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1.
Comparative study of conventional and micro WEDM based on machining of meso/micro Sized Spur Gear 总被引:1,自引:0,他引:1
Mohammad Yeakub Ali A. N. Mustafizul Karim Erry Yulian T. Adesta Ahmad Faris Ismail ’Aisy Anuarin Abdullah Mohd Nazrol Idris 《International Journal of Precision Engineering and Manufacturing》2010,11(5):779-784
This paper discusses the comparison of micro machining process using conventional and micro wire electrical discharge machining
(WEDM) for fabrication of miniaturized components. Seventeen toothed miniaturized spur gear of 3.5 and 1.2 mm outside diameter
were fabricated by conventional and micro WEDM respectively. The process parameters for both conventional and micro WEDM were
optimized by preliminary experiments and analysis. The gears were investigated for the quality of surface finish and dimensional
accuracy which were used as the criteria for the process evaluation. An average surface roughness (Ra) of 50 nm and dimensional accuracy of 0.1–1 μm were achieved in micro WEDM. Whenever applied conventional WEDM for meso/micro
fabrication, a Ra surface roughness of 1.8 μm and dimensional accuracy of 2–3 μm were achieved. However, this level of surface roughness and
dimensional accuracy are acceptable in many applications of micro engineering. A window of conventional WEDM consisting of
low energy discharge parameters is identified for micromachining. 相似文献
2.
The tribological behavior of polyphenylene sulfide (PPS) composites filled with micro and nano CuO particles in water-lubricated
sliding condition were studied. Pin-on-disk sliding tests were performed against a steel counterface of surface roughness
0.09–0.11 μm. The lubrication regimes were established from friction data corresponding to various combinations of loads and
sliding speeds. Later experiments were performed using the sliding speed of 0.5 m/s and contact pressure of 1.95 MPa, which
corresponded to boundary lubrication regime. Micro CuO particles as the filler were effective in reducing the wear of PPS
but nano CuO particles did not reduce wear. The steady state wear rate of PPS-30 vol.% micro CuO composite was about 10% of
that of unfilled PPS and the coefficient of friction in this case was the lowest. The examination of the topography of worn
pin surfaces of nano CuO-filled PPS by SEM revealed grooving features indicating three-body abrasion. The transfer films formed
on the counterfaces during sliding were studied by optical microscopy and AFM. The wear behavior of the composites in water-lubricated
sliding is explained using the characteristics of worn pin surfaces and transfer films on the counterface. 相似文献
3.
Cemented carbide has been investigated as a useful material for the fabrication of micro devices. Focused ion beam (FIB) micro-milling has been found to be one of the most appropriate methods for the fabrication of micro devices. The experimental FIB micro-milling on cemented carbide have been conducted according to the L16 orthogonal array of Taguchi technique. Beam current, extraction voltage, angle of beam incidence, dwell time and percentage overlap between beam diameters have been considered as process variables of FIB micro-milling in experimental design. Material removal rate (MRR) and surface roughness have been determined experimentally for FIB micro-milling of cemented carbide and beam current has been identified as the most significant parameter. The minimum surface roughness of 5.6 nm has been reported on cemented carbide, which is not a usual practice to achieve on such polycrystalline material, and hence it may be considered as a significant research contribution. Maximum MRR of 0.4836 μm3/s has been reported. Moreover, genetic algorithm toolbox of MATLAB has been utilized for multi-objective optimization between MRR and surface roughness. The corresponding optimum values of MRR and surface roughness for multi-objective optimization have been represented by pareto optimum solution generated by genetic algorithm. The research work presented in this paper determines the setting of process parameters of FIB micro-milling for achieving a specific combination of MRR and surface roughness on cemented carbide. 相似文献
4.
Zhao Qingliang Brinksmeier Ekkard Riemer Oltmann Rickens Kai 《Frontiers of Mechanical Engineering in China》2007,2(3):350-355
In this paper, a novel conditioning technique using copper bonded diamond grinding wheels of 91 μm grain size and electrolytic
in-process dressing (ELID) is first developed to precisely and effectively condition a nickel-electroplated monolayer coarse-grained
diamond grinding wheel of 151 μm grain size. 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.
The conditioning force was monitored by a force transducer, while the modified wheel surface status was 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 atomic force microscope (AFM) and scanning
electric microscope (SEM), 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 the potential
of super abrasive diamond wheels in ductile machining brittle materials.
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Translated from Chinese Journal of Mechanical Engineering, 2006, 42(10): 95–101 [译自: 机械工程学报] 相似文献
5.
Design and development of PCD micro straight edge end mills for micro/nano machining of hard and brittle materials 总被引:1,自引:0,他引:1
Xiang Cheng Zhigang Wang Kazuo Nakamoto Kazuo Yamazaki 《Journal of Mechanical Science and Technology》2010,24(11):2261-2268
One of the biggest challenges for mechanical micro/nano milling is the design and fabrication of high precision and high efficiency
micro milling tools. Commercially available micro milling tools are either too expensive (around several hundred US dollars)
or simply made from downsizing of macro milling tools, which is sometimes not appropriate for the specific micro/nano milling
requirements. So the design and fabrication of custom micro milling tools are necessary. In this paper, a micro straight edge
endmill (SEE) is designed. Static and dynamic FEM analyses have been done for the SEEs with different rake angles trying to
identify their stiffness and natural frequencies. By wire electrical discharge machining (WEDM), the SEEs made of polycrystalline
diamond (PCD) with three different rake angles have been fabricated. The evaluation milling on tungsten carbide (WC) and silicon
wafer have processed on a nano milling center. Experimental results show the SEEs have a good ability to simultaneously micro/nano
milling of both the side and bottom surfaces with submicron surface roughness, and the SEE has high accuracy for large aspect
ratio thin wall machining. The milling experiments on silicon wafer have successfully demonstrated that ductile mode machining
was achieved and the coolant played an important role in silicon wafer milling. 相似文献
6.
J. J. Hu R. Wheeler J. S. Zabinski P. A. Shade A. Shiveley A. A. Voevodin 《Tribology Letters》2008,32(1):49-57
To better understand the fundamentals of solid lubrication, microstructural analyses on the wear scar surface and contact
interface of Mo–W–S–Se composite films produced by pulsed laser deposition were completed. Focused ion beam (FIB), transmission
electron microscopy (TEM), and X-ray energy dispersive spectroscopy were employed to study the cross-sectional microstructure
and chemistry of wear scars. In particular, a novel microtribometer was built for in situ tribological measurements within
a FIB microscope. The sliding tip was welded in contact to the wear scar surface on the film under load by re-deposition of
sputtering materials from the FIB cut of the tip. Using this technique, cross-sectional TEM specimens were prepared precisely
at the contact point without tip/film separation. Here, the in situ FIB microtribometer is critically important for retaining the microstructure of lubricant films as formed
at the sliding contact interface between the tip and film without separation. It provides the unique ability to stop sliding,
section the contact, and reveal microstructural changes to that contact without disrupting the sliding interface. The cross-sectional
TEM measurements were performed on the sliding contact interface for both the regions in contact and just past contact, and
both the reorientation and recrystallization of lubricant films were revealed. 相似文献
7.
A numerical study is performed to investigate the effect of inner surface roughness and microparticles on adiabatic single
phase frictional pressure drop in a perfect square micro channel. With the variation of particles sizes (0.1 to 1 μm) and
occupied volume ratio (0.01 to 10%) by particles, the Eulerian multi-phase model is applied to a 100 μm hydraulic diameter
perfect square micro channel in laminar flow region. Frictional pressure loss is affected significantly by particle size than
occupied volume ratio by particles. The particle properties like density and coefficient of restitution are investigated with
various particle materials and the density of particle is found as an influential factor. Roughness effect on pressure drop
in the micro channel is investigated with the consideration of roughness height, pitch, and distribution. Additionally, the
combination effect by particles and surface roughness are simulated. The pressure loss in microchannel with 2.5% relative
roughness surface can be increased more than 20% by the addition of 0.5 μm diameter particles. 相似文献
8.
Nowadays the attention is focused on machining of non-silicon materials for miniaturized devices. High speed steel (HSS) is a non-silicon tool material, which is used in metal cutting applications as well as in micro-medical applications. Focused ion beam (FIB) milling process is highly suited for the fabrication of micro tools and other micro devices manufactured from HSS material. This study investigates the machinability aspects of HSS for FIB milling process. Beam current, extraction voltage, angle of incidence, dwell time and percentage overlap between beam diameters are the FIB process parameters, which have been analyzed experimentally to optimize FIB milling process for maximum material removal rate and minimum surface roughness. Beam current is found as the most significant parameter for controlling the material removal rate and surface roughness. 相似文献
9.
Masahiko Yoshino Takashi Matsumura Noritsugu Umehara Yoichi Akagami Sivanandam Aravindan Takenori Ohno 《Wear》2006,260(3):274-286
This paper proposes a new concept of the ‘engineering surface’, which extends the conventional idea of a functional surface by combining it with micro/nano manufacturing technology. Characteristic features and possibilities of the engineering surface are discussed in detail. This paper reviews studies on micro/nano fabrication technologies for advanced materials and evaluation technology for surface function. New fabrication technologies, micro machining and nano forming, are introduced, which will be basic manufacturing processes of the engineering surface. Also, a new surface evaluation technique is introduced for the surface energy of the nano fabricated surface. Design of a new DNA micro array chip is introduced as an example of applications of the engineering surface. Controllability of surface property by nano fabrication is studied. 相似文献
10.
Byung Yun Joo Young Ki Son Soo-Ik Oh 《The International Journal of Advanced Manufacturing Technology》2007,32(3-4):265-271
The objective of this study is to establish the limit of the metal forming process in terms of size and accuracy. In the present
investigation, micro channel forming with ultra thin metallic foil by the sheet metal forming process was studied. In order
to examine the fabrication limit of the process, both the channel size needed to be as small as possible and the sheet thickness
to be as thin as possible. Copper foil 1.0 μm thick was made into 5.6 μm wide and 3.2 μm deep channels. The shapes of the
channels were straight line, concentric circle, cross, and other curved shapes. Forming was done by cold isostatic pressing.
Single crystal silicon wafer was used as the die material, and die grooves were made by micro machining techniques. The die,
metallic foil, and plasticine as the pressure-transmitting medium were vacuum packed in a bag made of multilayered film. The
forming was conducted with a cold hydrostatic press where the forming pressure was 240 MPa. The formed channels were examined
in terms of their dimensions and surface qualities. Based on the examinations, channel formability was also discussed. 相似文献
11.
We have developed a laser and focused ion beam (FIB) compound process for press mold dies of a micro lens array (MLA) and a micro needle array (MNA) in a glassy carbon (GC). The press mold die of the MLA was roughly fabricated by UV-YAG laser. After this process, we finished this surface by scanning FIB. As a result, higher accuracy and good roughness of surface profile can be realized. An optical glass is used to confirm the shape of lens. Moreover, we fabricated 6 × 6 through-holes in the GC by the spiral drilling in addition to the focus position movement of the UV laser for press mold die of the MNA. After the FIB process, we were able to make the needle die of surface and hole wall roughness less than 0.9 μm. A silicon rubber is used to confirm the shape of the holes. 相似文献
12.
M. A. Tarasov L. S. Kuzmin N. S. Kaurova 《Instruments and Experimental Techniques》2009,52(6):877-881
Various aluminum-based thin-film structures were manufactured and investigated at temperatures of 50 mK–3 K. Multilayer films
of Al and Si, Al and Cr, and Al in the presence of oxygen were deposited by the thermal evaporation technique. As the thickness
of pure-Al films decreases from 20 to 3 nm, the temperature of the superconducting transition increases from 1.30 to 2.45
K. An increase in the oxygen pressure to 5 × 10−6 mbar during deposition of Al films results in an increase in the critical temperature to 2.4 K. The presence of a chromium
sublayer with a thickness of <0.5 nm may lead to complete suppression of superconductivity, whereas a thicker layer, 1–4 nm,
deposited at a higher temperature with preliminary sputtering reduces the critical current of Al/Cr two-layer films to a lower
degree. An atomic-force microscope was used to study the surface morphology and granularity and the roughness of manufactured
film structures. The smallest linear roughness having a size of 0.29 nm for a 3-nm-thick film shows the advantage of using
thinner films for creating a homogeneous tunneling barrier. 相似文献
13.
The economic and environmental benefits of using light-weighting technology in automotive applications continue to attract
attention for feasible commercial solutions. This study investigates the use of pulsed electron beam melting of a hypereutectic
Al–Si alloy as a possible modification procedure for cylinder crankcase bore facing surfaces. Machined surfaces of an A390
alloy were subjected to five pulsed electron doses with an applied cathode potential between 16.5 and 36 kV. It was found
that increasing beam accelerating voltages led to an initial decrease (1.4 μm R
a) but subsequent increase (4.0 μm R
a) in average surface roughness values associated with surface crater formation due to sub-surface melting and eruption. Surfaces
were tested under dry sliding tribological conditions against 52100 bearing steel in a reciprocating geometry. Average dynamic
friction coefficients were higher (0.9) compared to the untreated alloy surface (0.6) as a result of a greater degree of adhesion
to the counterface. However, FIB cross sections of worn surfaces indicated that this activated an oxidative type wear process
which ultimately led to the formation of a beneficial surface tribo-film on the EBM-treated surfaces, improving the specific
wear rates by up to 66%. 相似文献
14.
R. Minev M. Ilieva J. Kettle G. Lalev S. Dimov D. Tzaneva I. Dermendjiev R. Shishkov 《The International Journal of Advanced Manufacturing Technology》2010,47(1-4):29-35
For micro replication, the base of a die should be ductile and the surface layer that will undergo processing should have a good machining response to various tool-making processes. At the same time, the resulting working surfaces of the tooling cavities should be hard; having low roughness, low wettability and high erosion resistance. To achieve such diverse properties, nano-crystalline CrC coatings deposited onto 12% Cr tool steel were investigated in this research. To verify the properties of such coatings various metallographic techniques were applied. In particular, the corrosion resistance was studied by means of potentiodynamic anodic polarisation. A scanning transmission electron microscopy analysis of the structure was performed on samples prepared with focused ion beam (FIB) machining. The mechanical properties and grain size distribution were determined and statistically analysed. In addition, X-ray diffraction, scanning electron microscopy and atomic force microscopy were used in studying the surface properties of these coatings. To investigate the response of the CrC coatings to micro- and nano-structuring technologies with high specific energy, a series of rectangular trenches were produced by FIB milling. The effects of the ion beam current, exposure time and ion fluence on the sputtering yield and roughness of the produced micro-structures were especially investigated. Some essential parameter windows for performing FIB milling with relatively high sputtering rates, higher than 1?µm/min, and at the same time achieving the best possible surface integrity were determined during the experiments. 相似文献
15.
Evolution of residual stress and crack morphologies during 3D FIB tomographic analysis of alumina 总被引:1,自引:0,他引:1
Three‐dimensional focused ion beam (FIB) tomography is increasingly being used for 3D characterization of microstructures in the 50 nm–20 μm range. FIB tomography is a destructive, invasive process, and microstructural changes may potentially occur during the analysis process. Here residual stress and crack morphologies in single‐crystal sapphire samples have been concurrently analyzed using Cr3+ fluorescence spectroscopy and FIB tomography. Specifically, maps of surface residual stress have been obtained from optically polished single‐crystal alumina [surface orientation (1 ī 0 2)], from FIB milled surface trenches, from Vickers micro‐indentation sites (loads 50 g–300 g), and from Vickers micro‐indentation sites during FIB serial sectioning. The residual stress maps clearly show that FIB sputtering generates residual stress changes. For the case of the Vickers micro‐indentations, FIB sputtering causes significant changes in residual stress during the FIB tomographic serial sectioning. 3D reconstruction of the crack distribution around micro‐indentation sites shows that the cracks observed are influenced by the location of the FIB milled surface trenches due to localized stress changes. 相似文献
16.
Friction between titanium spheres and an artificially structured silicon surface was measured with a friction force microscope.
Two spheres with radii of 2.3 μm and 7.9 μm were firmly glued to the tip of the microscope cantilever. A periodic stripe pattern
with a groove depth of 26 nm and systematically increasing groove width from 500 nm to 3500 nm was fabricated from a silicon
wafer with a focused ion beam. The sphere substrate friction coefficient shows a strong enhancement at a certain groove periodicity,
which is related to geometrical interlocking of the two surfaces. This shows that careful modification of the surface roughness
can help to control the tribological behavior of mesoscale contacts. 相似文献
17.
Kyriaki Polychronopoulou Jungkyu Lee Christos Tsotsos Nicholaos G. Demas Ryan L. Meschewski Claus Rebholz Andreas A. Polycarpou 《Tribology Letters》2011,44(2):213-221
Ti-based protective thin films with thicknesses below 100 nm, intended for miniature applications were deposited using physical
vapor deposition magnetron sputtering. X-ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy
were employed for the assessment of microstructure, morphology, film thickness, surface topography, and roughness. XRD pattern
showed the formation of f.c.c TiN, TiCN, and TiC phases with different preferred orientations for films prepared in Ar/N2, Ar/N2 + C2H2, and Ar/C2H2 gas mixtures, respectively. Nanotribological performance was investigated using multipass nanoscratch technique at variable
applied normal loads (100–400 μN). The nanoscale coefficient of friction was found to be in the 0.08–0.1 range, a sufficiently
low value showing the potential of these films for miniature applications, such as microelectromechanical systems. The nanowear
resistance at mean contact pressures in the range of 5–8.5 GPa for each sample was evaluated in terms of the average residual
wear depth and an abrasive-dominated wear mechanism was found. 相似文献
18.
Single phase pressure drops in micro tubes were investigated through an experimental measurement and a numerical simulation.
Experimental Po was obtained in circular micro tubes with 87 and 118 μm diameter with distilled water. Experiments were carried
out in laminar flow region with varying the Re 15–450 for the 87 μm diameter tubes and 60–1300 for the 118 μm diameter tube.
No early transition from laminar to turbulent flow was detected for the experimental range. The computational estimation of
pressure drop in the 87 μm diameter tube was performed with the aid of CFD software. Boundary conditions from experiments
were used for the numerical simulation. The results of experimental and numerical studies showed a good agreement with the
conventional macro theory. 相似文献
19.
Multiple fabrications of sacrificial layers to enhance the dimensional accuracy of microstructures in maskless projection microstereolithography 总被引:1,自引:0,他引:1
In-Baek Park Jae-Won Choi Young-Myoung Ha Seok-Hee Lee 《International Journal of Precision Engineering and Manufacturing》2009,10(1):91-98
Microstereolithography (MSL) is a promising technology for producing fully three-dimensional microstructures with overhanging
features and high-aspect ratios. In conventional stereolithography (SL), a layer thickness of ≈50–100 μm is obtained by using
a recoater. However, a recoater cannot be used in MSL, where the layer thickness is typically ≈10 μm or less, since resin
flow may break or distort the pre-fabricated layers. In most MSL systems, the resin surface (or layer thickness) is controlled
by a free surface technique that employs resin gravity to refresh the resin surface over a given settling time. In addition,
a sacrificial layer must be fabricated in MSL to create a flat initial surface and provide support, just as in SL. In this
paper, the fabrication methodology and functionality of the sacrificial layer is investigated for microstereolithography microstructures
fabricated using the free surface technique. Experimental data are presented that indicate the greater the number of sacrificial
layers, the sharper the dimensional accuracy of the microstructures in the building direction. This is because multiple fabrications
of the sacrificial layer affect the resin ‘wetting’ status on the substrate or pre-cured surfaces. Several microstructures
were fabricated to verify the effect of multiple fabrications of the sacrificial layer on dimensional accuracy in the building
direction. 相似文献
20.
Qingliang Zhao Junyun Chen Haitao Huang Xiaoyan Fang 《International Journal of Precision Engineering and Manufacturing》2011,12(1):5-13
Coarse-grained wheels can realize high efficient grinding of optical glass. However, the serious surface and subsurface damage
will be inevitably introduced by the coarse-grained wheels. In this paper, the grinding damage of a copper-resin bond coarse-grained
diamond wheel with grain size of 150μm was investigated on optical glass BK7. The wheel was first properly trued with a metal
bond diamond wheel, then pre-dressing for the wheel and grinding experiments are carried out on a precision grinder assisted
with electrolytic in process dressing (ELID) method. The surface roughness (Ra) of ground surface was measured using an atomic
force microscope (AFM) and the surface topography were imaged by a white light interferometer (WLI) and the AFM. The subsurface
damage level of ground surface was evaluated by means of both MRF spot method and taper polishing-etching method, in term
of the biggest depth of subsurface damage, distribution of micro defects beneath the ground surface, the cluster depth of
subsurface damage, relationship between subsurface damage (SSD) and PV surface roughness (SR), propagating distance and pattern
of cracks beneath the ground surface. Experimental results indicate that a well conditioned copper-resin bond coarse-grained
diamond wheel on a precision grinder can generate good surface quality of Ra less than 50nm and good subsurface integrity
with SSD depth less than 3.5ε for optical glass BK7. 相似文献