Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79 Received for review: 2023-07-05
© 2024 The Authors. CC BY 4.0 Int. Licensee: SV-JME Received revised form: 2023-10-10
DOI:10.5545/sv-jme.2023.718 Original Scientific Paper Accepted for publication: 2023-11-07
*Corr. Author’s Address: Faculty of Mechanical Engineering and Robotics, AGH University of Science and Technology, 30-059 Cracow, Poland, gstruzik@agh.edu.pl 70
Investigation of the Titanium Alloy Turning Process with Prime A 
Tools under High-Pressure Cooling Conditions 
Struzikiewicz, G.
Grzegorz Struzikiewicz
*
AGH University of Science and Technology, Poland
When turning titanium alloys, it is difficult to ensure the required quality with maximum machining efficiency. A typical problem in the 
turning process of titanium alloys is to achieve effective breaking and removal of chips from the machining zone. The combination of the 
new construction of cutting tools and machining methods in the machining of titanium alloys increases the efficiency of the machining. For 
this reason, the use of tools typical for the Prime Turning method in combination with the high-pressure cooling (HPC) method was analysed. 
The longitudinal turning of the Ti6Al4V ELI titanium alloy was performed using Sandvik Coromant grade 1115 carbide tools. An increase in 
the pressure of the cutting fluid to p = 70 bar was used. Measurements of the components of the total cutting force for finishing machining 
with variable cutting parameters in the range of: feed rates f = <0.1;0.4> mm/rev, cutting depth a
p
 = <0.25;1.0> mm and cutting speed 
v
c
 = <40;80> m/min were performed. It has been shown that the values of cutting force are mainly dependent on the feed and the depth 
of cut. An analysis of the forms of chips obtained is presented. The dependence of the applied cutting parameters on the value of the chip 
breakage coefficient C
ch
 was determined. The method of searching for the maximum efficiency of the turning process was determined, taking 
into account the desired value of the chip breakage coefficient.
Keywords: turning, titanium alloy, cutting forces, chip form, chip breakage index
Highlights
• 	 Using the carbide cutting insert CP-A1104-L5 and the HPC method is an effective means of improving productivity in the 
turning process of the Ti6Al4V ELI titanium alloy. 
• 	 The cutting parameters have a significant impact on the values of the components of the total cutting force and the chip 
breakage index.
• 	 It is possible to increase the efficiency of the machining process by maintaining the required chip form.
0  INTRODUCTION
The optimization of existing titanium alloy machining 
processes and the use of new machining techniques 
enable the achievement of the expected efficiency 
and quality of machining at low cost [1]. This is 
particularly significant for the machining of expensive 
materials or demanding materials. Titanium alloys, 
next to nickel alloys and heat-resistant steels, are 
difficult-to-cut materials. This is due to the specific 
mechanical and chemical properties that characterize 
this group of materials [2] and [3]. 
Due to their high strength, corrosion resistance 
and inertness, titanium alloys are most often used 
by the automotive, aerospace, chemical and medical 
industries [4]. On-going research broadens knowledge 
in the field of machining titanium alloys. The area 
of research described in the literature concerns the 
influence of cutting parameters on the roughness of 
the machined surface and the determination of the 
value of forces or temperature in the cutting zone [5]. 
Another important issue is the process of breaking 
chips during machining and the use of calculation 
methods that enable the simulation of cutting 
processes [6] and [7]. Accelerated wear of cutting tools 
due to high temperatures in the cutting zone and stress 
concentration at the edge of the cutting insert are also 
frequently analysed issues [1] and [8]. 
The machinability of titanium alloys can be 
increased as a result of the use or combination of 
different techniques and machining methods. For 
example, the use of various cooling methods in the 
cutting processes of titanium alloys yields measurable 
results. The literature describes the results of research 
on machining under dry cutting conditions, with 
minimal quantity or high pressure of the cutting fluid, 
as well as cryo-machining [8] to [12]. 
Increasing the efficiency of the titanium alloy 
machining process can be achieved using the 
high-pressure cooling (HPC) method. Currently, 
the pressure range recommended by cutting tool 
manufacturers to work with titanium alloys is 50 bar 
to 300 bar. This method allows faster heat dissipation 
and lower temperatures in the cutting zone. Compared 
to typical cooling, this results in a longer cutting tool 
life of up to 15 times. HPC machining greatly supports 
the chip-breaking process and chip removal outside 
the machining zone [4] and [10]. This is particularly 
important for turning and drilling processes [13].

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
71 Investigation of the Titanium Alloy Turning Process with Prime A Tools under High-Pressure Cooling Conditions 
In the case of turning titanium alloys under 
HPC conditions, the selection of tool materials is 
important. Palanisamy et al. [15] described the results 
of experimental studies on the machining of inserts 
made of cemented carbide. The authors showed that 
HPC machining increases tool life by almost three 
times compared to conventional cooling. Furthermore, 
they showed that the mechanical effect of the liquid 
jet on the chips supports the process of breaking and 
removing chips from the cutting zone. HPC machining 
has been shown to produce short, segmented chips. In 
turn, Ezugwu et al. [16] analysed the machinability of 
titanium alloys under conventional and high-pressure 
cooling conditions with tools made of cemented 
carbides and coated with various coatings. They also 
demonstrated reduced cutting tool wear under HPC 
machining conditions. Da Silva et al. [17] analysed the 
mechanism of tool wear during high-speed machining 
of titanium alloys. They showed that tool life 
decreased with increasing cutting speed, and increased 
productivity was achieved during high-pressure 
cooling. In turn, Stolf et al. [18] analysed the method 
of tool wear due to tool-chip contact conditions during 
HPC machining of the Ti6Al4V alloy. They found that 
the coolant pressure and the maximum wear on the 
flank surface are inversely proportional. This is due to 
the effect on the process of abrasion of heat acting on 
the surface of the cutting tool application. The authors 
also pointed out that HPC machining has a positive 
effect on lowering the temperature of the tool and 
on the chip breakage process. Kaminski and Alvelid 
[19] showed that high coolant pressure causes fluid to 
enter the slip zone, reducing friction and temperature. 
In addition, the high-pressure cutting fluid stream 
reduces the chip winding radius and shortens the 
contact time between the tool and the chips.
In turn, Liang et al. [20] performed Ti6Al4V 
surface integrity tests at different cooling pressures 
and injection positions of cutting fluid. The researchers 
examined three injection positions, i.e., only injection 
in the rake face, only in the flank face, and injection 
in both rake/flank face directions. They observed 
that compared to dry cutting and HPC conditions, 3D 
surface roughness parameters were reduced during 
high-pressure jet-assisted machining. Masek et al. 
[21] analysed the influence of the direction of liquid 
supply to the cutting zone during polycrystalline 
diamond (PCD) machining. Their study showed 
that double cooling is strongly recommended when 
machining titanium alloys, both on the rake surface 
and on the flank surface, and the results showed that 
the appropriate HPC intensity was around 60 bar. This 
results in an increase in the efficiency of the chip-
breaking process with reduced tool wear. Çolak [22] 
optimized the HPC machining process using genetic 
algorithms due to the desired surface roughness. 
Surface roughness and chip breaking were selected 
as optimisation criteria due to their importance for the 
finishing turning process. 
One of the recently developed concepts for 
increasing the efficiency of the machining process 
is the so-called Prime Turning method. This concept 
takes into account the changed geometry of the 
cutting tool. These cutting inserts have three edges for 
longitudinal, face and profiling turning. This ensures 
efficient use of the edges and a longer tool life. 
Krajčoviech et al. wrote about the use of this type of 
tool for steel machining [23]. The authors showed that 
the depth of cut has the most significant impact on the 
values of cutting forces. 
According to a review of the literature presented, 
researchers investigated various HPC strategies with 
the common goal of reducing tool wear or increasing 
process efficiency. However, the impact of machining 
efficiency of various cutting conditions is connected 
with different cutting parameter values and tool 
geometry, methods of cutting liquid delivery, etc. 
Furthermore, analysis of the quality of the cutting 
process could be realized from different points of 
view. In this regard, there are still few analyses that 
take chip forms into account. Due to the problems 
described above for obtaining effective machining 
of titanium alloys, Ti6Al4V ELI alloy turning tests 
were carried out under conditions of feeding the 
cutting fluid with increased pressure and using Prime 
A turning tools. The experimental research plan took 
into account three variables, i.e., feed, depth, and 
cutting speed. During the experiments, the processes 
of cutting forces were recorded, microscopic analysis 
of the chip form was carried out and the chip 
breakage coefficient was determined. The concept of 
maximising machining efficiency is presented, taking 
into account the favourable form of the chips.
1  METHODS
The experimental research plan was developed 
according to the Taguchi method [24] for three 
variables, i.e., feed f, depth of cut a
p
 and cutting 
speed v
c. 
The 16th test systems were designated. For 
statistical analysis, every group of the experimental 
run was done three times, for a total of 48 trials (16×3 
runs). Table 1 shows the assumed ranges of cutting 
data values. The values of the cutting parameters are 
within the range of cutting parameters recommended 
by the tool manufacturer for turning titanium alloys. 

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
72 Struzikiewicz, G.
Table 1.  The variables values in the research plan
No. Coded parameter Real parameter Value
1 A f [mm/rev] 0.1 0.2 0.3 0.4
2 B a
p
 [mm] 0.25 0.50 0.75 1.0
3 C v
c
 [m/min] 40 80
The signal-to-noise (S/N) ratio analysis strategy 
was adopted as “the lowest-best” according to Eq. (1) 
[24].
 SN
n
y
i
n
i
/.  








10
1
1
2
log (1)
A modified classification and characteristics 
of the chips presented by Fang et al. [25] and Lee et 
al. [26] were adopted. The aim of the modification 
was to adapt the classification of chips to practical 
industrial use. In general, chips can be described using 
words and numbers. In practice, a typical approach 
is to characterize chips using language terms such as 
“good”, “weak”, etc. 
The authors of the paper presented a concept in 
which there are four different types of chip shapes, 
i.e., arch/bulky, spiral/circular, helical/tubular and 
ribbon. For each chip type, two main dimensional 
characteristics of the chips were assigned, which in 
turn were converted into numerical values. These 
values can be used to classify and determine the chip 
breakage coefficient [27]. During the investigation, the 
analysis of the form of the chips and their classification 
and evaluation were carried out. Only two forms of 
chips obtained during machining tests were observed, 
i.e., arc/bulky and helical/tubular type chips. For these 
types of chips, the dimensional characteristics were 
adopted according to Table 2. 
Table 2.  Dimensional features of chips obtained during cutting 
tests
Group Chip index characterization
Arc/Bulky
W
ch
 - Width
H
ch
 
- Height
Helical/Tubular
L
ch
 - Length 
D
ch
- Diameter
Based on the dimensions of the measured chip, 
the chip breakage coefficient C
ch
 was determined 
according to Eqs. (2) to (4). In the investigation, a 
simplified method of chip classification was adopted, 
according to which the chip breakage index C
ch
 takes 
values from 0 to 1 and is described by Eq. (2). Lower 
C
ch
 values represent better chip breakability.
CD im
DimD im Dim
DimD im
ch
ch ch ch limit
ch ch li
 
 

00 10
1
2
.
_
_
if
if
m mit2





, ,(2)
where
•	 Dim
ch_limit1 
≤ 5 mm;  
correct chips (0 < C
ch
 ≤ 0.2);
•	 Dim
ch_limit 1
 > 5 mm and Dim
ch_limit 2
 ≤ 20 mm; 
acceptable chips (0.2 < C
ch
  <1.0);
•	 Dim
ch_limit 2
  > 20 mm;  
unfavourable chips (C
ch
 = const. = 1.0).
Where Dim
ch
 were described for arc/bulky chips 
by Eq. (3) and for helical/tubular chips by Eq. (4):
 DimWH
ch ch ch
, (3)
 DimLD
ch ch ch
. (4)
Fig. 1.  Sample of chips photographs for parameters:  
a) f = 0.4 mm/rev, a
p
 = 0.50 mm, v
c
 = 40 m/min,  
b) f = 0.4 mm/rev, a
p
 = 0.75 mm, v
c
 = 80 m/min, and  
c) f = 0.1 mm/rev, a
p
 = 1.00 mm, v
c
 = 40 m/min
The main criterion for the assessment of chip 
form was the chip dimensions, i.e., length and height 
for arc chips or length and spiral diameters for tubular 

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
73 Investigation of the Titanium Alloy Turning Process with Prime A Tools under High-Pressure Cooling Conditions 
chips. A three-stage assessment of the chip form was 
assumed, i.e., correct chips up to 5 mm, acceptable 
chips up to 5 mm to 20 mm and incorrect chips over 
20 mm. The following markings were adopted when 
assessing the form of chips: “+” chips correct (good); 
“–” chips unfavourable (poor); “0” chips acceptable 
(fair). Example photographs of chips are shown in 
Fig. 1.
2  EXPERIMENTAL
Ti6Al4V-ELI (extra low interstitials) titanium alloy 
contains less oxygen, nitrogen, carbon, and iron than 
a typical Ti6Al4V alloy. This improves the ductility 
and resistance to cracking of the material, which 
means that this alloy is used in dentistry and medicine, 
for example, for orthopaedic implants [27]. The 
material to be processed was a shaft with a diameter 
of Dc = 50 mm. The mechanical properties of the 
alloy were as follows: tensile strength = 902 MPa, 
hardness = 29 HRc, elongation 13 %, Yield 
strength
0.2%
 = 815 MPa. Chemical composition ware: 
Al 6.1 %, V 4.13 %, Fe 0.05 %, O 0.1 %, N 0.01 %, 
C < 0.01 %, H 0.003 % and Ti remainder. 
The longitudinal turning process was analysed 
under conditions of coolant supply with increased 
pressure. The cutting fluid was fed to the rake face by 
the cutting tool through the tool holder nozzle. 
In cutting tests, cutting inserts of type Prime A 
turning (Fig. 2) type CP-A1104-L5 grade 1115 and 
the tool holder QS-CP-30AR-2020-11C from Sandvik 
Coromant were used. The value of the corner radius 
of the cutting insert was r
Ɛ
 = 0.4 mm. A new cutting 
edge was used in each machining test. The impact of 
cutting-edge wear was not analysed. A constant cutting 
liquid pressure of p = 70 bar was used, and Blaser’s 
10 % Blasocut 2000 universal emulsion was used as 
the cutting fluid. The selected cutting parameters were 
within the range of finishing titanium alloys. The tests 
were carried out on a conventional lathe, equipped 
with a 150 bar pressure high-pressure plunger pump. 
Fig. 2.  Cutting tool Prime A
During the research, measurements of the 
components of the total cutting force and microscopic 
measurements of the chip dimensions were carried 
out. To record and analyse the components of the 
cutting forces, a measuring track system consisting 
of a 9257B dynamometer and a Kistler 5070B 
amplifier was used. Chip analysis was carried out 
using a Keyence VHX-7000 type 3D microscope with 
dedicated measurement software.
Table 3. Test results for measurements of cutting force F
c
 and chip breakage coefficient C
ch
No A B C f [mm/rev] a
p 
[mm] v
c 
[m/min] F
c_mean 
[N] S/N
Fc
C
ch_mean
S/N
Cch
1 1 1 1 0.1 1.00 40 255.4 –48.2 1.00 0.0
2 1 2 1 0.1 0.75 40 208.7 –46.4 0.17 15.2
3 1 3 2 0.1 0.50 80 140.0 –42.9 0.07 22.9
4 1 4 2 0.1 0.25 80 68.2 –36.7 0.05 26.6
5 2 1 1 0.2 1.00 40 462.3 –53.3 0.41 7.5
6 2 2 1 0.2 0.75 40 395.3 –52.0 0.13 17.6
7 2 3 2 0.2 0.50 80 210.6 –46.5 0.07 23.2
8 2 4 2 0.2 0.25 80 122.0 –41.7 0.05 26.4
9 3 1 2 0.3 1.00 80 610.0 –55.7 0.42 7.4
10 3 2 2 0.3 0.75 80 445.9 –53.0 0.14 17.2
11 3 3 1 0.3 0.50 40 285.4 –49.1 0.05 25.2
12 3 4 1 0.3 0.25 40 152.3 –43.7 0.04 27.3
13 4 1 2 0.4 1.00 80 776.0 –57.8 0.20 14.0
14 4 2 2 0.4 0.75 80 545.0 –54.7 0.10 19.6
15 4 3 1 0.4 0.50 40 351.2 –50.9 0.06 24.8
16 4 4 1 0.4 0.25 40 184.1 -45.3 0.05 25.9

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
74 Struzikiewicz, G.
3  RESULTS
In accordance with the adopted research plan, 
measurements of the components of the total cutting 
force and geometrical dimensions of the chips 
obtained were made. The influence of the assumed 
variables, i.e., feed values f [mm/rev] and depth a
p
 
[mm] and cutting speed v
c
 [m/min] on the values 
of components of the total cutting force, i.e., main 
cutting force F
c
 [N], feed force F
f
 [N] and resistive 
F
p
 [N] was analysed. Table 3 presents the results of 
the average values of the cutting force F
c_mean
, and the 
chip breakage coefficient C
ch_mean
 and the values of 
the SN parameter obtained in individual test systems. 
Tables 4 and 5 present a statistical analysis of the 
results. 
Figs. 3 and 4 show the influence of individual 
variables on the average value of the main cutting 
force F
c
 and the values of the chip breakage coefficient 
C
ch
.
4  DISCUSSION
The analysis of the measurement results showed a 
linear dependence of the values of all components of 
the total cutting force on the assumed values of the 
a)                b) 
c) 
d) 
Fig. 3.  Influence of the analysed cutting parameters on the mean values of the cutting force F
c
;  
a) each parameter in separate graphs: feed f, depth of cut a
p
 and cutting speed v
c
; b) only depth of cut a
p
;  
c) only depth of cut a
p
 and feed f; and d) only cutting speed v
c
 and feed f

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
75 Investigation of the Titanium Alloy Turning Process with Prime A Tools under High-Pressure Cooling Conditions 
cutting parameters during the HPC turning of the 
titanium alloy Ti6Al4V ELI.
The most significant factors (Fig. 3) on the value 
of the cutting force F
c
 were depth of cut a
p
 and feed 
f. The depth of cut contributed 58 % and the feed rate 
contributed 30 % in the F
c
 response of the cutting 
force during the machining of the alloy. This was due 
to the increase in the cross section of the cut layer, 
which required the cutting process to use higher 
cutting forces. A fourfold increase in feed value or 
cutting depth results in about a fourfold increase in the 
average cutting force. In turn, a twofold increase in 
cutting speed, that is, from v
c
 = 40 m/min to v
c
 = 80 m/
min, resulted in an increase (by about 50 N) in the 
average cutting force F
c
. For cutting speed v
c
 = 80 m/
min, an increase in the intensity of increase in cutting 
forces was observed, both as a function of depth of cut 
a
p
 and feed f (Fig. 3c and d).
The analysis of the data obtained showed that the 
chip form and average values of the chip breakage 
coefficient in the longitudinal turning process 
are significantly influenced by the tested cutting 
parameters (Fig. 4a), with the cutting depth a
p
 most 
significantly. The depth of cut contributed 70 % in 
chip breakage coefficient C
ch
 responses during the 
turning of the tested alloy. The cutting speed v
c
 and 
a)                b) 
c) 
d) 
Fig. 4.  Influence of the analysed cutting parameters on the mean values of the chip breakability index C
ch
;  
a) each parameter in separate graphs: feed f, depth of cut a
p
 and cutting speed v
c
; b) only depth of cut a
p
;  
and c) only cutting speed v
c
; and d) only feed f and depth of cut a
p

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
76 Struzikiewicz, G.
the feed rate f contributed, respectively, 16 % and 14 
%. 
In this case, the correct and acceptable form 
of chips results from the simultaneous action of the 
pressure of the cutting fluid and the shape of the chip 
groove on the rake surface of the insert. For increasing 
depth of cut and feed values, the chip groove is filled 
with the chip material to a greater degree. The chip 
winding radius is also reduced (more short arc chips). 
The pressure of the cutting fluid additionally supports 
the process of chip winding and cracking. The chip-
cracking process may also be supported by the impact 
of the chip formed against the unfinished surface of 
the workpiece or the flank surface of the cutting insert. 
In contrast, increasing values of depth of cut 
cause a much faster increase in the average values 
of the chip breakage coefficient C
ch
 (Fig. 4b). An 
increase in the depth of cut value causes an increase 
in the width of the created chip. The chip strength are 
increased. The pressure of the cutting fluid may not be 
sufficient to initiate the chip cracking process. 
The determined regression equations F
c
(f,a
p
,v
c
) 
and C
ch
(f,a
p
,v
c
) are shown below.
Ff av fa v
cp cp c
,, .,

    366 964 534 19 5 (5)
Cf av fa
vf
ch pc p
c
,, .. .
.. .

 
  
0 711 1 899 1 192
0 00257 2 479 1
2
4 418
2
a
p
.(6)
A confirmatory test was performed to verify 
the predicted values compared to the experimental 
values. The results obtained (Table 6) showed a good 
precision of the predicted cutting force values and the 
classification of chips based on the chip breakability 
index C
ch
.
It was also observed that for the cutting speed 
v
c
 = 80 m/min, lower values of the C
ch
 coefficient and 
thus a more correct form of chips were obtained (Fig. 
4c). The unacceptable form of chips (Fig. 4d) was 
obtained for low feed values (e.g., f = 0.1 mm/min) 
and large depth of cut values (e.g., a
p
 = 1.0 mm). It is a 
prerequisite to look for an increase in the efficiency of 
the machining process, taking into account the correct 
form of the chips. This is particularly important for 
the finishing machining titanium alloys. 
Analysing the results obtained, it can be concluded 
that increased machining efficiency should be sought 
by selecting higher values of depth or cutting speed. It 
is well-known that the feed value has a significant and 
negative effect on the surface roughness. Therefore, 
for finishing machining, it may be difficult to increase 
productivity by increasing feed value. 
An example illustrating the method is shown in 
Fig. 5. In the analysed case, F
c
 ≤ 200 N and C
ch
 ≤ 
0.2 (correct form of chips) were adopted as limiting 
criteria to not exceed the cutting force value. The 
cutting force diagrams F
c
 and C
ch
 were determined 
on the basis of the regression equations presented in 
Eqs. (5) and (6). The material removal rate Q
v
 was 
established according to Eq. (7):
 Qf av fa v
vp cp c
,, .

   [cm
3
/min]. (7)
Taking into account the limiting criteria, it can 
be noted that the adoption of a higher cutting speed 
value (i.e., v
c 
= 80 m/min) results in an increase in 
the material removal rate, from Q
v 
= 4 cm
3
/min to 
Q
v 
= 6.2 cm
3
/min, which is an increase of more than 
50 % in efficiency. Despite the reduction in depth of 
Table 4.  Analysis of variance for mean values for cutting force F
c
Source DF SeqSS AdjSS AdjMS F P % Contribution
f 3 188287 188287 62762 18.96 0.001 30
a
p
3 357200 357200 119067 35.96 0.000 58
v
c
1 24255 24255 24255 7.33 0.027 12
Residual Error 8 26486 26486 3311
Total 15 596228
Table 5.  Analysis of variance for mean values for chip breakability index C
ch
Source DF SeqSS AdjSS AdjMS F P % Contribution
f 3 0.107 0.107 0.036 1.36 0.323 14
a
p
3 0.558 0.558 0.186 7.09 0.012 70
v
c
1 0.042 0.042 0.042 1.61 0.240 16
Residual Error 8 0.210 0.210 0.026
Total 15 0.917

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
77 Investigation of the Titanium Alloy Turning Process with Prime A Tools under High-Pressure Cooling Conditions 
cemented carbides under machining conditions with 
increased pressure of the cutting fluid. The main 
area of analysis was to determine the influence of 
the cutting parameters (f, a
p
, v
c
) on the values of the 
cutting forces, as well as the chip breakage coefficient 
C
ch
 and the form of the chips. The results of the 
analysis showed that:
• the values of the cutting force F
c
 depend linearly 
on the cutting parameters adopted. According to 
the statistical analysis, the cutting depth a
p
 was 
the most significant parameter, followed by feed 
f, which affects the cutting force. The cutting 
speed v
c
 affected the mean cutting force to a 
much lesser extent.
• the cutting depth a
p
 was the most significant 
parameter which affects the chip breakability 
index C
ch
. The obtained form of chips (correct, 
acceptable, and incorrect) depends on the range 
of cutting parameters used. On average, for 
the tested ranges of cutting parameter values, a 
correct chip form was obtained for: a
p
 ≤ 0.75 mm, 
f ≥ 0.2 mm/rev. A higher cutting speed value, that 
is, for v
c
 = 80 m/min, reduced the chip breakage 
coefficient value.
• obtaining a correct form of chips in the finishing 
turning of titanium alloy Ti6Al4V under HPC 
machining conditions depends on the synergistic 
impact of factors such as the values of cutting 
parameters, the shape and degree of filling 
of the chip breaker on the rake face, as well as 
the pressure of the cutting fluid. Under these 
cut a
p
 resulting from the limitation of the permissible 
value of the cutting force F
c
. 
It should be noted that an increase in the cutting 
speed may accelerate the wear of the cutting tools. 
This may result in higher manufacturing costs. The 
presented method does not take into account the tool 
life of the cutting edge.
Fig. 5.  Method of searching for an increase in  
material removal rate Q
v
5  CONCLUSIONS
The purpose of the experimental research was 
to analyse the machinability of the Ti6Al4V ELI 
titanium alloy with Prime A turning tools made of 
Table 6.  Results for confirmation test
No
F
c_mean  
[N]
F
c_anticipated  
[N]
F
c
 percentage error 
[%]
C
ch_mean
Chips class. C
ch_mean_anticipated
Anticip. chips class.
1 255.4 342.4 34.1 1.00 unfavo. 0.67 accept.. 
2 208.7 208.9 0.1 0.17 correct 0.35 accept.
3 140.0 153.4 9.6 0.07 correct 0.10 correct
4 68.2 19.9 70.8 0.05 correct 0.13 correct
5 462.3 438.8 5.1 0.41 accept. 0.55 accept. 
6 395.3 305.3 22.8 0.13 correct 0.23 accept.
7 210.6 249.8 18.6 0.07 correct 0.00 correct
8 122.0 116.3 4.7 0.05 correct 0.02 correct
9 610.0 613.2 0.5 0.42 accept. 0.38 accept.
10 445.9 479.7 7.6 0.14 correct 0.06 correct
11 285.4 268.2 6.0 0.05 correct 0.02 correct
12 152.3 134.7 11.6 0.04 correct 0.05 correct
13 776.0 709.6 8.6 0.20 correct 0.37 accept.
14 545.0 576.1 5.7 0.10 correct 0.05 correct
15 351.2 364.6 3.8 0.06 correct 0.00 correct
16 184.1 231.1 25.5 0.05 correct 0.04 correct

Strojniški vestnik - Journal of Mechanical Engineering 70(2024)1-2, 70-79
78 Struzikiewicz, G.
conditions, it is possible to increase the machining 
efficiency by selecting the cutting speed. In 
the case presented, the increase in the material 
removal rate Q
v
 of the machining was more than 
50 %. 
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