R. DUBOVSKÁ et al.: INVESTIGATING THE INFLUENCE OF CUTTING SPEED ...
439–445
INVESTIGATING THE INFLUENCE OF CUTTING SPEED ON THE
TOOL LIFE OF A CUTTING INSERT WHILE CUTTING DIN 1.4301
STEEL
PREISKAVA VPLIVA HITROSTI REZANJA NA ZDR@LJIVOST
VLO@KA ZA REZANJE PRI REZANJU JEKLA DIN 1.4301
Rozmarína Dubovská1, Jozef Majerík2, Robert ^ep3, Karel Kouøil4
1University of Hradec Kralove, Faculty of Education, Department of Technical Subjects, Rokitanského 62,
500 03 Hradec Králové, Czech Republic
2Alexander Dubcek University of Trencin, Faculty of Special technology, Department of Engineering, Pri Parku 19, 911 05 Tren~ín, Slovakia
3Technical University of Ostrava V[B, Faculty of Mechanical Engineering, Department of Machining and Assembly, 17.listopadu 15,
708 33 Ostrava, Czech Republic
4Brno University of Technology, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, Technická 2896/2,
616 69 Brno, Czech Republic
robert.cep@vsb.cz
Prejem rokopisa – received: 2015-02-10; sprejem za objavo – accepted for publication: 2015-05-20
doi:10.17222/mit.2015.036
The main aim of this paper is to assess the tool life T = f(vc) during the dry turning of 1.4301 austenitic stainless steel with a
CNMG 120408 coated carbide cutting insert. Experimental tests of the selected material were realized in an Aero Turn BT-380
CNC machine tool with a Fanuc 21i TB control system. The effect of the applied cutting parameters on the surface finish, tool
wear, tool life and surface roughness were investigated during the realized experiments. The aim of the present paper is to focus
scientific research on the impact of the various cutting speeds during the outer longitudinal turning. The presented approach and
results will be helpful for understanding the machinability of 1.4301 austenitic stainless steel during dry turning. This paper,
together with the achieved results, is a basis to optimize the performance of the machining (i.e., turning) of austenitic stainless
steel 1.4301 used for special industrial applications with their dominant functional areas.
Keywords: austenitic stainless steel, CNC turning, cutting speed, tool life, surface finish
Glavni namen ~lanka je oceniti preiskovano zdr`ljivost orodja T = f(vc) pri stru`enju, brez mazanja avstenitnega nerjavnega jekla
1.4301, s karbidnim rezalnim vlo`kom CNMG 120408 s prevleko. Preizkusi izbranega materiala so bili izvr{eni na CNC stroju
Aero Turn BT-380 s Fanuc 21i TB kontrolnim sistemom. Med preizkusi je bil preiskovan vpliv uporabljenih parametrov pri
rezanju na kvaliteto povr{ine, obrabo orodja, zdr`ljivost orodja in hrapavost. Namen ~lanka je usmeriti raziskavo na vpliv
razli~nih uporabljenih vrednosti hitrosti rezanja pri zunanjem vzdol`nem stru`enju. Vsi predstavljeni pribli`ki in rezultati bodo
pomagali pri razumevanju obdelovalnosti avstenitnega nerjavnega jekla 1.4301 pri stru`enju brez mazanja. Dobljeni rezultati so
osnova za optimiranje stru`enja avstenitnega nerjavnega jekla 1.4301, ki se ga, na podlagi posebnih lastnosti, uporablja pri
posebnih industrijskih namenih.
Klju~ne besede: avstenitno nerjavno jeklo, CNC stru`enje, hitrost rezanja, zdr`ljivost orodja, kvaliteta povr{ine
1 INTRODUCTION
High productivity and reliability are necessary in
today’s very highly competitive world of production. In
this context, the appropriate selection of cutting tool
geometry and tool material is crucial to be competitive,
especially in the field of difficult-to-machine materials,
such as stainless steels.1,2 Problems such as poor surface
finish and high tool wear are common in the machining
of austenitic stainless steel. The authors3 carried out turn-
ing tests on the 1.4301 austenitic stainless steel to deter-
mine the optimum machining parameters. Austenitic
stainless steel is among the difficult-to-cut material and
difficulties such as poor surface finish and rapid tool
wear are common.4–8 Stainless steels are widely used in
several industrial sectors, such as engine production, the
medical and chemical industries. Their high strength,
low thermal conductivity, high ductility and high ten-
dency towards work hardening are the main factors for
their poor machinability.9 The turning of parts made of
austenitic stainless represents nearly 24 % of all ma-
chined parts made of steel. Various special chemical
compositions of stainless steels are a challenge for all
machining technologies. High-speed machining (HSM)
is applied with significantly higher cutting speeds vc with
relatively small cross-sections being cut. HSM techno-
logy is realized with extremely hard and heat-resistant
cutting tools.10 With the trend in technology develop-
ment, stainless steel has been broadly adopted because it
has the characteristics of high toughness, low thermal
conductivity, and a high strain hardening coefficient.
This has a negative effect on the surface finish of
a machined product and results in a reduced tool life.11
Such is the case for austenitic stainless steels, which in
spite of being materials of high economic and techno-
logical value, their behaviour with respect to machining
is still not well understood in some aspects. There are
Materiali in tehnologije / Materials and technology 50 (2016) 3, 439–445 439
UDK 620.179.5:621.9:669.018.26 ISSN 1580-2949
Professional article/Strokovni ~lanek MTAEC9, 50(3)439(2016)
not reliable and updated technological data about
austenitic stainless steels in industry.12 The austenitic
stainless steel AISI 304 (according to DIN 1.4301) is the
second most widely used anti-corrosive material with
excellent corrosion resistance, cold formability and
weldability. The steel 1.4301 is resistant to water, steam,
humidity, edible acids, weak organic and inorganic
acids.13 Austenitic stainless steel is not hardenable. How-
ever, its strength can be increased by cold forming. It is
characterized by the need for a solution treatment to
ensure corrosion resistance in contact with a wide range
of substances. The AISI 304 is approved for a thermal
stress of 300 °C. When machining the 1.4301 it is
necessary to work with sharp cutting tools of high-speed
alloyed steel or cemented carbides because of the
tendency to harden. The steel 1.4301 (AISI 304) is used
in the engineering and nuclear industries, in architecture,
in transport facilities, the food industry, the pharma-
ceutical and cosmetic industries, the construction of
chemical apparatus and vehicles, the manufacture of
surgical instruments, sanitary installations, objects and
appliances and works of art. The shape of the individual
components for the automotive industry and subse-
quently the time and relative complexity of the conver-
sion work and tool paths for CNC (Computer Numerical
Control) program preparation led to the establishment of
internal and external graphics support for the creation of
individual programs.14 CNC machines are commonly
used in automated factories for producing machined
parts. In this study, the AISI 304 austenitic stainless steel
was used to help the manufacturers. In this work, the
values for the flank wear were investigated and in this
way the best cutting parameters were determined. Apart
from classic methods, it was also investigated that the
process sound generated during machining could be used
to assess machinability.15 Surface integrity is an import-
ant factor in evaluating the machinability of the steels.16
Numerous experimental investigations have been carried
out over the years to study the effect of the cutting para-
meters and tool geometries on the workpieces’ surface
integrity using several types of workpiece materials.17
Currently, companies prefer to order material according
to DIN or AISI.
2 MATERIALS AND METHODS
The basic factor that causes the flank wear of carbide
tools is the high temperature of the cutting edge. In order
to increase tool life, we have to reduce this temperature.
For machining is necessary to use a stable and solid
CNC machine tool with the appropriate cooling. The
workpiece material and cutting tools must be firmly
clamped in the CNC machine with a small overhang. It is
important to create the conditions for cutting, to prevent
the formation of vibrations. Progressive solutions in
terms of cutting tools seem to be new cutting materials
for machining stainless, especially austenitic, steels.
There are cutting tools with changeable cutting inserts
with a fine-grained or ultrafine-grained substrate. The
carbide grain size is from 0.3 μm to 0.5 μm. On the ce-
mented carbide is deposited a multilayer with the coat-
ings type TiC+Al2O3+TiN on the surface, the substrate is
WC+Co. The austenitic stainless steels are generally
annealed for austenitizing, so that they are heated to
1000–1150 °C. Subsequently, they are quickly cooled in
water or air, to prevent the precipitation of the carbides at
the grain boundaries. This resulted in a homogeneous
austenitic structure. The structure increases with the
resistance of these steels to intergranular corrosion and
the metallurgical point of view is correct. The disadvant-
age is a significant increase in the ductility and plasticity
of these steels, which is highly undesirable during ope-
ration. From the metallurgical point of view, the disting-
uishing feature of poor machinability is the kinematic
coarse austenite, almost carbides. The sign of good
machinability is a fine-grained austenite with plenty of
finely distributed carbides. Machinability is related to the
economy of production. The aim is to produce the maxi-
mum performance with the available resources. Machin-
ability influences and even determines the cutting forces,
heat and cutting temperature, chip formation, wear and
tool life, but also the surface integrity. Cutting parame-
ters such as the cutting speed vc and the feed rate f play
critical roles in the cutting temperature and the surface
roughness in the turning processes. The surface rough-
ness, which is used for the evaluation of the product
quality, is an important performance characteristic in
turning processes.18 That is, cutting speeds out of the
range recommended by tool manufacturers (cutting
speed in the range of vc = 180–250 m min–1) were tested.
The objective was to analyse the effect of cutting speed
over the work material–toolpair.19 I. Korkut et al.19 and
I. Ciftci et al.20 reported that during the turning of AISI
304 austenitic stainless steel using a multilayer (CVD)
coated tool, the tool flank wear decreases with an
increasing cutting speed up to 180 m min–1 and the sur-
face roughness values decrease with the increasing the
cutting speed. The poor performance of the tool at lower
cutting speeds can be explained by the influence of the
heat on the cutting tool. That is because, metal cutting
involves the generation of a large amount of heat and in
the machining of AISI 304 stainless steel it is not
dissipated rapidly due to the low thermal conductivity of
this material. The heat generation principally occurs in
three areas: the shear zone, the rake face and on the
clearance side of the cutting edge.20 W. Grzesik et al.21,
studied the machinability of AISI 304 and C45 steel
using CVD TiC, TiN/ TiC and TiN/Al2O3/TiC coated and
uncoated (P20) cemented carbide tools. They found that
in the case of TiC and TiN/Al2O3/TiC coating the spe-
cific cutting pressure decreases and for the TiC/TiN
coating it increases. In another study they found a low
value of the surface roughness for the coating
TiC/Al2O3/TiN. In addition, they found that as the
R. DUBOVSKÁ et al.: INVESTIGATING THE INFLUENCE OF CUTTING SPEED ...
440 Materiali in tehnologije / Materials and technology 50 (2016) 3, 439–445
cutting speed increases the cutting force and the contact
length decreases. A. Hosokawa et al.22 reported that
during its own realization of turning tests of stainless
steel (AISI 304) were carried out in order to examine the
tool-wear characteristics. W. I. H. Liew23 investigated the
wear characteristics of PCBN (polycrystalline cubical
boron nitride) tools in the ultra-precision machining of
stainless steel.22 During lathe turning, the machined
surface is work hardened. This work-hardened surface is
machined on the next lathe turning step, which accele-
rates the tool wear.23 This results in the degradation of
the surface quality and the acceleration of the adhesive
wear of the tools used.24 All of these experiments deter-
mine that the purpose and the machinability significantly
affect the cutting process. The machining of high-
strength materials can cause brittle fracture of the cutting
edge parts. This is due to the high cutting forces during
machining. In a practical assessment of the size of the
wear it is most common to use parameters such as the
width of the wear pads on the back of the VBk and the
depth of the groove at the forefront of the KT (according
to ISO 3685). The intensity of the wear may affect the
cutting conditions. The biggest influence is the cutting
speed, then the feed rate and a smaller minimum is the
depth of cut. When turning austenitic stainless steels,
they are a generally chosen criterion of the flank wear
VBk, given the increase in cutting forces with increasing
wear. There is also an increase in the temperature and the
intensity of the wear of the cutting tool. The duration of
the work of the cutting tool with a target of VBk wear, the
tool life T can be determined within minutes of the
machining time, the number of machined parts or the
cutting tool path. The cutting tool’s ability to restore its
sharpness or setting a new cutting edge with a cutting
tool exchange. In practice we try to choose the criterion
of wear, so that we have the maximum tool life.
Selection criteria and the process limits the wear and
machined surface roughness achieved, increased cutting
forces, and the emergence of oscillations in the system’s
working. We are talking about the technological criterion
of wear. The tool life depends on the cutting conditions,
the geometry of the cutting wedge-shaped tools, the
cutting material, the fluency of the cutting process, the
method and type of operation and the workpiece
material.
3 EXPERIMENTAL DETAILS
The main aim of the paper was the measurement of
the tool life T = f (vc) for various cutting speeds. The
experiments were performed in the tool AERO TURN
BT-380 CNC machine (Figure 1) with a maximum
spindle speed nmax = 4500 min–1 and performance Pc =
11.5 kW with a turret for clamping the cutting tools
(Figure 2) and a CNC control system FANUC Series 0i
– TC. The workpiece material was austenitic stainless
steel 1.4301(microstructure can be seen in Figure 3),
Ø 60 mm × 200 mm, hardness HB 190. The clamping
was in a three-jaw chuck with the turned inside diameter
Ø 60 mm in length l = 15 mm, clamping the workpiece
by the tail stock. The cutting tool was a side cutting tool
holder r = 95°, with geometry PCLNR 2525 (PRAMET
Tools). The carbide cutting insert was CNMG
120408E-NM, carbide type GC 2025 (PRAMET Tools),
used for rough machining of the austenitic stainless
steels (SEM microstructure of cutting edge’s appearance
can see in Figure 4).
Cutting conditions:
• Depth of cut ap0 = 1.0 mm,
• Feed rate f0 = 0.15 mm/rev,
• Cutting speed vc1 = 250 m min–1, vc2 = 200 m min–1,
vc3 = 150 m min–1 with usage of the coolant E5%.
R. DUBOVSKÁ et al.: INVESTIGATING THE INFLUENCE OF CUTTING SPEED ...
Materiali in tehnologije / Materials and technology 50 (2016) 3, 439–445 441
Figure 2: a) Cutting area of CNC machine tool with clamped work-
piece, b) control panel of the AERO TURN BT-380 CNC machine
tool with system FANUC Series 0i – TC, c) view of the workpiece
(tested part) used for the turning experiments
Slika 2: a) Podro~je CNC stru`enja z vpetim obdelovancem, b) kon-
trolna plo{~a CNC stru`nice AERO TURN BT-380 s sistemom
FANUC Serije 0i-TC, c) izgled obdelovanca (vzorca) na katerem so
bili izvr{eni preizkusi stru`enja
Figure 1: Overall view of the AERO TURN BT-380 CNC machine
tool
Slika 1: Izgled CNC stru`nice AERO TURN BT-380
4 RESULTS AND DISCUSSION
To determine the dependence of T = f (vc) we must
satisfy the condition vcmax = 2.5 vcmin and the cutting-tool
wear criteria of VBk = 0.2 mm. The scheme of the
gradual removal of material during the turning in the
virtual interface of the CATIA V5 Lathe Machining
system is shown in Figure 5. The turning tests were
carried out for the following values of the cutting speeds
vc1 = 250 m min–1, vc2 = 200 m min–1, vc3 = 150 m min–1,
and the cutting speed vc4 = 100 m min–1 was determined
by the calculation method. The CNC machine tool cal-
culates vc = const. directly from the turning diameter. For
the average diameter Ø58 the cutting speed vc = 250
m min–1 and the spindle speed n = 1348 min–1. For the
maximum removed diameter the cutting speed vc = 254
m min–1. With each cut the spindle speed of the CNC
machine tool also changes. With a change of the dia-
meter from Ø60 mm to Ø30 mm there is also a change of
the feed velocity vf. Even the machining time for one cut
also changes as follows.
Different criteria can be used for the measurement of
tool life such as the average of the maximum flank wear,
the surface roughness and the number of components per
tool. In this experimental investigation the criterion of an
average flank wear VB = 0.2 mm was considered for the
tool-life measurement. Fernández-Abbia et al.1,2 reported
that the cutting speed in the range of 200 to 300 m min–1
is favourable for the machining of 1.4301 stainless steel.
After each pass, the cutting insert was used for a
measurement of the tool wear and thus wear progress
was obtained. Figure 6 shows the tool-life curves at
(150, 200, 250) m min–1 cutting speed for a constant feed
rate and depth of cut. The tool life demonstrates three
wear stages. Flank wear VB of carbide insert at vc2 = 200
m min–1 can be seen in Figure 7.
Table 1: The calculation table to determine the tool life T (min)
Tabela 1: Tabela za izra~un ~asa T (min) zdr`ljivosti orodja
N vci Ti log vci log Ti log vci .log Ti
log vci2
1 150 48.8 2.17609 1.68842 3.67416 4.73537
2 200 28.9 2.30103 1.46090 3.36157 5.29474
3 250 19.5 2.39794 1.29003 3.09343 5.75012
 – – 6.87506 4.43935 10.12915 15.77998
Auxiliary calculation ( log vci)2 = 6.875062 = 47.2664
R. DUBOVSKÁ et al.: INVESTIGATING THE INFLUENCE OF CUTTING SPEED ...
442 Materiali in tehnologije / Materials and technology 50 (2016) 3, 439–445
Figure 4: Surface morphology of the CNMG 120408E-FM carbide
cutting insert (edge) surface appearance, SEM image
Slika 4: SEM-posnetek morfologije povr{ine CNMG 120408E-FM
karbidnega rezalnega vlo`ka (rob)
Figure 3: The microstructure of DIN 1.4301 (AISI 304) with an auste-
nitic structure. The microstructure consists of large grains of austenite
(grey) and small grains of carbides (black).13
Slika 3: Avstenitna mikrostruktura jekla DIN 1.4301 (AISI 304).
Mikrostruktura je sestavljena iz velikih zrn avstenita (sive barve) in
majhnih karbidnih zrn (~rne barve).13
Figure 6: The graphical dependence of the tool flank wear on the
machining time during the turning of DIN 1.4301
Slika 6: Grafi~na odvisnost obrabe boka orodja od ~asa stru`enja jekla
DIN 1.4301
Figure 5: 3D simulation of the longitudinal turning process in CATIA
Slika 5: CATIA tridimenzionalna simulacija vzdol`nega procesa
stru`enja
In the process of investigating the quality indicators
in terms of the surface integrity during the turning of
1.4301 austenitic stainless steel, the authors of the article
also dealt with the dependence of the arithmetic mean
surface roughness Ra = f (vc) in changing the fillet radius
of the used cutting tool (the difference can see in Figure
8). The surface roughness measurement was carried out
on the machined surfaces using a Taylor Hobson measur-
ing device. The value reported represents the average of
the surface roughness value obtained from at least three
measurements. The surface quality of the machined
surface is mainly dependent on the used cutting condi-
tions and it plays a significant role in the functionality
and fatigue life of the component.
The measured spindle speeds ni, the feed velocity
rates vfi and the machining times for the individual cuts
were determined from a calculation. Sample no. 4 was
machined with the same method and with the same
cutting parameters as the sample no. 3. Flank wear con-
trol was carried out after 23.3 min, 28.8 min, and 33.06
min, and then the sample no. 5 was machined with a
flank wear measurement after 39.83 min, 45.33 min, and
50.83 min. The measured values of the flank wear VBmax
for vc1 = 250 m min–1, vc2 = 200 m min–1, vc3 = 150
m min–1, with ap = 1.0 mm and f = 0.15 mm/rev are
determined in this experiment. Then follows an exchange
(rotation) of the cutting insert again. Then continued the
completion of the turning of sample no. 5 from the
diameter Ø40 mm to the diameter Ø30 mm on the L =
180 mm with vc2 = 200 m min–1 = const. with the same
cutting parameters ap = 1.0 mm, f = 0.15 mm/rev, with
usage of coolant. The measured spindle speeds ni, the
feed velocity rates vfi and the machining times for the
individual cuts were determined using a calculation.
During this phase of the experiment we turned samples
no. 5, 6, 7, and 8 from the overall number of 10 pieces.
The graphical dependence of the cutting tool wear on the
machining time for the cutting speeds vc1, vc2, vc3 from the
turning of austenitic stainless steel 1.4301 with a cutting
parameter depth of cut ap = 1.0 mm and feed rate f = 0.15
mm/rev, with coolant is shown in Figure 6. Three points
of the measurement in the dependence T = f (vc) accord-
ing to the relevant equation and determines the shape of
the curve as linear in the logarithmic coordinates. For the
calculation we used values directly from Table 1. The
PRAMET Tools (Sandvik Group Sweden) is recom-
mended for the tool life of the cemented cutting inserts
with the coating type GC 2025 at the cutting speed vc =
250 m min–1 with the value of tool life T = 18 min, esta-
blishing the criterion of wear VBk = 0.2 mm. Since the
cemented carbide insert type GC 2025 has a multilayer
coating TiN+Al2O3+TiC on the fine-grained substrate
WC+Co it achieves an even higher durability.
There is an analytical description for determining the
dependence of the tool life T = f (vc) with a value of vc =
100 m min–1 in the following section. The linear regres-
sion of the single parameter is:
y = b0 · x0 + b1 · x1 (1)
Then the x0 is a fictitious value, which has a value of
1 for the integer scale. For the logarithmic scale of log 10
= 1, the x1 is an independent variable, the b0 is an additive
constant, which shows the growth on the axis "y", and
the b1 indicates the slope of the regression function. The
values b0, b1 are then calculated using the following
Equation (2) (x) to (y):
b
N T v T v
N v
i i
i
N
i
N
i
N
i i
1
1 11
2
=
⋅ ⋅ − ⋅
⋅
= ==
∑ ∑∑ (lg lg ) lg lg
(lg
c c
c ci i
v
i
N
i
N
) lg−
⎛
⎝
⎜ ⎞
⎠
⎟
==
∑∑
1
2
1
(2)
Substituting b1 into the Equation (2) we obtain the
constant b0, Equation (3):
b
T b v
N
i
i
N
i
N
i
0
1
11=
−
==
∑∑ lg lg c
(3)
where i to N is the number of measurements
R. DUBOVSKÁ et al.: INVESTIGATING THE INFLUENCE OF CUTTING SPEED ...
Materiali in tehnologije / Materials and technology 50 (2016) 3, 439–445 443
Figure 7: Flank wear VB of cemented carbide insert at cutting speed
vc2 = 200 m min–1, established criterion of the flank wear VB = 0.2 mm
Slika 7: Obraba roba VB karbidnega vlo`ka pri hitrosti rezanja vc2 =
200 m min–1, uveljavljeno merilo za obrabo roba VB = 0,2 mm
Figure 8: The graphical dependence Ra = f (vc) in the turning of DIN
1.4301 steel with CNMG 12048E with different r

Slika 8: Grafi~na odvisnost Ra = f (vc) pri stru`enju jekla DIN 1.4301
z CNMG 12048E, z razli~nimi r

b1
3 1012915 4 43935 6 87506
3 15 77998 47 266
=
⋅ − ⋅
⋅ −
( . ) ( . , )
. . 4
= –1.81327
b0
4 43935 181327 687506
3
=
− − ⋅. ( . ) .
= 5.63523
y = b0 · x0 + b1 · x1 = 5.63523 · x0 – 1.81327 · x1
The introduction of the substitution for b0 = log CT
and for y = log T is then CT = 105,63523 = 431,748.103.
Then the value is tg  = 1.81327, thereof  = arctg 1.81327
and consequently the size of the angle is  = 61° 21’.
The inclination angle of the line in the logarithmic
coordinates is –b1 = m = tg , and from which we obtain
the value of the angle .
The shape of the linear regression for the tool life has
the following form:
log T = log CT – m log vc (4)
The equation according to Taylor (2) for the material
1.4301 (AISI 304) will be in the following form for the
cutting conditions ap = 1 mm and f = 0.15 mm/rev.
T
v c
=
⋅431748 10 3
1 81327
.
.
Then for the tool-life calculation of cutting edge for
the cutting speed vc4 = 100 m min–1 the following for-
mula is used:
T
T
v
v
c
c
m
4
1
1
4
=
⎛
⎝
⎜
⎞
⎠
⎟ then T4
1 81327
195
250
100
102 7= ⎛⎝
⎜ ⎞
⎠
⎟ =. .
.
min
5 CONCLUSIONS
The main aim of the presented paper is an experi-
mental determination of the tool life depending on the
cutting speed according to Taylor in turning the auste-
nitic stainless steel 1.4301 (AISI 304). The cutting speed
and the feed rate have a significant effect on the flank
wear. The tool life is significantly influenced by the
cutting parameters, the surface roughness and the flank
wear. The obtained results are statistically processed
using a linear regression analysis with the method of
least squares. The results and values are shown in Table 1,
and the graphical dependence of the flank wear VBk on
the time is shown in Figure 6. The flank wear (Figure 7)
and the tool life of the cemented carbide insert were
monitored so that there is no reduction in the quality of
the surface finish. These areas were defined by the
technical documentation. For the cemented carbide insert
wear always occurs at one point when there is a variable
depth of cut (can see in Figure 7). For example, this can
be avoided by using of the CNC program preparation in
the three-dimensional CATIA interface (Figure 5). The
CNC program divides the allowance for machining so
that the next depth of cut was slightly smaller than the
previous one. The advantage of this cycle is the fact that
the cutting tool is not still loaded in the same area, but
over the range of applied depth of cuts. When machining
austenitic stainless steels we should follow these rules,
which help to increase the durability of the cutting edge
of the carbide cutting tool and thus the quality of the
machined surface.
• The first rule is basically to use cutting inserts coated
with CVD+PVD (for example, TiC+Al2O3+TiN on
the cutting tool surface).
• The second is to use a washer of cemented carbide
directly below the cemented carbide inserts.
• The third rule is to visually diagnose and timely eli-
minate the causes of premature damage to the cutting
edge (notch).
• The fourth rule is to use the best applications for the
changeable cutting inserts for dimensionally demand-
ing workpieces.
In terms of the defined cutting parameters the
greatest impact comes from the cutting speed vc, a lower
feed rate f and the least depth of cut ap. We did not study
more tool life depending T = f(f) and T = f(ap) for this
reason in CNC machine tools, and the size of the ob-
served flank wear. This creates space for the realization
of further research in this area. The applied, discovered
knowledge from the literature sources and the experi-
ments conducted here can be used in the future for the
manufacture of specific parts on CNC machine tools
with new, progressive cutting tools.
Acknowledgement
This paper was supported in the frame of the project
"Alexander Dub~ek University of Tren~ín – Faculty of
special technology wants to offer high-quality and
modern science/research and education", ITMS code
26110230099, based on the Operational Programme
Education. Modern education for knowledge society /
The project is co-funded by European Social Fund and
also includes the results of the grant VEGA no.
1/9428/02 titled "The technological heredity of the
machined surfaces – surface integrity".
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