Ultra-precision Process Research Articles

Response of Ultra Precision Machine under Micro Environment Vibration

For the study of response of ultra-precision machine under environment vibration and its influences on machining precision, the numerical simulation method is adopted in this paper, the equipment modes are analyzed for the rationality of established model compared to the test results; and the frequency response of the machine excited by the measured ambient vibration acceleration power spectral shows that the table displacement reaches up to 0.396μm, exceeding the value allowed. Therefore, it’s significant to consider the micro environment vibration in ultra-precision processing.

The Characteristic Analysis of Double Vibration Isolation Model Based on MRF and Piezoceramics

with the rapid development of ultraprecise process technology, the precision of instrument is being improved fast. Then instruments are more sensitive to the vibration of environment. This paper took advantage of the controlled character of MRF’s shear force, using actuators made of PZT,and put forward the double vibration isolation model based on MRF and piezoceramics. Through the theoretical analysis we arrival at a conclusion that the model has a good Isolation effect on both high frequency vibration and low frequency vibration especially ultralow frequency vibration.

The Study of Error Separation in On-Site Measurement Based on Bayesian Network

The measurement error contains many errors in NC machine tools processing and those errors will be mapped to workpiece at certain regularity. The control of error caused by cutting parameters during the precision and ultra precision process is one of the key technologies in NC machine tools processing. This article introduces Bayesian networks into the dynamic error separation modeling, with the learning process of Bayesian network structure and establishes the error separation model based on Bayesian networks, then carries out the comparison and analysis between simulate and experimental data to verify the feasibility of the method.

The Research of ELID Grinding Effect and Surface Quality on Carbonized Cold-Rolled Steel

In this document, the electrolytic in-process dressing ( ELID ) grinding technique is used for ultra-precision processing experimental research on the carbonized cold-rolled steel (HRC60～80).A surface roughness of Ra6～8nm was obtained after ELID precision grinding. The results proved that adopting micro grain size (W1.5～W36) and high hardness cast iron based diamond grinding wheel, increasing the wheel peripheral velocity (18～20m/s) and reducing grinding depth can effectively improve surface quality and bring the surface roughness down. The wheel peripheral velocity, grinding depth as well as grinding fluid are the main factors during ultra-precision grinding.

Concept for performance-enhancement of ultra-precision dicing for bulk hard and brittle materials in micro applications by laser dressing

Adapted ultra-precision dicing processes are required for implementing hard and brittle materials such as sintered silicon carbide (SSiC) into MEMS applications. Wear and accuracy loss of resin-bonded dicing blades are significant when processing SSiC. Metal-bonded dicing blades can better resist the harsh environment during dicing of SSiC but require frequent dressing to renew the worn-out diamond grains. This paper presents laser dressing of metal-bonded dicing blades to show its capability as an online dressing tool. The laser dressed blades achieve equal sharpness as conventional dressed blades with the advantage of a smaller and more consistent reduction of the blade diameter. Laser pulse lengths of 655 and 12ps with a wavelength of 532nm are studied for laser dressing. The dicing blades dressed with 655ps achieved higher cutting performances in terms of increased substrate roughness and better cutting depth consistency.

The Application of Adaptive Kalman Filter Technology in Aspheric Surface Machining and Detection

The grinding machining parameters of large-caliber aspherics ultra-precision grinding processing depend on the analysis of online profile accuracy detection data .and the detection data has the second order of non-stationary characteristic . The research of second order of non-stationary data processing technique and isolate and reduce the random error of online detection data is key technology of ensure the precision of aspheric surface grinding accuracy . This paper proposed a parallel recursive identification of improved adaptive kalman filtering method , the simulation analysis and φ500mm aspheric surface element grinding experiment proved this method can real-time process second order of non-stationary data of online detection data , isolate and reduce the random error , make a best estimate of time-varying signal, provide correction parameter of grinding process , processed aspherical face proflie accuracy≤4μm.

The Composite Ultra-Precision Processing Technology for the Small Aspheric Mould of Stainless Steel

Stainless steel; Aspheric mould; Ultra-precision turning; Magnetorheological polishing Abstract. The ultra precision turning and the inclined-axis type of magnetorheological polishing were introduced for the small aspheric mould of stainless steel. The method was based on the principle of two kinds of processing methods, and the processing feature of stainless steel material. Firstly, the ultra-precision turning was employed to shape aspheric surface rapidly and obtain a relatively good surface. And then, the inclined-axis type of magnetorheological polishing as the final finishing was used to decrease sub-surface damage to obtain better precision. Several of experiments were carried out, the experimental results show that surface roughness can be achieved for Ra 0.0073μm.

Research on Flexible Bonnet Polishing Process Method and Related Technology

Bonnet tool polishing is one kind of methods that can obtain higher surface quality of the ultra precision processing for producing flat, aspheric and other mould free surface, etc. The latest development and research results on bonnet polishing technology at home and abroad were reviewed. The core technologies of bonnet polishing were analyzed, including polishing principles, polishing tool, the rate of material removal, edge control, dwell time, path planning etc. The results show that the bonnet polishing method is an economic, efficient, practical and high precision polishing technology.

Motion Control Design for X-Y Positioning Platform

X-Y positioning system subject to rapid development of high technique is becoming one of the core parts in modern industries. The requirement of motion control for such systems advances rapidly, such as ultra-precision processing, micro/nano manufacturing, packing and so on. In addition to the demand of positioning precision, coordinated movement is also specified. In this paper, a scheme of X-Y positioning platform based on ACS motion controller is proposed. Then, system configuration and parameter optimization are presented. Simulation results demonstrating the effectiveness of the accurate tracking for the desired trajectory are given.

LED用サファイヤ単結晶基板の超精密CMP加工技術とそのPSS加工プロセスへの応用

LED用サファイヤ単結晶基板の超精密CMP加工技術とそのPSS加工プロセスへの応用

A Bluge Rotational Tool in Thin Film Nanostructures Removal

A bluge rotational tool has been developed as an effective precision electrochemical removal for the thin film nanostructures from LCD panels. This ultra-precise process effectively removes defective Indium-Tin-Oxide layers allowing LCD panels to be returned to the production line and significantly reduces costs. In the current experiment a 7th Generation TFT-LCD panel was used. A high rotational speed of the cheek rotational tool elevates discharge mobility and improves the removal effect. A negative electrode of large diameter with a small end radius provides higher current density and also improves the removal affect. Pulsed direct current can improve the effect of dregs discharge and is advantageous when combined with a higher electric power. A fast feed combined with a high current flow results in very effective removal of the color filter layer. This novel design using electrochemical removal as a precision recycling process for removing ITO layers from LCD panels is clean, effective and very fast.

A Model of CMP about Magnetic Fluid and its Numerical Simulations

Chemical mechanical polishing (CMP) is one of the most effective technologies in modern ultra-precision processing. In this paper, we consider the slurry is ferromagnetic fluid and the influence of the centrifugal force, and then obtain the equations about this slurry in CMP. The slurry pressure distribution, resultant forces and moments acting on the wafer are calculated in typical conditions, and the affects of film thickness, roll and pitch angles are also calculated.

Numerical Simulation for the Interaction of the Semi-Fixed Abrasive Plate with the Workpiece

In order to improve the efficiency of ultra-precision processing, the semi-fixed abrasive plate (SFAP) is developed to reduce or eliminate the surface and subsurface defects and improve the process efficiency. The interaction of the semi-fixed abrasive plate-workpiece is the key factor for the processing. The complex plate-workpiece interaction is taken into consideration in the generation of the semi-fixed abrasive surface in this paper. A numerical model which allows describing the elastic-plastic contact load of the isotropic fractal surface and the real contact area of plate-workpiece is developed for the semi-fixed abrasive plate. The results shows that the real contact area is only a part of the workpiece and it changed with the contact load alteration, it is useful to determine the processing parameter of SFAP lapping.

Software Datum Design for Cross-Axis Motion Measurement of X-Stage Based on Least Uncertainty Criterion

Cross-axis translational motion of a table on a machine tool is important in ultraprecision processes. Currently, conventional software datums that separate the cross-axismotion fromthe straightness profile of the straightedge by using multiple sensors and/or multiple arrangements are well-known. However, in large sampling numbers, the multiple sensor method tends to propagate random error. In this paper, a novel software datum for cross-axis motion measurement that can reduce the uncertainty due to the datum profile, pitch motion and random error is proposed. The proposed method consists of a weighted addition and inverse filtering. The suitable weight for the weighted addition yielding the least uncertainty is derived by an equation using standard deviations of the datum profile, pitch motion and random error of the sensors.

High Precision Grinding Wheel Dressing Control Based on PLC

This paper explains PLC control method dealing with grinding wheel dressing, which can be utilized for ultra-precision aviation face gear processing etc. Among the previous processings, shapers and sphericity hob were applied. Whereas gear slotting processing and gear hobbing processing can not achieve project precision. Therefore this new solution was designed: fristly deal with wheel dressing problem, secondly dress face gear with grinding wheel previously dressed. This paper resolved the first problem, within which most crucial part is precise control of switching time. Timers application realized synchronization. There is a PLC managing two driving motors’ synchronization. Two motors working in different but fixed speeds, whilst switching directions at a precisely same time.

Nano-Process of SiC Ceramics by Molecular Simulation

SiC ceramics have been widely used in a variety of areas due to the excellent physical and chemical properties. However, the process of SiC ceramics is difficult and high-cost, molecular simulation is an effective and feasible method to study the nano-process of SiC ceramics. In this paper, a molecular model is presented to simulate the stress and energy in the nano-cutting of SiC ceramics. The influences of the cutting depth and cutting speed on the kinetic energy and potential are analyzed. The results show that potential energy increases with the decrease of the cutting depth. Kinetic energy increases with the increase of the cutting speed. The results are very helpful for improvement the level of ultra-precision processing and nano-processing of brittle ceramics.

A Removal Modus of Thin Film Nanostructures via a Gear Form Tool

A effective method for the precision electrochemical removal of thin film nanostructures from LCD panels using a gear-shaped electrode tool has been developed. This ultra-precise process effectively removes defective Indium-Tin-Oxide layers allowing LCD panels to be returned to the production line and significantly reduces costs. In the current experiment a 7th Generation TFT-LCD panel was used. A high rotational speed of the gear-shaped negative electrode elevates discharge mobility and improves the removal effect. Pulsed direct current can improve the effect of dregs discharge and is advantageous when combined with a fast workpiece feed rate. A fast feed combined with a high current flow results in very effective removal of the color filter layer. A negative electrode of large diameter with a small edge radius provides higher current density and also improves the removal affect. This novel design using electrochemical removal as a precision recycling process for removing ITO layers from LCD panels is clean, effective and very fast.

Investigation of Semi-Fixed Abrasive Plate Wear Characteristics

In order to reduce or eliminate the surface defects caused by abrasive grains and improve the efficiency of ultra-precision processing, the technique of semi-fixed machining has been proposed for machining advanced ceramics. A semi-fixed abrasive tool (SFAT) has been manufactured; it has performances of semi-fixed machining technique. This document demonstrates wear characteristics of SFAT through experiments of machining silicon wafer. It showed that wet status or dry status of SFAT has greatly influenced wear characteristics of SFAT. Wear characteristic of SFAT presented mostly blockage and little grain-off occurred in dry status; mostly grain-off and little blockage presented in wet status.

The fundamentals of modelling abrasive machining using molecular dynamics

The development of ultra-precision processes which can achieve excellent surface finish and tolerance at the nanometre level is now a critical requirement for many industrial applications. At present, it is very difficult to observe the diverse microscopic physical phenomena occurring in nanometric machining through experiments. The use of molecular dynamics (MD) simulation has proved to be an effective tool for the prediction and the analysis of these processes at the nanometre scale. The crucial task in a MD simulation is the selection of the potential function. The lack of clear understanding about the scope and the limitations of a given potential function may lead to nonsensical results. This article presents the backgrounds of popular potentials used in the modelling of materials processes and the algorithms for the solution of the equations encountered in the simulation. Current applications of MD in abrasive machining are reviewed.

ITO Thin-Film Removal Process Using Design of Rolling Tool

Although the low yield rate of ITO thin-film during the production of semiconductor techniques is easily seen. Current work presents a new modus of electrochemical machining using a design rolling tool as electrodes constructs a precision recycle process offering faster performance in removing the color filter surface’s ITO thin-film. Through establishing an ultra-precise recycling process to remove the thin-film microstructure, this helps the semiconductor optoelectronic industry to reduce both production costs and pollution. The design features of the removal processes for a thin-film and the tool design of rolling electrodes are of major interest. Higher electrical current is not required when an effective feeding electrodes is used to reduce the response area. In the current experiment, the author utilizes a 5th Generation TFT-LCD. The design electrodes (rolling tool) are used with continuous and pulsed direct current in the electrochemical machining experiment. A displays’ color filter with a fast feed rate is combined with enough electric power to provide highly effective removal. High rotational speed of the rolling tool and high flow velocity of the electrolyte elevates the discharge mobility and improves the removal effect. A larger diameter of the fictitious rotation circle of the cathode and a small end radius of the cathode provide better removal effect. A precision recycling process is presented using an effective rolling tool in the electrochemical machining. It only needs a short period of time to remove the ITO thin-film easily and cleanly.