• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.775-778
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• 2000

Magnetorheological Finishing(MRF) is a newly developed and recently commercialized for finishing optical components. The magnetorheological fluid consists of a water based suspension of carbonyl iron, nonmagnetic polishing abrasives, and small amounts of stabilizer. Theoretical analysis of MRF, based on Bingham lubrication theory, is illustrated and a correlation between surface shear stress on the workpiece and material removal is obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.557-560
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• 2003

Magnetorheological finishing(MRF) is a newly developed and recently commercialized for finishing optical components. The magnetorheological fluid consists of a water based suspension of carbonyl iron, nonmagnetic polishing abrasives, and small amounts of stabilizer. This magnetorheological fluid is pumped from conditioner on the rotating wheel and suctioned back to the conditioner, where it cooled to setpoint temperature and evaporative losses are replaced. This method could produce some problems in suction. So newly designed MRF tools is proposed in which MR fluid is not circulated and conditioned by the slurry. The new polishing mechanism is experimented. Measured surface roughness supports the validity of this mechanism.

• Korea-Australia Rheology Journal
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• v.19 no.3
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• pp.117-123
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• 2007

There has been considerable interest in recent years in field-responsive suspensions, which are of some importance in industry in many different applications. The microstructure of these materials is a significant issue which can be probed by rheological measurements. In this study, measurements were made of a magnetorheological fluid (MRF) under steady and oscillatory shear flow, with and without a magnetic field. Mathematical inversion was used to derive the relaxation time spectrum of the MRF from oscillatory shear data. Experimental evidence is presented of the gel-like properties of this MRF.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1840-1843
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• 2003

The Magnetorheological fluid has the properties that its viscosity has drastic changed under some magnetic fields therefore, Magnetorheological fluids has been used for micro polishing of the micro part( for example, a aspherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorheological finishing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fluid ate brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate for glass polishing lends support the validity of the approach.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.7
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• pp.46-52
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• 2004

The Magnetorheological fluid has the properties that its viscosity has drastic changed under some magnetic fields therefore, Magnetorheological fluids has been used fur micro polishing of the micro part(for example, a spherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorheological finishing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fluid are brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate for glass polishing lends support the validity of the approach.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.347-357
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• 2018

Steady shear response of a magnetorheological fluid (MRF) system containing porous mono-disperse magnetite ($Fe_3O_4$) spheres synthesized by solvothermal method is demonstrated. In applied magnetic field the interaction between the spherical particles leads to form strong columnar structures enhancing the yield strength and viscosity of the MRFs. The yield strengths of the MRFs also scale up with the concentration of magnetic particles in the fluid. Considering magnetic dipolar interaction between the particles the magneto-mechanical response of the MRFs is explained. Unlike metallic iron particles, the low-density corrosion resistant soft-ferrimagnetic $Fe_3O_4$ spherical particles make our studied MRF system efficient and reliable for shock-mitigation/vibration-isolation applications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.350-355
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• 2005

This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR Product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant Properties; the minor loop property and the wiping-out property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.3-11
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• 2006

This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant properties; the minor loop property and the wiping-out. property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.324-328
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• 2003

The Magnetoeheological fluid has the properties that it's viscosity has dramastic changed under some magnetic fields therefore, Magnetorhlogical fluids has been used for micro polishing of the micro part( for example, a aspherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorhological finshing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fulid ate brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate f3r glass polishing lends support the validity of the approach.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.464-467
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• 2005

Among several polishing techniques for micro structures, polishing process using magnetorheological(MR) fluid has advantages in the finishing process of 3-D micro structures because abrasives in the fluid can reach surfaces with complex feature and play their role. Although many researchers have been trying to reveal its polishing mechanism of the MR polishing, it has not been successful because in-situ measurement of state variables is difficult and process parameters are complex. In fact, one of the key factors for applying process control methodologies, such as Run-to-Run control, is the measuring and monitoring of slurry quality because the process strongly depends on the fluid property. Therefore, it is necessary to maintain consistent slurry quality to guarantee the process repeatability. The proposed equipment achieves the longer life cycle of MR fluid and reduces the variability of products. A new method to measure the material removal rate in MRF polishing process is also proposed and discussed.