ultrasonic vibration-assisted grinding of micro-structured surfaces on silicon carbide ceramic...
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DOI: 10.1177/0954405411423574
originally published online 21 December 2011 2012 226: 553Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture
B Guo, Q-L Zhao and M J Jacksonmaterials
Ultrasonic vibration-assisted grinding of micro-structured surfaces on silicon carbide ceramic
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Ultrasonic vibration-assisted grinding of micro-structured surfaces on silicon carbide ceramic materialsB Guo1,2*, Q-L Zhao1, and M J Jackson2
1Center of Precision Engineering, School of Mechatronics Engineering, Harbin Institute of Technology, Harbin,
People’s Republic of China2Center for Advanced Manufacturing, Purdue University, West Lafayette, Indiana, USA
The manuscript was received on 18 August 2011 and was accepted after revision for publication on 25 August 2011.
DOI: 10.1177/0954405411423574
Abstract: Precision grinding of silicon carbide ceramic micro-structured moulds is becomingmore common in the area of the moulding of glass materials. However, in micro-structuredgrinding of super-hard and brittle materials, problems frequently occur in terms of chippingand rounding of micro-structural edge features. In order to overcome these technological con-straints, a promising method using ultrasonic vibration of workpiece materials is proposed.The design of a novel ultrasonic vibration apparatus and the experimental investigation ofultrasonic vibration assisted grinding of SiC micro-structures are presented. The experimentalresults show that the application of ultrasonic vibration can enhance the ground surface qual-ity and improve the edge features of micro-structures.
Keywords: ultrasonic vibration assisted grinding, micro-structured surfaces, silicon carbide
(SiC) ceramic, edge
1. INTRODUCTION
Micro-structured optical elements made of glass are
generally replicated by hot pressing with super-hard
materials, such as silicon carbide (SiC) and tungsten
carbide (WC). These materials are now widely used
in glass moulding owing to their excellent character-
istics, such as high wear resistance, high tempera-
ture strength, excellent chemical resistance, high
thermal conductivity, and thermal shock resistance
[1]. For efficient manufacturing of these moulds, the
precision grinding (PG) of super-hard materials
micro-structured moulds is a stringent requirement
[2–5]. However, the grinding of these micro-struc-
tures is very difficult because of the super hardness
and high brittleness, which results in chipping and
rounding of micro-structured edges and surface
roughness [6–8].
Ultrasonic vibration assisted grinding (UVAG)
methods are suitable to machine difficult materials
precisely, especially for ceramics. In contrast to PG,
the advantages of UVAG are that ultrasonic vibrations:
(a) improve the ground surface quality [9, 10];
(b) decrease the grinding forces [11, 12];
(c) reduce the subsurface damage induced by
grinding processes [13, 14].
These previous researches focused on continuous
surfaces, such as a plane and spherical surface.
However, few works have been carried on the UVAG
of micro-structured surfaces because of the interfer-
ence between the vibration path and functional
structure of the ground surface.
In this paper, a new PG method for micro-struc-
tured surfaces, that applies ultrasonic vibration to
improve the surface quality and protects the edges
and tips of micro-structured surfaces, is presented.
Machining surface quality of the novel grinding
approach for SiC ceramic microgroove generation was
evaluated using an ultraprecision planar grinder
*Corresponding author: Center of Precision Engineering, School
of Mechatronics Engineering, Harbin Institute of Technology,
Harbin, People’s Republic of China
email: [email protected]
SHORT COMMUNICATION 553
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integrated with the devised ultrasonic vibration table.
The effects of vibration amplitude, feedrate on surface
roughness, and edge radius were studied. The mor-
phology of surface and microgroove edges was exam-
ined with a scanning electron microscope (SEM), while
the surface roughness was measured by a laser interfe-
rometer. In addition, a contact probe profilometer was
used to assess the radius of micro-structured edges.
2. EXPERIMENTAL APPARATUS
The structure and shape of the ultrasonic table were
designed using finite element analysis as shown as
Fig. 1. In order to avoid the interference between
machined micro-structural features and vibration
tracks, a high frequency and low amplitude ultraso-
nic vibration was superimposed on the movement
of the workpiece. The axial vibration mode was
selected and the vibration direction of the table was
parallel to the wheel feed direction. The table used
the rectangular section with double vibration nodal
plane support design for increasing the grinding
stiffness. The vibration amplitude was amplified by
the booster and the dumb-bell-shape vibration table
and transmitted to the workpiece attached to the
middle of the table. The vibration frequency was
34.3 kHz, while the amplitude was designed to be
adjustable in the range of 0 mm and 10 mm.
The grinding experiments were performed using
a CNC grinder (MUGK7120X5, Hangzhou Machine
Tool Group Co. Ltd, People’s Republic of China).
Within this work an UVAG process for the struc-
tured surfaces exhibiting an Echelle grating (a type
of diffraction grating that is characterized by a rela-
tively low groove density, but is optimized for high
diffraction orders) mould has been developed. A
universal table was used under the workpiece in
order to control the angle between the workpiece
and wheel, as well as adjust the direction of vibra-
tion. The schematic illustration and photograph of
the experimental set-up for micro-structured sur-
face grinding is shown in Fig. 2.
In the experiments, in order to reduce the edge
wear of grinding wheel, a bigger diamond grinding
wheel (Ø200) compared with typical micro-struc-
tured surface PG was employed. Considering the
spindle power and vibration character with a bigger
grinding wheel, a lower spindle speed (2000 r/min)
was used. The machining parameters are summar-
ized in Table 1. The tests were carried out for both
UVAG and PG with the same instrument. During the
PG the ultrasonic table was switched off.
3. EXPERIMENTAL RESULTS AND DISCUSSION
The surface and edge morphology formed by PG
and UVAG (A = 4.5 mm and f = 34.3 kHz) at the same
grinding parameters (n = 2000 r/min, ae = 300 mm,
vf = 1 mm/min) are shown in Fig. 3, respectively.
Compared with PG, the ground surface was smooth-
er with fewer cracks than with ultrasonic vibration.
The SEM examination results proved that ultrasonic
vibration would lead to ductile material removal
and better surface quality in the grinding process.
Furthermore, the grain traces were obviously
reduced on ground surfaces using UVAG. The
micro-structure edges were more integrated when
using ultrasonic vibration, as shown in Fig 3. The
ground edge by UVAG not only had less fragmenta-
tion caused by cracks, but also had less spurs and
build-up bulges than that demonstrated using PG.
Apparently, one of the reasons for these improve-
ments is the change of the grinding process, which
increases the critical ductile grinding depth of cera-
mic [15]. Accordingly, there are improvements in
the surface quality and a reduction in brittle
Fig. 1 Ultrasonic vibration table with piezoelectricactuators (frequency: 34.3 kHz)
Fig. 2 The schematic illustration and photograph ofthe experimental set-up (reproduced with per-mission of Harbin Institute of Technology)
554 B Guo, Q-L Zhao, and M J Jackson
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fragmentation. The other reason is the high-fre-
quency repetitive finishing on ground surfaces by
the grinding wheel due to the change of the
kinematic path of the grinding wheel relative to the
workpiece, which results in the removal of spur and
build-up bulge on edges, the reduction of grain
traces and the decrease of surface roughness.
The average three-dimensional surface roughness
(SRa) values of ten measured points were measured
by means of a laser interferometer (Olympus,
OLS3000, Japan) on the ground surface, as shown in
Fig. 4. The top of the bar means maximum surface
roughness value, while the bottom of bar means
minimum value. The average value of roughness
SRa was 452 nm when using traditional grinding,
while it was improved to 178 nm by induced ultraso-
nic vibration. A contact probe profilometer (Form
Talysurf PGI 1240, Taylor Hobson Ltd, UK) was used
to assess the edge radius R of micro-structured
Table 1 Major machining parameters
Grinding wheel Ø200, resin-bond, D25, 100 %CWorkpiece SiC ceramic (grain size: 4–10 mm)Feedrate, vf 0.2–0.5–1–2 mm/minSpindle speed, n 2000 r/minDepth of cut, ae 300 mmUltrasonic vibration
frequency, f34.3 kHz
Ultrasonic vibrationamplitude, A
0–3–4.5–6.5–8.5 mm
Coolant Water–oil emulsionDressing tool D25 grit size diamond block
Fig. 3 SEM photographs of micro-structured surface and edge: (a) ground surface by PG; (b)ground edge by PG; (c) ground surface by UVAG; (d) ground edge by UVAG
Ultrasonic vibration-assisted grinding of micro-structured surfaces on silicon carbide ceramic materials 555
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surface (the radius of the profilometer’s probe is
1 mm). For PG, the fragmentation of edge had a sig-
nificant impact on the increase of edge radius, the
average edge radius R by five measures using the
contact probe profilometer was more than 3.2 mm,
while the average R of UVAG was about 2.1 mm. The
results of the experiment show that lower surface
roughness and sharper edges will be obtained due
to ultrasonic vibration.
The effect of feedrate and vibration amplitude on
surface roughness and edge radius were studied.
Fig. 5 shows the SEM photographs of surface mor-
phology formed by different feedrates. Experiments
were carried out at n = 2000 r/min, ae = 300 mm,
f = 34.3 kHz, and A = 4.5 mm. When feedrate, vf, was
less than 1 mm/min, the ground surfaces show that
Fig. 4 Surface roughness of PG and UVAG (A = 4.5 mmand f = 34.3 kHz)
Fig. 5 SEM photographs of ground surface with different federate: (a) vf = 2 mm/min; (b) vf =1 mm/min; (c) vf = 0.5 mm/min; (d) vf = 0.2 mm/minde
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low-damage grinding had been achieved, although
some cracks were observed on the surface of micro-
structures. The ground surfaces were formed pri-
marily by the ductile material removal process. The
grain traces reduced with the decrease in feedrate.
Fig. 6 shows the SEM photographs of micro-struc-
tureal edges at vf = 2 mm/min and at vf = 0.2 mm/
min, respectively. The edge radius at the feedrate of
0.2 mm/min was sharper than that at 2 mm/min.
The effect of feedrate vf on surface roughness
SRa values and edge radius R of micro-structures
are shown in Fig. 7. The results show surface
roughness and edge radius were both improved
when the feedrate decreased, which is consistent
to SEM observations. The reason is that a slow
feedrate not only reduces the depth of cut per rev-
olution, as well as for conventional grinding, but
also enhances the repetitive finishing effect. At
the feedrate of 2 mm/min, the largest average SRa
value of 272 nm, and R value of 2.5 mm was
obtained. Decreasing the feedrate from 2 mm/
min to 0.2 mm/min resulted in the smallest SRa
value of 128 nm and R value of 1.5 mm.
The SEM photographs of surface morphology
formed by different vibration amplitudes A at n =
2000 r/min, ae = 300 mm, vf = 2 mm/min, and f =
34.3 kHz is shown in Fig. 8. The results show that
on the ground surface, the cracks caused by the
brittle removal process were decreasing when A
increased in the range of 3 mm to 6.5 mm. However,
the bigger amplitude of 8.5 mm produces no benefit
beyond 6.5 mm. This may indicate that there is a
threshold beyond which no additional benefit
occurs.
The surface roughness SRa and edge radius R of
micro-structural features as a function of A are
shown in Fig. 9. First, the surface roughness
decreases with increasing amplitude, and then
shows an increased tendency after 8.5 mm ampli-
tude, which corresponds to the observed results of
SEM examinations. The effect of amplitude on edge
radius is the same with that on surface roughness.
Setting the amplitude A of 6.5 mm resulted in the
best micro-structured surface with the smallest SRa
of 146 nm and sharpest R of 1.8 mm.
According to the experiments results, the Echelle
grating was ground on SiC ceramic using UVAG at
n = 2000 r/min, ae = 300 mm, vf = 0.2 mm/min, f =
34.3 kHz, and A = 6.5 mm, as shown as Fig. 10. The
average edge radius R was 1.6 mm, and the average
surface roughness SRa was less than 106 nm.
Fig. 6 SEM photographs of edges with different feedrate: (a) vf = 2 mm/min; (b) vf = 0.2 mm/min
Fig. 7 The effect of vf on SRa and R
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4. CONCLUSIONS
A novel UVAG of SiC ceramic micro-structured sur-
faces was proposed. Experimental results showed
that the application of ultrasonic vibration leads to
significant improvements of the surface roughness
and edges of micro-structures compare with tradi-
tional PG processes. In addition, the effect of feedrate
and vibration amplitude on ground quality was also
investigated. The surface roughness and edge radius
were both reduced when the feedrate decreased. As
the amplitude increased in the range of 3 mm to
6.5 mm, the ground surface was improved first.
However, there is likely to be a threshold beyond
which higher amplitudes would produce no addi-
tional advantage. Finally, an Echelle grating of SiC
Fig. 8 SEM photographs of ground surface with different amplitude: (a) A = 3 mm; (b) A = 4.5 mm;(c) A = 6.5 mm; (d) A = 8.5 mm
Fig. 9 The effect of A on SRa and R
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with surface roughness of 106 nm and edge radius of
1.6 mm was obtained.
For future research, the focus on investigating the
amplitude threshold, the grinding force, and the
effects of ultrasonic vibration on the integrity of
micro-structural surfaces will be conducted.
FUNDING
This work was supported by National Natural
Scientific Foundation of China [grant number
51075093]; and Chinese State Key Project of NC (04)
Technology [grant number 2009ZX04001-101].
ACKNOWLEDGEMENTS
The authors would like to thank the Joint
Laboratory for Ultra-Precision Grinding Technology
(JLUPG) of Harbin Institute of Technology and
Hangzhou Machine Tool Group Co., Ltd. The
authors would also like to thank Purdue University
for hosting the first two authors as visiting scholars
in the Center for Advanced Manufacturing.
� IMechE 2011
REFERENCES
1 Park, K. S., Bahk, Y. K., Park, S. K., Lee, J. H., Go, J.S., Kanghyperlink, M. C., and Lee, C. M. Rapidmanufacturing of SiC molds with micro-sized holesusing abrasive water jet. T. Nonferr. Metall. Soc.,2009, 19(Supp 1), 178–182.
2 Brinksmeier, E., Mutlugunes, Y., Klocke, F.,Aurich, J. C., Shore, P., and Ohmori, H.
Ultra-precision grinding. CIRP Ann. Mfg Technol.,2010, 59(2), 652–671.
3 Xu, K.-Z., Wei, C.-J., and Hu, D.-J. Geometric errorcompensation of spherical surface grinding system.Proc IMechE, Part B: J. Engineering Manufacture,2011, 225(B4), 473–482.
4 Huo, F. W., Guo, D. M., Jin, Z. J., Kang, R. K., andZhang, Z. Y. Ultra-precision grinding of a hydro-static mechanical sealing ring face with extremelyshallow taper angle. Proc IMechE, Part B: J. Engi-neering Manufacture, 2011, 225(B4), 463–472.
5 Oh, J. H. and Lee, S. H. Prediction of surfaceroughness in magnetic abrasive finishing usingacoustic emission and force sensor data fusion.Proc IMechE, Part B: J. Engineering Manufacture,2011, 225(B6), 853–865.
6 Klocke, F., Dambon, O., Bulla, B., andHeselhaus, M. Direct diamond turning of steelmolds for optical replication. Proc. SPIE, 2009;7282, 728202.
7 Klocke, F., Brinksmeier, E., Riemer, O., Klink, A.,Schulte, H., and Sarikaya, H. Manufacturing struc-tured tool inserts for precision glass moulding witha combination of diamond grinding and abrasivepolishing. Ind. Diamond Rev. 2007, 4(4), 65–69.
8 Xie, J., Zhou, Y. W., and Tan, T. W. Experimentalstudy on fabrication and evaluation of micro pyra-mid-structured silicon surface using a V-tip of dia-mond grinding wheel. Precision Eng., 2011, 35(1),173–182.
9 Isobe, H., Hara, K., Kyusojin, A., Okada, M., andYoshihara, H. Ultrasonically assisted grinding formirror surface finishing of dies with electroplateddiamond tools. Int. J. Precision Engng Mf., 2007,8(2), 28–43.
10 Denkena, B., Friemuth, T., Reichstein, M., andTonshoff, H. K. Potentials of different processkinematics in micro grinding, CIRP Ann. Mfg Tech-nol., 2003, 52(1), 463–466.
11 Suzuki, K., Mishiro, S., Shishido, Y., Iwai, M.,Mei, W., and Uematsu, T. A micro ultrasonicgrinding device with very high frequency and itsapplication, Key Eng. Mater., 2007, 329, 45–50.
12 Onikura, H., Ohnishi, O., and Take, Y. Fabricationof micro carbide tools by ultrasonic vibrationgrinding. CIRP Ann. Mfg Technol., 2000, 49(1),257–260.
13 Ghahramani, B. and Wang, Z. Y. Precision ultraso-nic machining process: a case study of stress analy-sis of ceramics (Al2O3). Int. J. Mach. Tools Mfg,2001, 41(8), 1189–1208.
14 Qu, W., Wang, K., Miller, M. H., Huang, Y., andChandra, A. Using vibration-assisted grinding toreduce subsurface damage. Precision Eng, 2000,24(4), 329–337.
15 Gao, G. F., Zhao, B., Xiang, D. H., and Kong, Q. H.Research on the surface characteristics in ultraso-nic grinding nano-zirconia ceramics. J. Mater. Pro-cess Technol., 2009, 209(1), 32–37.
Fig. 10 SEM photographs of Echelle grating
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