R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
441–451
EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING
OF TI-6AL-4V ALLOYS
VPLIV TEKSTURIRANIH REZALNIH VLO@KOV NA MIKRO
STRU@ENJE ZLITIN VRSTE Ti-6Al-4V
Rajesh Babu Tere, G. L. Samuel
*
Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India
Prejem rokopisa – received: 2023-03-15; sprejem za objavo – accepted for publication: 2023-07-25
doi:10.17222/mit.2023.828
There is an increasing demand for higher machining quality and service life of the cutting tools used for the machining of
high-strength alloys. Various studies revealed that textured cutting tools could improve the cutting performance by enhancing
the tribological characteristics of the cutting regime. Advances in precision machining enabled the creation of micro/nano-tex-
tures on tool surfaces with excellent dimensional control. In this work, distinct micro designs, viz. horizontal line, vertical line
and cross-hatch, are made, varying the pitch on the rake faces of coated carbide cutting inserts (CCMT060202LF KC5010). An
in-house micro-turning machine was utilized to perform all the experiments in dry-cutting conditions. Micro-turning operations
were performed using plain and textured inserts and varying the cutting parameters under dry conditions. The effectiveness of
micro-scale textures at a contact interface was evaluated based on the cutting forces, tool flank wear and surface roughness.
Compared to non-textured inserts, the machining using cross-hatch textured inserts with 100 μm pitch resulted in 50 % lower
cutting forces, a 45 % improved surface finish and 37 % reduced tool flank wear. When machining with horizontal-line textured
inserts with a 100 μm pitch, cutting forces are reduced by 46 %, the surface finish is enhanced by 34 % and the tool flank wear
is lowered by 30 %. Similarly, when machining with vertical-line textured inserts with a 100 μm pitch, cutting forces are mini-
mized by 38 %, the surface finish is improved by 20 % and the tool flank wear is lowered by 26 %. Additionally, a durability
test was conducted for the inserts, and the results showed that the cross-hatch textured tool life improved by 80 %, the life of the
horizontal-line textured tool increased by 50 % and the life of the vertical-line textured tool increased by 40 % compared to
plain inserts. The heat dissipation and tool-chip friction during machining are thus significantly influenced by the texturing,
namely by its design, dimensions and orientation.
Keywords: micro-texturing, micro-turning, femtosecond laser, titanium alloy, surface roughness, wear
V svetu so se mo~no pove~ale zahteve po kakovostni mehanski obdelavi in pove~anju dobe trajanja rezalnih orodij med
mehansko obdelavo zlitin z visoko trdnostjo. Izvedene so bile {tevilne {tudije, ki so pokazale, da teksturirana rezalna orodja
lahko izbolj{ajo kakovost rezanja zaradi izbolj{anih tribolo{kih lastnosti re`ima rezanja. Napredek pri precizni mehanski
obdelavi je omogo~ilo kreiranje mikro oziroma nano teksture na povr{inah orodij z isto~asno odli~nim nadzorom dimenzij. V
tem ~lanku avtorji opisujejo posebne mikro horizontalne in vertikalne linijske dizajne teksture s pre~nimi {rafurami z variranjem
pre~nega nagiba vrha rezalnega orodja oziroma rezalnega vlo`ka (plo{~ice) iz prevle~ene karbidne trdine s komercialno oznako
CCMT060202LF KC5010. Na doma~i mikro stru`nici so avtorji izvedli vse preizkuse v pogojih suhega rezanja. Uporabili so
ploske (gladke) in teksturirane rezalne vlo`ke in pri tem spreminjali pogoje suhega rezanja. U~inkovitost mikro tekstur na meji
kontakta so ovrednotili z dolo~itvijo sil rezanja, bo~ne obrabe vlo`kov in povr{inske hrapavosti. Primerjava mehanskih obdelav
med neteksturiranimi vlo`ki in vlo`ki s 100 μm korakom {rafirano teksturo je pokazala 50 % manj{e rezalne sile, 45 %
izbolj{anje kakovosti (gladkosti) povr{ine in njihovo 37 %-no manj{o bo~no obrabo. Mehanska obdelava s horizontalno 100 μm
korakom linijsko teksturo rezalnih vlo`kov je pokazala 46 % zman{anje rezalnih sil, 34 % izbolj{anje kakovosti povr{ine in
30 % zmanj{ano bo~no obrabo. Podobno so se pri uporabi vertikalno 100 μm teksturiranih rezalnih vlo`kov rezalne sile
zmanj{ale za 38 %, kakovost povr{ine se je izbolj{ala za 20 % in bo~na obraba se je zmanj{ala za 26 %. V primerjavi s
konvencionalnimi neteksturiranimi (gladkimi) rezalnimi vlo`ki se je `ivljenska doba teksturiranih vlo`kov mo~no podalj{ala, s
{rafirano teksturo za 80 %, z horizontalno linijsko teksturo za 50 % in vertikalno linijsko teksturo za 40 %. Avtorji v zaklju~ku
povdarjajo, da pri mehanski obdelavi, tekstura rezalnega orodja, oblika, dimenzije in orientacija mo~no vplivajo na prenos
oziroma disipacijo toplote ter trenje med ostru`ki in rezalnim orodjem.
Klju~ne besede: mikro teksturiranje, mikro rezkanje, femto sekundni laser, zlitine na osnovi titana, povr{inska hrapavost, obraba
1 INTRODUCTION
The manufacturing of miniaturized components is
crucial in many industries, including precision engineer-
ing, medical technology, optics and electronics. There is
growing demand for highly accurate and compact com-
ponents in a wide range of industries. The limitation to a
0.05-mm feed and depth of cut is no longer a barrier in
micro machining as advancements in the machine tool
technology now allow for cutting depths below 0.05 mm,
with exceptional precision and rigidity. Micromachining
involves the manufacturing of components, features or
cutting tools with dimensions that typically fall within
the range of 1–500 μm.
1,2
Additionally, they can help
with miniaturization, which is essential for implantable
and portable devices. The micro-components made of
Ti6Al4V alloys are widely used in the aerospace indus-
tries due to their high strength-to-weight ratio and great
fatigue strength and in medical industries because of
their exceptional wear and corrosion resistance. How-
Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451 441
UDK 669.018.256 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 57(5)441(2023)
*Corresponding author's e-mail:
samuelgl@iitm.ac.in (G. L. Samuel)

ever, the mechanical machining of these alloys is chal-
lenging due to their limited heat conductivity, high
strength and substantial chemical reactivity with the cut-
ting tool material.
3,4
Micro-turning is a popular machin-
ing method for producing small, precise axi-symmtric
components, which can be particularly challenging for
this alloy. Micromachining requires high cutting speeds,
producing extremely high temperatures at the tool-chip
interface. In order to increase the machining quality and
tool life, removing these temperatures from the cutting
zone is necessary. The heat and the cutting chips can be
removed from the machining zone by applying cutting
fluids such as mineral oils, vegetable oils, synthetic flu-
ids, etc.
5,6
The use of lubrication oil during machining is
an environmental hazard if not followed by proper han-
dling and disposal procedures. Lubrication oil may in-
clude harmful substances, such as carcinogenic com-
pounds or toxic metals or oncogenic compounds, which
can pollute soil and water if they are not properly dis-
posed of. Also, if the oil is not carefully handled while
being used, the emissions of volatile organic compounds
might lead to air pollution.
7,8
The cutting tools with different textures are advised
to use for conventional machining to minimize the usage
of hazardous cutting fluids. The patterns on different
faces of the cutting tools improve the tribological fea-
tures at the tool-chip interface and maximize the heat
dissipation from the machining region. Therefore, textur-
ing of the cutting tool enhances the machining quality
and prolongs the tool life.
9
Coated carbide cutting tools
perform better with titanium alloys as they do not react
with them and prevent the diffusion of ingredients of the
machining materials.
10
In micro-turning the surface qual-
ity improves with an increase in the cutting speed be-
cause of the thermal softening of the work material at
high speeds. The depth of cut should be larger than the
edge radius of the cutting inserts, otherwise ploughing
occurs instead of shearing and it results in a poor surface
finish.
11
Several studies
12–14
concentrate on comprehend-
ing the cutting abilities of textured tools in terms of mod-
ifying their dimensions and form, creating new coatings,
modelling with the finite element method, machining un-
der multiple lubrication conditions and fabricating tex-
tures using various techniques. Devraj et al. investigated
the effectiveness of micro-dimple-pattern inserts in a
turning process by altering the dimple size, depth and
pitch. They revealed that the size of a dimple influences
localized stress and chip development while the depth of
the dimple influences friction, and the pitch of the dim-
ple influences lubrication and chip breakage.
15
Vasumathy and Anil Meena examined the efficacy of
line-pattern-textured WC-Co inserts. They discovered
that the lay angle has a significant impact on the
tool-chip contact area and lubrication.
16
Arulkirubakaran
et al. investigated the performance of linear textured in-
serts for dry machining Al-Cu/TiB
2
composites and iden-
tified reduced cutting force, specific energy and tool
wear.
17
Prasad and Ismail investigated the effect of pro-
truded textured HSS tools made with a reverse EDM
method for turning operations. They discovered that
these tools had a 110-% longer tool life and better ma-
chining quality than untextured tools.
18
From the previous studies, it is evident that surface
texturing has the capability to enhance the tribological
features at the tool-chip interface by lowering the fric-
tion, cutting forces and heat generation. However, litera-
ture shows that there is a need for studying different
sizes, shapes and orientation of textures, which is essen-
tial for understanding the chip flow and heat-dissipation
behaviour that are crucial in deciding on the friction and
temperature at the tool-chip interface. Also, relatively
few researchers focused on how the form, dimensions
and orientation of texturing on cutting tools influence the
machining quality and tool life in micro turning.
In this study, a femtosecond laser facility is utilized
to create different patterns, such as horizontal lines, ver-
tical lines, and cross-hatch patterns, on the rake face of
the coated carbide cutting inserts. Such textured inserts
and non-textured inserts were employed in the mi-
cro-turning of the Ti6Al4V alloy under dry cutting con-
ditions. The experiments were conducted by varying the
cutting parameters, and the performance parameters such
as cutting force, surface roughness and tool wear were
measured. The effects of different textures on the rake
face in terms of performance parameters were investi-
gated and compared with the results of conventional cut-
ting inserts. Also, durability tests of various textured in-
serts were performed for further analysis of the longevity
of the textured and plain tools.
2 EXPERIMENTAL STUDY
The experiments were carried out using an indoor ta-
ble-top micro-turning machine that was built in the lab,
as illustrated in Figure 1. The machine tool consists of a
bed with the size of 600 mm × 600 mm made of cast
iron, mounted on an antivibration optical table. An
air-cooled bearing spindle of 24,000 min
–1
is mounted
onto the base with clamps, controlled by a variable fre-
quency drive (VFD) with a resolution of 6 min
–1
, which
can be operated manually or automatically. The X-Y
stage with a precision of 1 μm and maximum speed of
4 mm per second is installed to control the feed and
depth of cut. A Kistler mini dynamometer is attached un-
der the tool holder with the support of a tool post to mea-
sure the cutting forces during a machining operation.
This dynamometer with a piezoelectric sensor has the ca-
pability of measuring forces from 1–200 N.
All the experiments are carried out in dry conditions.
The tool holder is mounted onto the X-Y stage with the
help of the tool post to accommodate the cutting insert.
Titanium nitride (TiN) coated carbide cutting inserts
with a nose radius of 100 μm (CCGT060201LF) are uti-
lized for all the experiments. Various line textures and
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
442 Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451

cross hatch are designed in AutoCAD and then imported
to the Kyla software, used to operate the femtosecond la-
ser. Table 1 shows the parameters established during the
laser machining process. The horizontal-line, verti-
cal-line and cross-hatch patterns fabricated by varying
the pitch in the range of (100, 150 and 200) μm by keep-
ing a stand-off distance of 500 μm from the cutting tool
nose are depicted in Figures 3a to 3i. Figure 3j illus-
trates the plain tool, featuring a nose radius of 100 μm.
The line width and depth of the texturing achieved are
30 μm and 40 μm, respectively. Because of the limita-
tions in manufacturing, the stand-off distance of 500 μm
could not be achieved due to manual positioning. As a
result, a tolerance of ±25 μm has been taken into consid-
eration. All the experiments are performed by varying
the feed (20 and 40 μm) and depth (20, 40 and 60) μm of
the cut while keeping the cutting speed constant at
12,000 min
–1
. The experiments were carried out with
untextured and variously textured inserts, including hori-
zontal line, vertical line and cross hatch with different
pitches of (100, 150 and 200) μm. With a combination of
speed, feed and depth of cut, six experiments were con-
ducted with each insert, a new insert being utilized in
each experiment. A total of 60 experiments were con-
ducted, with each experiment being repeated three times
for a more comprehensive analysis.
Table 2: Design of Experiments
Design of
texturing
Pitch
(μm)
Speed
(min
–1
)
Feed
(μm/rev)
Depth of
cut (μm)
Plain
100
150
200
12000
20
40
20
40
60
Vertical line
100
150
200
20
40
20
40
60
Horizontal
line
100
150
200
20
40
20
40
60
Cross-hatch
100
150
200
20
40
20
40
60
Ti-6Al-4V alloy samples of 5 mm in diameter and
50 mm in length were utilized for all the experiments,
and the workpiece was held in the spindle using an ER
11 collet. The work material was initially measured to
have a hardness of 364 ± 2.4 HV using the Vickers hard-
ness test. During each experiment, the cutting force was
measured using a Kystler mini dynamometer, mounted
under the tool holder with the help of a tool post, as
shown in Figure 1. The cutting force data were collected
by applying a drift allowance and operating an amplifier
for three hours prior to the measurement, which allowed
the drift to be eradicated. The cutting force data was ana-
lysed using the Dynoware software, as shown in Fig-
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451 443
Figure 1: Micro-turning machine – 1. spindle, 2. VLT drive, 3. X-Y stage, 4. micro-motion controller, 5. tool post, 6. mini dynamometer, 7. tool
holder
Table 1: Parameters that are established during the laser operation
Parameter Range Parameter Range
Wavelength 1030 nm Repetitions 100
Power 20 W Spot diameter 20 ìm
Pulse energy 40 ìJ Lens 1064 nm
Pulse duration 500 fs Beam quality, M
2
<1.2
Repetition rate 2 MHz Scanning speed 100 mm/s

R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
444 Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451
Figure 3: Horizontal-line (perpendicular to the chip flow direction) textured insert: a) 100 μm pitch, b) 150 μm pitch, c) 200 μm pitch,
vertical-line (parallel to the chip flow direction) textured insert: d) 100 μm pitch, e) 150 μm pitch, f) 200 μm pitch; cross-hatch textured insert:
g) 100 μm pitch, h) 150 μm pitch, i) 200 μm pitch; j) plain insert; k, l) tool wear measurement
Figure 2: a) cutting force measurement, b) surface roughness measurement

ure 2a. The average surface roughness (Ra) of a ma-
chined sample was measured using a contact-type
surface roughness tester Mahr surf M400 with a stylus
radius of 2 μm. After each experiment, readings were
collected at three different places on the circumference
of each sample and the average of these readings was re-
corded as the actual Ra of the respective sample, as illus-
trated in Figure 2b.
After the completion of each experiment, the worn
area on the rake face of the cutting tool was captured us-
ing an inverted GX 200 microscope at a magnification of
10×, as shown in Figures 3k and 3l. The width of the
worn area was then measured from the acquired images
of the cutting tool tip and considered as the tool wear.
The image magnification range of this microscope is
5–200×.
In order to gain a more comprehensive understanding
of the durability of textured inserts, further experiments
were undertaken using new inserts for machining the
Ti64 alloy at dry conditions. It is found that 100 μm pitch
textured inserts have demonstrated superior performance
compared to 150 μm and 200 μm pitch inserts. Hence,
various textured inserts with a 100 μm pitch and a plain
insert were utilized in these additional experiments. The
experiments continued until the tool reached the state of
failure. Each experiment involved turning a Ti64
workpiece with a diameter of 5 mm and a turning length
of 25 mm, with a total of 14 passes made for one sample
with a 100 μm depth of cut, 30 μm feed and 12,000 min
–1
speed. This process was repeated until the tool failed.
The determination of tool failure was based on the mea-
surement of the cutting forces during the operation. If the
cutting forces exceeded 100 N and emitted flames were
observed during cutting, it was considered an indication
of tool failure. Upon a closer examination, it was ob-
served that a taper had formed at the end of turning after
multiple passes. The taper on a sample was measured for
all the samples, machined with both textured and
non-textured inserts.
Figure 4 exhibits the measurements of the cutting
force, average roughness and tool wear for each experi-
ment. In order to evaluate measurement uncertainty, each
experiment was repeated three times. Error bars were
plotted for all these measurements, providing a visual
representation of the variability or uncertainty associated
with each data point. These error bars allow for a better
understanding of the reliability and variation in the mea-
sured values for the cutting force, average roughness and
tool wear across the experiments. Figure 4d specifically
showcases a clear trend, being followed in the cutting
force measurement. In Figure 4, the error bars demon-
strate a relatively low amount of error across the re-
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451 445
Figure 4: Error bar chart: a) cutting force measurement, b) surface roughness measurement, c) tool wear measurement, d) cutting force for
cross-hatch tool machining

peated experiments. This indicates a consistent and reli-
able trend in the measured values. Based on the analysis
of the error bar chart, it can be concluded that the ob-
served variations within the measurements are within an
acceptable range. This suggests that the experimental re-
sults are reliable and support the conclusion that the ob-
served trend from Figure 4 is valid and meaningful.
3 RESULTS AND DISCUSSION
The cutting force, tool wear and surface roughness
were measured as performance parameters and plotted
against the experiments. With this analysis, we examined
how different designs, pitches and texturing orientations
on a cutting-insert rake face affected these performance
parameters. Figures 5 and 6 visually represent the rela-
tionship between the performance parameter data and
conducted tests, providing valuable insights into the im-
pact of the variables mentioned above on the rake face of
a cutting insert.
The influence of the pitch variation in the texture on
the cutting insert was analysed based on the information
presented in Figure 5. Figures 5a to 5c show the plots of
cutting forces that were measured during the turning op-
erations using horizontal, vertical and cross-hatch
textured inserts with various pitch values. The results de-
picted in Figures 5a to 5c indicate that machining with
the 100 μm pitch textured inserts led to lower cutting
forces compared to machining with inserts of larger
pitches of 150 μm and 200 μm. However, it was observed
that there was a minimal difference between the results
obtained for the 100 μm and 150 μm pitch inserts. This is
because, despite a smaller pitch (100 μm) providing an
increased surface area for heat dissipation, the key fac-
tors related to the chip interaction, such as chip flow di-
rection and chip obstruction, remained consistent for
both pitches. This indicates that the change in the pitch
from 100 μm to 150 μm did not have a significant impact
on the chip interaction, which plays a crucial role in de-
termining the heat transfer and overall performance.
Consequently, the observed similarity in the results can
be attributed to the stability of the chip interaction re-
gardless of the pitch variation.
Figures 5d to 5i provide insights into the effects of
pitch variation on the surface roughness and tool wear. It
is observed that the use of 100 μm pitch textured inserts
resulted in a reduced surface roughness and less tool
wear when compared to the inserts with pitches of
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
446 Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451
Figure 5: Cutting force during machining with a) horizontal-line textured inserts, b) vertical-line textured inserts, c) cross-hatch textured inserts;
Tool wear after each machining pass with d) horizontal-line textured inserts, e) horizontal-line textured inserts, f) cross-hatch textured inserts;
Surface roughness of the workpiece machined with g) horizontal-line textured inserts, h) vertical-line textured inserts, c) cross-hatch textured in-
serts

150 μm and 200 μm. This indicates that finer texture pat-
terns with a pitch of 100 μm contribute to an improved
surface quality and prolonged tool life. In summary, the
analysis of pitch variation in the texture, as presented in
Figure 5, demonstrates that machining with textured in-
serts of 100 μm pitch on the horizontal line, vertical line
and cross-hatch yields advantages in terms of reduced
cutting forces, improved surface roughness and de-
creased tool wear when compared to the inserts with
larger pitch values of 150 μm and 200 μm. The use of
100 μm pitch textured inserts leads to decreased cutting
forces, tool wear and surface roughness. This is because
these inserts have a larger surface area and less contact
area between the chip and the tool compared to the other
inserts.
As a result, heat dissipation is maximized and the
friction between the tool and chip is reduced. In order to
assess the impact of the texturing design on the rake face
of the cutting insert, a comparative analysis was per-
formed. This analysis involved plotting the data for the
average surface roughness, cutting force and tool wear
during machining with 100 μm pitch textured inserts and
untextured inserts. These results can be observed in Fig-
ures 6a to 6c, respectively.
In these figures, the square with a continuous line
represents the average surface roughness, cutting force
and tool wear for machining with untextured tools. The
triangle with a dashed line represents the average surface
roughness, cutting force and tool wear for machining
with vertically textured tools. The asterisk with a dotted
line denotes the average surface roughness, cutting force
and tool wear for machining with horizontally textured
tools. Lastly, the rhombus with a continuous line repre-
sents the average surface roughness, cutting force and
tool wear for machining with cross-hatch textured tools.
These plots revealed that the surface roughness, cutting
force and tool wear are lower with textured tools. The
comparative analysis of the plain, vertical, horizontal and
cross-hatch textured inserts reveals that the cross-hatch
textured tools yield improved results compared to the
other types. The vertically textured tools demonstrate a
better performance than the plain tools but they are not
as good as the horizontally textured tools. This differ-
ence can be attributed to the interaction with the chip
during machining. The vertical texture facilitates a
smoother chip-tool interaction, resulting in the formation
of continuously serrated chips that are not prone to
breaking. Also, similar to the plain tool machining, a
built-up edge formation was observed with the vertically
textured tools. Horizontally textured tools exhibit even
better enhancements in the surface finish, reduced cut-
ting forces and minimized tool wear compared to vertical
textured tools. This improvement can be attributed to the
reduced chip-tool interaction facilitated by the horizontal
texture. The presence of the horizontal texture obstructs
the chip flow on the tool face, resulting in a decreased
tool-chip interaction and minimizing the chip flow over
the rake face. Consequently, the improved results ob-
served with horizontally textured tools surpass those
achieved with vertically textured tools.
Cross-hatch textured tools exhibit superior perfor-
mance in enhancing the surface finish, reducing the cut-
ting forces and minimizing the tool wear compared to
horizontal tools. This is attributed to the increased sur-
face area created by the cross-hatch pattern, which en-
hances heat dissipation and reduces the friction. Addi-
tionally, the cross-hatch texture further decreases the
chip-tool interaction and obstructs the chip flow on the
rake face, resulting in improved machining outcomes. As
a result, cross-hatch textured tools outperform the hori-
zontal texture, vertical texture and plain tools in achiev-
ing a better surface finish, reduced cutting forces, and
minimized tool wear.
In order to further study the durability of textured in-
serts, further experiments were undertaken using new
100 μm pitched vertical, horizontal, cross-hatch textured
and plain inserts for machining the Ti64 alloy. The plain
tool exhibited failure after completing ten samples. Each
sample required 14 passes over a total length of 23 mm.
During the machining of these samples, the minimum
cutting force recorded was 115.4 N, and the maximum
flame was observed during the last pass of the 14th sam-
ple. Additionally, the taper angle on the last sample,
which was the 10th sample investigated, was 2.4 degrees.
This presence of taper on the sample can be attributed to
the thermal softening of the cutting insert caused by ex-
cessive heat accumulation at the insert’s tip. As a result
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451 447
Figure 6: Machining with various textured and untextured inserts: a) surface roughness of the workpiece, b) cutting force, c) tool wear after each
pass

of this thermal softening, the depth of cut towards the
end of the turning pass was reduced. This reduction in
depth resulted in a taper at the end of the turning pass,
leading to the observed taper on the sample. The verti-
cally textured inserts experienced failure during the turn-
ing of the 14th sample, resulting in a maximum cutting
force of 118.4 N during the final pass. Flames similar to
those observed during plain-tool machining were present
during the machining of the last sample. A taper angle of
1.9 degrees indicated slight dimensional changes towards
the end of the turning pass. Similarly, the horizontally
textured inserts failed during the turning of the 15th sam-
ple, with a maximum cutting force of 104.4 N recorded
during the final pass. The flames observed were less pro-
nounced compared to both plain and vertically textured
inserts. The taper angle was 1.6 degree, indicating minor
dimensional changes.
In contrast, the cross-hatch textured inserts exhibited
failure during the turning of the 18th sample, with a
maximum cutting force of 110.4 N recorded during the
final pass. Notably, no significant flames were observed
during the machining of the last sample. The taper angle
was 1.2°, indicating minimal dimensional changes. Over-
all, these results suggest that the cross-hatch textured in-
serts demonstrated better durability compared to the hor-
izontally textured, vertically textured and plain inserts.
The cross-hatch textured inserts exhibited lower cutting
forces, less pronounced flames and smaller taper angles,
indicating their potential for longer-lasting performance
in turning operations. To gain a deeper understanding of
the performance and potential failure mechanisms of the
textured and plain tools, scanning electron microscopy
(SEM) images and energy dispersive spectroscopy
(EDS) reports on the cutting inserts were collected be-
fore and after machining and illustrated in Figures 7 to
10. These images provide valuable insights into the pres-
ence of delamination, work material inclusions, built-up
edge formation and other relevant aspects. In Figure 7d,
the presence of workpiece inclusions on the rake face of
the plain insert is clearly observed, along with an in-
crease in the nose radius to 175 μm. Additionally, Fig-
ure 7b illustrates the accumulation of a built-up edge on
the tool nose edge, while Figure 7e highlights the pres-
ence of workpiece inclusions. Figures 7c and 7f provide
a comparison of the material compositions before and af-
ter machining, with Figure 7f showing the complete ex-
tent of workpiece inclusions.
From Figure 8a, it is clear that the titanium coating
was removed at the laser marks and other areas, resulting
in only 21 % of the coating weight remaining after verti-
cal texturing. However, the coating still provides some
benefits even after texturing the vertically textured insert.
Figure 8d displays the workpiece inclusions and an in-
creased nose radius after machining 14 samples with 14
passes. This suggests that the machining caused the for-
mation of inclusions and an increase of 62.5 μm in the
nose radius. Figure 8b demonstrates the presence of a
built-up edge on the edge radius and inclusions in the
slots. This indicates that during machining, the material
accumulated on the edge radius, resulting in the forma-
tion of a built-up edge, and inclusions can be observed in
the slots. In Figure 8e, it is apparent that the workpiece
inclusions are more prominent in the plain insert com-
pared to the vertically textured insert. This can be attrib-
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
448 Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451
Figure 7: SEM and EDS details of the plain insert before and after machining

uted to the fact that more chips accumulate in the slots of
the texture during machining, leading to increased inclu-
sions. Figures 8c and 8f show EDS reports before and
after machining, and these figures demonstrate a 12 %
reduction in the coating and an 87 % increase in the
workpiece material accumulation after machining, indi-
cating the changes that occur during the process. Figure
9d displays a SEM image of a horizontally textured in-
sert after the machining of 15 samples, each undergoing
14 passes. In comparison to the vertically textured in-
serts, Figures 9d and 9b reveal a minor increase in the
nose radius that is 150.5 and a lower occurrence of the
built-up edge formation. Additionally, Figures 9c and 9f
show that the coating was reduced to 8 % after horizontal
texturing, and the workpiece material inclusions
amounted to 76 % after machining, which is 11 % less
than for the vertically textured inserts.
Figure 10d presents SEM images of a cross-hatch in-
sert after machining 18 samples, each undergoing 14
passes. The tool nose radius is shown to have increased
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451 449
Figure 9: SEM and EDS details of a horizontally textured insert before and after machining
Figure 8: SEM and EDS details of a vertically textured insert before and after machining

to only 43 μm, which is smaller than in the cases of the
plain, horizontally and vertically textured tools. Figures
10b and 10e demonstrate the occurrence of built-up edge
and the presence of workpiece material inclusions after
machining. The built-up edge is less prominent than for
the horizontally textured, vertically textured and plain in-
serts. Additionally, Figure 10c shows a coating reduc-
tion by 16 % after texturing. This reduction occurs be-
cause the laser needs to machine the same plane twice to
create this specific texture. Furthermore, Figure 10f in-
dicates that the workpiece material inclusions after ma-
chining amounted to 88 % due to the cross-hatch texture
accommodating more workpiece particles than other tex-
tures. The durability of cross-hatch textured tools is in-
creased by 80 % compared to plain tools, 29.5 % com-
pared to vertically textured tools and 20 % compared to
horizontally textured inserts.
The wear mechanism was adhesive wear where high
temperatures and pressures at the tool-workpiece inter-
face cause material transfer between the workpiece and
insert. This transfer of material leads to localized adhe-
sion and subsequent material build-up on the insert sur-
face, resulting in wear. Another significant wear mecha-
nism was abrasive wear. These micro-textured inserts
have small surface features, such as micro-grooves, slots
and cross-hatch, designed to enhance the heat dissipation
and chip interaction mechanism. However, these surface
features can also act as potential sites for the accumula-
tion of abrasive particles, such as chips or debris. These
abrasive particles can cause localized wear on the insert
surface. Furthermore, in dry cutting conditions, the ab-
sence of a cutting fluid or coolant can lead to increased
tool wear.
4 CONCLUSIONS
In this work, coated carbide cutting inserts were tex-
tured based on various designs, such as a horizontal line,
perpendicular to the chip flow direction, a vertical line,
parallel to the chip flow direction and cross-hatch pat-
terns with different pitches on the cutting inserts using a
femtosecond laser facility. The textured inserts were uti-
lized to perform micro-tuning operations. In terms of
cutting forces, tool wear and surface roughness, the im-
pact of varied texturing on the rake faces of the cutting
inserts for the micro-turning of Ti6Al4V alloy under dry
cutting conditions was compared to conventional cutting
inserts. The following conclusions are drawn from the
present study.
Machining with textured inserts such as horizontal
line texturing with a pitch of 100 μm, vertical line textur-
ing with a pitch of 100 μm and cross-hatch texturing
with a pitch of 100 μm cause reduced cutting forces,
lower tool wear and better surface finish than machining
with textured inserts with pitches of 150 μm and 200 μm.
100 μm textured inserts have more surface area and less
chip-tool contact area than other inserts, which helps in
maximizing heat dissipation and reducing the friction be-
tween the tool and chip.
Due to machining with horizontally textured inserts
with a 100 μm pitch, cutting forces are reduced by 46 %,
the surface finish is enhanced by 34 % and the tool-flank
wear is reduced by 30 %.
R. B. TERE et al.: EFFECT OF TEXTURED CUTTING INSERTS IN MICRO-TURNING OF TI-6AL-4V ALLOYS
450 Materiali in tehnologije / Materials and technology 57 (2023) 5, 441–451
Figure 10: SEM and EDS details of a cross-hatch textured insert before and after machining

Similarly, when machining with vertically textured
inserts with a 100 μm pitch, cutting forces are reduced
by 38 %, the surface finish is improved by 20 % and the
tool-flank wear is reduced by 26 %. The tool-chip fric-
tion during machining is thus significantly influenced by
the texturing, namely by its design, dimensions and ori-
entation.
The appropriate design and dimensions of the
cross-hatch pattern on the rake faces of the cutting in-
serts enhance the tool life by 80 % while the horizontal
texture improves it by 50 % and the vertical texture im-
p r o v e si tb y4 0% .
In the present research all the machining tests were
performed under a dry condition. The effectiveness of a
texture is more predominant when using cutting fluids
(hydrodynamic lubrication). This will be the scope of the
continuation of the present research.
The work can be further extended to study the effect
of various textures on both the flank and rake faces of a
cutting insert in dry and wet conditions. Also, a simula-
tion-based analysis can be carried out to examine the in-
fluence of various designs, dimensions and orientations
of the texturing as the tribological characteristics of the
micro-cutting regime are challenging to be analysed in
practice.
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