With the development of semiconductors, optics, aerospace, and other fields, the requirements for surface finish are constantly increasing. This requires not only better surface quality but also ...higher finishing efficiency. In order to improve the surface quality, the magnetic abrasive finishing process using an alternating magnetic field was proposed in the previous research. In this process, the magnetic clusters constantly fluctuate due to the periodic change of the current, thereby realizing the circulation of the abrasive particles in contact with the workpiece. It has been proved through previous studies that a better surface quality can be obtained in an alternating magnetic field. However, there are still some unclear mechanisms. For example, the fluctuation of magnetic cluster mainly depends on the change of current, but it is not clear which current change mode is more suitable for improving finishing efficiency and surface quality. Therefore, in this study, the influence of the current change mode on the magnetic field, finishing force, and finishing characteristics are discussed. Furthermore, SUS304 stainless steel plate was used as the object to conduct a series of experiments. According to the experimental results, when the abrasive particles are WA#8000, the average diameter of the magnetic particles is 75 μm, and the frequency is 1 Hz; in the case of pulse current with a duty cycle of 80%, a higher material removal rate can be achieved. The material removal rate is 1.7 times that of the static magnetic field and 1.45 times that of the sinusoidal alternating magnetic field.
Magnetic abrasive finishing (MAF) is an effective surface finishing method. At present, most of the research on plane MAF focuses on finishing characteristics. However, due to the “edge effect” of ...the magnetic field and the rotational movement of the magnetic brush, the uniformity and flatness of the finished surface are poor. In order to further improve the accuracy of the finished surface, the surface uniformity and flatness are improved by changing the shape of the magnetic pole and the trajectory of the magnetic brush. At the same time, the surface flatness is evaluated not only by the maximum height difference of the cross section but also by the standard deviation to evaluate the surface uniformity and flatness. Through magnetic field simulation and experiments, it is proved that the bottom groove of the magnetic pole helps to make the magnetic particle distribution more uniform in the processing area, which can effectively improve the surface quality. In addition, through experiments, changing the trajectory of the magnetic brush can also effectively improve the surface flatness of the finished surface.
In order to achieve the precision machining of the alumina ceramic surface, we propose surface finishing of alumina ceramic by the magnetic abrasive finishing (MAF) process using low-frequency ...alternating magnetic field. In previous studies, the effects of important process parameters on finishing force and finishing characteristics were investigated when the magnetic particle diameter was 6 and 30 μm. Due to the higher hardness of alumina ceramics, greater finishing force is needed, so we studied the effect of magnetic particle diameter and alternating magnetic field frequency on the finishing force. In order to determine the best experimental conditions, we study the effect of important process parameters on the finishing characteristics. The experimental results prove that the surface finishing of alumina ceramic can be achieved. The surface roughness of the alumina ceramic plate can be improved from 244.6 nm
Ra
to 106.3 nm
Ra
.
In order to achieve the finishing of complex microsurface, the magnetic abrasive finishing process using alternating magnetic field was proposed. In this paper, the mechanism of the magnetic abrasive ...finishing process using alternating magnetic field was investigated. At the same time, the influence of magnetic particle size and magnetic field frequency on magnetic cluster changes was observed and the relationship between finishing force and alternating magnetic field was analyzed. In addition, the feasibility of ultraprecision finishing of 5052 aluminum alloy plate through this process was studied, and the influence of relevant process parameters on the finishing characteristics was analyzed. The experimental results show that the surface roughness of 5052 aluminum alloy plate improved from 318 to 3 nm
Ra
in 15 min.
This research proposes an effective plane magnetic abrasive finishing (MAF) process which was combined with electrolytic process in order to improve machining efficiency of traditional plane MAF ...process. The new plane finishing process can make surface of workpiece to be planarized and softened through formed passive films from electrolytic process. Meanwhile, the passive films are removed by magnetic brush-generated mechanical processing force to achieve efficient precision machining. This finishing process is called electrolytic magnetic abrasive finishing (EMAF). In this research, we have developed a novel machining tool of compound magnetic poles and electrodes, which is able to achieve two different processes. The SUS304 stainless steel plane is used as workpiece. In order to select electrolytic finishing time for EMAF process, the investigation of electrolytic process has been carried out before EMAF process. Then, the comparative experiments of EMAF process and MAF process have been conducted in order to investigate the effect of EMAF process. The experimental results show that EMAF process can a little obtain higher quality surface, and machining efficiency is improved by about 50%, which compared with that of traditional plane MAF process. Furthermore, the surface roughness can be reduced to 30.94 nm
R
a
from original roughness of 393.08 nm
R
a
in 40 min by the EMAF process.
In order to improve the machining efficiency of a traditional plane magnetic abrasive finishing (MAF) process, the MAF combined with an electrolytic process (EMAF) was proposed. Because the relation ...among the magnetic field, the electric field, and the flow field of the electrolyte is very complicated in the EMAF process, the machining mechanism has not yet been investigated clearly. In this paper, the mechanism of the EMAF process was investigated, and mainly discusses the influencing factors of finishing stability and surface quality. First, a set of current measurements and recording devices was designed to investigate the current changes during the finishing process. The measured current value curve was used to evaluate the processing status. Then, validation experiments were performed; the influence of the particle size and supply amount of magnetic particles on processing was observed. Experimental results show that it was clarified that the optimal experimental conditions existed, and the best results were obtained when using the electrolytic iron powder (330 μm in mean diameter) and a supply amount of 0.6 g.
The magnetic abrasive finishing process using the magnetic machining tool was proposed to finish the internal surface of the thick tube (the thickness of the tube is 5~30 mm). It has been proved that ...this process can improve the roundness while improving the roughness. In this paper, we mainly study the machining mechanism of roundness improvement. Firstly, the influence of finishing characteristics on the roundness improvement was discussed, including the rotational speed of the magnetic machining tool and the rotational speed of the tube. It was concluded that the roundness improvement increases with the increase in the rotational speed through the analysis of finishing force and finishing times. Furthermore, the influence on roundness improvement of different distributions of magnetic particles were experimentally compared. After finishing, due to the magnetic force generated by the magnetic machining tool and the magnetic pole unit exerting pressure on the magnetic particles, a fixed magnetic brush is formed. The experimental results show that the circumferential length of the fixed magnetic brush is different due to the different distribution areas of magnetic particles. It was concluded that the roundness improvement increases with the circumferential length of the fixed magnetic brush increases by discussing the relationship between the circumferential length of the fixed magnetic brush and the wavelength of the roundness curve. When the circumferential length of the fixed magnetic brush is 76 mm, the roundness was improved from 379 μm to 236 μm after 60 min of finishing.
On the basis of ordinary plane magnetic abrasive finishing, a finishing method is proposed that can improve the flatness of a plane workpiece. In this method, the feed speed is varied during ...finishing according to the profile curve of the initial surface and the material removal efficiency, to control the effective finishing time in different areas and thereby improve the surface flatness. A small magnetic pole with an end face diameter of 1 mm is designed, and a ferromagnetic plate is placed under the workpiece to improve the uniformity of the magnetic field distribution near the magnetic pole. An experiment on an A5052 aluminum alloy plate workpiece shows that after 60 min of finishing using the proposed method, the extreme difference of the workpiece surface can be reduced from 14.317 μm to 2.18 μm, and the standard deviation can be reduced from 3.322 μm to 0.417 μm. At the same time, according to the measurement results, a similar flatness can be achieved at different positions on the finishing area. Thus, the proposed variable-speed finishing method leads to obvious improvements in flatness.
The magnetic abrasive finishing combined with electrolytic (EMAF) process was proposed to improve the finishing efficiency of the traditional magnetic abrasive finishing (MAF) process. Since the EMAF ...process contains electrolysis reactions, the machining mechanism of processing different metal is different. In this paper, a series of experiments were conducted to explore the feasibility of using the compound processing tool to finish aluminum alloy A5052, and to preliminary explore the machining mechanism. Surface roughness and material removal are used to evaluate the finishing effect and the finishing efficiency, respectively. The EMAF processing current curve is used to evaluate and analyze the EMAF process. The feasibility of the EMAF processing is proved by the analysis of simulations and the experimental results. Finally, through a series of exploration experiments and parameter optimization experiments, the main conclusions are as follows: (1) Compared with the traditional MAF process, when finishing the surface of aluminum alloy A5052 by the same compound processing tool and at the same experimental conditions (except the electrolysis conditions), the EMAF process, which includes electrolysis reactions, can achieve higher finishing efficiency. (2) In this study, when the working gap is 1 mm and the concentration of NaNO3 solution is 15%, the recommended processing voltage is about 3.4 V.
An internal magnetic abrasive finishing process using a magnetic machining tool was proposed for finishing the internal surface of the thick tubes. It has been proved that this process is effective ...for finishing thick tubes, and it can improve the roundness while improving the roughness. However, the mechanism of improving the roundness is not clear, so it is necessary to study it theoretically. In this research, firstly, the roundness curve expression was derived using the principle of roundness measurement by the assumed center method, and the expression of roundness curve expanded by Fourier series was obtained. The influencing factors of roundness improvement were then analyzed. Secondly, the experiments were carried out on SUS304 stainless steel tubes. By confirming the mechanism analysis results and the experimental results, it was concluded that the internal magnetic abrasive finishing process using the magnetic machining tool was effective for improving the roundness of the thick tubes whose thickness is from 10 mm to 30 mm. As the thickness of the tube increased, the improvement in roundness decreased.
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