Magnetic Abrasive Powder Research Articles

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.

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.

Modeling of material removal by magnetic abrasive finishing of the inner wall of Co-Cr alloy cardiovascular stent tube with diamond magnetic abrasive powder prepared by plasma melting

Modeling of material removal by magnetic abrasive finishing of the inner wall of Co-Cr alloy cardiovascular stent tube with diamond magnetic abrasive powder prepared by plasma melting

Research on grinding force modelling of spherical alumina magnetic abrasive powder

Research on grinding force modelling of spherical alumina magnetic abrasive powder

Synthesis and characterization of environment-friendly spherical cubic boron nitride magnetic abrasives by plasma molten metal powders bonding with hard materials

In this investigation, globular cubic boron nitride magnetic abrasive powders (cBN-MAPs) were synthesized with additive-free via plasma molten metal powders bonding with hard materials (PM2BH) for finishing hard and brittle materials. Experiments were carried out with cBN powder flow rates of 60–300 g/min, which significantly affected the performance and microstructure of the composites. It illustrates that: the composites are composed of cBN and α-Fe; the cBN is not transformed into hBN, which can be reused; a linear increase in the amount of cBN grains bound to the apparent layer of the ferrous substrate with increasing powder flow rate, the proportion of MAPs in the 180–230 μm size distribution and the magnetic permeability decrease; when the powder flow rate is maximum, the powder embedded in ferrous substrate completely covers the surface of the matrix, forming spherical MAPs, after 50 min of machining, surface finish of AlN ceramics improved from 342 nm to 93.5 nm, with cBN-MAPs showing normal wear within 80 min. A novel, highly efficient strategy for additive-free cBN/Fe composites is presented in this paper.

Study on finishing inner wall of Co[sbnd]Cr alloy cardiovascular stent tube via novel atomized CBN/metal spherical magnetic abrasive powders

In this study, in order to solve the problem that the inner wall of the cardiovascular stent is difficult to polish, the magnetic abrasive finishing (MAF) method is used to finish the inner wall of the CoCr alloy tube that is used for the manufacture of the cardiovascular stent. The surface defects such as wrinkles, cracks and pits generated in the production process are removed, and the internal surface roughness is decreased to obtain better surface quality. Firstly, aiming at the problem of poor performance of traditional magnetic abrasive powders (MAPs), “gas-solid two-phase double-stage atomization and rapid solidification” is proposed and a novel atomized CBN/metal spherical MAPs with different sizes are successfully prepared. This MAP is used for MAF of the inner wall of CoCr alloy cardiovascular stent. Secondly, the slotted magnetic pole is designed according to the numerical simulation, and the MAF setup for the inner wall of ultra-fine and ultra-long tubes is developed. Finally, the orthogonal experiment is carried out with surface roughness as the evaluation index. Through the analysis of range theory, the order of the apparent degree of each process parameter on surface roughness is as follows: tube rotational speed > feed speed of magnetic pole > MAPs filling quantity > MAP particle size. According to the result, a model of surface roughness prediction based on whale optimization algorithm (WOA) and least squares support vector machine (LSSVM) is constructed. The interaction between tube rotational speed and other process parameters is analyzed based on the model fitting results, and the process parameters are optimized. The result show that MAF technology can effectively remove the defects of the inner wall of the CoCr alloy cardiovascular stent tube and accurately predict the surface roughness. After MAF under the optimized process parameters, the surface roughness Ra decreases from 0.485 μm to 0.092 μm.

Polishing Characteristics of Cemented Carbide Using Cubic Boron Nitride Magnetic Abrasive Powders.

This paper describes the application of bonded magnetic abrasive powders (MAPs) in the magnetic abrasive finishing (MAF) process. In order to improve the poor finishing performance and short service life of MAPs in polishing super-hard materials, a double-stage atomization technique was used to successfully manufacture MAPs with a CBN as an abrasive phase. The prepared results show that CBN abrasives with their original structure were deeply and densely embedded on the surface of spherical MAPs. Based on the MAF process, a five-level and four-factor central composite design experiment was carried out to verify the developed MAPs polishing performance on the finishing of cemented carbide parts (864 Hv). Working gap, rotational speed, feed rate of a workpiece, and mesh number of MAP were considered as influence factors. The analysis data was used to understand different interactions of significant parameters. A regression model for predicting the change of surface roughness was obtained, and the optimal parameter combination was figured out through a solution of a quadratic equation in Design-Expert software. According to MAF results, the strong cutting ability of atomized CBN MAPs improved the surface roughness of cemented carbide by over 80% at the optimum parameters. The strong cutting ability of atomized CBN MAPs can produce good surface quality on the hard materials. The findings of this research can promote a large-scale application of MAF technology in the surface polishing of hard materials.

Achieving polycrystalline diamond magnetic abrasive tools via double-stage gas atomization

Although magnetic abrasive finishing (MAF) is an efficient surface finishing technique, its promotion and use in the precise polishing of high-hardness objects are constrained by the poor finishing performance and short service life of magnetic abrasive powders (MAPs). In this study, a double-stage atomization technique is employed to successfully manufacture MAPs with a polycrystalline diamond (PCD) as an abrasive phase. Analysis was performed on the graphitization of PCD abrasive and the circularity of the created MAPs as a result of cooling temperature. Therefore, the pressure ranges of the first-stage atomizer are suggested based on the theoretically designed kinetic model of PCD abrasives' penetration behavior into liquid metal. As revealed in the preparation experiment findings, PCD abrasives with their original crystal structure were deeply embedded on the surface of a spherical iron matrix. The generated PCD MAPs with smaller particle sizes exhibited better soft magnetic characteristics due to the atomization process’ quick cooling. The MAF results implied that PCD MAPs curtailed the roughness of cemented carbide from 302 nm to 85.2 nm, and their service life exceeds 60 min. The findings of this research can provide technical assistance for the creation of high-performance PCD MAPs.

Parametric Studies on Finishing of AZ31B Magnesium Alloy with Al2O3 Magnetic Abrasives Prepared by Combining Plasma Molten Metal Powder with Sprayed Abrasive Powder

High-performance iron-based Al2O3 magnetic abrasive powder (MAP) prepared by combining plasma molten metal powder with sprayed abrasive powder is used for magnetic abrasive finishing (MAF) of AZ31B magnesium alloy to remove surface defects such as creases, cracks, scratches, and pits generated during the manufacturing process of the workpiece, and to reduce surface roughness and improve its wear and corrosion resistance. In order to solve the problem of magnetic abrasive powder splash in the MAF process, the force analysis of the MAP in the processing area is conducted, and a composite magnetic pole processing device was designed and simulated to compare the effects of both devices on MAF, confirming the feasibility of composite magnetic pole grinding. Then, experiments have been designed using Response Surface Methodology (RSM) to investigate the effect of four factors-magnetic pole rotation speed, grinding gap, magnetic pole feed rate, magnetic abrasive filling quantity-on surface roughness and the interactions between them. The minimum surface roughness value that can be obtained is used as the index for parameter optimization, and the optimized parameters are used for experiments, and the results show that the established surface roughness model has good predictive ability.

Study on the Micro Removal Process of Inner Surface of Cobalt Chromium Alloy Cardiovascular Stent Tubes

Due to the special manufacturing process of cobalt–chromium alloy cardiovascular stent tubes, there are serious surface defects in their inner walls, which affects the therapeutic effect after implantation. At the same time, the traditional processing technology cannot finish the inner wall of a cardiovascular stent tube. In light of the above problems, magnetic abrasive finishing (MAF) equipment for the inner wall of an ultra-fine and ultra-long cardiovascular stent tube is proposed, and MAF technology is used to improve the surface quality of its inner wall. High-performance spherical magnetic abrasive powders are used to finish the inner wall of a cobalt–chromium alloy cardiovascular stent tube with an inner diameter of 1.6 mm and an outer diameter of 1.8 mm. The effects of finishing time, tube rotational speed, feed speed of the magnetic pole, MAPs filling quantity, and MAP abrasive size on the surface roughness and material removal thickness of cobalt–chromium alloy cardiovascular stent tube are investigated. The results show that the surface roughness of the inner wall of the cobalt–chromium alloy cardiovascular stent decreases from 0.485 μm to 0.101 μm, and the material removal thickness of the defect layer is 4.3 μm. MAF technology is used to solve the problem of the poor surface quality of the inner walls of ultra-fine and ultra-long cobalt–chromium alloy cardiovascular stent tubes.

Achieving in-situ alloy-hardening core-shell structured carbonyl iron powders for magnetic abrasive finishing

The finishing accuracy and efficiency of magnetic abrasive finishing (MAF) are mainly depending on magnetic abrasive powders (MAPs). A new kind of core–shell structured carbonyl iron powders (CI-MAPs) with a hard Fe/Al intermetallic shell for magnetic abrasive finishing is successfully synthesized by in-situ alloy-hardening the surface of spherical carbonyl iron powders in this study. The feasibility of such an in-situ alloy-hardening strategy is theoretically designed according to the Fe/Al intermetallic compound formation chemical reaction using the Gibbs free energy principle and the TG-DSC testing, and thus the experimental thermodynamics temperature and time ranges of such chemical reactions are proposed. Experimental results shown that a densely zigzag-like uniform alloy-hardening layer with a thickness of about 11 μm, which are composed of Fe3Al, FeAl, and Fe2Al5 intermetallic compounds, was in-situ chemically synthesized on the surface of the spherical carbonyl Fe powders. The achieved core–shell structured powder is performed to finishing a Zirconium tube experimentally, and the roughness (Ra) of the Zirconium tube is greatly improved from 0.361 μm to 0.085 μm by 3 MAF passes.

Magnetic abrasive finishing of non-magnetic materials (Al 6061) using flexible magnetic brush

Abstract Magnetic abrasive finishing (MAF) of Al6061with unbounded magnetic abrasive particles is responsible for surface finish of the order of nanometer. In the present work MAF experiments on Aluminum 6061 with four important controllable process parameters have been used such as grain size, working gap, rotational speed and the voltage. The silicon carbide (SiC) abrasive particle were mechanically mixed with iron powder of mesh size 300 & 400 respectively used to form magnetic abrasive powder (MAF) and added some amount of lubricant (servo engine oil) to obtained desired surface finish of the order of nanometer. The “MINITAB” software was used for linear regression model for the response & for analysis of variance (ANOVA). It was noted that process parameters like grain size, working gap, rotational speed and voltage play an important role in obtaining good surface finish.

Study the effect of concentration ratio (magnetic abrasive powder and castor oil) in magnetic abrasive finishing process

The new technology can however be incorporated in conventional machine tools in order to minimize cost of new equipment. In present work, the effect of magnetic abrasive powder and castor oil mixture in magnetic abrasive finishing process is investigated. The lower concentration of lubricating oil results in higher heat accumulation which further decreased the cutting efficiency due to blunting action of abrasives. On the other hand, the larger quantity of lubricating oil prevents blunting which resulted in higher cutting efficiency.

Characteristics of a novel atomized spherical magnetic abrasive powder

Magnetic abrasive powders (MAPs) form a flexible abrasive brush as a polishing tool and deliver a fine finish on the workpiece surface during the magnetic abrasive finishing (MAF) process. However, hard abrasives are easily thrown away from the magnetic field at high rotational speeds. The small holding force affects the finishing performance and efficiency. Therefore, a bonded type of spherical MAPs was developed via an atomization technology to overcome this disadvantage. Cubic boron nitride (CBN) abrasives were densely and uniformly embedded into the surface of MAPs. The low coercivity (Hc) and small remnant magnetization (Mr) for the prepared CBN/Fe-based MAPs suggest that the samples have excellent soft magnetic properties. The atomized MAPs were used to polish Ti-6Al-4 V in the MAF process. The effect of working gap, rotational speed of the magnetic pole, and size of MAPs on the surface roughness and material removal efficiency were investigated. Experimental results demonstrated that a fine 42-nm roughness was produced after 15 min of polishing and an optimum 17.2 mg material removal was obtained in the MAF process. Therefore, spherical CBN/Fe-based MAPs can produce a smooth surface on Ti-6Al-4 V.

Synthesis and Characterization of Sintered Magnetic Abrasives Used in Advance Finishing Processes Through Powder Metallurgy Route

The magnetic field-assisted surface finishing process needs a sintered magnetic abrasive powder which could be a mixture of SiC and CIP particles. Tube furnaces have been used to develop SiC-based sintered magnetic abrasives. The focus of this article is to investigate the anticipated results and to carry out the fabrication setup of sintered magnetic abrasive for the super-finishing of composite materials and their coating. The article depicts a significant effect on the mechanical properties such as microhardness and compressive strength and analyzes SiC and CIP composite-based microstructure. The synthesis of the powder involves four major processes like blending; compaction and sintering. Characterization of sintered magnetic abrasives has been done using SEM, EDS, XRD to study morphology, chemical composition, crystallography, and magnetic properties. The results have been compared with the un-bonded magnetic abrasives. This paper also presents a brief literature review of the state-of-the-art technology of high-performance surface finishing processes used in manufacturing industries. Finally, the downside and stray aspects of the related literature are spotlighted and a list of prospective issues for future research directions is recommended.

Finishing of Tubes using Bonded Magnetic Abrasive Powder in an Abrasive Medium

Abstract Magnetic abrasive flow finishing (MAFF) is an unconventional process capable of producing fine finishing with machining forces controlled by a magnetic field. This process can be utilized for hard to achieve inner surfaces through the activity of extrusion pressure, combined with abrasion activity of a magnetic abrasive powder (MAP) in a polymeric medium. MAP is the key component in securing systematic removal of material and a decent surface finish in MAFF. The research background disclosed various methods such as sintering, adhesive based, mechanical alloying, plasma based, chemical, etc. for the production of bonded MAP. This investigation proposes bonded MAP produced by mechanical alloying followed by heat treatment. The experiments have been conducted on aluminum tubes to investigate the influence of different parameters like magnetic field density, extrusion pressure and number of working cycles. The bonded magnetic abrasive powder used in MAFF is very effective to finish tubes’ inner surfaces and finishing is significantly improved after processing.

Modeling of material removal in magnetic abrasive finishing process with spherical magnetic abrasive powder

This study describes the application of a magnetic abrasive finishing (MAF) process to yield a fine finish on planar workpiece (SS304). The grinding tool is a flexible abrasive brush using diamond particles embedded in a spherical iron matrix. This bonded type of spherical MAPs was developed via an atomization technology to solve the problem that hard particles were easily thrown from the magnetic field at high rotational speed. Theoretical model of the material removal was composed of the mechanical properties of work material and four applied process parameters such as working gap, rotational speed of magnetic pole, feed rate of workpiece, and size of magnetic abrasive powder (MAP). The magnitude and distribution of generated magnetic flux was simulated by finite element analysis to evaluate the normal pressure of MAP. The single factor experiment was conduct to analyze the relationship between surface roughness reduction and material removal. Scanning electron microscopy was used to understand the effect of different abrasive material on the finished surface of workpiece. Under the same optimum processing condition, diamond MAPs produced a better surface roughness and more material removal than CBN MAPs and alumina MAPs did. The established theoretical model brought out that high material removal corresponds to a fine surface roughness in the MAF process with atomized spherical MAPs.

Preparation and characterization of spherical diamond magnetic abrasive powder by atomization process

In this work, the atomization process was utilized in order to fabricate significantly high content of diamond powders on the surface of spherical magnetic abrasive powder (MAP). The impact of the different feed rates of diamond powder on the surface morphology, size distribution and magnetic properties of atomized MAPs were investigated. The results showed that a feed rate at 2 kg/min atomized MAPs were obtained with good spherical morphology and uniformly embedded fine diamond powders on the surface of MAP, confirmed the compositional contribution in the iron matrix. As per the size distribution, the refinement of MAPs improved the utilization ratio of the ideal size (100-200 μm) of atomized MAPs and resulted in dense distribution. The saturated magnetization and coercivity were 117.394 emu/g and 3.605 Oe, respectively. Importantly, the rapid cool solidification process of MAPs solved the weak adhesion behavior of diamond powders in the iron matrix. Additionally, the formed stiff junction between the diamond powders and the iron matrix provided service life of 60 mins for MAPs. The dense cutting edges of the embedded diamond powders and uniform indentation depth of spherical MAPs reduced the surface roughness from 0.432 μm to 0.046 μm of Ti-6Al-4 V.

Preparation, Microstructure Evaluation and Performance Analysis of Diamond-Iron Bonded Magnetic Abrasive Powder

AbstractThe customary edged tool for machining is uneconomical for harder and hard to machine materials and furthermore the level of surface finish accomplished is not that great. As of late, a lot of consideration in mechanical engineering has been centered on finishing tasks. Not many investigations have been accounted for till date on the advancement of substitute magnetic abrasive powder (MAP). In this paper, to improve the finishing performance, the abrasive powder were prepared by mechanical alloying of diamond powder and iron (Fe) powder, compacting these with universal testing machine (UTM) and then sintered at different temperature in a sintering machine in an inert gas (H2) atmosphere. These compacts were crushed and sieved to obtain various sizes of MAP. This abrasive powder were micro-structurally examined. The results indicate that the densification increases and porosity decreases with increasing temperature. Moreover, the prepared bonded MAP has potential performance as a new MAP for fine finishing in Magnetic Abrasive Flow Machining (MAFM) process.

Polishing of paramagnetic materials using atomized magnetic abrasive powder

ABSTRACTThis paper reports on the polishing of paramagnetic materials in the magnetic abrasive finishing (MAF) process by using atomized-type magnetic abrasive powder (MAP). After atomization process, a spherical MAP with captured Al2O3 hard particles was obtained. The MAF process was experimented on two plane workpieces with different hardnesses. An orthogonal array containing five factors with three levels was applied in the experiment. Based on analysis results, the model of surface roughness was obtained, and the rotational speed of the MAPs played the most dominant role in the surface quality of both finished experimental materials. By comparing the value of the finished surface roughness at different process parameters, the influence of single process parameter on processing quality was analyzed. Furthermore, the minimum surface roughness of both materials was obtained at the best combination of process parameters. Finally, the experiment of the material removal and the produced surface morphology was examined in order to understand the finishing characteristics of the atomized MAPs during the MAF process.