Takeo Shinmura

Study on Magnetic Abrasive Finishing

This paper describes a new finishing process using magnetic abrasives in which the finishing pressure is generated by a magnetic field. The process principle and the finishing characteristics are described. Specifically, the effect of the magnetic abrasive particle size on stock removal and surface finish is investigated for cylindrical finishing. Based on the results, diamond coated magnetic abrasives were newly made to finish Si3N4 fine ceramic bars (12mm in dia.) and its finishing performances were clarified. The surface roughness of 0.45μmRa before finishing was improved to 0.04μmRa. It was also clarified that the precision edge finishing of about 0.01mm in radius was performed easily by this process.

Study of the surface modification resulting from an internal magnetic abrasive finishing process

An internal magnetic abrasive finishing process was proposed for producing highly finished inner surfaces of tubes used in critical applications including clean gas or liquid piping systems. Most of the previous research has explored the process characteristics and mechanism from a macroscopic point of view making use of surface roughness profiles. However, those approaches did not adequately characterize the behavior of abrasive cutting edges acting against the surface to remove material in the process. This paper examines the microscopic changes in the surface texture resulting from processing. In addition to the surface roughness measurement, atomic force and scanning electron microscopy were used to characterize the material removal process and provide a fundamental understanding of the process mechanism. The observed surface texture shows that the process is an accumulation of the micro-scratches from the abrasive cutting edges, generating a characteristic magnetic abrasive finished surface. Moreover, the surface is finished by removing the material from not only the peaks but also the valleys of the surface, as far as the cutting edges of the magnetic abrasive are introduced into the valleys. However, the relatively longer wavelength components of the roughness profile tend to remain on the surface after processing; this shows that the magnetic abrasive finishing process belongs to the category of pressure-copying processes.

Study of an internal magnetic abrasive finishing using a pole rotation system: Discussion of the characteristic abrasive behavior

An internal magnetic abrasive finishing process using a pole rotation system was proposed to produce highly finished inner surfaces of workpieces used in critical applications. Previous research found that the process incorporating one of the characteristic behaviors of the abrasive, the jumbling of the abrasive, results in aggressive contact of the abrasive against the inner surface, disturbing the smooth surface finish. The aim of this paper, therefore, is to characterize the in-process abrasive behavior against the surface and its effects on the finishing characteristics and to describe the finishing mechanism. The magnetic force acting on the magnetic abrasive, controlled by the field at the finishing area, is considered the primary influence on the abrasive behavior against the inner surface of the workpiece. This study examines the relationships between the magnetic field, the force on the abrasive, and the abrasive behavior. The surface roughness and material removal measurements resulting from finishing experiments demonstrate the effects of the abrasive behavior on the surface modifications. This paper also proposes a method to monitor the in-process abrasive behavior to facilitate processing.

Study of internal finishing of austenitic stainless steel capillary tubes by magnetic abrasive finishing

This paper studies the internal finishing of capillary tubes using a magnetic abrasive finishing process. Such tubes are used with nanoscale technologies and meet the demands of the present age in medical and chemical equipment. The finishing characteristics are influenced by the magnetic abrasive behavior against the inner surface of the capillary, which is controlled by the supplied amount of magnetic abrasive and the magnetic force acting on it. The development of the finishing unit identifies the characteristics of the magnetic field, which controls the magnetic force, required for the necessary magnetic abrasive behavior. Finishing experiments using SUS304 austenitic stainless steel capillary tube with 800 μm inner diameter demonstrate the effects of the supplied amount of the magnetic abrasive on the finishing characteristics, and the results suggest a standard method to determine the amount to achieve sufficient finishing. The run-out of the capillary while rotating at high speed under the cantilever tube support method causes instability of the magnetic abrasive behavior. The effects on the finishing characteristics are discussed, and a method to diminish the run-out is applied. Accordingly, this paper presents the conditions required for the internal finishing of capillary tubes and proposes methods to realize them. The internal finishing of 400 μm inner diameter capillary tubes conveys an understanding of the mechanisms involved and demonstrates the usefulness of the proposed methods.

Development of a new precision internal machining process using an alternating magnetic field

Abstract Imparting compressive residual stress to a surface improves the fatigue structural integrity of components, which is particularly important for components used in such critical applications as high-pressure gas or liquid piping systems. This paper proposes a new precision internal machining process that controls the surface integrity of internal surface of these components. This process utilizes an alternating magnetic field to control the force and dynamic motion of the tools needed for machining. An experimental set-up was developed to test the processing principle. This study characterizes the in-process tool behavior—that is, the relationships between the magnetic field, the tool properties, and the tool behavior—and reveals the properties of the tools required to achieve the desired results: magnetic anisotropy and a specific geometric restriction. The surface roughness, hardness, and residual stress measurements following machining experiments demonstrate the effects of the tool behavior on the machining characteristics. This paper also proposes methods to obtain desired surface characteristics.

Uniform Internal Finishing of SUS304 Stainless Steel Bent Tube Using a Magnetic Abrasive Finishing Process

This research studies the factors affecting the conditions required for successful uniform internal finishing of SUS304 stainless steel bent tube by a Magnetic abrasive finishing process. In particular, the effects of the magnetic field and ferrous particles were investigated. Local intensification of the magnetic field is accomplished by offsetting the axis of pole rotation from elbow axis. This effect enables local control of the material removal rate, which leads to uniformity in the finished surface regardless of the initial surface conditions. A two-phase finishing process controlling the size of the ferrous particles is proposed to achieve efficient fine surface finishing.

Development of Effective Magnetic Deburring Method for a Drilled Hole on the Inside of Tubing Using a Magnetic Machining Jig

A new magnetic deburring method for a drilled hole on the inside of tubing is proposed in this study. This internal deburring method applies the magnetic field assisted machining process by using a magnetic machining jig (permanent magnet tool). In this research, we examined experimentally the deburring of a drilled hole on the inside of SUS304 stainless steel tubing. A processing unit and magnetic machining jig were made, and the processing unit was set on a lathe machine. The deburring experiment was performed for a drill hole 3 mm in diameter. The results showed that the internal burr could be removed using this magnetic deburring process and the height of the burr could be successfully decreased from 163 μm to 1 μm. Thus, it was proved that this magnetic deburring method was effective for the internal deburring of long tubing.

Study of Internal Magnetic Field Assisted Finishing for Copper Tubes with MRF (Magneto-Rheological Fluid)-Based Slurry

This research studied the internal magnetic field assisted finishing with MRF (Magneto-rheological Fluid)-based slurry for copper tubes.MRF-based slurry that included diamond abrasives was applied to the internal magnetic field assisted finishing for copper tubes and the finishing characteristics were studied. The results showed that the exciting current and the abrasive size changed the finishing characteristics of MRF-based slurry. This finishing process creates a smooth mirror finished surface with few directional cutting marks on the surface of the copper tube.

Material Removal Mechanism in Vibration-Assisted Finishing

In this paper, it is explored the material removal mechanism in vibration-assisted finishing process. On the basis of some experiments, the finishing characteristics are represented summarily. Though the analysis, it is shown that the vibration assistance method may increase cutting distance and speed of abrasive and material removal in per unit finishing distance which is affected by vibration frequency and amplitude, in-process abrasives behavior. What more, the increase in material removal rate is mainly due to an increase in material removal per unit finishing distance which is affected by the effects of abrasives cross-cutting.

Magnetic Finishing Abrasive with Nickel-Plated Active Carbon

A novel magnetic abrasive particle (MAP) was developed by using electroless nickel or nickel-diamond composite plating on active carbon (AC) powder. The chelating compound of picolinic acid with nickel anion was used in the activated process instead of the conventional PdCl 2 and SnCl 2 . X-ray diffraction and scanning electron microscopy images showed the completely coated nickel or nickel-diamond electroless deposits on the AC particles. A mirror finish of Cu plate was obtained by using the newly developed MAP in practice in the process of magnetic-field-assisted finishing.