Electrorheological Polishing Research Articles

Progress in the study of electrorheological polishing: A review

Electrorheological polishing (ERP) is an important field-assisted polishing method, which can reduce abrasive loss and improve machining efficiency by using the electric field-induced electrorheological (ER) effect to help the abrasive to overcome the centrifugal force caused by high rotating speed during polishing. ERP has many advantages, including high efficiency, high precision, facile polishing for a small object, and a good application prospect in polishing optical devices and hard molds. This review describes the research progress in ERP in the past two decades. The mechanism of electrorheological polishing is analyzed from two aspects of electrorheological effect and dielectrophoresis. According to the time sequence of electrorheological polishing development, two kinds of ERP materials including the simple mixing system and composite particle system are introduced. ERP electrodes including off-axis bipolar electrode, needle-ring electrode, needle-like single electrode, one-sided patterned electrode, and one-sided simple composite electrode are described. From the two characterization quantities of removal rate and surface quality, the industrial factors affecting the ERP effect are discussed. The advantages and disadvantages of ERP and other polishing processes are compared. Finally, the remaining challenges and possible development trends in ERP technology for the future outlook are proposed.

Enhanced Electrorheological Polishing Efficiency of Alumina-Doped Titanium Dioxide Particles.

Electrorheological (ER) polishing is a novel polishing technology having flexible and tunable characteristics. At present, ER polishing uses ER particles to drive abrasive particles to polish the material surface. Under the action of high-speed centrifugation, the abrasive particles are easily separated from ER particles due to their significantly different ER effect, and this can easily cause the degradation of polishing ability. In this work, alumina-doped titanium dioxide ER polishing particles were developed via a sol-gel method. As a classical abrasive, alumina has higher hardness and can improve the ER effect of titanium dioxide by doping. Thus, alumina-doped titanium dioxide particles simultaneously possess high ER effect and high hardness. No phase separation appears in the polishing process and the result shows that alumina-doped titanium dioxide has a good polishing efficiency for materials with Mohs hardness of 3 and below.

Electrorheological polishing performance of cerium-doped titanium dioxide particles

Electrorheological (ER) polishing as a new type of polishing technique has flexibility and controllability. However, ER polishing cannot be widely used in actual processing because the present ER polishing fluid is usually prepared by simple mixing abrasive materials into ER fluid, which is easy to occur phase separation and decreased ER performance. This paper develops a new type of ER polishing material based on cerium-doped titanium dioxide. As a classic abrasive, the cerium oxide not only has high polishing performance but also can enhance ER performance of titanium dioxide by doping effect, which endows the cerium-doped titanium dioxide with high ER polishing efficiency compared to ER polishing fluid prepared by a simple mixing method. Cerium-doped titanium dioxide particles were prepared by the sol-gel method. The size, surface morphology and elemental distribution were characterized. The ER properties were tested. The effects of different concentrations, machining gap, voltage and rotation speed on polishing performance were studied. Under the conditions of a 0.2 mm machining gap, 3 kV voltage and 200 r/min rotation speed, the surface roughness (Ra) of the copper workpiece decrease from 136 nm to 14.4 nm after 0.5 h of polishing, which is far higher than the polishing efficiency of simple mixed ER polishing fluid.

A new modelling method of material removal profile for electrorheological polishing with a mini annular integrated electrode

This paper addresses the problem of material removal in electrorheological (ER) polishing with a mini annular integrated electrode both theoretically and experimentally. The model of the material removal profile in ER polishing is proposed based on the evaluation of the amount of material removed from the surface along the direction orthogonal to the tool path. Firstly, the electric field distribution around the tool head is deduced theoretically. On this basis, the contact pressure model in the ER polishing area is established. Considering the feed rate and tool spindle speed of ER polishing, the distribution of the relative sliding velocity in the polishing area is modeled. On the basis above, the innovative approach to calculate the material removal profile is developed for the ER tool polishing along a straight path. The model is validated by a series of designed polishing experiments, which demonstrates that the material removal model established in this paper has high prediction accuracy of material removal profile in ER polishing.

Study on the rheological and polishing properties of electromagnetic two-phase composite particles with abrasive characteristics

Electromagnetic composite rheological polishing (EMRP) is a new ultra-precision machining technology that combines electro-rheological polishing (ERP) and magneto-rheological polishing (MRP). The key technology of the polishing method is the preparation of electromagnetic composite rheological fluid (EMRF) with both ERP and MRP, especially the preparation of composite particles with electro- and magneto-rheological effects. In this study, the EMRF was prepared by using electromagnetic two-phase particles with abrasive characteristics. The electromagnetic two-phase composite particles are synthesized in two steps: the coupling method and sol-gel method. The two-step method successfully prepared the electromagnetic two-phase composite particles with nano-diamond particles embedded randomly on the surface. The electro-rheological shear stress of EMRF can reach 160.7 Pa when the test parameter voltage is 2.5 kV, and magneto-rheological shear stress of EMRF can reach 4076 Pa when the electromagnet excitation current is 3 A. When a fused silica glass is polished under a single magnetic field, the material removal depth reaches a maximum of 2.7 μm at a radius of 13.5 mm. Under the action of the electromagnetic compound field, the removal profile of the work-piece is smoother, and the material removal depth reaches the maximum value of 2.1 μm at a radius of 10.5 mm. This proves that the stiffness distribution of the polishing pad under the electromagnetic composite field is more dispersed than that under a single field. Therefore, the distribution of electromagnetic two-phase composite particles can be controlled by applying an electromagnetic composite field, which provides a good foundation for the abrasive control technology of EMRP.

Study on the Electrorheological Ultra-Precision Polishing Process with an Annular Integrated Electrode.

Electrorheological (ER) polishing, as a new ultra-precision super-effect polishing method, provides little damage to the workpiece surface and is suitable for polishing all kinds of small and complex curved surface workpieces. In this paper, an ER polishing tool with an annular integrated electrode is developed. The orthogonal experiments are carried out on the six influencing factors of ER polishing which include the applied voltage, the abrasive particle size, the abrasive concentration, the polishing gap, the polishing time and the tool spindle speed. The influence order of these six factors on the ER polishing is obtained. On this basis, the effect of a single process parameter of ER polishing on surface roughness is studied experimentally.

Experimental Investigation into Electrorheological Fluid-Assisted Polishing of Glass-Ceramic

A series of experiments are conducted to polish glass-ceramic by a circular-type integrated electrode tool in the electrorheological(ER) fluid-assisted polishing process. In this study, the microstructure of fibrous columns formed by particles perpendicular to the electrodes is observed when the electrical field is applied. The mass of ER polishing fluid gathered on the tip of tool electrode and the normal pressure in polishing area are measured by the dynamometer. The influential regularities of the concentrations of abrasive particles, the applied voltage, the spindle rotational speed, mixing ratio for abrasives and the gap between tool electrode and workpiece on the surface roughness are obtained by experiments.

Investigation into Normal Pressure during Electrorheological Fluid-Assisted Polishing

The normal pressure in polishing area is investigated in electrorheological (ER) fluid-assisted polishing process. Under the influence of the non-uniform electric field, the dielectric particles in the ER polishing fluid are polarized to form the rigid core attached to the tool electrode due to the ER effect. In this work, the rigid core generated by the gathered mass of ER polishing fluid on the tip of tool electrode with the applied electric field is analyzed. The material is removed by abrasive particles under the effect of normal pressure and velocity. Based on the theory of hydrodynamic lubrication, a mathematical model taking into account the normal pressure is derived. Further experiments about the normal pressure experiments changing with the applied voltage, spindle rotational speed and working gap are conducted and the experimental results are compared with the theoretical results, which confirm the validity of the presented model

Study on Material Removal in Electrorheological Fluid-Assisted Polishing

The material removal is investigated in electrorheological (ER) fluid-assisted polishing of conductive materials. The combination structure of ER particles with abrasive particles in ER polishing fluid is discussed when the electric field is applied. The forces exerted on the abrasive particles for material removal are analyzed. According to Preston’s equation, a model for material removal of the polished conductive workpiece is derived. Polishing experiments with diamond particles for WC is conducted and the experimental results are compared with the theoretical predictions, which confirm the validity of the presented model.