Papers by Author: Bo Wang

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Authors: Peng Zhang, Bo Wang, Mark J. Jackson, Xing Mao
Abstract: Current requirements for producing highly precise and ultra-smooth micro structured surfaces of small parts are proposed in certain situations. The following question arises: how to make a highly precise and ultra-smooth micro-structured surface with high efficiency and low cost? Novel desktop lapping and polishing devices should be developed to satisfy these requirements. In order to improve the surface topography and remove the surface damaged layer of a highly precise and ultra-smooth micro thin-walled structure after milling with the width of 150 μm and the depth of 10 μm, a novel lapping desktop device is designed and developed. There are two key points in the design of the lapping desktop device: one is the vertical coupled macro-micro movement axis; the other is the fixture with a thin and flexible hinge structure, which has the capability of measuring both force and displacement as a double-feedback sensor to control both the micro lapping force and the depth of lapping. The experimental results show that the surface topography of the micro thin-walled structured surface is much improved after lapping, and that the three-dimensional surface roughness decreased from 329 nm to 82.2 nm.
Authors: Lin Che, Bo Wang, Guo Li
Abstract: In this paper, micro tensile method was combined with micro bridge dynamic test method as a new testing method for mechanics performance to be put forward, and a novel testing system for mechanics properties of the thin-walled micro components was established. The micro testing specimen were designed and manufactured. And related mechanics performance tests were carried on to verify the feasibility and reliability of the test system. The experimental results show that displacements of the testing system are measured with 0.01μm resolution and axial loads are measured with 0.005N resolution.
Authors: Bo Wang, Qing Liang Zhao, Lang Ping Wang, Shen Dong
Abstract: This paper presents a novel, rapid and damage-free method to polish the ultra-smooth surface of the SiC optics. First, the basic philosophy of this method is introduced, which uses the active radicals got from CF4 in the atmospheric pressure plasma zone to react with the SiC material at the optics surface to generate the vaporization of SiF4. Then, the design of the atmospheric pressure plasma jet and the corresponding prototyping polishing facility are introduced. The theoretical analysis on the necessary conditions to generate the excited radicals is also presented in this part. To verify the effectiveness of this novel polishing method, experiments on the generation of atmospheric pressure plasma and the SiC optics polishing are carried out with our prototyping facility. The experiment results show that plasma discharge is stable at the atmospheric pressure and sub-nanometer roughness of the polished SiC surface can be obtained.
Authors: Na Li, Peng Zhang, Qiang Xin, Jiang Jin, Bo Wang
Abstract: Silicon carbide (SiC) is widely used in terrestrial and space applications because of its good mechanical, thermal and optical properties. Nevertheless, traditional grinding and polishing technologies cannot meet the machining requirements due to the high hardness and brittleness. In this paper, Inductively Coupled Plasma (ICP) is utilized to process the SiC optics. The effects of different processing recipes on the removal rate and temperature are investigated. The results show that the removal rate almost keeps stable with processing time and changes with the flow rate of plasma gas, reaction gas, the ratio of CF4/O2 and the power. The input power and processing time are the two main influence factors on the processing temperature.
Authors: Bo Wang, Ju Xiang Wang, Ying Chun Liang
Abstract: To manufacture the micro parts or micro structures effectively and precisely, a high precision 3-axis micro milling machine is built. All the three axis are driven by linear piezoelectric ultrasonic motors and the slides are supported by cross-roller guide. Investigations are firstly made to analyze the impact of the non-linear characteristics in the servo mechanism on the performance of the servo system. To achieve the positioning and tracking accuracy at sub-micrometer and micrometer level respectively, on one hand, a optical linear encoder with the resolution of 50nm is applied to close the control loop and a high performance DSP based motion control card is used to carried out the reference command. On the other hand, sophisticated control and compensation strategies are also implemented to overcome the non-linear characteristics in the servo system. Positioning and tracking experiments show that, with this well-tuned control system, the positioning and tracking accuracy are ±0.5μm and ±2.4μm respectively. Using this machine, a micro part with 5μm thin-walled structure is machined successfully.
Authors: Yong Zhi Cao, Ying Chun Liang, Shen Dong, T. Sun, Bo Wang
Abstract: In order to investigate nanoindentation data of polymer film-substrate systems and to learn more about the mechanical properties of polymer film-substrate systems, SEBS (styreneethylene/ butylene-styrene) triblock copolymer thin film on different substrate systems have been tested with a systematic variation in penetration depth and substrate characteristics. Nanoindentation experiments were performed using a Hysitron TriboIndenter with a Berkvoich tip. The resulting data were analyzed in terms of load-displacement curves and various comparative parameters, such as hardness and Young’s modulus. The results obtained by the Oliver and Pharr method show how the composite hardness and Young’s modulus are different for different substrates and different penetration depth.
Authors: Peng Zhang, Li Hua Lu, Bo Wang, Ying Chun Liang
Abstract: To meet the requirement for the machining of the ultra-precision, ultra-smooth and micro-structure surface, an ultra-precision three axes micro milling machine was developed with the positioning accuracy better than ±0.25μm and the repetitive positioning accuracy better than ±0.2μm of all the three axes. The machine is proved to achieve the nanometer scale step response. Through milling experiments with micro-diameter tungsten carbide milling tool, the cutting performance has been further proved: the milling accuracy of 50μm-high step on the workpiece of aluminum alloy is better than ±0.3μm; and the 3D surface of pure copper workpiece is as smooth as mirror, with a roughness reaching 40nm. At last, the thin-walled structure of 10μm thickness on the workpiece of aluminum alloy is milled.
Authors: Dong Xu Wu, Guo Li, Bo Wang, Zheng Qiao, Lei Lv
Abstract: In this paper, a five-axis ultra precision machine tool for fabrication of microstructured surfaces is presented. This machine consists of two rotary axes (C&B) and three linear axes (X&Y&Z). High precision aerostatic bearing and torque motor are adopted in C axis (main spindle) and B axis. X axis and Z axis use the hydrostatic guideway and are driven by linear motors. Y axis is driven by torque motor and precision ball screw. This machine is able to realize multiple processing methods, including ultra precision diamond turning, ultra precision milling, fly-cutting, fast tool servo and slow tool servo diamond turning.Furthermore, a large number of experiment researches are carried out. Some typical microstructure surfaces are manufactured, for sinusoidal grid surface, the surface roughness Ra is 11.9nm, which is machined by slow tool servo diamond turning. Micro pyramid array surface is fabricated by using fly-cutting, which performs well both in the profile accuracy and the repeatability. These experiment researches prove that this ultra precision machine is superior in accuracy and system reliability.
Authors: Yan Shen Wang, Ying Chun Liang, Shen Dong, Wei Wei An, Bo Wang
Abstract: High-energy femtosecond laser pulses were utilized to ablate single-crystalline silicon wafer. Collateral damage areas around the ablation zone can be observed in microscope. The morphology in such areas changes gradually. The microscopic morphology and nanomechanical properties of the pre-polished back surface were measured by AFM and Hysitron TriboIndenter respectively. The topography and roughness in the ablated, metamorphic and unaffected zone are almost equal. Yet the elastic ratio and hardness on the back surface vary gradually with indent positions, which coincide with the gradual morphological changes in the metamorphic zone on the front surface. Such regular changes in nanomechanical properties, to some extent, reflect the distribution of collateral damages near the ablated zone on the back surface. And they also testify the occurrence of the ill effects that go against micromachining during high-energy femtosecond laser irradiation.
Authors: Yan Fu Zhang, Bo Wang, Shen Dong
Abstract: Optics with free form surface can be achieve special imaging effects and reduce component amounts in optical systems. However, it is difficulty to fabricate high accuracy, damage-free optical surface with free form surfaces by conventional method. Atmospheric plasma machining is a non-contact chemical processing method which can fabricate optics without damaged layer. Numerical controlled atmospheric pressure plasma machining (NC-APPM) method is proposed to machine optical free form surfaces. A new atmospheric pressure plasma jet generator was designed to get Gaussian rotational symmetry removal spot and the spot maximum diameter is 1.5mm. Base on dwelling time algorithm, a sinusoidal wave structure, the pitch 2mm and the amplitude 500 nm, is fabricated on a pre-polished flat silica quartz surface using three-axis numerically controlled machine made by ourselves. The result shows that the amplitude error is 59 nm compare to the expectation value surfaces using numerical controlled atmospheric plasma machining method.
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