is established. Secondly, using the simulation software ABAQUS, a simulation model is constructed to investigate the influence of grit size, quantity of abrasives, impact angle, disk rotation speed, and tool rotation speed on stress, energy, impact depth, and impact volume. Furthermore, the feasibility of the simulation and the reliability of the mathematical model are verified.

Investigation of the Effect of Debris Position on the Detection Stability of a Magnetic Plug Sensor Based on Alternating Current Bridge.

Magnetic plug-type abrasive particle sensors have a wide range of applications in oil detection, but there is little literature on the effect of abrasive particle position on detection accuracy. In this paper, an alternating current (AC) bridge-type abrasive particle detection sensor is designed, in which the sensing module utilizes permanent magnets to attract iron particles, and the induction coil is specially designed to detect the magnetic field fluctuation caused by iron particles. A corresponding model was also designed to evaluate the sensor's sensitivity at different locations. In this paper, the magnetic field distribution of the sensor was first analyzed using finite element analysis software to obtain the magnetic field strength at different positions. Then, the response sensitivity of the sensor to particles and the effect of different positions on the detection results are explored through experiments. The simulation and the experimental results show substantial signal difference signal at different sensor positions. The method outlined in this article can determine the optimal sensing range for subsequent magnetic plug-type abrasive particle detection sensors and subsequently improve their reliability.

Optimizing processing performance of Fe-6.5 wt%Si–SiC magnetic abrasive particles by in-situ formation of FexSiy interlayer

The Magnetic Abrasive Finishing (MAF) technology has demonstrated significant potential for precision machining due to its adaptable processing characteristics. However, the current methods for preparing Magnetic Abrasive Particles (MAPs) suffer from issues such as high cost, uneven particle size distribution, and unsatisfactory structure. In this paper, a two-step ball milling method is proposed to address these problems and produce MAPs with a uniform core-shell structure. During the ball milling process, nanoscale iron powder (NIP) is added and forms a coated intermediate bonding layer on the Fe-6.5 Si powder core, increasing the adhesion between the ferromagnetic phase core and the abrasive hard phase. The study found that the addition of 10 wt% NIP as a mass percentage can optimize the MAP structure. During the sintering process at 1169.7 °C, the NIP interface transforms into a metallic interface layer, namely FexSiy (Fe5Si3 and Fe3Si), between the hard phase and the ferromagnetic phase. This intermediate layer combines the hard phase with the ferromagnetic phase, enhancing the magnetic saturation intensity while reducing the coercivity. The developed MAPs were applied to the polishing of Zr alloy tubes and effectively removed localized defects on the outer surface of the tubes. After six polishing cycles, the surface roughness decreased from 0.361 µm to 0.085 µm. This study establishes the correlation between interface behavior and magnetic properties and proposes a new strategy for the preparation of high-performance MAPs.

Experimental comparison of unbonded, agglutinated and sintered SiC-based magnetic abrasive particles in magnetic abrasive finishing process

Aluminum grabs a spot in the top ten light metals and henceforth finds a wide range of applications in the aerospace industry and other concerned/allied industries. A high surface finish is obligatory in a few components. The objective of this research is to compare and analyze the internal surface finish obtained by unbonded, agglutinated, and sintered silicon carbide (SiC) based magnetic abrasives in aluminum pipes using magnetic abrasive finishing process. Scanning electron microscopy and atomic force microscopy (AFM) have aided in a close inspection of the topography of the surfaces. AFM topographic images indicate that sintered magnetic abrasive particles yielded a surface roughness value (Ra = 17.7 nm) followed by agglutinated (Ra = 34.98 nm) and unbonded magnetic abrasive particles (Ra = 99.3 nm). Maximum percentage improvement in surface finish (PISF) of 87 % in terms of Ra has been obtained at rotational speed of workpiece (1000 rpm), magnetic flux density (0.85 Tesla), quantity of abrasive particles (15 gm), size of abrasives (80 μm) and machining time (30 mins.).

Finishing mechanism modelling on magnetic abrasive finishing behaviours with core-shell magnetic abrasive particles

Finishing mechanism modelling on magnetic abrasive finishing behaviours with core-shell magnetic abrasive particles

Achieving environment-friendly spherical polycrystalline diamond magnetic abrasives via plasma molten metal powders bonding with hard materials

High performance magnetic abrasive particles (MAPs)can contribute to the promotion of magnetic abrasive finishing (MAF) industry. In this work, environmentally friendly spherical polycrystalline diamond magnetic abrasive particles (PCD-MAPs) were prepared by plasma molten metal powders bonding with hard materials. The effects of inlet mode, outlet angle and powder concentration on the erosion wear of the spray tray were first investigated, followed by the effect of PCD powder concentration on the preparation of MAPs, and finally the microscopic morphology, phase composition, particle size distribution, magnetic properties and finishing performance of the MAPs were characterised and analyzed. The results revealed that: the erosion wear of the spray tray was smaller for the opposing inlet type with an outlet angle of 65°; the PCD-MAPs were regular spherical; the cutting edge of PCD was not carbonized and mechanically bonded to the surface layer of iron powder tightly and uniformly; the concentration of PCD powder affected the bonding number on the surface of iron powder particles; the proportion of particle size distribution between 160–212 μm and the saturation magnetic induction intensity decrease with increasing PCD concentration; the recovered PCD powder can still be used; the Ra value of TC4 titanium alloy decreases from 0.386 μm to 0.096 μm within 25 min, and the service life of PCD-MAPs exceeds 60 min. This study can provide technical support for the bonding of PCD/metal composites.

Investigation of Spherical Al2O3 Magnetic Abrasive Prepared by Novel Method for Finishing of the Inner Surface of Cobalt-Chromium Alloy Cardiovascular Stents Tube.

In this investigation, spherical Al2O3 magnetic abrasive particles (MAPs) were used to polish the inner surface of ultra-fine long cobalt-chromium alloy cardiovascular stent tubes. The magnetic abrasives were prepared by combining plasma molten metal powder and hard abrasives, and the magnetic abrasives prepared by this new method are characterized by high sphericity, narrow particle size distribution range, long life, and good economic value. Firstly, the spherical Al2O3 magnetic abrasives were prepared by the new method; secondly, the polishing machine for the inner surface of the ultra-fine long cardiovascular stent tubes was developed; finally, the influence laws of spindle speed, magnetic pole speed, MAP filling quantities, the magnetic pole gap on the surface roughness (Ra), and the removal thickness (RT) of tubes were investigated. The results showed that the prepared Al2O3 magnetic abrasives were spherical in shape, and their superficial layer was tightly bound with Al2O3 hard abrasives with sharp cutting; the use of spherical Al2O3 magnetic abrasives could achieve the polishing of the inner surface of ultra-fine cobalt-chromium alloy cardiovascular bracket tubes, and after processing, the inner surface roughness (Ra) of the tubes decreased from 0.337 µm to 0.09 µm and had an RT of 5.106 µm.

Ultrasonic assisted magnetic abrasive finishing of DIN 1.2738 tool steel using vitrified bonded magnetic abrasive particles

Ultrasonic-assisted magnetic abrasive finishing (UAMAF) process has been developed to reduce the finishing time of hard materials. In this process, in addition to the rotation of the magnetic tool, ultrasonic vibrations are also applied to the workpiece simultaneously in the longitudinal direction. In the present work, the effects of UAMAF process parameters, including ultrasonic power, the rotational speed of the magnetic tool, working gap, and weight of magnetic abrasive particles (MAPs) on the percentage change in surface roughness (%ΔRa) of 1.2738 tool steel are discussed with an experimental approach. In this regard, besides the development of the UAMAF process, the sintering of MAPs with glass powder is proposed. The experiments are designed according to the Taguchi method. Then, the input parameters of the UAMAF process are modeled and optimized using the signal-to-noise (S/N) ratio analysis to achieve the maximum %ΔRa. Statistical analysis of experimental data shows that the most significant contribution in improving %ΔRa is attributed to the weight of MAPs. Furthermore, according to the comparative study, %ΔRa in the UAMAF process for finishing the DIN 1.2738 tool steel is improved by 86.62% under optimized conditions. In comparison, this value in the MAF process is equal to 48.62% under the same conditions. The results of the surface morphology also underline that abrasive particles in the UAMAF process hit the peaks of the surface roughness due to vibration applied to the workpiece, which leads to a high-quality finished surface.

Multi-response optimization of magnetic abrasive finishing for AZ-31 alloy using RSM-GRA approach

A magnetic abrasive finishing is a non-traditional technology utilizes a flexible magnetic abrasive brush comprises of magnetic abrasive particles under the influence of the magnetic field to perform nano-finishing. The material removal (MR) and percentage change in surface roughness (%∆R a ) are responses governing the efficiency of the finishing process. But, a high material removal during the finishing operation leads to the loss in form/shape of the finished surface. A compromise has to be made considering the two responses for an optimized finishing operation. In this work, a multi-response optimization was executed using grey relation analysis (GRA). The objective functions considered are to maximize %∆R a and minimize MR. The experiments were designed and conducted using response surface methodology. The workpiece material was taken as AZ-31 alloy. The optimized conditions observed were %∆R a as 67.43% and MR as 63 mg at the working gap of 2 mm, rotational speed of 600 rpm, voltage of 18 volts and abrasive particle mesh number of 400 mesh. The GRA also reveals that the working gap has the strongest influence on the finishing considering both responses concurrently. The ANOVA analysis was also executed to analyze the significant interaction effects of process parameters on output responses.

Internal Surface Enhancement by Magnetic Abrasive Finishing of Brass Pipe at Different Speeds and Particle Composition

Abstract: This study examined the effect of magnetic field on the interior surface finish of Brass UNS C26800 pipe. The parameters sliding velocity of electromagnets, concentration ratio (castor oil and magnetic abrasive particles), and number of cycles were modified within a predetermined range, and their effects on surface finish (%Ra) and material removal rate were determined (MRR). The remaining process parameters remained unchanged throughout the duration of the experiment. In the case of 7:3 and 8:1 concentration ratios, the percentage improvement in surface finish (%Ra) increases and subsequently drops as the sliding velocity of electromagnets increases. The only explanation is because the blunting of abrasives occurs at greater sliding speeds, which reduces the improvement of surface finish. In the event of a concentration ratio of 9:1, however, the percentage increase in surface finish increases with the increase in sliding velocity as a result of the work hardening of the surface, which enables the simple removal of surface peaks. Also, for sliding velocities of 0.62 mm/sec and 1.23 mm/sec, the percentage improvement in surface finish falls with increasing concentration ratio due to the slurrification of magnetic abrasives in the lubricant as a result of increasing oil concentration. At a sliding velocity of 2.46 mm/sec, the improvement in surface finish is proportional to the amount of oil applied due to the increased control and velocity of the surface. In addition, two cycles of electromagnets relative to the workpiece provided the finest surface finish. The MRR increases as sliding velocity increases. Consequently, MRR is minimal at the slowest sliding velocity.