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Progress in abrasive and grinding technology
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Progress in Abrasive
and Grinding Technology
Progress in Abrasive
and Grinding Technology
Special topic volume with invited papers only.
Edited by
Xipeng Xu
TRANS TECH PUBLICATIONS LTD
Switzerland • UK • USA
Copyright 2009 Trans Tech Publications Ltd, Switzerland
All rights reserved. No part of the contents of this publication may be reproduced or
transmitted in any form or by any means without the written permission of the publisher.
Trans Tech Publications Ltd
Laubisrutistr. 24
CH-8712 Stafa-Zurich
Switzerland
http://www.ttp.net
Volume 404 of
Key Engineering Materials
ISSN 1013-9826
Full text available online at http://www.scientific.net
Distributed worldwide by and in the Americas by
Trans Tech Publications Ltd. Trans Tech Publications Inc.
Laubisrutistr. 24 PO Box 699, May Street
CH-8712 Stafa-Zurich Enfield, NH 03748
Switzerland USA
Phone: +1 (603) 632-7377
Fax: +41 (44) 922 10 33 Fax: +1 (603) 632-5611
e-mail: [email protected] e-mail: [email protected]
Preface
Grinding and abrasive processing of materials are the machining processes that
use bonded or loose abrasives to remove workpiece materials. Due to the
well-known advantages of grinding and abrasive processes, advances in abrasive
and grinding technology are of importance to enhance both productivity and part
quality. In order to introduce the progresses in this field, the vice president of
Trans Tech Publications, Thomas Wohlbier, invited me to edit this special volume
last year. I have invited 21 contributions from different countries and regions in an
attempt to gather together the achievements of different researchers into a single
publication.
The 21 invited papers, review or research, are from Australia, China, Germany,
Japan, Singapore, Taiwan (China), UK, and USA. The abrasive processes
addressed in the volume involve not only grinding and polishing, but also wire
sawing and abrasive waterjet machining. The topics include either fundamental
aspects or novel techniques. It is therefore the hope of the editor that this volume
will be valuable to production and research engineers, research students and
academics in the area.
At the completion of this volume, I am grateful to all the contributors for the
enthusiasm with which they wrote about their topics. Thanks are also given to Mr.
Guoqin Huang at HuaQiao University for his secretarial and editing work; and
Trans Tech Publications for publishing the volume.
Xipeng Xu Ph.D
Professor in Manufacturing Engineering
HuaQiao University
Quanzhou, Fujian 362021, China
Tel.: +86-595-22693598; fax: +86-595-22692667
E-mail address: [email protected]
Table of Contents
Preface
Development in the Dressing of Super Abrasive Grinding Wheels
B. Denkena, L. de Leon, B. Wang and D. Hahmann 1
High Speed Grinding of Advanced Ceramics: A Review
H. Huang 11
Experimental Investigations on Material Removal Rate and Surface Roughness in Lapping
of Substrate Wafers: A Literature Review
W.L. Cong, P.F. Zhang and Z.J. Pei 23
A Focused Review on Enhancing the Abrasive Waterjet Cutting Performance by Using
Controlled Nozzle Oscillation
J. Wang 33
A Review of Electrolytic In-Process Dressing (ELID) Grinding
R. Mustafizur, A. Senthil Kumar and I. Biswas 45
On the Coherent Length of Fluid Nozzles in Grinding
M.N. Morgan and V. Baines-Jones 61
Surface Characteristics of Efficient-Ground Alumina and Zirconia Ceramics for Dental
Applications
H. Kasuga, H. Ohmori, Y. Watanabe and T. Mishima 69
Optimization of Cutting-Edge Truncation in Ductile-Mode Grinding of Optical Glass
J. Tamaki and A. Kubo 77
On the Polishing Techniques of Diamond and Diamond Composites
Y. Chen and L.C. Zhang 85
Super Polishing Behaviour Investigation of Stainless Steel Optical Lens Moulding Inserts
K. Liu, S.T. Ng, K.C. Shaw and G.C. Lim 97
Corrective Abrasive Polishing Processes for Freeform Surface
X. Chen 103
Applications of Contact Length Models in Grinding Processes
H.S. Qi, B. Mills and X.P. Xu 113
Polishing Performance of Electro-Rheological Fluid of Polymerized Liquid Crystal
Contained Abrasive Grit
T. Tanaka 123
Study on Tribo-Fabrication in Polishing by Nano Diamond Colloid
W.M. Lin, T. Kato, H. Ohmori and E. Osawa 131
Efficient Super-Smooth Finishing Characteristics of SiC Materials through the Use of FineGrinding
H. Kasuga, H. Ohmori, W.M. Lin, Y. Watanabe, T. Mishima and T.K. Doi 137
Polishing of Ultra Smooth Surface with Nanoparticle Colloid Jet
F.H. Zhang, X.Z. Song, Y. Zhang and D.R. Luan 143
An Experimental Study on High Speed Grinding of Granite with a Segmented Diamond
Wheel
X.P. Xu, X.W. Zhu and Y. Li 149
Thinning Silicon Wafer with Polycrystalline Diamond Tools
P.L. Tso and C.H. Chen 157
Mechanisms of Al/SiC Composite Machining with Diamond Whiskers
G.F. Zhang, B. Zhang and Z.H. Deng 165
Effect of Slurry and Nozzle on Hole Machining of Glass by Micro Abrasive Suspension Jets
C.Y. Wang, P.X. Yang, J.M. Fan and Y.X. Song 177
Experimental Investigation of Temperatures in Diamond Wire Sawing Granite
H. Huang, N. Guo and X.P. Xu 185
Development in the Dressing of Super Abrasive Grinding Wheels
B. Denkena1,a, L.D. Leon1,b, B. Wang1,c and D. Hahmann1,d
1
Leibniz Universität Hannover, Institute of Production Engineering and Machine Tools,
An der Universität 2, D-30823, Germany
a
[email protected]; [email protected];
d
Keywords: Electro contact discharge dressing, Profile dressing, Microprofiles, Super abrasives
Abstract. Harder workpiece materials and increased efficiency requirements for grinding processes
make the use of super abrasive grinding wheels indispensable. This paper presents newly developed
processes for the dressing of super abrasive grinding wheels. The different bond systems of
grinding wheels require distinct dressing process. In this paper, dressing processes for metal and
vitrified bonded grinding wheels are investigated. It introduces the method of electro contact
discharge dressing for the conditioning of metal-bonded, fine-grained multilayer grinding wheels. A
description of the essential correlation between dressing parameters and the material removal rate of
the bond material is presented. The considered parameters are the dressing voltage, the limitation of
the dressing current and the feed as well as the infeed of the electrode. For the grinding of
functional microgroove structures, multiroof profiles with microscopic tip geometries are dressed
onto the grinding wheel. For this, a profile roller in combination with a special shifting strategy is
applied on finegrained vitrified bonded grinding wheels.
Introduction
High performance components with high hardness and wear resistance are applied with increasing
frequency in order to enhance the efficiency of technical systems. Furthermore, miniaturized
products and microstructured functional surfaces entail new challenges for machining processes.
Grinding processes with super abrasive CBN and diamond grinding wheels can be used for the
economical machining of such components and microgeometries. Depending on the bond system of
the grinding wheel, different dressing processes should be used [1, 2]. To assure small form and
dimensional tolerances over an adequate number of workpieces, the grinding wheels have to be
regularly redressed. In the following, electro contact discharge dressing for metal bonded grinding
wheels and a novel dressing strategy using special shift kinematics for vitrified bonded grinding
wheels are described. The focus of these dressing processes is the profiling of grinding wheels.
Electro Contact Discharge Dressing
The effects of continuous wear on process stability as well as on shape and dimension accuracies of
a component are more significant for fine-grained grinding tools used for micro-machining than
they are for “conventional” precision grinding. In order to counterbalance those influences,
wear-resistant grinding tools and procedures for the regeneration of the tool profile are necessary.
Due to their high wear-resistance and the resulting profile retention, multilayered, metallically
bonded diamond grinding wheels are more suitable for micromachining than vitrified or resin
bonded tools. The main problem is the dressing of those metallically bonded tools. Electro contact
discharge dressing is a promising method to cope with this challenge. It has so far only been used
for sharpening, but not for the dressing of tools [3~5].
In the following, the effects of the process variables on the contact erosive removal of the bond
material are described. It is determined under which conditions a continuous removal of the bond
material and thus a durable dressing effect can be achieved. Emphasis is put on the significant
variables such as the dressing voltage Ud0, the limitation of the dressing current Id0 and the chip
Development in the Dressing of Super Abrasive Grinding Wheels
B. Denkena1,a, L.D. Leon1,b, B. Wang1,c and D. Hahmann1,d
1
Leibniz Universität Hannover, Institute of Production Engineering and Machine Tools,
An der Universität 2, D-30823, Germany
a
[email protected]; [email protected];
d
Keywords: Electro contact discharge dressing, Profile dressing, Microprofiles, Super abrasives
Abstract. Harder workpiece materials and increased efficiency requirements for grinding processes
make the use of super abrasive grinding wheels indispensable. This paper presents newly developed
processes for the dressing of super abrasive grinding wheels. The different bond systems of
grinding wheels require distinct dressing process. In this paper, dressing processes for metal and
vitrified bonded grinding wheels are investigated. It introduces the method of electro contact
discharge dressing for the conditioning of metal-bonded, fine-grained multilayer grinding wheels. A
description of the essential correlation between dressing parameters and the material removal rate of
the bond material is presented. The considered parameters are the dressing voltage, the limitation of
the dressing current and the feed as well as the infeed of the electrode. For the grinding of
functional microgroove structures, multiroof profiles with microscopic tip geometries are dressed
onto the grinding wheel. For this, a profile roller in combination with a special shifting strategy is
applied on finegrained vitrified bonded grinding wheels.
Introduction
High performance components with high hardness and wear resistance are applied with increasing
frequency in order to enhance the efficiency of technical systems. Furthermore, miniaturized
products and microstructured functional surfaces entail new challenges for machining processes.
Grinding processes with super abrasive CBN and diamond grinding wheels can be used for the
economical machining of such components and microgeometries. Depending on the bond system of
the grinding wheel, different dressing processes should be used [1, 2]. To assure small form and
dimensional tolerances over an adequate number of workpieces, the grinding wheels have to be
regularly redressed. In the following, electro contact discharge dressing for metal bonded grinding
wheels and a novel dressing strategy using special shift kinematics for vitrified bonded grinding
wheels are described. The focus of these dressing processes is the profiling of grinding wheels.
Electro Contact Discharge Dressing
The effects of continuous wear on process stability as well as on shape and dimension accuracies of
a component are more significant for fine-grained grinding tools used for micro-machining than
they are for “conventional” precision grinding. In order to counterbalance those influences,
wear-resistant grinding tools and procedures for the regeneration of the tool profile are necessary.
Due to their high wear-resistance and the resulting profile retention, multilayered, metallically
bonded diamond grinding wheels are more suitable for micromachining than vitrified or resin
bonded tools. The main problem is the dressing of those metallically bonded tools. Electro contact
discharge dressing is a promising method to cope with this challenge. It has so far only been used
for sharpening, but not for the dressing of tools [3~5].
In the following, the effects of the process variables on the contact erosive removal of the bond
material are described. It is determined under which conditions a continuous removal of the bond
material and thus a durable dressing effect can be achieved. Emphasis is put on the significant
variables such as the dressing voltage Ud0, the limitation of the dressing current Id0 and the chip
Key Engineering Materials Vol. 404 (2009) pp 1-10
© (2009) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/KEM.404.1
volume over the dressing time Qd. These parameters all vary depending on the strategy chosen for
the electrode infeed frd and the electrode feed vfd.
As start-up phase for electro contact discharge dressing, the split stroke travel with idle stroke is
chosen. Thus the effects of the variables can be determined (Fig.1). The aim of the dressing strategy
is to attain an even distribution of graphite particles over the thickness of the grinding wheel.
1. The electrode is aligned radially next to the dressing wheel (1).
2. The electrode is then passed diagonally into the grinding layer (vfd, lfda1) until the electrode
and the grinding wheel overlap axially (2).
3. In the second partial stroke, there is no further radial infeed (vfda, lfda2). This is to increase the
influence on the grinding layer during the electrode withdrawal and to guarantee an even electrode
profile (3).
4. The axial return stroke (vfda) to the initial position is also carried out without radial infeed (1).
This is to provide a further smoothing of the profile.
The current Id and the voltage Ud, both recorded during the process, show the effect of the
different partial strokes on the process activity. The highest process activity occurs when the
diagonal feed of the electrode is carried out and when the electrode and the grinding wheel overlap.
In the following axial progress of the electrode, the activity slowly decreases and comes to a
standstill when there is no more contact between the two interacting parts. The following idle stroke
leads to low process activity.
Fig. 1 Start-up phase of electro contact discharge dressing with idle stroke
The effects of the variables on the process are described by the specific material removal rate
Q’ds and by the quality factor Gd. The quality factor Gd is the ratio of the bond material volume
removed from the dressing wheel and the machined volume of the electrode.
The experiments were carried out in distilled water, which has proved to be a suitable medium in
preexaminations. The dressing voltage Ud0 is the off-load voltage, while the dressing current Id0 is
the maximal current in a short circuit which can be set at the power supply unit. They can be
adjusted reproducibly. The actual voltage Ud and the current Id vary throughout the process.
At first, the dressing voltage Ud0 is varied, while the current Id0 is constant (Fig. 2, left). In order
to attain a dressing effect, the voltage has to exceed a critical value which causes a maximal grain
protrusion and a continuous removal of bond material. Under given boundary conditions, there is no
measurable removal of bonding material at Ud0 = 15 V. When Ud0 is further increased, the volume
flow rate Q’ds increases. At a voltage of Ud0 = 30 V, the maximal attainable volume flow rate Q’ds is
volume over the dressing time Qd. These parameters all vary depending on the strategy chosen for
the electrode infeed frd and the electrode feed vfd.
As start-up phase for electro contact discharge dressing, the split stroke travel with idle stroke is
chosen. Thus the effects of the variables can be determined (Fig.1). The aim of the dressing strategy
is to attain an even distribution of graphite particles over the thickness of the grinding wheel.
1. The electrode is aligned radially next to the dressing wheel (1).
2. The electrode is then passed diagonally into the grinding layer (vfd, lfda1) until the electrode
and the grinding wheel overlap axially (2).
3. In the second partial stroke, there is no further radial infeed (vfda, lfda2). This is to increase the
influence on the grinding layer during the electrode withdrawal and to guarantee an even electrode
profile (3).
4. The axial return stroke (vfda) to the initial position is also carried out without radial infeed (1).
This is to provide a further smoothing of the profile.
The current Id and the voltage Ud, both recorded during the process, show the effect of the
different partial strokes on the process activity. The highest process activity occurs when the
diagonal feed of the electrode is carried out and when the electrode and the grinding wheel overlap.
In the following axial progress of the electrode, the activity slowly decreases and comes to a
standstill when there is no more contact between the two interacting parts. The following idle stroke
leads to low process activity.
Fig. 1 Start-up phase of electro contact discharge dressing with idle stroke
The effects of the variables on the process are described by the specific material removal rate
Q’ds and by the quality factor Gd. The quality factor Gd is the ratio of the bond material volume
removed from the dressing wheel and the machined volume of the electrode.
The experiments were carried out in distilled water, which has proved to be a suitable medium in
preexaminations. The dressing voltage Ud0 is the off-load voltage, while the dressing current Id0 is
the maximal current in a short circuit which can be set at the power supply unit. They can be
adjusted reproducibly. The actual voltage Ud and the current Id vary throughout the process.
At first, the dressing voltage Ud0 is varied, while the current Id0 is constant (Fig. 2, left). In order
to attain a dressing effect, the voltage has to exceed a critical value which causes a maximal grain
protrusion and a continuous removal of bond material. Under given boundary conditions, there is no
measurable removal of bonding material at Ud0 = 15 V. When Ud0 is further increased, the volume
flow rate Q’ds increases. At a voltage of Ud0 = 30 V, the maximal attainable volume flow rate Q’ds is
2 Progress in Abrasive and Grinding Technology
reached. When the off-load voltage increases further, there is no further rise in Q’ds, which means
that the run of the curve has approached a critical value. In the following, a possible explanation for
Q’ds development against the voltage is presented. The sizes of the graphite particles cut off from
the electrode show a distinct distribution. At low voltages, only few particles are large enough to
enable discharges. When the voltage increases, the number of suitable particles and thus the
probability of discharge increase. An analogy investigation, carried out under the same electric and
geometric conditions as in the real process, showed that at about 35 V, discharges even occur
without any graphite particles implied. This shows that the maximal probability of discharge is
reached. The limiting factor is that there can only be one discharge at a time.
When a current limit Id0 is determined in advance, this limit directly influences the intensity of
the electro contact discharge process (Fig. 2, right). The electrode current in the spark gap occurs at
the electrode voltage Ud as a consequence of the existing resistance according to Ohm’s law. It is
the sum of the local single currents which cause the removal of the bond material. Low current
limits Id0 lead to a low volume flow rate Q’ds. In analogy to the voltage Ud0, the maximal volume
flow rate of about Q’ds = 0.13 mm3
/mm s is attained at Id0 = 1 A. When Id0 further increases, there is
no more rise in the volume flow rate at the grinding wheel. This can be explained by the energy
released at each discharge under the assumption of a constant discharge duration. The energy
released at a discharge and thus the temperature in the metal bond increase with a rise in the current.
At a certain energy level, the metal bond starts to melt locally. The maximal volume of bond which
can be molten is limited by the specific boiling temperature and the specific thermal conductivity.
The temperature of the molten material cannot exceed the boiling temperature. Thermal
conductivity limits the volume of material which reaches the melting temperature due to heat
dispersion, assuming a constant discharge duration. The duration will be determined from the
experimental data.
Fig. 2 Specific material removal rate during electro contact discharge dressing
In Fig. 3, the quality factor Gd is shown against the dressing voltage Ud0 and the current limit Id0.
Up to Ud0 = 30 V, the quality factor rises with about Gd = 4.5 at the maximal volume flow rate Q’ds.
When Ud0 increases further, the quality factor stays on a constant level. The quality factor shows a
similar behavior by a variation of Id0. The maximal quality factor is reached at a current level of
about Id0 = 1 A. The quality factor also stays on a constant level when Id0 increases further. The
development of the quality factor in both diagrams can be explained by the constant specific
material removal rate at the electrode, which is itself due to constant infeed and feed throughout the
investigation. Thus the quality factor corresponds to the specific material removal rate.
reached. When the off-load voltage increases further, there is no further rise in Q’ds, which means
that the run of the curve has approached a critical value. In the following, a possible explanation for
Q’ds development against the voltage is presented. The sizes of the graphite particles cut off from
the electrode show a distinct distribution. At low voltages, only few particles are large enough to
enable discharges. When the voltage increases, the number of suitable particles and thus the
probability of discharge increase. An analogy investigation, carried out under the same electric and
geometric conditions as in the real process, showed that at about 35 V, discharges even occur
without any graphite particles implied. This shows that the maximal probability of discharge is
reached. The limiting factor is that there can only be one discharge at a time.
When a current limit Id0 is determined in advance, this limit directly influences the intensity of
the electro contact discharge process (Fig. 2, right). The electrode current in the spark gap occurs at
the electrode voltage Ud as a consequence of the existing resistance according to Ohm’s law. It is
the sum of the local single currents which cause the removal of the bond material. Low current
limits Id0 lead to a low volume flow rate Q’ds. In analogy to the voltage Ud0, the maximal volume
flow rate of about Q’ds = 0.13 mm3
/mm s is attained at Id0 = 1 A. When Id0 further increases, there is
no more rise in the volume flow rate at the grinding wheel. This can be explained by the energy
released at each discharge under the assumption of a constant discharge duration. The energy
released at a discharge and thus the temperature in the metal bond increase with a rise in the current.
At a certain energy level, the metal bond starts to melt locally. The maximal volume of bond which
can be molten is limited by the specific boiling temperature and the specific thermal conductivity.
The temperature of the molten material cannot exceed the boiling temperature. Thermal
conductivity limits the volume of material which reaches the melting temperature due to heat
dispersion, assuming a constant discharge duration. The duration will be determined from the
experimental data.
Fig. 2 Specific material removal rate during electro contact discharge dressing
In Fig. 3, the quality factor Gd is shown against the dressing voltage Ud0 and the current limit Id0.
Up to Ud0 = 30 V, the quality factor rises with about Gd = 4.5 at the maximal volume flow rate Q’ds.
When Ud0 increases further, the quality factor stays on a constant level. The quality factor shows a
similar behavior by a variation of Id0. The maximal quality factor is reached at a current level of
about Id0 = 1 A. The quality factor also stays on a constant level when Id0 increases further. The
development of the quality factor in both diagrams can be explained by the constant specific
material removal rate at the electrode, which is itself due to constant infeed and feed throughout the
investigation. Thus the quality factor corresponds to the specific material removal rate.
Key Engineering Materials Vol. 404 3
Fig. 3 Quality factor in electro contact discharge dressing
Fig. 4 Specific material removal rate in electro contact discharge dressing
Besides by the electric variables of electro contact discharge dressing, the process is also
influenced by the radial electrode infeed frd and by the feed vfd. In the investigations, the feed is
identical for all single strokes (see Fig. 1).
The feed and infeed develop against the volume flow rate Q’ds in the same way as the electric
variables described above. When frd increases, initially the volume flow rate Q’ds rises. The maximal
volume flow rate of about Q’ds = 0.1 mm3
/mm s is reached with an infeed of about frd = 10 µm. A
further increase in frd causes no further rise in the volume flow rate Q’ds. A variation of the feed of
the electrode vfd leads to very similar results. In this case the maximal volume flow rate is achieved
at vfd = 20 mm/min. A possible explanation for the development of both curves is the mean particle
size of the graphite particles that are cut off from the electrode. The mean particle size rises both
when the feed or the infeed increase. This is due to the increase in the equivalent mean chip
thickness. The probability of discharge increases with the particle size until the maximal probability
of discharge is reached. The limiting factor is that there can only be one discharge at a time.
Fig. 3 Quality factor in electro contact discharge dressing
Fig. 4 Specific material removal rate in electro contact discharge dressing
Besides by the electric variables of electro contact discharge dressing, the process is also
influenced by the radial electrode infeed frd and by the feed vfd. In the investigations, the feed is
identical for all single strokes (see Fig. 1).
The feed and infeed develop against the volume flow rate Q’ds in the same way as the electric
variables described above. When frd increases, initially the volume flow rate Q’ds rises. The maximal
volume flow rate of about Q’ds = 0.1 mm3
/mm s is reached with an infeed of about frd = 10 µm. A
further increase in frd causes no further rise in the volume flow rate Q’ds. A variation of the feed of
the electrode vfd leads to very similar results. In this case the maximal volume flow rate is achieved
at vfd = 20 mm/min. A possible explanation for the development of both curves is the mean particle
size of the graphite particles that are cut off from the electrode. The mean particle size rises both
when the feed or the infeed increase. This is due to the increase in the equivalent mean chip
thickness. The probability of discharge increases with the particle size until the maximal probability
of discharge is reached. The limiting factor is that there can only be one discharge at a time.
4 Progress in Abrasive and Grinding Technology
Investigations concerning the graphite particle size for varied feed and infeed values will have to be
carried out to proof this assumption.
Fig. 5 Quality factor in electro contact discharge dressing
Unlike the volume flow rate Q’ds, the quality factor Gd develops contrary to the electrical
variables Ud0 and Id0 when frd and vfd vary (Fig. 5). An increase in frd or in vfd leads to a decrease of
the quality factor. This can be explained by the fact that the specific material removal rate reaches
its limit at higher feed and infeed levels of the electrode while the machined volume of the electrode
increases. The results presented above show that the variables Ud0, Id0, frd and vfd significantly
influence both the volume flow rate and the quality factor of the dressing process. Independent of
the examined variables, an increase in the volume flow rate is only possible until a certain critical
value is reached. In order to obtain the maximal quality factor, a compromise has to be found in the
choice of frd and vfd, that is between a high volume flow rate Q’ds and a low wear at the electrode.
Both straight as well as v-shaped dressing wheel profiles [6] can be produced with this new process
for electro contact discharge dressing.
Profile Dressing with Special Shift Kinematics for the Generation of Microprofiles
In recent years, the manufacturing of microstructured functional component surfaces has become
the focus of many research works. As a typical example, longitudinal microgroove structures,
known as riblets, have been extensively investigated during the last decade and proven to reduce
skin friction and wall shear stresses in turbulent flow up to 10% compared with smooth surfaces
[7, 8]. For most technical applications of riblets, microgroove structures with a width of less than
100 µm and a depth of the half of the width are required on large-area surfaces. In comparison to
other machining processes, grinding offers high potential for large-area microstructuring. The main
reason for this is the fact that several groove structures can be produced by one run over the surface
with a multiprofiled grinding wheel. Grinding wheel profiles with microscopic profile peak
geometries have to be generated by a dressing process to produce microgrooves using profile
grinding. For the current investigations, vitrified bonded wheels are selected due to their good
dressability and profile holding properties compared to other bonding systems [1]. In the following,
a novel profile dressing method using special profile shift kinematics is introduced.
For the dressing of multiprofiled vitrified grinding wheels, there are two main dressing methods
(Fig. 6). The first method is form dressing using a diamond form roller (Fig. 6, left). The contour of
the wheel is generated by NC-programs and dressed by the dressing tool along the axial direction.
The whole wheel profile is generated layer by layer. Due to the axial dressing path over all of the
Investigations concerning the graphite particle size for varied feed and infeed values will have to be
carried out to proof this assumption.
Fig. 5 Quality factor in electro contact discharge dressing
Unlike the volume flow rate Q’ds, the quality factor Gd develops contrary to the electrical
variables Ud0 and Id0 when frd and vfd vary (Fig. 5). An increase in frd or in vfd leads to a decrease of
the quality factor. This can be explained by the fact that the specific material removal rate reaches
its limit at higher feed and infeed levels of the electrode while the machined volume of the electrode
increases. The results presented above show that the variables Ud0, Id0, frd and vfd significantly
influence both the volume flow rate and the quality factor of the dressing process. Independent of
the examined variables, an increase in the volume flow rate is only possible until a certain critical
value is reached. In order to obtain the maximal quality factor, a compromise has to be found in the
choice of frd and vfd, that is between a high volume flow rate Q’ds and a low wear at the electrode.
Both straight as well as v-shaped dressing wheel profiles [6] can be produced with this new process
for electro contact discharge dressing.
Profile Dressing with Special Shift Kinematics for the Generation of Microprofiles
In recent years, the manufacturing of microstructured functional component surfaces has become
the focus of many research works. As a typical example, longitudinal microgroove structures,
known as riblets, have been extensively investigated during the last decade and proven to reduce
skin friction and wall shear stresses in turbulent flow up to 10% compared with smooth surfaces
[7, 8]. For most technical applications of riblets, microgroove structures with a width of less than
100 µm and a depth of the half of the width are required on large-area surfaces. In comparison to
other machining processes, grinding offers high potential for large-area microstructuring. The main
reason for this is the fact that several groove structures can be produced by one run over the surface
with a multiprofiled grinding wheel. Grinding wheel profiles with microscopic profile peak
geometries have to be generated by a dressing process to produce microgrooves using profile
grinding. For the current investigations, vitrified bonded wheels are selected due to their good
dressability and profile holding properties compared to other bonding systems [1]. In the following,
a novel profile dressing method using special profile shift kinematics is introduced.
For the dressing of multiprofiled vitrified grinding wheels, there are two main dressing methods
(Fig. 6). The first method is form dressing using a diamond form roller (Fig. 6, left). The contour of
the wheel is generated by NC-programs and dressed by the dressing tool along the axial direction.
The whole wheel profile is generated layer by layer. Due to the axial dressing path over all of the
Key Engineering Materials Vol. 404 5
profiles to be dressed, dressing using a form roller is a highly time consuming process. Furthermore,
the actual geometry of the dressing tool is required for the dressing tool correction in the
NC-program. Due to the ongoing wear of the dressing tool, this actual geometry is very difficult to
determine. Besides that, the stability of the machine axis control system can be negatively
influenced by the temperature effects due to the long dressing time. The second method is dressing
using a diamond profile roller. The negative profile of the grinding wheel is mapped on the dressing
roller. The whole wheel profile is generated within a plunge movement of the dressing tool toward
the grinding wheel. Compared to the form dressing process, profile dressing offers a higher dressing
efficiency and process stability. On the other hand, the dressing force could be higher due to the
longer tool contact width, which is to be considered to achieve a stable dressing process.
Fig. 6 Dressing kinematics for form dressing and profile dressing
In the current riblet grinding studies, multiroof profiles with a microtip geometry on the grinding
wheel (Rpeak < 30 µm, Fig. 6) are required. However, it is currently not possible to produce
microprofiles on grinding wheels with a profile tip radius smaller than 50 µm directly by profile
dressing. This is due to the limited minimal profile geometry on the diamond profile dressing roller,
which can be produced [9]. Hence a novel dressing strategy using profile rollers is introduced in the
following (Fig. 7). With the new dressing strategy, roof profiles with an ideal sharp profile tip can
be produced, if the breakout behavior of the grinding layer is not being considered. In the first
plunge movement, one flank of the profiles is dressed. The second plunge movement is carried out
with an axial offset of the dressing roller, whereby the other flank of the profiles is dressed. Due to
the special process kinematics, all roof profiles on the grinding wheel can be produced within two
plunge movements. Furthermore, generally the tip areas of the dressing roller profile undertake a
higher load than the flank areas. Using the new dressing kinematics, the flank areas of the dressing
roller profile are deciding for the generation of the tips of the roof profiles and enable a higher wear
resistance.
profiles to be dressed, dressing using a form roller is a highly time consuming process. Furthermore,
the actual geometry of the dressing tool is required for the dressing tool correction in the
NC-program. Due to the ongoing wear of the dressing tool, this actual geometry is very difficult to
determine. Besides that, the stability of the machine axis control system can be negatively
influenced by the temperature effects due to the long dressing time. The second method is dressing
using a diamond profile roller. The negative profile of the grinding wheel is mapped on the dressing
roller. The whole wheel profile is generated within a plunge movement of the dressing tool toward
the grinding wheel. Compared to the form dressing process, profile dressing offers a higher dressing
efficiency and process stability. On the other hand, the dressing force could be higher due to the
longer tool contact width, which is to be considered to achieve a stable dressing process.
Fig. 6 Dressing kinematics for form dressing and profile dressing
In the current riblet grinding studies, multiroof profiles with a microtip geometry on the grinding
wheel (Rpeak < 30 µm, Fig. 6) are required. However, it is currently not possible to produce
microprofiles on grinding wheels with a profile tip radius smaller than 50 µm directly by profile
dressing. This is due to the limited minimal profile geometry on the diamond profile dressing roller,
which can be produced [9]. Hence a novel dressing strategy using profile rollers is introduced in the
following (Fig. 7). With the new dressing strategy, roof profiles with an ideal sharp profile tip can
be produced, if the breakout behavior of the grinding layer is not being considered. In the first
plunge movement, one flank of the profiles is dressed. The second plunge movement is carried out
with an axial offset of the dressing roller, whereby the other flank of the profiles is dressed. Due to
the special process kinematics, all roof profiles on the grinding wheel can be produced within two
plunge movements. Furthermore, generally the tip areas of the dressing roller profile undertake a
higher load than the flank areas. Using the new dressing kinematics, the flank areas of the dressing
roller profile are deciding for the generation of the tips of the roof profiles and enable a higher wear
resistance.
6 Progress in Abrasive and Grinding Technology
Fig. 7 Dressing strategy for the generation of microprofiles using a diamond profile roller
The dressing experiments have been carried out on a high precision surface grinding machine of
the type Blohm, profimat 407 with an integrated profile dressing system. According to the results of
the last studies on form dressing [10], a fine grained vitrified bonded SiC-wheel with an average
grain size of 17 µm and an outer diameter of 300 mm was selected at the beginning. The influences
of the profile dressing parameters on the grinding wheel topography have already been described in
the literature [11, 12]. The conclusions show that the actual surface roughness of the grinding wheel
after dressing Rt
increases with a rising radial feed frd. Considering the ratio of the dressing speed
qd, the up dressing mode generates a smoother wheel topography than the down dressing mode. For
the current application of grinding microgrooves, microscopic wheel profiles are required. The main
issue of the dressing experiments is to investigate the minimal achievable wheel profile geometry.
Due to the mechanical load on the vitrified wheel layer during the dressing process, breakouts occur
at the profile tip, where the structure strength is not high enough to withstand the dressing force.
The difference ∆h between the target profile height with an ideal sharp profile tip htarget and the
actually achieved profile height hactual after the dressing process has been used to evaluate the
dressing results (Fig. 6).
At a profile angle of 45°, both the radial feed frd and the ratio of the dressing speed qd have been
varied. The new dressing strategy with the special profile shift kinematics has been applied. The
dressing results show a significant influence of the dressing parameters on the profile height
difference ∆h. With an increasing dressing infeed frd, the dressing force and load on the wheel layer
increase, which causes larger breakouts of the profile tip. On the other hand, the profile accuracy
improves with a decreasing dressing speed ratio from the down dressing to the up dressing mode.
The reason can be explained by the smaller single chip thickness hdcu at the up dressing mode [13].
Among the different variations in the matrix, the best result (∆h = 20 µm) has been achieved at
qd = -0.7 and frd = 0.1 µm/rev. Due to the limitation of the machine axis accuracy, frd under 0.1
µm/rev. has not been investigated.
Fig. 7 Dressing strategy for the generation of microprofiles using a diamond profile roller
The dressing experiments have been carried out on a high precision surface grinding machine of
the type Blohm, profimat 407 with an integrated profile dressing system. According to the results of
the last studies on form dressing [10], a fine grained vitrified bonded SiC-wheel with an average
grain size of 17 µm and an outer diameter of 300 mm was selected at the beginning. The influences
of the profile dressing parameters on the grinding wheel topography have already been described in
the literature [11, 12]. The conclusions show that the actual surface roughness of the grinding wheel
after dressing Rt
increases with a rising radial feed frd. Considering the ratio of the dressing speed
qd, the up dressing mode generates a smoother wheel topography than the down dressing mode. For
the current application of grinding microgrooves, microscopic wheel profiles are required. The main
issue of the dressing experiments is to investigate the minimal achievable wheel profile geometry.
Due to the mechanical load on the vitrified wheel layer during the dressing process, breakouts occur
at the profile tip, where the structure strength is not high enough to withstand the dressing force.
The difference ∆h between the target profile height with an ideal sharp profile tip htarget and the
actually achieved profile height hactual after the dressing process has been used to evaluate the
dressing results (Fig. 6).
At a profile angle of 45°, both the radial feed frd and the ratio of the dressing speed qd have been
varied. The new dressing strategy with the special profile shift kinematics has been applied. The
dressing results show a significant influence of the dressing parameters on the profile height
difference ∆h. With an increasing dressing infeed frd, the dressing force and load on the wheel layer
increase, which causes larger breakouts of the profile tip. On the other hand, the profile accuracy
improves with a decreasing dressing speed ratio from the down dressing to the up dressing mode.
The reason can be explained by the smaller single chip thickness hdcu at the up dressing mode [13].
Among the different variations in the matrix, the best result (∆h = 20 µm) has been achieved at
qd = -0.7 and frd = 0.1 µm/rev. Due to the limitation of the machine axis accuracy, frd under 0.1
µm/rev. has not been investigated.
Key Engineering Materials Vol. 404 7
Fig. 8 Dressing results at parameter variations using a diamond form roller
Fig. 9 Influences of the profile angle on the profile dressing process
Based on the results at the SiC400 wheel, a vitrified bonded CBN wheel with a grain size of
16 µm (MB16) has been applied for the following dressing experiments. In comparison with
conventional wheels, CBN wheels offer a large potential regarding tool wear resistance. However,
the bonding system of CBN wheels is generally much harder than that of conventional grinding
wheels. The pictures in the right in Fig. 9 show SEM-pictures of the topography of the SiC400 H
(on top) and those of the CBN wheel (below). The SiC grains and the pores are distributed
uniformly troughout the bond. The bonding bridges are very short shaped. At the CBN wheel, the
grains build many clusters which are fully surrounded by the bond material. During the first
dressing experiment at the CBN wheel with a target profile angle of 45°, sidewise profile breakouts
could be observed at large areas, which lead to a blunt profile tip geometry (∆h = 45 µm).
When the profile angle is increased from 45° to 90°, the profile holding performance improves
and the achieved tip geometry dimension decreases. The ∆h is about 7 µm at a profile angle of 90°
Fig. 8 Dressing results at parameter variations using a diamond form roller
Fig. 9 Influences of the profile angle on the profile dressing process
Based on the results at the SiC400 wheel, a vitrified bonded CBN wheel with a grain size of
16 µm (MB16) has been applied for the following dressing experiments. In comparison with
conventional wheels, CBN wheels offer a large potential regarding tool wear resistance. However,
the bonding system of CBN wheels is generally much harder than that of conventional grinding
wheels. The pictures in the right in Fig. 9 show SEM-pictures of the topography of the SiC400 H
(on top) and those of the CBN wheel (below). The SiC grains and the pores are distributed
uniformly troughout the bond. The bonding bridges are very short shaped. At the CBN wheel, the
grains build many clusters which are fully surrounded by the bond material. During the first
dressing experiment at the CBN wheel with a target profile angle of 45°, sidewise profile breakouts
could be observed at large areas, which lead to a blunt profile tip geometry (∆h = 45 µm).
When the profile angle is increased from 45° to 90°, the profile holding performance improves
and the achieved tip geometry dimension decreases. The ∆h is about 7 µm at a profile angle of 90°
8 Progress in Abrasive and Grinding Technology
and the required profile tip geometry for riblet-grinding in the current study can be achieved. This
behavior can be explained by the higher structure stability and bonding force, which are due to the
sidewise bonding support at the profile tip. To analyze the structure stability at the profile tip,
FEM-modeling has been carried out at a varied profile angle from 45°, 60° to 90°. The wheel
profile was modeled as a homogenous body. A constant dressing load is applied on the wheel tip
and the results show that at the smaller angle of 45° the maximal von Mises stress in the grinding
layer is about four times higher than at a 90° profile angle. The same trend can also be proved at the
SiC wheel during the dressing experiments. However the skip is not as significant as with the CBN
wheel with a more closed bonding structure. To compare the real geometry for different profile
angles, the profile tip height at a fixed profile width should be used for the evaluation. Furthermore,
the resulting profile stability at grinding should also be taken into account.
Summary
In this Paper two different processes for the dressing of super abrasive grinding wheels have been
presented. For metal bonded grinding wheels electro contact discharge dressing was applied. For
vitrified bonded grinding wheels a novel dressing strategy using special shift kinematics was
introduced.
The application of electro contact discharge dressing allows generating the topography and
geometry of fine grained grinding wheels in one process. The topography is generated at lower
dressing voltages Ud0 and the geometry is generated at higher dressing voltages Ud0. The specific
material removal rate Q'sd and the G ratio in dressing are significantly influenced by the dressing
parameters. The specific material removal rate Q'sd increases by raising the dressing voltage Ud0, the
limitation of the dressing current Id0 or the radial feed of the electrode frd up to a certain value. A
further increase in the dressing parameters does not affect a further increase in the specific material
removal rate Q'sd. The G ratio is proportional to the radial feed of the electrode frd if the dressing
voltage Ud0 and limitation of the dressing current Id0 are kept at a constant level. Furthermore, the G
ratio is proportional to the specific material removal rate in dressing Q'sd for the dressing voltage
Ud0 and the limitation of the dressing current Id0. The generated profile of the grinding wheel
depends on the movement path of the electrode.
For the grinding of functional microgroove structures like riblets a novel dressing strategy using
a profile roller in combination with shift kinematics was applied to vitrified bonded SiC and CBN
grinding wheels. By this method, the limit of the smallest dressable wheel profile tip geometry at
profile dressing could be reduced significantly. To achieve smaller profile breakouts and higher
profile accuracy, a small dressing infeed and the up dressing mode should be chosen at dressing
microprofiles. Furthermore, the angle of the roof profile has a high impact on the profile stability at
dressing especially for super abrasive CBN wheels with a hard bonding system.
References
[1] F. Klocke, W. König: Fertigungsverfahren 2: Schleifen, Honen, Läppen. Springer Verlag
Berlin (2005), ISBN 978-3-540-23496-8.
[2] H.K. Tönshoff, B. Denkena: Spanen. Springer Verlag Berlin (2003), ISBN 978-3-540- 00588-9
[3] Y. Falkenberg: Elektroerosives Schärfen von Bornitridschleifscheiben. Dr.-Ing. Dissertation,
Universität Hannover, Germany (1997)
[4] T. Friemuth: Schleifen Hartstoffverstärkter Keramischer Werkzeuge. Dr.-Ing. Dissertation,
Universität Hannover, Germany (1999)
[5] J. Xie, J. Tamaki: In-process Evaluation of Grit Protrusion Feature for Fine Diamond Grinding
wheel by Means of Electro-Contact Discharge Dressing. Journal of Materials Processing
Technology, Vol. 180 (2006), pp. 83-90.
and the required profile tip geometry for riblet-grinding in the current study can be achieved. This
behavior can be explained by the higher structure stability and bonding force, which are due to the
sidewise bonding support at the profile tip. To analyze the structure stability at the profile tip,
FEM-modeling has been carried out at a varied profile angle from 45°, 60° to 90°. The wheel
profile was modeled as a homogenous body. A constant dressing load is applied on the wheel tip
and the results show that at the smaller angle of 45° the maximal von Mises stress in the grinding
layer is about four times higher than at a 90° profile angle. The same trend can also be proved at the
SiC wheel during the dressing experiments. However the skip is not as significant as with the CBN
wheel with a more closed bonding structure. To compare the real geometry for different profile
angles, the profile tip height at a fixed profile width should be used for the evaluation. Furthermore,
the resulting profile stability at grinding should also be taken into account.
Summary
In this Paper two different processes for the dressing of super abrasive grinding wheels have been
presented. For metal bonded grinding wheels electro contact discharge dressing was applied. For
vitrified bonded grinding wheels a novel dressing strategy using special shift kinematics was
introduced.
The application of electro contact discharge dressing allows generating the topography and
geometry of fine grained grinding wheels in one process. The topography is generated at lower
dressing voltages Ud0 and the geometry is generated at higher dressing voltages Ud0. The specific
material removal rate Q'sd and the G ratio in dressing are significantly influenced by the dressing
parameters. The specific material removal rate Q'sd increases by raising the dressing voltage Ud0, the
limitation of the dressing current Id0 or the radial feed of the electrode frd up to a certain value. A
further increase in the dressing parameters does not affect a further increase in the specific material
removal rate Q'sd. The G ratio is proportional to the radial feed of the electrode frd if the dressing
voltage Ud0 and limitation of the dressing current Id0 are kept at a constant level. Furthermore, the G
ratio is proportional to the specific material removal rate in dressing Q'sd for the dressing voltage
Ud0 and the limitation of the dressing current Id0. The generated profile of the grinding wheel
depends on the movement path of the electrode.
For the grinding of functional microgroove structures like riblets a novel dressing strategy using
a profile roller in combination with shift kinematics was applied to vitrified bonded SiC and CBN
grinding wheels. By this method, the limit of the smallest dressable wheel profile tip geometry at
profile dressing could be reduced significantly. To achieve smaller profile breakouts and higher
profile accuracy, a small dressing infeed and the up dressing mode should be chosen at dressing
microprofiles. Furthermore, the angle of the roof profile has a high impact on the profile stability at
dressing especially for super abrasive CBN wheels with a hard bonding system.
References
[1] F. Klocke, W. König: Fertigungsverfahren 2: Schleifen, Honen, Läppen. Springer Verlag
Berlin (2005), ISBN 978-3-540-23496-8.
[2] H.K. Tönshoff, B. Denkena: Spanen. Springer Verlag Berlin (2003), ISBN 978-3-540- 00588-9
[3] Y. Falkenberg: Elektroerosives Schärfen von Bornitridschleifscheiben. Dr.-Ing. Dissertation,
Universität Hannover, Germany (1997)
[4] T. Friemuth: Schleifen Hartstoffverstärkter Keramischer Werkzeuge. Dr.-Ing. Dissertation,
Universität Hannover, Germany (1999)
[5] J. Xie, J. Tamaki: In-process Evaluation of Grit Protrusion Feature for Fine Diamond Grinding
wheel by Means of Electro-Contact Discharge Dressing. Journal of Materials Processing
Technology, Vol. 180 (2006), pp. 83-90.
Key Engineering Materials Vol. 404 9