Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale
Distribution characterization of geometry shape and size of abrasive grits with high quality in tight size band and exact pattern is crucial for modern tool manufacturer to make fine powder abrasive tool and other powder tools, but complex to be classified and evaluated accurately due to the lack of...
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Chen, Y. Chen, X. AIOuarab, L. Opoz, T. Xu, X.P. Yu, G. 2020-03-24T13:34:54Z 2020-03-24T13:34:54Z 2019 Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale / Y. Chen, X. Chen, L. AIOuarab, T. Opoz, X.P. Xu, G. Yu // Надтверді матеріали. — 2019. — № 3 (239). — С. 62-76. — Бібліогр.: 26 назв. — англ. 0203-3119 https://nasplib.isofts.kiev.ua/handle/123456789/167312 548.7:621.921.1 Distribution characterization of geometry shape and size of abrasive grits with high quality in tight size band and exact pattern is crucial for modern tool manufacturer to make fine powder abrasive tool and other powder tools, but complex to be classified and evaluated accurately due to the lack of scientific method. In contrast to industrial methods with sieving mesh size or simplified projection criteria with circumscribed (inscribed or escribed) circle or rectangle, a set of new systemic criteria is developed and validated by measuring three representative grits samples in micron scale under 2D/3D microscopy platform. Характеристика розподілу геометричної форми та розміру абразивних зерен з високою якістю у щільному діапазоні розмірів і точна картина є вирішальною для сучасного виробника інструменту для виготовлення абразивного інструменту з дрібнодисперсного порошку та інших порошкових інструментів, складних для класифікації та оцінки з огляду на відсутність наукового методу. На відміну від промислових методів класифікації по розмірам сітчастих комірок або спрощених критеріїв проекції з обмеженим (вписаним або описаним) колом або прямокутником, розроблено та затверджено набір нових системних критеріїв шляхом вимірювання трьох репрезентативних зразків зерен в мікронній шкалі під 2D/3D мікроскопією. Характеристика распределения геометрической формы и размера абразивных зерен с высоким качеством в плотном диапазоне размеров и точная картина является решающим для современного производителя инструмента для изготовления абразивного инструмента из мелкодиспетного порошка и других порошковых инструментов, сложных для классификации и оценки, учитывая отсутствие научного метода. В отличие от промышленных методов классификации по размерам сетчатых ячеек или упрощенных критериев проекции с ограниченным (вписанным или описанным) кругом или прямоугольником, разработан и утвержден набор новых системных критериев путем измерения трех репрезентативных образцов зерен в микронной шкале под 2D/3D микроскопией. This work is supported by the State Key Program of National Natural Science of China (Grant No 51235004), the National Natural Science Foundation of China (Grant No 51575198). en Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України Сверхтвердые материалы Інструмент, порошки, пасти Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale Article published earlier |
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Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale |
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Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale Chen, Y. Chen, X. AIOuarab, L. Opoz, T. Xu, X.P. Yu, G. Інструмент, порошки, пасти |
| title_short |
Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale |
| title_full |
Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale |
| title_fullStr |
Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale |
| title_full_unstemmed |
Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale |
| title_sort |
morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale |
| author |
Chen, Y. Chen, X. AIOuarab, L. Opoz, T. Xu, X.P. Yu, G. |
| author_facet |
Chen, Y. Chen, X. AIOuarab, L. Opoz, T. Xu, X.P. Yu, G. |
| topic |
Інструмент, порошки, пасти |
| topic_facet |
Інструмент, порошки, пасти |
| publishDate |
2019 |
| language |
English |
| container_title |
Сверхтвердые материалы |
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Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України |
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Article |
| description |
Distribution characterization of geometry shape and size of abrasive grits with high quality in tight size band and exact pattern is crucial for modern tool manufacturer to make fine powder abrasive tool and other powder tools, but complex to be classified and evaluated accurately due to the lack of scientific method. In contrast to industrial methods with sieving mesh size or simplified projection criteria with circumscribed (inscribed or escribed) circle or rectangle, a set of new systemic criteria is developed and validated by measuring three representative grits samples in micron scale under 2D/3D microscopy platform.
Характеристика розподілу геометричної форми та розміру абразивних зерен з високою якістю у щільному діапазоні розмірів і точна картина є вирішальною для сучасного виробника інструменту для виготовлення абразивного інструменту з дрібнодисперсного порошку та інших порошкових інструментів, складних для класифікації та оцінки з огляду на відсутність наукового методу. На відміну від промислових методів класифікації по розмірам сітчастих комірок або спрощених критеріїв проекції з обмеженим (вписаним або описаним) колом або прямокутником, розроблено та затверджено набір нових системних критеріїв шляхом вимірювання трьох репрезентативних зразків зерен в мікронній шкалі під 2D/3D мікроскопією.
Характеристика распределения геометрической формы и размера абразивных зерен с высоким качеством в плотном диапазоне размеров и точная картина является решающим для современного производителя инструмента для изготовления абразивного инструмента из мелкодиспетного порошка и других порошковых инструментов, сложных для классификации и оценки, учитывая отсутствие научного метода. В отличие от промышленных методов классификации по размерам сетчатых ячеек или упрощенных критериев проекции с ограниченным (вписанным или описанным) кругом или прямоугольником, разработан и утвержден набор новых системных критериев путем измерения трех репрезентативных образцов зерен в микронной шкале под 2D/3D микроскопией.
|
| issn |
0203-3119 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/167312 |
| citation_txt |
Morphology analysis and characteristics evaluation of typical super abrasive grits in micron scale / Y. Chen, X. Chen, L. AIOuarab, T. Opoz, X.P. Xu, G. Yu // Надтверді матеріали. — 2019. — № 3 (239). — С. 62-76. — Бібліогр.: 26 назв. — англ. |
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http://stmj.org.ua 62
Інструмент, порошки, пасти
UCD 548.7:621.921.1
Y. Chen1, 2,*, X. Chen3, L. AIOuarab3, T. Opoz3,
X. P. Xu2, G. Yu4
1College of Mechanical Engineering and Automation,
Huaqiao University, Xiamen, PR China
2Ministry of Education Engineering Research Center for Brittle
Materials Machining, Huaqiao University, Xiamen, PR China
3Faculty of Engineering and Technology, Liverpool John Moores
University, Liverpool, UK
4Roll forging institute, Jilin University, Changchun, PR China
*42371502@qq.com
Morphology analysis and characteristics
evaluation of typical super abrasive grits
in micron scale
Distribution characterization of geometry shape and size of abrasive
grits with high quality in tight size band and exact pattern is crucial for modern tool
manufacturer to make fine powder abrasive tool and other powder tools, but complex
to be classified and evaluated accurately due to the lack of scientific method. In con-
trast to industrial methods with sieving mesh size or simplified projection criteria with
circumscribed (inscribed or escribed) circle or rectangle, a set of new systemic criteria
is developed and validated by measuring three representative grits samples in micron
scale under 2D/3D microscopy platform. The features of micron abrasive grits under
morphology classification include total four groups, six sub-groups and eighteen sub-
types in consideration of spatial geometry and statistical size distribution. For grinding
performance analysis and simulation, it would be better to use a set of dominant
volumetric geometries rather than use single simple geometry. Furthermore, the
significance of abrasive grits geometries in grinding performance is discussed.
Keywords: super abrasive grit, morphology analysis, characteristics
categorization, microscopy technique, size distribution.
INTRODUCTION
Morphology knowledge on characteristics and distribution of ge-
ometry shape and size of abrasive grit is a prerequisite for abrasive tool producers,
researchers and users to analyse and improve grinding performance. In grinding,
the main task of abrasive grits characterised by size, shape stochastic distribution
and other mechanical-thermal properties is to conduct either material removal by
© Y. CHEN, X. CHEN, L. AIOUARAB, T. OPOZ, X. P. XU, G. YU, 2019
ISSN 0203-3119. Надтверді матеріали, 2019, № 3 63
forming chip in ductile material or surface shattering in brittle material [1–4]. Thus
not only morphological but also physicochemical properties of abrasive grits,
together with abrasive tool preparation and grinding conditions, are crucial to
achieve better ground surface, dimensional tolerance and process stability.
In many previous researches on grinding dynamics, the shapes of abrasive grits
are commonly assumed to be either individual cone or pyramid with designated
angles, even simplest sphere, or ellipsoid [1, 3, 5, 6] for solid grit modelling and
grinding simulation to analyse elastic-plastic deformation and stress-strain distribu-
tion in material removal. In fact, the actual grits distributed on the circumference of
abrasive tool are not exactly same even far away from aforementioned geometrical
assumption in grinding. As a result, the conclusions drawn from scratching tests
utilizing single grit or multiple grits with predefined and simplified geometrical
shape do not convince very well and the grinding behaviour in the grit-material
contact zone can hardly be elaborated with satisfied accuracy.
To determine morphology distribution of abrasive grits, electrical sensing zone,
forward and right angle light scattering, dynamic light scattering, centrifugal sedi-
mentation and automated image analysis (optical or scanning electron microscope
(SEM)) are used widely in industry by implementing two-dimension similarity
criteria of regular shapes projection [7–9]. Some facilities, such as particle size
analyzers, are currently available for the determination of size distribution of sub-
sieve diamond and cubic boron nitride (CBN) powders [10–13]. However until
now, the studies find that no single measurement apparatus and no relative three-
dimension evaluation criteria are available to determine all information on grit
quality, property and performance.
With the development of special market demands of designated grits, abrasive
tool producers are facing challenges driven by customers, which requires new gen-
eration of tool products with optimized morphology and strict size distribution in
micron scales. In order to investigate ideal material removal mechanism for better
grinding behaviour and ground surface quality, highly-engineered abrasive tools
are manufactured with specially defined grit pattern or with micro-cutting edges,
i.e. with controlled size, required shape and distribution on surface of abrasive
tools [14–17]. Due to aforementioned extraordinary uncertainty and dissimilarity
of randomly distribution or irregularly abrasive shapes, there are few procedures
and criteria on abrasive assessment and classification published. This paper at-
tempts to comprehensively expound a more feasible procedure on identifying spa-
tially volumetric geometrical characteristics with high accuracy (i.e. how close a
measured value is to the true value), precision (i.e. the variation in repeated meas-
urements conducted by same device and operator) and size distribution of micron
grits in microscopy assessment. A set of newly presentd systemic criteria of mor-
phology categorization are proposed to define dominant morphological characteris-
tics of the grits with mathematic statistical methods, which will benefit core com-
petency of stakeholders, such as abrasive grit producers, grinding tool users and
researchers for grinding dynamics analysis using finite element method (FEM)
simulation and experimental technique. Furthermore, the presented microscopy
technique, categorization criteria and 3D abrasive morphological distribution defi-
nition could provide a good guidance for abrasive tool manufacturers and users to
appraise pre-process quality of abrasive grits and to predict their grinding perfor-
mance.
SAMPLE MEASUREMENT PRINCIPLE
In practical application, a series of pre-processing procedures in accordance
with international standard, including milling and grading, acid cleaning, sieving,
http://stmj.org.ua 64
sedimentation, washing and drying, blending, quality controlling etc, are selec-
tively implemented in terms of specific demands of product specification and prop-
erties [18]. In the paper, the focus is on geometrical characteristics.
Sieving process
Sieving is a regular process performed easily either by manual work or by
machine to separate abrasive grits from uniform sieves in different mesh size
grades. Coarse abrasive grits are definitely classified in terms of sieving mesh size.
Finer or powder grits are classified by sedimentation process in terms of multiple
national and international standards, such as ANSI, FEPA, FEPA, GB/T ISO, etc.
[19].
In measurement test, it is noted that determining a grit dimension by means of
sieving mesh size does not imply an accurate value, but rather a size band. The
band is definitized by means of a set of sieving instruments retaining or passing a
number of grits with specific size. However, the quality of sieving process with the
physical method largely depends on the shape features of the grits. For example,
for the grits in shape of round or bulky cube and triangle, mesh size defines their
approximate diameter or circumference, but for the grits in irregular shape (e.g. in
needle or spike shape), the maximum dimension of the analyte might be larger than
the mesh size as the grits could pass through sieves with their smallest cross-
section profile. Therefore, wider size distribution of irregular grits is, higher uncer-
tainty of shape distribution of the grits increases.
Sample preparation process
In sample preparation process, well-dispersed, rather than clusters or over-
lapped samples sprayed on the glass slide are needed to avoid difficult-to-capture
situation and to carry out microscopy observation tests. In the study, three types of
representative samples that have great grinding performance and physical proper-
ties with higher hardness, excellent mechanical-thermal properties and highest
occupation rate of industrial market worldwide, namely A (coarse diamond grit), B
(finer CBN micron grit) and C (finer diamond grit) are listed in Table 1.
Table 1. Specification and properties of the samples
Sample
types
Geometry
properties
ANSI grain size,
μm,
and standards
(ANSI-B74-16)
Physical
properties
A
(diamond)
Coarse and dark
Sharp polygon edges
302–456;
40/50#
Irregular monocrystal
Moderate strength
Resin bond
B
(CBN)
Finer and dark brown
Sharp triangle edges
127–165;
100/120#
Complete crystal form
High strength
High thermal stability
Resin bond
C
(diamond)
Powder and light grey
Concentrated size dis-
tribution
12–22;
9#
Uniform lump microstructure
High thermal stability
Metal bond
ISSN 0203-3119. Надтверді матеріали, 2019, № 3 65
Due to different size magnitudes of three types of samples, a large number of
the particles are composed in even just one carat of the samples. The number of the
sampled particles observed in tests is only very small proportion of the whole sam-
ples. Thus, proper sampling density in tests is crucial to fulfil statistical analyse
(i.e. to improve the objectivity of the classification). To eliminate the subjectivity
of decision made by the operator, each test is conducted with at least 2–3 inde-
pendent groups of the samples. Each group of the samples is composed of over 50
particles randomly-captured under an optical microscopy vision area.
Microscopy measurement process
Optical microscopy technique is commonly used to measure sub-sieve powder
diamond grits and micron CBN grits by capturing their clear images. The samples
in the images are then dimensioned for size analysis and shape classification by
means of accessional image software. The process allows the operator to observe
the positioned samples and to evaluate their shape characteristics and size band. In
general, the sample size is defined as the diameter of minimum circumscribed cir-
cle that completely encloses the 2D projected image of the sample (i.e. equivalent
circle diameter) or recorded with the longest single dimension of grit edges (LSD)
[12].
Prior to measurement, the scale calibration of microscopy device is essential to
significantly assure reliability of the test according to accuracy standard and size
distribution of the samples. The purpose of scale calibration is to establish a unified
metric basis for dimensioning size of the samples in sub-sieve accurately. After
that, different size distribution of the samples could be constructed by visually
classifying and accumulating counts in sequence. Following such a defined proce-
dure, the characterization criteria of size and shape distribution is elaborated in
next section.
So far, automated optical scanning system (e.g. using optical or SEM micro-
scope coupled with a computerized image analyzer) can eliminate most of the fa-
tiguing measurement works [13]. However besides high cost, not a single tech-
nique or feasible device is available to measure and identify the size and shape
spectrum of the particles at consistent accuracy. Each technique/device is capable
of providing optimal application in a certain size range based on specific 2D profile
similarity (e.g. circularity and sphericity ) characterization.
In the investigation, the images of the particles are captured under a Leica DFC
295/CH9435 optical microscope (Leica Microsystem Ltd, Germany) [20] coupled
with an objective lens of magnification 100×, 50×, 20×, 10×, 5×. The microscope,
which scanning distance from 0.5 μm to 2000 μm is equipped with a digital camera
OLYMPUS BX51M. The size and morphology analysis are carried out with an
image analysis software (LAS V3.6). The images of particles are shown in Fig. 1
(sample group A, magnification 5×, scale calibration: 200 μm), Fig. 2 (sample
group B, magnification 20×, scale calibration: 125 μm) and Fig. 3 (sample group
C, magnification 10×, scale calibration: 10 μm).
In Fig. 1, it is clearly shown that there are many truncated particles with smooth
top-surfaces (Area S1) formed due to natural crystalline fracture in previous milling
process. Similar situation is observed from a few of CBN particles in Fig. 2 and
some diamond particles in Fig. 3. In contrast to commonly blunt flanks of the
particles in Fig. 1 and Fig. 3, sharper flanks of the particle exist in Fig. 2. Further,
all length dimensions of the samples edges both at top-surface (Area S1) and at
bottom-surface (Area S2) in planar shapes of triangle, quadrilateral, pentagon or
hexagon, are measured clockwise according to calibrated scale and incrementally
http://stmj.org.ua 66
recorded with Origin 8.0 software. Meanwhile for the samples in shape of polygon,
maximum size and minimum size between longest single dimension of edges
(LSD) and relative dimension of vertical line from the farthest vertex away from
LSD are depicted as length (L) and width (W) of the grit only at bottom projection
surface (Area S2) in accordance with sieving mesh size. The length (L) and width
(W) of the samples in shape of rhomb or ellipse correspond to major axis and minor
axis. By substituting the edges dimensions into quantitative area formulas in Origin
8.0 software, projection areas of the samples, including truncated-surface area
(Area S1) and bottom profile area (Area S2) and length (L) and width (W) of the
grits are obtained and dimensioned in Fig. 1, b, Fig. 2, b, Fig. 3, b. For most parti-
cles in Fig. 2, b and Fig. 3, b, Area S2 almost overlaps with Area S1. The aspect
ratio (AR) of width to length of each grit is calculated automatically as an impor-
tant variable to assess shape features.
a b
Fig. 1. Sample group A with 5× magnification in full image (a), in enlarged image (b).
a b
Fig. 2. Sample group B with 50× magnification in full image (a), in focusing image (b).
GRIT MORPHOLOGY CLASSIFICATION CRITERIA
Due to the lack of key volumetric information on 2D projection (matt or
glossy), the microrelief of the particles with spatially volumetric features could be
identified by utilising back light microscopy, surface division scanning technique
on Bruker ContourGT platform (version 64) [21] and scanning electron
microscopy (SEM) techniques. Combining with essential exposure highlight skills
ISSN 0203-3119. Надтверді матеріали, 2019, № 3 67
(e.g. enhancing light intensity, hues, saturation and contrast and depth of measured
field), some examples are shown in Fig. 4. The randomly captured geometry char-
acteristics, including spiky apex, contour peaks, truncated profiles and prismatic
columns, are visually extracted from top-surface/flanks inscribed with dotted lines
or circles to determine dominant frustums and bases so as to dimension all samples
edges according to calibration metrics and then calculate the ratio of top-surface
area (S1) to bottom-profile area (S2) by conducting aforementioned quantitative
dimension analysis of each grit edges. In contrast to many previous conclusions on
2D shape distribution determined by simple AR or circumscribed circle, a new
categorisation method is proposed to classify the grits into four groups (e.g.
ellipsoid, frustum pyramid, truncated cone and arbitrary polyhedron), six
subgroups and eighteen subtypes of 3D characteristics categories. The identifi-
cation criteria of categorisation are illustrated in Table 2 to identify and classify
abrasive grits according to their geometries with acceptable similarity, uniqueness
and practicability disregarding the broken or torn edges.
a b
Fig. 3. Sample group C with 10× magnification in full image (a), in enlarged image (b).
a b
Fig. 4. SEM images group B (a), group C (b).
RESULT AND DISCUSSION
Particle geometry and morphology distribution
Based on the classification methods defined in Table 2, the 3D morphological
distributions of abrasive grits in groups A, B and C, whose sample numbers are
http://stmj.org.ua 68
102, 159 and 133 respectively, are visually illustrated in Fig. 5 to Fig. 7 with
histogram and pie charts to indicate the relationship between the sample amounts
(in sub-histogram (a)) or morphology proportion (in sub-chart (b)) and relevant
geometries. The geometrical shapes of each sample group are categorised with
detailed sharp, broken and torn situations of particle edges are presented
elaborately to facilitate the evaluation of quality control in milling and sieving
processes and grinding performance. It can be seen that only a few types of
geometrical shapes dominate the population of abrasive grits. Tetrahedron and
pyramid shapes are among the most popular one.
Table 2. Morphology categorization criteria
Morphology categorization
Group Subgroup Sub-type Geometry
Characteristics
formulae
Projection
disambiguata-
tion
Sphere S1:S2 ≥ 0.8
Ellipsoid S1:S2 < 0.8
None
Triangular
pyramid
Three edges
and one high-
lighted peak
Rectangular
pyramid
Four edges and
one highlighted
peak
Pentahedron Five edges and
one highlighted
peak
Rhombohedron
S1:S2 ≤ 0.1
Six edges and
one highlighted
peak
Frustum
pyramid
Three edges
and one trun-
cated top-
surface
Truncated
tetrahedron
Four edges and
one truncated
top-surface
Truncated
pentahedron
Five edges and
one truncated
top-surface
Truncated
rhombohedron
0.1 < S1:S2 <
0.8
Six edges and
one truncated
top-surface
Triangular
prism
S1:S2 ≥ 0.8 Three edges
and one trun-
cated top-
surface
ISSN 0203-3119. Надтверді матеріали, 2019, № 3 69
Table 2. (Contd.)
Quadrangular
prism
Four edges and
one truncated
top-surface
Pentahedral
prism
Five edges and
one truncated
top-surface
Rhombohedral
prism
Six edges and
one truncated
top-surface
Cone S1:S2 ≤ 0.1 Round bottom-
surface and one
peak
Truncated
cone
0.1 < S1:S2 <
0.8
Round bottom-
surface and one
top-surface
Cylinder S1:S2 ≥ 0.8 Round bottom-
surface and one
top-surface
Arbitrary
polyhedron
S1:S2 ≥ 0.8 or
Number of
edges > 6
Arbitrary poly-
gon in top-
surface
a b
Fig. 5. Morphology distribution of group A in histogram (a), in categorized pie charts (b).
a b
Fig. 6. Morphology distribution of group B in histogram (a), in categorized pie charts (b).
http://stmj.org.ua 70
a b
Fig. 7. Morphology distribution of group C in histogram (a), in categorized pie charts (b).
Particle size and size distribution
The absolute values of maximum and mean in length and width bands and their
size distribution of the samples are illustrated in Fig. 8. As an important index of
morphological characteristics to indicate random distribution from measurement
tests in industry, the variable ix is defined as the AR of the width Wi to the length
Li of each abrasive grit, depicted as:
i
i
i L
x
W= . (1)
Sample number Sample number
a b
Sample number
c
Fig. 8. Size and size distribution of three samples group A (a), group B (b), group C (c):
maximum of length (1), mean of length (2), maximum of width (3), mean of width (4).
ISSN 0203-3119. Надтверді матеріали, 2019, № 3 71
The mean of AR is calculated as
=
=
n
i
i
n
x
x
1
, (2)
where n is total number of the samples.
The standard deviation σ of size distribution of the width and length of the grits
and their AR is defined to depict how all data of the grits sizes are spread out from
the mean (the expected value), calculated by
=
−=σ
n
i
i
n
xx
1
2)(
. (3)
The AR distribution of three groups of samples and their distribution density
comparison diagram are shown in Fig. 9. By combining its size band with the
standard deviation σ of the AR distribution, the shape and variation of abrasive
distribution could be assessed for the conformance of production. The tighter the
AR distribution of the grits in its size band, the greater the conformance of
production is. The AR distribution of group A would be approximated as a
Gaussian distribution which expected value is set to the mean of the AR and the
probability density function is depicted as [22]
2
2
2
)(
2
1
)( σ
−−
σπ
=
xxi
exf . (4)
a b
c d
Fig. 9. AR distribution of three samples group A (a), group B (b), group C (c), their resultant
diagram (d).
With Gaussian distribution function, the results of group A in Fig. 9, a illustrate
that the conformance of grit AR within ],[ σ+σ− xx is 79 % (empirical reference
value in industry is 68.3 %) and within ]2,2[ σ+σ− xx is 100 % (empirical refer-
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ence value is 95.4 %) respectively [23]. The similar analysis results are observed in
Figs. 9, b and c.
Moreover, as illustrated in Fig. 9, d, the bigger σ, the wider the AR values
scatter (e.g. group B) and the greater the random variation. However, the narrower
distribution of the AR values (e.g. group A) does not necessarily lead to less
variation of the morphological geometries within the size band of the grits. In fact,
the Group A presents more morphological types of grits than other groups.
Although the conformance proportion of abrasive grits size and AR values could
reveal quality satisfaction of abrasive production, it does not reveal the abrasive
grit shape variation. This convinces that 3D morphological features are necessary
to provide a rational guidance to improve core competency for abrasive tool
manufacturers and users.
Morphology analysis and its significance
Combined with all data from Fig. 5 to Fig. 9, the properties and geometry
characteristics of all studies samples that are interested for different stakeholders
are summarized in Table 3.
Table 3. Comparison of geometry, size and their distribution
of all samples
Sample types Group A Group B Group C
Particle scale Coarse micron Finer micron Sub-sieving powder
Dominant geometries
and proportion
Tetrahedron, 29 %
Pentahedron, 17 %
Pyramid, 16 %
Arbitrary polyhedron, 10 %
Pyramid, 36 %
Tetrahedron, 29 %
Arbitrary polyhedron, 9 %
Pentahedron, 7 %
Tetrahedron, 32 %
Ellipsoid, 23 %
Pyramid, 20 %
Sphere, 18 %
Mean of length, μm 390.5 178 23.5
Standard deviation
of length (σ)
43.8 24.56 3.92
Size range of dimen-
sioned length
and conformance
proportion within
],[ σ+σ− xx
[354, 438]
72 %
[140, 200]
77 %
[18, 27]
73 %
Mean of width, μm 343.3 134 18.7
Standard deviation
of width σ
35.7 19.2 3.21
Size range of dimen-
sioned width
and conformance
proportion within
],[ σ+σ− xx
[304, 378]
79 %
[101, 152]
65 %
[13, 20]
72 %
Mean of AR
of width/length
0.76 0.75 0.71
Probability density
of AR
2.98 2.6 2.66
Sieving mesh size, μm
(ANSI-B74-16)
[302, 456] [127, 165] [12, 22]
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In Table 3, the particles of group A in coarse micron scale have a mean value of
width (343.3 μm) close to the low limit of sieving mesh size standard ([302,
456] μm) (Reference: ANSI-B74-16 [19]) and a size range ([304, 378] μm) with
highest conformance proportion (79 %) in three samples. It demonstrates the vali-
dation of measurement results [23] but unsatisfying level of milling and sieving in
the pre-process, which makes comparatively smaller particles than required stan-
dard ones around sieving mesh size. Moreover, the arbitrary polyhedron with great
proportion of 10 % of the samples also confirms the unsatisfying situation. The
pre-process should be improved to obtain satisfying shape (with consistent features
of dominant grit shapes) and size band (around the mean of standard size range) of
the particle in the future. The real dominant geometries of the particle are tetrahe-
dron, pentahedron and pyramid in proportion order, as shown in Fig. 5, even
though internal features, e.g. cutting edges companying with irregular broken, torn
and sharp are observed in captured images. It is essential for researchers by taking
tetrahedron or pentahedron geometrical shapes as key features in modelling group
A grit performance and to conduct dynamics signals monitoring and simulation and
further to predict grinding performance, friction and wear behaviour of abrasive
tools [16, 24].
The particles of group B, as finer micron grits, have a mean value of width
(134 μm) close to the low limit of sieving mesh size standard ([127, 165] μm)
shows a wider size distribution band ([101, 152] μm) but the lowest conformance
proportion of width band of 65 % (less than 68.3 %). It demonstrates that a certain
proportion of tiny or over-sized grits with wider distribution band shown in
Fig. 9, b and a diverse morphology distribution (e.g. arbitrary polyhedron, irregular
sphere and ellipsoid with shattered edges, etc) blended with of the dominant
geometries of the particle, which cause the measurement difficulty on exactly
morphology identification. The dominant geometries of the particles are pyramid
and regular tetrahedron (the sum of two proportions is 65 %), as shown in Fig. 6.
Thus, these two geometries should be approximately considered in modelling the
simplified geometry for simulating chip formation, dynamic friction and wear
behaviour. Furthermore, a large number of grit geometries with shattered edges and
irregular morphology distribution make it more complex in abrasive tool
preparation for designated pattern and grinding dynamics prediction. During
grinding ductile materials (e.g. copper), because the different shapes of micro-
cutting edges (i.e. circular/square/triangular base frustums) would influence the
grinding performance (e.g. shearing/fracturing/plastic deformation, surface texture,
surface roughness, specific cutting forces), the increased number of cutting edges
on grits could produce more localised material pile-up and reduce plastic chip
removals [2, 3, 16]. Moreover, the shearing/fracturing phenomena were
preponderant in the material removal mechanism when using square/triangular
shaped grits while major plastic deformations were found for circular base frustum
during grinding brittle materials (e.g. sapphire or ceramics) [16]. The sharp cutting
edges of single grit, as shown in Fig. 2, would easily result in grit fracture, crack
propagations and re-sharpening during grinding process even though the git mate-
rial is of high strength and thermal stability, which are beneficial to achieve finish
ground surface.
The particles of group C, as a sub-sieving powder, which mean value of width
(18.7 μm) is closer to the upper limit of sieving mesh size standard ([12, 22] μm)
than the other two particles, have a tighter size band ([13, 20] μm) as shown in
Fig. 8, c. This is the evidence that the high quality control of milling, sieving and
sedimentation techniques has been implemented in pre-process procedure. The
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morphology distribution of the particle mainly composes of tetrahedron and ellip-
soid with high proportion (the sum of two proportions is 55 %), accompanying
with pyramid and sphere at high proportion as well. The proper mean of AR (0.71)
as shown in Fig. 9, c, is ideal and optimal for practical manufacture process to
improve the holding force distribution of the diamond abrasives [5, 6]. Meanwhile,
most of the grits with bulky and unbroken edges, which induce block shear
behaviour, are beneficial to achieve smoother workpiece surface roughness, less
clogging and abrasive grit wear. This results in predominantly bulk material
displacement or plastic deformation in orthogonally orientated working-surface
when machining difficult-to-machine ductile materials with high hardness at high
and super-high speed [16, 25, 26].
CONCLUSIONS
Through high quality control in pre-process and pro-process procedures,
abrasive grits at a tight size band and high forming accuracy remains one of the
most important influence factors on abrasive grinding/polishing tools preparation,
removal mechanism and grinding performance. Because particle-sorting techniques
and quality-evaluating system are often accompanied with special device,
microscopy techniques and comprehensive identification criteria with low
efficiency and high cost, they are seldom openly discussed. It is widely required
among grit providers, abrasive machining tool manufacturer and user to have
scientific insight on the identification and morphology categorization of spatially
volumetric geometry and size distribution of abrasive grits in micron scale.
For this purpose, a new categorisation method is proposed to enable the size
and morphological distribution of volumetric geometries of abrasives to be
standardised for grinding dynamics analysis and simulation, which is beneficial to
grinding performance prediction. By means of conducting microscopy
measurement tests, three types of abrasive grits were assessed in terms of the
aspect ratio of width to length of the samples, dominant volumetric shapes, tight
size distribution, their standard deviation and conformance proportion. It is found
that only a few types of grit morphologic geometries dominate the grit population.
After the analysis of current methods used in abrasive machining research, it is
suggested that the analysis of abrasive processing should focus on a set of
dominant grit shapes rather than just single simplified geometry. With the
observation and analysis, the dominant volumetric geometries of grits are
tetrahedron and pentahedron for sample group A, tetrahedron and ellipsoid for
sample group B and geometries of pyramid and tetrahedron for sample group C.
FUNDING
This work is supported by the State Key Program of National Natural Science
of China (Grant No 51235004), the National Natural Science Foundation of China
(Grant No 51575198).
Характеристика розподілу геометричної форми та розміру абразивних
зерен з високою якістю у щільному діапазоні розмірів і точна картина є вирішальною для
сучасного виробника інструменту для виготовлення абразивного інструменту з дрібноди-
сперсного порошку та інших порошкових інструментів, складних для класифікації та
оцінки з огляду на відсутність наукового методу. На відміну від промислових методів
класифікації по розмірам сітчастих комірок або спрощених критеріїв проекції з обмеже-
ним (вписаним або описаним) колом або прямокутником, розроблено та затверджено
набір нових системних критеріїв шляхом вимірювання трьох репрезентативних зразків
зерен в мікронній шкалі під 2D/3D мікроскопією. До особливостей мікронних абразивних
зерен за морфологічною класифікацією належать чотири групи, шість підгруп та
ISSN 0203-3119. Надтверді матеріали, 2019, № 3 75
вісімнадцять підтипів з урахуванням просторової геометрії та статистичного розподілу
розмірів. Для аналізу та моделювання продуктивності шліфування було б краще викори-
стовувати набір домінуючих об’ємних геометрій, а не використовувати одну просту
геометрію. Крім того, обговорюється значення геометрії абразивних зерен при
шліфуванні.
Ключові слова: суперабразивний порошок, морфологічний аналіз,
категоризація характеристик, техніка мікроскопії; розподіл розмірів.
Характеристика распределения геометрической формы и размера аб-
разивных зерен с высоким качеством в плотном диапазоне размеров и точная картина
является решающим для современного производителя инструмента для изготовления
абразивного инструмента из мелкодиспетного порошка и других порошковых инстру-
ментов, сложных для классификации и оценки, учитывая отсутствие научного метода. В
отличие от промышленных методов классификации по размерам сетчатых ячеек или
упрощенных критериев проекции с ограниченным (вписанным или описанным) кругом или
прямоугольником, разработан и утвержден набор новых системных критериев путем
измерения трех репрезентативных образцов зерен в микронной шкале под 2D/3D микро-
скопией. К особенностям микронных абразивных зерен по морфологической классифика-
ции относятся четыре группы, шесть подгрупп и восемнадцать подтипов с учетом про-
странственной геометрии и статистического распределения размеров. Для анализа и
моделирования производительности шлифования было бы лучше использовать набор
доминирующих объемных геометрий, а не использовать одну простую геометрию. Кроме
того, обсуждается значение геометрии абразивных зерен при шлифовании.
Ключевые слова: суперабразивний порошок, морфологический анализ,
категоризация характеристик, техника микроскопии; распределение размеров.
1. Darafon A., Warkentin A., Bauer R. 3D metal removal simulation to determine uncut chip
thickness, contact length and surface finish in grinding. Int. J. Adv. Manuf. Technol. 2013.
Vol. 66, no. 9–12. P. 1715–1724.
2. Aurich J.C., Kirsch B. Kinematic simulation of high-performance grinding for analysis of chip
parameters of single grits. CIRP Ann. Manuf. Sci. Technol. 2012. Vol. 5, no. 3. P. 164–174.
3. Rasim M., Mattfeld P., Klocke F. Analysis of the grit shape influence on the chip formation in
grinding. J. Mater. Proc. Technol. 2015. Vol. 226, no. 9. P. 60–68.
4. Chen Y., Huang G.Q. Development and research on the dynamics simulation system for sur-
face grinding process with diamond wheel. Key Eng. Mater. 2014. Vol. 589–590. P. 658–664.
5. Li X.K., Wolf S., Zhu T.X., Geng Z., Rong Y.M. Modelling and analysis of the bonding
mechanism of CBN grit for electroplated superabrasive tools–part 2: finite element modeling
and experimental verification. Int. J. Adv. Manuf. Technol. 2015. Vol. 77, no. 1–4. P. 43–49.
6. Fu Y.C., Tian L., Xu J.H., Yang L. Development and application on the grinding process
modelling and simulation. J. Mechan. Eng. 2015. Vol. 51, no. 7. P. 198–205.
7. Benea I.C. Particle size and size distribution of superabrasive powders. Diam. Tooling J. 2010.
Vol. 10, no. 3. P. 39–46.
8. List E., Frenzel J., Vollstadt H. A new system for single particle strength testing of grinding
powder. Ind. Diam. Rev. 2006. Vol. 66, no. 1. P. 42–47.
9. Petasyuk G.A. System and criterial method of the identification and quantitative estimation of
the geometrical shape of the abrasive powder grit projection. Powder Technol. 2014.
Vol. 264. P.78–85.
10. Agata S., Pawel Z., Andrzej B. Selection of shape parameters that differentiate sand grits
based on the automatic analysis of two-dimensional images. Sedi. Geo. 2015. Vol. 327,
no. 70. P. 14–20.
11. Mahamed G.H., Ayed S., Engellbrecht A.P. Dynamic clustering using particle swarm optimi-
zation with application in image segmentation. Pat. Analysis Appl. 2006. Vol. 8, no. 4.
P. 332–344.
12. Igathinathane C., Pordesimo L.O., Columbus E.P. Shape identification and particle size
distribution from basic shape parameters using Image L. Comput. Electron. Agric. 2008.
Vol. 63, no. 2. P. 168–182.
13. Kröner S., Doménech-Carbŏ M.T. Determination of minimum pixel resolution for shape
analysis: proposal of a new data validation method for computerized images. Powder Tech-
nol. 2013. Vol. 245, no. 8. P. 297–313.
http://stmj.org.ua 76
14. Aurich J.C., Herzenstiel P., Sudermann H., Magg T. High-performance dry grinding using a
grinding wheel with a defined grit pattern. CIRP Ann. Manuf. Technol. 2008. Vol. 57, no. 1.
P. 357–362.
15. Herzenstiel P., Aurich J.C. CBN-grinding wheel with a defined grit pattern – extensive nu-
merical and experimental studies. Mach. Sci. Technol. 2010. Vol. 14, no. 3. P. 301–322.
16. Axinte D., Butler-Smith P., Akgun C., Kolluru K. On the influence of single grit micro-
geometry on grinding behaviour of ductile and brittle materials. Int. J. Mach. Tools Manuf.
2013. Vol. 74, no. 8. P. 12–18.
17. Koshy P., Iwasaki A., Elbestawi M.A. Surface generation with engineered diamond grinding
wheels: insights from simulation. CIRP Ann. Manuf. Technol. 2003. Vol. 52, no. 1. P. 271–
282.
18. Linke B.S. A review on properties of abrasive grits and grit selection. Int. J. Abra. Technol.
2015. Vol. 7, no. 1. P. 46–58.
19. American National Standard Institute (1992) Norm ANSI B74.4-1992: Procedure for Bulk
Density of Abrasive Grain. Nov. 12. 1992.
20. Leica Application Suite (LAS) Handbook (2010) [online] http:// www.leica-microsys-
tems.com. Solms, Germany.
21. Bruker Handbook Measurement and Characterization of Surface Topography. Bruker coop-
eration. Karlsruhe, Germany, 2012.
22. Soong T.T. Probability and Statistics for Engineers and Scientists. Chichester: John
Wiley&Sons, 2004.
23. Liang C.C., Li R., Shi X.W. A compact closed form of standard normal distribution. J. Xi-
dian. Univ. 2003. Vol. 4(3). P. 289–292 (in Chinese).
24. Pirard E. The cutting edge of superabrasives quality control. Ind. Diam. Rev. 2003. Vol. 3,
no. 3. P. 49–50
25. Malkin S., Guo C. Grinding Technology: Theory and Application of Machining with Abra-
sives. New York: Industry Press, 2008.
26. Doman D.A., Warkentin A., Bauer B. A survey of recent grinding wheel topography models.
Int. J. Mach. Tools Manuf. 2006. Vol. 46, no. 3–4. P. 343–352.
Received 21.05.18
Revised 27.06.18
Accepted 27.06.18
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