Hybrid Polishing Research Articles

Controllable hybrid side-polishing method (CHPM) for optical fibers by combination of polishing and etching

We introduce the controllable hybrid polishing method (CHPM), which is a combination of enhanced side-polishing and etching methods, leading to a more controllable and precise clad polishing process for optical fibers. The two key advantages of CHPM are enabling of real-time monitoring of the etching process with a resolution of ~100 nm and fabrication of a 34% smoother polished surface than that of traditional polishing methods. Bearing in mind that these two factors are very important for the fabrication of any polished fiber devices, such as plasmonic sensors, the CHPM should prove highly useful in related industrial and scientific applications.

전해-자기 복합 가공을 이용한 미세 그루브형상의 가공 특성에 관한 연구

Magnetic abrasive polishing is an advanced deburring process for nonmagnetic materials and micropattern products that have non-machinability characteristics. Despite these advantages, there are some problems with using MAP for deburring. MAP has introduced geometric errors into microgrooves because of an over-cutting force caused by uncontrolled magnetic abrasives in the MAP tool. Thus, in this study, to solve this problem, an EP (electrolyte polishing)-MAP hybrid polishing process was developed for deburring microgrooves in an STS316 material. In addition, an evaluation of EP-MAP for the deburring of microgrooves was carried out by profiling the burrs. The results of the experiment showed geometric errors after the deburring process using MAP. However, in the case of EP-MAP, no geometric error was observed after the process because of the lower material removal rate in EP-MAP.

Mechanism and Experimental Investigation on Silicon Wafer Hybrid Polishing by Ultrasonic-Elliptic-Vibration Chemical-Mechanical

Considering the technical status and existing problems of traditional silicon wafer chemical mechanical polishing (CMP), especially for the diameter of silicon wafer increasing, constantly, the surface quality and efficiency of silicon wafer polishing are becoming an urgent problem to be solved, so the research subject of ultrasonic vibration hybrid polishing new technique was proposed. By means of mechanism theoretical analysis research, firstly, the processing mechanism of hybrid polishing was studied systematically. An investigation of polishing mechanisms based on the micro-contact model between the polishing pad and the polishing surface of silicon wafer was developed. Polishing mechanism theoretical analysis shows that when ultrasonic vibrations combined with mechanical and chemical, the performance of polishing slurry is improved in the process of CMP, therefore to create favorable conditions. To verify the established theory, then, a series of experiments to investigate the traditional CMP are conducted, as well as the polishing tool with the forms of ultrasonic vibration, the polishing pad, the polishing surface quality, velocity at polishing point v, and slurry supplying Q on silicon wafer polishing. Experiment findings showed that, in the same polishing conditions, especially, hybrid polishing by ultrasonic-elliptic-vibration has gained more advantage over the effect of silicon wafer polishing. When ultrasonic-elliptic-vibration is put in polishing tool, the silicon wafer polished surface roughness Ra from the traditional method of polishing 0.077μm going down to the 0.042μm, the no-smooth rate KR which describes the polished surface morphology is significantly improved, and the material removal rate increases by 18%. Experimental research findings of the surface quality and the material removal mechanism are shown to be consistent with the theoretical analysis.

An Investigation on PRMMC Polishing with Electrochemical Mechanical Machining Process

Since Particle Reinforced Metal Matrix Composites (PRMMC) normally applied Al2O3, SiC particle and other hard material as reinforce item, traditional manufacturing processes are hard to machine PRMMC with high efficiency and low tool cost. This paper presents an electrochemical mechanical (ECMM) hybrid polishing procedure for PRMMC, and the influences of parameters such as work voltage, grinding area proportion, the formula and concentration of electrolyte has been investigated. Through a hybrid polishing compound with a no Z direction feed pure mechanical grinding progress in Vx opposite direction, Ra around 0.5um PRMMC surface can be achieved.

Process optimization of the serial-parallel hybrid polishing machine tool based on artificial neural network and genetic algorithm

A kind of serial-parallel hybrid polishing machine tool based on the elastic polishing theory is developed and applied to finish mould surface with using bound abrasives. It mainly consists of parallel mechanism of three dimensional moving platform, serial rotational mechanism of two degrees of freedom and the elastic polishing tool system. The active compliant control and passive conformity of polishing tool are provided by a pneumatic servo system and a spring, respectively. Considering the contradiction between the machining quality and efficiency, the optimization model of process parameters is found according to different machining requirements, namely single objective optimization and multi-objective optimization, which provide a choice of parameters as a basis for the operators in practice. Many polishing experiments are conducted to collect the data samples. The genetic algorithm integrated with artificial neural network is used for researching for the optimal process parameters in term of the various optimization objectives. This research also lays the foundation for further establishing polishing expert system.

Hybrid polishing mechanism of single crystal SiC using mixed abrasive slurry (MAS)

Single crystal SiC is a mechanically hard and chemically inert material used in optical and power devices. This work proposes the development of a hybrid polishing technique using a mixed abrasive slurry (MAS) with colloidal silica and nano-diamond. Hybrid removal mechanism of the MAS on the SiC is investigated by polishing results, chemical analyses and AFM studies. Each role of two abrasives is distinguished by scratching tests with AFM contact mode on the chemically reacted SiC surface. Finally, this paper provides an optimum MAS condition to realize highly efficient material removal rate (MRR) keeping defect-free surface.

Polishing Characteristics on Silicon Wafer Using Fixed Nano-Sized Abrasive Pad

A mechanical polishing process was used to reduce surface roughness through mechanical fracturing and removal of the substrate’s roughened regions. It was thus necessary to understand the effect of grain size and morphology on the material removal mechanisms of silicon wafers by stepwise polishing using a fixed abrasive pad. A hybrid process combining the optimized silicon polishing recipe for rapid roughness reduction with a micro-sized diamond, and then polishing using a nano-sized diamond to produce a final finished surface, may be the optimum approach. The best result using the hybrid polishing process was the surface roughness (Ra) value of 3.32 nm.

Experiment on Dynamics of the Hybrid Polishing Kinematics Machine Tool with Clearance Based on the Flexible Multi-Body Systems

This paper develops a novel five DOF hybrid polishing kinematics machine tool in order to obtain more stable machining result in the elastic polishing on the free-form surfaces. Because the machine tool is a complex multi-body system that comprises many close-loop structures, jointing clearance becomes the important influence factor to its moving stability. The unified rigid multi-body and flexible multi-body dynamics equation of for the parallel mechanism of hybrid polishing kinematics machine tool is respectively built, which considers the influence of joint with clearance and applies the kinematics model of Newton second state. The result of analysis shows that the moving stability of the hybrid polishing kinematics machine tool is reduced due to the existing jointing clearance. However, the interior flexibility of the mechanism can reduce the shock effect of collision in the part of motion pair. It can improve the working stability of mechanism.

A study of the inverse dynamics of a hybrid polishing kinematical machine tool based on the flexible multi-body systems

This paper presents a novel 5-DOF Hybrid Polishing Kinematical Machine Tool (HPKMT), which is made up of '3 axes parallel + 2 axes series' to obtain more stable machining result in the elastic polishing on the free-form surfaces. The dynamic characteristics of HPKMT are studied in detail by means of the theory of dynamics of flexible multi-body systems. Its characteristics of the kinematics and dynamics need be known deeply to control HPKMT effectively. The analysis of the inverse of mechanism is the important part in the research of dynamics. Adopting the same experiment condition with simulation analysis, the inverse kinematical trace of the three sliders can be obtained. It is shown that the simulation result is almost the same as the measured result from the experiment.

Research on the Inverse Dynamics of the Flexible Multi-Body Systems for the Hybrid Polishing Kinematics Machine Tool

The hybrid polishing kinematics machine tool (HPKMT) which is made up of “3 axes parallel + 2 axes series” is developed with the specially designed elastic polishing tool system for the polishing operation on the free-form surfaces by using the characteristic of the elastic polishing adequately by the authors. In order to control the HPKMT effectively, its characteristic of the kinematics and dynamics need be known deeply. Moreover, the problem of inverse dynamics is the theory foundation to apply dynamic control of the HPKMT. The analysis of the inverse of mechanism is the important part in the research of dynamics. On the basis of the differential equations of flexible multi-body dynamics, this paper discusses on the condition of knowing the trace, posture and velocity for the end of bodies how to solve the constraint force and constraint moment of each joint on the 3- PTT parallel mechanism and two-joint series mechanism.

Study on the Modeling and Experiments for the Virtual Axis Hybrid Polishing Machine Tool by the Flexible Multibody Dynamics

The virtual axis hybrid polishing machine tool (VAHMPT) is the novel equipment developed by the authors that is aimed at the precision machining on the free-form curved surfaces. This paper establishes the dynamic equations of the spatial rigid-flexible coupling multibody systems considering the coupling for the rigid movement of the whole VAHMPT with the elastic deformation of each leg by means of the theory of dynamics of flexible multibodysystems. Meanwhile the dynamic characteristics of the hybrid machine tool is studied in detail by the dynamics simulation analysis. The dynamic simulation of the machine shows that the elastic deformation of each leg is very small during the movement of the machine and the influence of the flexibility of each leg on the trace of moving platform is not obvious due to the characteristics of joints. The dynamic characteristics of the VAHPMT is verified combining with the experiments. It is shown that the experiments result is almost accorded with the simulation analysis. The satisfied polishing effect on the curved surfaces can be obtained and the demand of the polishing can be achieved by the VAHPMT.

Study on the dynamic characteristics of a virtual-axis hybrid polishing machine tool by flexible multibody dynamics

This paper establishes the dynamic equations of the spatial rigid-flexible coupling multibody systems for a five-coordinate virtual-axis hybrid polishing machine tool, namely model JDYP51 developed by the authors. The dynamic characteristics of the hybrid machine tool are studied in detail by means of the theory of dynamics of a flexible multibody system and the finite element models of the whole machine tool and each leg respectively. The dynamic simulation of the machine shows that the elastic deformation of each leg is very small during the movement of the machine and the influence of the flexibility of each leg on the trace of moving platform is not obvious due to the characteristics of joints. At the beginning of the movement of the machine, the fundamental frequency of parallel mechanism easily leads to vibration of the machine. Therefore, the stable status of polishing can be obtained at all periods of the movement of the machine except the beginning of the movement.