JP2008254106A - Paste material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paste material capable of carrying mirror finishing at high grade even on a member hard to be subjected to surface processing such as soft metal material, and efficiently carrying out work of surface processing by minute cutting action. <P>SOLUTION: A magnetic polishing liquid 4 includes metal particles having magnetism, a solvent, and a low welting point resin. The solvent is vegetable oil and fat, and the low melting point resin is formed from resin material insoluble in the solvent and has a low melting point. The magnetic metal particles is a non-spherical shape with a sharp angle portion. A diameter of the particle is made to be 10 μm to 300 μm, and saturated magnetization when volume magnetization is 4πM is made to be not less than 15kG. When a magnetic field of a permanent magnet 20 effects, the magnetic metal particles attract each other to generate a magnetic cluster. The magnetic metal particles also function as abrasive grains, and the magnetic cluster becomes a magnetic brush carrying minute shaving. The magnetic metal particles which are the abrasive grains is prevented from remaining in the magnetic brush and permeating out due to the effect of the magnetic field. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a paste material for performing a surface treatment by a precise cutting action on an object of a relatively soft soft metal material such as aluminum or an alloy thereof, more specifically, by the action of a magnetic field. The present invention relates to an improvement in a composition that exhibits a precise shaving action in a magnetic polishing liquid (paste material) that flows in conjunction.

  In the case of metallic materials, a surface treatment that modifies the surface properties is necessary in terms of decorativeness and functionality in application to various industrial products. Surface treatment such as polishing and cleaning is performed on the surface. ing. As a metal material, iron-based materials that are used in large amounts and are in great demand are recently attracting attention because of demands for weight reduction, and aluminum-based materials such as aluminum and its alloys are attracting increasing demand.

  One of the surface treatments is a mirror finish, which is an important surface treatment even with the above-described aluminum-based materials. In other words, the mirror finish on the surface of the member is of particular importance not only for obtaining a beautiful appearance, but also for aluminum-based materials, for the purpose of creating a base before plating and improving the adhesion of the overlapping surface in a multilayer structure. .

  A so-called magnetic polishing technique is well known as a precision polishing technique that can be mirror-finished. This is performed by mixing a magnetic fluid (MF) or a magnetorheological fluid (MRF) with abrasive particles and moving the mixed liquid by a magnetic field.

  The polishing tool is equipped with a permanent magnet to serve as a magnetic field source. When a magnetic polishing liquid (paste material) is attached around the polishing tool, ferromagnetic particles (for example, iron particles) in MF or MRF are generated by magnetic attraction. , Many magnetite particles aggregate to form a magnetic cluster. Since this magnetic cluster follows the magnetic flux, it takes a form in which a large number of needles are arranged in opposition to the object to be polished. Therefore, the magnetic polishing liquid adheres to the polishing bite to form a magnetic brush.

  When the magnetic brush or the object to be polished rotates, the magnetic brush moves in contact with the surface of the object to be polished by relative movement between the two. As a result, the unevenness of the surface to be polished is polished by the magnetic brush with the abrasive particles, a smoother surface can be obtained, and non-contact fluid polishing can be performed.

With respect to a magnetic polishing liquid for performing non-contact fluid polishing by the action of such a magnetic field, for example, there is a disclosure of a technique as seen in Patent Document 1 and the like. Patent Document 1 discloses a composition in which iron that is ferromagnetic particles and nonmagnetic alumina that is abrasive particles are mixed.
JP-A-6-116549

  However, since the aluminum-based material is relatively soft and is a so-called soft metal material, fine scratches, white turbidity, and the like remain with the polishing process, and surface treatment such as mirror finish is not easy. That is, when the magnetic polishing method is applied, there is a problem that the abrasive grains contained in the magnetic polishing liquid are easily damaged. This is because the abrasive grains of the magnetic polishing liquid use alumina, silicon carbide, etc., but these abrasive grains have remarkably higher hardness than the soft metal material, and therefore the object (soft metal material) during magnetic polishing. ) Is scratched, and the surface becomes clouded by the scratch, so that it is not easy to obtain an advanced mirror surface.

  In addition, as another method, there are a chemical polishing method in which the surface is chemically treated with an organic solvent, an acid, an alkali, or the like, and an electrolytic polishing method in which the surface treatment is performed by ionization of an acid, an alkali, etc., but it is used for a soft metal material. This is not common due to reactivity issues.

  At present, buffing is performed for mirror finishing of aluminum-based materials. This is hand polishing by so-called buffing, and the efficiency is very low. Therefore, automation of the surface treatment of the aluminum-based material is required.

  As a problem in the magnetic polishing method, magnetic polishing by MF requires a long time magnetic polishing because the fixation of magnetic particles is weak when a magnetic field is applied and the polishing efficiency is low. Further, since MF is obtained by uniformly dispersing magnetic particles having a particle diameter of about 10 nm, it is difficult to clean after polishing, and magnetic particles are clogged in minute gaps and cannot be removed. In magnetic polishing by MRF, it is difficult to control the magnetic cluster, deep scratch marks are easily formed on the surface to be polished, and there is room for improvement in application to fine finishing.

  As is the case with Patent Document 1 described above, nonmagnetic particles such as alumina are generally used for the abrasive particles constituting the magnetic polishing liquid. However, during magnetic polishing, a large centrifugal force due to the rotational movement of the polishing tool acts on the magnetic polishing liquid, and due to the influence of the magnetic field distribution by the magnet of the polishing tool, some nonmagnetic particles are trapped in the magnetic cluster. There is a problem that the magnetic brush oozes out. Therefore, the non-magnetic particles that have exuded contaminate the processed surface, and the polishing efficiency is lowered by reducing the amount of the abrasive particles from the magnetic polishing liquid.

  In addition, as in Patent Document 1, the composition in which the ferromagnetic particles are iron (metal material) and this is mixed with nonmagnetic abrasive particles (alumina) has a poor life and is easy to break. There is concern about the stability of quality.

  The object of the present invention is to solve the above-mentioned problems. The purpose of the present invention is to provide a highly mirror-finished surface treatment work even with a difficult-to-surface material such as a soft metal material. Is to provide a paste material that can be efficiently performed.

  In order to achieve the above-described object, the paste material according to the present invention is provided with the object in order to perform a surface treatment by a fine cutting action on an object of a relatively soft soft metal material such as aluminum or an alloy thereof. A paste material that exists in the vicinity of a magnetic field generation source facing non-contact with each other and is interlocked by the action of a magnetic field, and includes magnetic metal particles and a solvent. The metal particles have a saturation magnetization of 15 kG at a volume magnetization of 4πM. This is the above (claim 1).

  The solvent is vegetable oil and fat (Claim 2), and the solvent is mixed with an insoluble and low melting point resin that does not dissolve in the solvent (Claim 3). The low melting point resin has a melting point of 40 ° C. or higher and 80 ° C. or lower (Claim 4).

  Further, the metal particles have a shape having corners (preferably sharp corners) (Claim 5). Further, the metal particles may have a particle size of 10 μm to 300 μm, preferably about 30 μm to 100 μm (Claim 6). As the metal particles, iron powder can be used (claim 7).

  In the present invention, the paste material is composed of magnetic metal particles and a solvent, and the magnetic metal particles exhibit a function of forming a magnetic cluster in so-called magnetic polishing and a function of an abrasive (abrasive grain) for polishing. It will be. That is, metal particles having magnetism form magnetic clusters by applying a magnetic field. And this magnetic metal particle becomes a generally hard member compared with the soft metal material etc. which were made into the target object. Therefore, the metal particles can function as abrasive grains for polishing, and the magnetic cluster itself becomes a magnetic brush that performs fine cutting. Therefore, it is possible to satisfactorily perform a surface treatment operation by a precise shaving action, for example, a mirror finish.

  In this case, the magnetic cluster itself becomes a magnetic brush that performs fine cutting, and the magnetic metal particles that are abrasive grains do not stay in the magnetic brush due to the magnetic field of the magnetic field generation source and do not ooze out. Therefore, there is no contamination of the processed surface and there is no decrease in abrasive grains, so that surface treatment by a precise cutting action can be performed with high efficiency.

  Since the metal particles are magnetized and the resulting magnetic cluster itself becomes a magnetic brush for polishing, the adhesion of the magnetic brush attached to the magnetic bite increases, and the response of the magnetic brush linked to the polishing bit improves. This also increases the polishing efficiency.

  In addition, when dirt such as organic matter adheres to the surface of the object, it is easy to scrape off because the organic substance is less hard than the object, and it can be easily removed by the fine shaving action of the magnetic brush with magnetic metal particles. So-called cleaning can be performed as a surface treatment without damaging the surface of the object.

  In order to obtain polishing power, the metal particles should have a shape with corners (preferably with sharp corners). The metal particles have a spherical shape when manufactured by the reduction method or atomization method, and the corners are not formed, so that the polishing force is weakened. In order to give corners and sharp corners to the particle shape, it is preferable to use particles produced by pulverization by mechanical force.

  In the paste material (magnetic polishing liquid), whether polishing is possible or not depends on the strength of the magnetic brush. If the magnetic brush is not strong enough, polishing cannot be performed. The strength of the magnetic brush depends on the strength of magnetization per particle that forms the magnetic brush, that is, the strength increases as the saturation magnetization of the magnetic metal particles increases, and the strength increases as the particle diameter increases. In order to obtain a sufficient polishing force, the magnetization of the metal particles should preferably have a saturation magnetization of 15 kG or more at a volume magnetization of 4πM, and the stronger the better.

  If the particle size of the metal particles is too small, it becomes impossible to polish, so it is preferable that the particle size be 10 μm or more. However, as the particle diameter increases, the scratches on the surface to be polished increase, so the upper limit is preferably 300 μm or less. More preferably, the particle size is desired to be 30 μm to 100 μm. As the metal particles, iron that is inexpensive and easily available can be said to be optimal.

  It can be said that the use of vegetable oil as a solvent is preferable from the viewpoint of safety and price.

  In addition, the paste material is mixed in the solvent with a low melting point resin that is insoluble in the solvent, so that the low melting point resin and the solvent have fluidity due to stress while maintaining the shape by compatibility. can do. When there is no stress at which no external force acts, the low melting point resin holds the metal particles in the solvent, so that sedimentation can be suppressed. And when an external force is applied, it can flow due to the fluidity of the solvent.

  If only a small amount of low melting point resin is mixed, separation of the metal particles and the solvent is caused. However, since the low melting point resin exists between the metal particles, the dispersibility is improved and mixing becomes easy. Is also effective. The mixing amount of the low melting point resin is determined according to the melting point, the particle diameter, the shape maintenance degree of the magnetic polishing liquid, and the viscosity of the low melting point resin.

  The melting point of the low melting point resin is, for example, about 100 ° C. or less. This is because the resin having a melting point of about 100 ° C. has a molecular weight of about 1000, but the resin having a melting point of about 120 ° C. has a molecular weight of about 10,000 and becomes hard. And it becomes a branching point where the molecular weight rapidly increases near the temperature exceeding 100 ° C. Therefore, it can be said that the resin at 100 ° C. or less before the increase is a low melting point resin.

  Further, the low melting point resin is preferably 40 ° C. or more because the low melting point resin is liquefied due to a change in environmental temperature and causes precipitation of ferrite particles. However, if the temperature is too high, it becomes hard and the compatibility with the solvent decreases, so the upper limit is preferably 80 ° C. or lower.

  In the paste material according to the present invention, the magnetic metal particles exhibit a function of forming a magnetic cluster and a function of a fine cutting action, so that the magnetic cluster itself becomes a magnetic brush for polishing. Therefore, magnetic metal particles, which are abrasive grains, do not stay and penetrate into the magnetic brush due to the action of a magnetic field, do not contaminate the machined surface, and do not reduce abrasive grains. Can be done. As a result, even a member that is difficult to surface-treat, such as a soft metal material, can be highly mirror-finished.

  In this case, the metal particles are magnetized, and the resulting magnetic cluster itself becomes a magnetic brush for polishing, so the degree of adhesion of the magnetic brush attached to the magnetic bite is increased, and the response of the magnetic brush linked to the polishing bit is improved. However, this also increases the polishing efficiency.

  In addition, dirt such as organic matter adhering to the surface of the object is easy to scrape because the hardness is smaller than the object, and can be easily removed by the precise shaving action of the magnetic brush with magnetic metal particles, So-called cleaning can be performed as surface treatment without damaging the surface of the object.

  That is, in the present invention, surface treatment such as mirror finishing and cleaning can be satisfactorily performed on relatively soft and easily damaged soft metal materials such as aluminum, alloys thereof, brass, silver, and nickel. Can be automated and performed with high efficiency.

  FIG. 1 shows a preferred embodiment of the present invention. The paste material according to the present invention is used for so-called magnetic polishing, and exhibits a fine shaving effect in magnetic polishing, so that the surface of a soft metal material or the like can be mirror-finished and dirt (deposits) can be removed. ing.

  The configuration for performing magnetic polishing includes a polishing tool 2 having a magnetic field generation source (permanent magnet 20), the polishing object 1 is fixed to the y-axis stage 3, and the polishing tool 2 faces the polishing object 1 in a non-contact manner. The paste material (magnetic polishing liquid 4) is present between the polishing object 1 and the polishing tool 2 is activated by driving the driving means 5 associated therewith, and a predetermined motion is performed. By starting the y-axis stage 3, the polishing object 1 is caused to perform a predetermined movement operation with respect to the y-axis, and fluid polishing is performed by a magnetic cluster generated in the magnetic polishing liquid 4.

  The polishing tool 2 is provided with a permanent magnet 20 at its tip to serve as a magnetic field generation source. The magnetic field generation source is not limited to the permanent magnet 20, and for example, an electromagnet can be preferably applied as long as it can act on the magnetic polishing liquid 4. The generation of the magnetic field does not have to be stationary in time, and a magnetic field that varies in time may be generated.

  The driving means 5 has a multi-axis control function for at least the x-axis and z-axis. When the driving means 5 is activated, the polishing tool 2 rotates and moves in a predetermined manner with respect to the x-axis and z-axis. Let the action take place. Of course, you may make it reciprocate in a uniaxial direction. As the driving means 5, for example, an NC machine tool may be used, and the shaft portion of the polishing tool 2 is attached to and detached from a rotating shaft (chuck portion) such as a drilling machine, a lathe, an NC lathe, or a milling machine.

  The magnetic polishing liquid 4 contains two components of magnetic metal particles and a solvent. Vegetable oil is used as the solvent. This magnetic polishing liquid 4 is supplied by a supply means between the polishing object 1 and the polishing bit 2.

  The magnetic metal particles form a magnetic cluster by applying a magnetic field. The metal particles may be any metal material that can be appropriately magnetized, and are generally harder members than the soft metal material or the like that is the subject of polishing 1. Therefore, the metal particles can function as abrasive grains for polishing, and the magnetic cluster itself becomes a magnetic brush for performing a surface treatment by a fine cutting action.

  In the present embodiment, the metal particles have a saturation magnetization of 15 kG or more at a volume magnetization of 4πM. The particle diameter of the metal particles is 10 μm to 300 μm, preferably about 30 μm to 100 μm. The metal particles are non-spherical particles, preferably having a sharp corner. The sharp corners can be formed by a mechanical grinding method or the like, which improves the function as abrasive grains. Therefore, the metal particles are preferably formed from, for example, iron powder.

  The magnetic polishing liquid 4 may be further mixed with a low melting point resin. In this case, the low melting point resin is preferably formed from an insoluble and low melting point resin material that does not dissolve in the solvent, and the average particle size is preferably several μm to several hundred μm. The melting point of the low melting point resin is preferably 40 ° C. or more and 80 ° C. or less. Examples of resin materials that do not dissolve in vegetable oils include polyethylene and polystyrene.

  The movement operation of the polishing tool 2 is, for example, an operation of scanning the entire surface of the polishing object 1 or a predetermined movement of the polishing object 1 with respect to the xy plane by setting the operation of the y-axis stage 3 and the driving means 5. An operation may be performed. At this time, the magnetic polishing liquid 4 is supplied to the periphery of the polishing tool 2, and the polishing tool 2 is caused to perform a rotating operation that reverses forward and backward in the axial direction. Or it is good also to perform the vibration operation | movement which vibrates predetermined.

  A magnetic polishing liquid 4 exists between the polishing tool 2 and the polishing object 1, and the magnetic polishing liquid 4 contains metal particles having magnetism. The permanent magnet 20 causes the magnetic polishing liquid 4 to change constantly or fluctuate in time. When a magnetic field is applied, a magnetic cluster is generated. That is, a large number of magnetic metal particles in the magnetic polishing liquid are aggregated by the magnetic attractive force to form a magnetic class. As described above, the metal particles function as abrasive grains for polishing, and the magnetic cluster itself becomes a magnetic brush that performs fine cutting. A large number of magnetic brushes are arranged in a needle shape in opposition to the object 1 to be polished along the magnetic flux, and metal particles that perform the abrasive action are held down on the surface of the object 1 to be polished. At this time, since the polishing tool 2 and the polishing object 1 move relative to each other, the metal particles move while making contact with the surface of the polishing object 1 to perform precise cutting. Therefore, it is possible to perform a surface treatment by a precise cutting action.

  As described above, the composition of the paste material (magnetic polishing liquid 4) includes metal particles having a magnetic property and a solvent. The magnetic metal particles have a function of forming a magnetic cluster in so-called magnetic polishing, and an abrasive for polishing. The function of (abrasive grains) will be exhibited.

  In this case, the magnetic cluster itself becomes a magnetic brush that performs fine shaving, and the metal particles that are abrasive grains remain in the magnetic brush due to the magnetic field of the permanent magnet 20 and do not ooze out. Therefore, there is no contamination of the processed surface and there is no decrease in abrasive grains, so that surface treatment by a precise cutting action can be performed with high efficiency. Here, the metal particles are not so strong as compared with general abrasive grains such as alumina, and express an appropriate polishing force. As a result, even a soft metal material that is relatively soft and difficult to surface-treat, such as aluminum and its alloys, can be highly mirror-finished.

  Since the metal particles are magnetized and the resulting magnetic cluster itself becomes a magnetic brush for polishing, the adhesion of the magnetic brush to the magnetic bite increases, and the response of the magnetic brush linked to the polishing bit improves. This also increases the polishing efficiency.

  Further, when dirt such as organic matter adheres to the surface of the object 1 to be polished, the organic substance has the same hardness as that of the object 1 to be polished, so that it can be easily scraped off. Can be easily removed, and so-called cleaning can be performed as a surface treatment without damaging the surface of the polishing object 1.

  Since the metal particles function as an abrasive as in the present invention, the hardness is inferior to alumina, diamond, silicon carbide, etc., which are generally known as abrasives. Although there is anxiety with respect to the hard material, the polishing power is sufficiently high with respect to relatively soft soft metal materials such as aluminum and its alloys, so that polishing can be performed with high efficiency.

  In order to obtain polishing power, the metal particles are non-spherical particles, and preferably have a shape with sharp corners. The metal particles have a spherical shape when manufactured by a reduction method or an atomization method, and sharp corners are not formed, so that the polishing force becomes weak. In order to give a sharp corner to the particle shape, particles produced by pulverization by mechanical force may be used.

  In the paste material (magnetic polishing liquid 4), whether or not polishing is possible depends on the strength of the magnetic brush. If the magnetic brush is not strong enough, polishing cannot be performed. The strength of the magnetic brush depends on the strength of magnetization per particle forming it, that is, the stronger the saturation magnetization of the metal particles, the stronger the particle diameter. In order to obtain a sufficient polishing force, the magnetization of the metal particles should preferably have a saturation magnetization of 15 kG or more at a volume magnetization of 4πM, and the stronger the better.

  If the particle size of the metal particles is too small, it becomes impossible to polish, so it is preferable that the particle size be 10 μm or more. However, as the particle diameter increases, the scratches on the surface to be polished increase, so the upper limit is preferably 300 μm or less. More preferably, the particle size is desired to be 30 μm to 100 μm. As the metal particles, iron that is inexpensive and easily available can be said to be optimal.

  It can be said that the use of vegetable oil as a solvent is preferable from the viewpoint of safety and price.

  In addition, the paste material is mixed with a low melting point resin that is insoluble in the solvent and has a low melting point, so that the low melting point resin and the solvent have a fluidity due to stress while maintaining the shape by compatibility. There can be. When there is no stress at which no external force acts, the low melting point resin holds the metal particles in the solvent, so that sedimentation can be suppressed. And when an external force is applied, it can flow due to the fluidity of the solvent.

  Since the low melting point resin is formed from a resin material that does not dissolve in the solvent, there is no interference with the solvent, a good polishing ability can be obtained, and highly precise surface polishing can be performed.

  If only a small amount of low melting point resin is mixed, separation of the metal particles and the solvent is caused. However, since the low melting point resin exists between the metal particles, the dispersibility is improved and mixing becomes easy. Is also effective. The mixing amount of the low melting point resin is determined according to the melting point, the particle diameter, the shape maintenance degree of the magnetic polishing liquid, and the viscosity of the low melting point resin.

  When the melting point of the low melting point resin is too low, the melting point is preferably 40 ° C. or higher because the low melting point resin is liquefied due to a change in environmental temperature and causes precipitation of ferrite particles. However, if the temperature is too high, it becomes hard and the compatibility with the solvent decreases, so the upper limit is preferably 80 ° C. or lower.

(Verification by experiment)
The sample was polished according to the configuration for magnetic polishing shown in FIG. That is, in order to demonstrate the effect of the present invention regarding the polishing ability, a plurality of paste materials (magnetic polishing liquid 4) having different compositions are prepared, and the polishing target is polished with each magnetic polishing liquid 4, and the surface after polishing Roughness Ra (arithmetic average roughness) and Ry (maximum roughness) were evaluated.

The magnetic polishing liquid 4 was composed of magnetic metal particles (pulverized iron powder) and solvent (vegetable oil) in wt% shown in Table 1 as a composition, and Example 1 was prepared by mixing these uniformly. In Comparative Examples 1 to 11, a combination in which alumina or ferrite as the abrasive grains is wt% shown in Table 1 and the solvent is changed to water (Comparative Examples 4 and 5), or the metal particles are spherical iron powder and spherical cobalt. , The combination was changed to non-spherical Sendust (registered trademark).

The object to be polished was a plate piece made of aluminum (Ry = 5.7 μm), and the surface was polished. This polishing object 1 was reciprocated by 15 mm at 2 mm / sec in the x-axis direction. A neodymium magnet was used as the permanent magnet 20 of the magnetic field generation source, and the polishing time was 2 minutes. The surface roughness was measured by a surface roughness level meter, and P-10 manufactured by Tencor Corporation was used for this. When the object to be polished was polished, the results shown in Table 2 were obtained.

  As is apparent from Table 2, polishing can be achieved by setting the particle size of the iron powder to 9 μm or more, but in Comparative Examples 3, 8, 9, 10, and 11 to which abrasive grains were added, white scratches occurred and white turbidity occurred. It was confirmed that the mirror surface was not obtained.

  In Comparative Example 8 to Comparative Example 11, polishing was performed by setting the particle diameters of ferrite particles added as abrasive grains to be sequentially reduced. As a result, if the particle size of the abrasive grains (ferrite particles) is small, the scratches become shallow, but white turbidity is unavoidable, and the composition that gave a mirror surface was only Example 1 in which no abrasive grains were mixed.

  Each metal particle used had a saturation magnetization at a volume magnetization of 4πM, iron powder of 20 kG, spherical cobalt of 17 kG, and non-spherical sendust of 10 kG.

  FIG. 2 is a graph showing the measurement results of the surface roughness of the object to be polished, and shows the surface roughness before polishing and the surface roughness after polishing in Example 1 and Comparative Example 2. As can be seen from the figure, in Example 1, the surface roughness after polishing was substantially zero, and a good mirror surface was obtained.

Further, as the magnetic polishing liquid 4, a composition in which the particle diameters of the spherical iron powder and the pulverized iron powder are changed is prepared, and a composition in which the solvent is changed to terpineol or silicone oil is also set, and polishing and evaluation of the polishing target are performed. It was. In other words, the magnetic polishing liquid 4 was prepared in four types from Example 2 to Example 5 according to the composition in which each component was wt% shown in Tables 3 and 4 and crushed iron powder was added. In Comparative Examples 12 to 21, the combinations were changed to spherical iron powder, spherical cobalt, and non-spherical sendust.

When the object to be polished was polished, the results shown in Table 5 were obtained. And the relationship between a particle diameter and surface roughness became clear about each metal particle, and the graph shown in FIG. 3 was obtained.

  As apparent from Table 5 and FIG. 3, as the magnetic metal particles, the spherical iron powder has a low polishing power, but the pulverized iron powder is well polished. This is because the pulverized iron powder has a sharp corner. It can be said that it is big. Further, it was confirmed that non-spherical sendust cannot be polished, and therefore, it is necessary to have a magnetization of a predetermined level or more together with the condition that the shape is non-spherical, preferably a shape having sharp corners.

Moreover, the dispersibility by adding a low melting point resin to the magnetic polishing liquid 4 was evaluated. As shown in Table 6, a low melting point resin (67 ° C.) having a low melting point (67 ° C.) was prepared for Example 1 by adding 20 wt% of the solvent, and the dispersibility after one week from the preparation was examined. As a result, it was confirmed that with the addition of the low melting point resin, the shape was maintained like a cream and the polishing power was maintained at the same level as that immediately after the preparation.

1 is a side view showing a preferred embodiment of the present invention. It is a graph which shows the measurement result of surface roughness about grinding | polishing object, and displays the surface roughness before grinding | polishing and the surface roughness after grinding | polishing in Example 1 and Sample 1. It is a graph which shows the relationship between a particle diameter and surface roughness about each metal particle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing object 2 Polishing tool 20 Permanent magnet 3 Y-axis stage 4 Magnetic polishing liquid (paste material)
5 Drive means

Claims (7)

In order to perform surface treatment by a precise cutting action on a relatively soft soft metal object such as aluminum or an alloy thereof, the object is present in the vicinity of a magnetic field generation source facing the object in a non-contact manner. Paste material that is linked by action,
A paste material comprising metal particles having magnetism and a solvent, wherein the metal particles have a saturation magnetization of 15 kG or more at a volume magnetization of 4πM.   The paste material according to claim 1, wherein the solvent is vegetable oil.   The paste material according to claim 1 or 2, wherein the solvent contains an insoluble low melting point resin that does not dissolve in the solvent mixed therein.   The paste material according to claim 3, wherein the low melting point resin has a melting point of 40 ° C. or higher and 80 ° C. or lower.   The paste material according to any one of claims 1 to 4, wherein the metal particles have a shape having corners.   The paste material according to any one of claims 1 to 5, wherein the metal particles have a particle size of 10 µm to 300 µm.   The paste material according to any one of claims 1 to 6, wherein the metal particles are iron powder.

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