Authors: Xiao Chen Gai, Zhi Wei Dong, Qing Liang Zhao, Hong Bin Liu
Abstract: Femtosecond laser micromachining technology shows abroad application background in the field of micro manufacturing due to its unique advantages, especially for micromachining of ultrahard materials such as Silicon carbide (SiC) ceramic. The femtosecond laser micromachining system was set up, by using the system, effects of scanning velocity and laser pulse energy on quality of micromachined features were evaluated. The optimized technological parameter was obtained as 8mW, 1mm/s with 1kHz repetition frequency respectively on the basis of the morphological characteristics and microstructure accuracy. Besides, V-shaped cavity of 300μm depth and 120°angle was generated with layer-by-layer scan machining. Thus femtosecond laser micromachining technology is an effective method for hard and brittle materials precision processing.
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Authors: Shao Hui Yin, Jing Wang, Feng Jun Chen, Jian Wu Yu, Yu Wang, Qing Liang Zhao, Hong Liang Li
Abstract: Through establishing the mathematical models of velocity and grinding force to optimize the installation angle with inclined axis grinding technology, the spherical surface of the ultra-hard alloy material was ground by formed electroplated diamond wheel. After analyzing the abrasion of grinding wheel, the results show that the inclined axis grinding technology of the formed grinding wheel can avoid the rotation dead spots of grinding wheel, and can make the grinding wheel surface contacted with work-piece fully which could make the worn more evenly. Finally, it obtains a surface in a high quality with the surface roughness of Ra is 12.88nm, and the form accuracy of PV is 124nm.
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Authors: Qing Liang Zhao, Jun Yun Chen, Jian Luo
Abstract: Experimental results indicate the previous theoretical model cannot predict well the surface roughness in single-point diamond turning on a precision lathe. In solving that, an improved model was presented in this paper. The difference between the previous model and the improved model is that the relative tool-workpiece vibration is measured before cutting operation using a capacitive displacement sensor in the previous model whilst the vibration is extracted from the measured surface profile in the improved model. The relative vibration was first studied under various cutting conditions to establish the vibration modes under corresponding cutting conditions. Then the surface roughness was predicted based on the vibration modes. The results prove that there is good agreement between the predicted values and measured values and the improved model is useful and reliable.
856
Authors: Qing Liang Zhao, Jun Yun Chen, Jun Yao
Abstract: In this paper, a copper-resin bonded diamond wheel was applied to machine the optical glass on a precision grinder. The process of truing and pre-dressing with ELID (electrolytic in-process dressing) were first carried out for the grinding wheels, then the ELID assisted grinding experiments were conducted with the special fine and coarse grained diamond wheels. The experimental results show that the fine and coarse grained wheels can all generated the smooth surface with the surface roughness in nanometer scale and the coarse grained diamond wheel correlates to the slightly more surface damage than the fine grained diamond wheel, which also proves that the high efficient grinding of the optical glass with a good surface quality can be realized with the coarse grained copper-resin wheel on a precision grinder and the grinding wheels were all well conditioned with the conditioning method presented in this paper.
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Authors: Qing Liang Zhao, Ekkard Brinksmeier, Otmann Riemer, Kai Rickens
Abstract: In order to realize ductile machining of optical glasses using mono-layer nickel
electroplated coarse-grained diamond grinding wheel, a novel conditioning technique features using
a copper bonded diamond grinding wheels of 15m grain size dressed by ELID (electrolytic inprocess
dressing) to condition the 46m grain sized diamond wheel has been developed. During the
conditioning process, a force transducer was used to monitor the conditioning force, a coaxial
optical distance measurement system was used to in-situ monitor the modified wheel surface status.
White-light interferometry (WLI), scanning electron microscopy (SEM) and atomic force
microscopy (AFM) were used to characterize the conditioned wheel surface status as well as the
ground optical glass surface topography correspondingly. The experimental result indicates that a
minimized wheel radial run-out error of less than 2μm as well as the top-flattened diamond grains
of constant wheel peripheral envelop profile were generated on a 5-axis ultra-precision machine
tool. The grinding experiment proved that the well conditioned 46μm coarse-grained diamond
wheel can be used in realizing the ductile grinding of optical glass BK7, which indicates that the
newly developed conditioning technique is feasible and applicable to introduce the coarse-grained
diamond wheels into precision machining of brittle and hard-to-machine materials.
578
Authors: Qing Liang Zhao, Guang Yu, Tao Sun, Shen Dong
Abstract: An advanced conditioning technique was developed to precisely and effectively
condition the nickel electroplated mono-layer coarse-grained diamond grinding wheel of 46m and
91m grain size with an aim to fabricate Diamond Micro Tool Arrays (DMTA), to meet the high
demands of form accuracy, surface quality and low subsurface damage in ductile machining of
silicon carbide (SiC). The precision machining experiments on SiC were carried out on a precision
grinder to determine the applicability of these fabricated diamond micro tool array (DMTA). The
experimental result indicates that the newly developed DMTA is applicable and feasible to realize
ductile machining on SiC with high efficiency and low diamond tool wear rate, which shows a good
prospect to apply this new concept diamond tool type in precision machining of SiC, as well as the
other brittle and hard-to-machine materials.
321
Authors: Qing Liang Zhao, Bo Wang, Ekkard Brinksmeier, Otmann Riemer, Kai Rickens, John Corbett
Abstract: This paper aims to evaluate the surface and sub-surface integrity of optical glasses which
were correspondingly machined by coarse and fine-grained diamond grinding wheels on Tetraform
‘C’ and Nanotech 500FG. The experimental results show that coarse-grained diamond grinding
wheels are capable of ductile grinding of optical glasses with high surface and sub-surface integrity.
The surface roughness values are all in nanometer scale and the sub-surface damages are around
several micros in depth, which is comparative to those machined by fine-grained diamond wheels.
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Authors: Qing Liang Zhao, Ekkard Brinksmeier, Otmann Riemer, Kai Rickens
Abstract: In this paper, a novel conditioning technique features using copper bonded diamond
grinding wheels of 91μm grain size assisted with ELID (electrolytic in-process dressing) as a
conditioner to precisely and effectively condition nickel electroplated monolayer coarse-grained
diamond grinding wheels of 151μm grain size was firstly developed. Under optimised conditioning
parameters, the super abrasive diamond wheel was well conditioned in terms of a minimized run-out
error and flattened diamond grain surfaces of constant peripheral envelope, with the conditioning
force monitored by a force transducer as well as the modified wheel surface status in-situ monitored
by a coaxial optical distance measurement system. Finally the grinding experiment on BK7 was
conducted using the well conditioned wheel with the corresponding surface morphology and
subsurface damage measured by AFM (atomic force microscope) and SEM (scanning electron
microscope) respectively. The experimental result shows that the newly developed conditioning
technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface
roughness, indicating a prospect of introducing super abrasive diamond wheels into ductile
machining of brittle materials.
382
Authors: Qing Liang Zhao, Da Gang Xie, Ekkard Brinksmeier, Otmann Riemer, Kai Rickens
Abstract: A novel conditioning technique to precisely and effectively condition the nickel
electroplated mono-layer coarse-grained diamond grinding wheel of 91m grain size was developed
to fabricate a Diamond Micro Tool Array (DMTA) in ductile machining of brittle materials. During
the fabricating process, a copper bonded diamond grinding wheels (91m grain size) dressed by
ELID (electrolytic in-process dressing) was applied as a conditioner, a force transducer was used to
monitor the conditioning force, and a coaxial optical distance measurement system was used to insitu
monitor the modified wheel surface status. The experimental result indicates that the newly
developed conditioning technique is applicable and feasible to generate required wheel topography
of less than 2μm run-out error and grain geometries. The taper cutting test on BK7 proves the
fabricated DMTA is capable of realizing ductile machining of brittle materials.
737
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.
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