An evaluation of some specifications of turbine blades made by 3D
printing and machining on CNC milling machines
PHAM HOANG ANH, LE HONG KY
Mechanical Department
Vinh Long University of Technology Education
73 Nguyen Hue Street, Vinh Long City, Vinh Long Province
VIETNAM
Abstract: - This paper presents the research results on manufacturing turbine blades in turbocharger machined on
Haas VF2 module TRT 160 5-axis CNC milling machine and by 3D printing method on Metal 3D printer HBD-
280 series with the same material AlSi10Mg. The research sample is the compressed turbine blades in the
HX40W turbocharger mechanism. CAD data files for machining programming and 3D printing of turbine blades
are scanned from an ATOS Core 80 scanner with GOM and Geomagic Design X softwares. Some specifications
of the two manufacturing methods are also presented. Research results show that the error of average diameter
and surface roughness of 3D printing method is larger than that of machining on a CNC milling machine.
Key-Words: - 3D printing, CNC milling, Rapid prototyping, Surface roughness, Turbine blade
Received: August 16, 2021. Revised: April 13, 2022. Accepted: May 15, 2022. Published: June 25, 2022.
1 Introduction
Turbocharger for engines is widely used not only in
the field of motor vehicles but also in the marine and
aviation fields. The turbine blade of the turbocharger
is a part with a complex contour, freeform surface
without regularity, and there are no studies on
geometric modeling, so it cannot be designed with a
common software [1-6]. Previously, the manufacture
of turbine blades was mainly by casting in metal
molds [7-9]. Currently, it is possible to design turbine
blades by reverse engineering from the original
model through specialized scanning equipment, and
after processing and editing with software, the
desired design file will be obtained [10-11]. Studies
[12-16] show that complex surfaces such as turbine
blades can be machined on 5-axis CNC Milling
machines. Authors Nguyen Chi Thong and Le Trung
Hau have published research results on the influence
of technological parameters on the accuracy of
diameter and surface roughness of compressed
turbine blades in the turbocharger mechanism
machined on HASS VF2 module TRT 160 5-axis
CNC Milling machines[17]. In general, although it is
possible to process turbine blades on 5-axis CNC
Milling machines, in terms of economic and technical
criteria, it has not yet replaced the casting method in
the traditional metal mold. Today, the technology of
Additive Manufacturing (AM) or 3D Printing using
developed metal materials is considered a
breakthrough in the manufacturing technology
industry. AM/ 3D printing is not only applied to rapid
prototyping, but this technology is also applied in
many fields such as the automotive industry,
aerospace and biomedical engineering to
manufacture metal parts for direct use [18]. From the
design file, complex structural parts such as turbine
blades can be manufatured by AM technology
through the following basic steps: Printing, cleaning
and sintering [19]. Selecting which method to
manufacture turbine blades is an issue that requires
scientific research and evaluation.
2. Research sample and measuring
device
2.1. Specifications of turbine blades
The turbine blade model selected in this study is a
compressed blade part in the HX40W turbocharger
mechanism (Fig. 1a).
2.1.1 Materials
The study used AlSi10Mg as the material for making
turbine blades. It is a typical casting alloy with good
casting properties and is commonly used for casting
parts with thin walls and complex geometrical
shapes. AlSi10Mg is a material with great strength
and hardness, so it is suitable for parts subjected to
high-speed working loads. AlSi10Mg components
are ideal for applications that require a combination
of good thermal properties and low weight such as
turbine blades.
Engineering World
DOI:10.37394/232025.2022.4.2
Pham Hoang Anh, Le Hong Ky
E-ISSN: 2692-5079
5
Volume 4, 2022
2.1.2 Geometric parameters
Coordinate Mesuring Machine (CMM) is used to
determine the average value of diameters Ø1 and Ø2
at 3 measurements and the average value of large
blades as Fig. 1. The measurement values and the
average diameter of the HX40W compressed turbine
blade model are summarized as shown in Table 1.
Table 1. Diameter measurement results of turbine
blade model.
Measurement
position
Measurement results (mm)
1st time
3rd time
ØAvS
Ø1
59.9999
60.0001
59.9999
Ø2
84.5002
84.4998
84.5001
1.2.3 Surface roughness
The study used the Mitutoyo SJ-210 roughness meter
to determine the surface roughness of 3 large blades
(Fig. 2). The measurement values and average value
of surface roughness of the HX40W compressed
turbine blade model are summarized as shown in
Table 2.
Table 2. Surface roughness measurement results of
turbine blades.
1st time
2nd time
3rd time
Overall mean
Ra
Rz
Ra
Rz
Ra
Rz
RaAvS
RzAvS
2.655
15.453
2.447
15.277
2.734
13.116
2.612
14.615
2.2 Turbine blade design
The study used ATOS Core 80 scanner and GOM
Inspect software to generate point cloud data from the
sample HX40W compressed turbine blades (Fig. 1a).
After processing point cloud data with Geomagic
Design X software, a CAD data file can be created
for machining and manufacturing turbine blades as
Fig. 1b [21].
a)
b)
Fig. 1. Designing turbine blades from samples
3. Machining turbine blades on CNC
milling machines
Turbine blades are machined through 4 operations:
Operation 1: Turn the positioning part and clamping
for the next operations, drilling holes smoothly.
HAAS TL2 lathe machine.
Operation 2: Milling and breaking the cylindrical
workpiece to create the designed workpiece shape
and widen the hole after drilling. HAAS VF3 Milling
machine.
Operation 3: Finely milling the Turbine blades on
Haas VF2 model TRT 160 5-axis CNC Milling
machine with cutting speed V = 60(m/min), feedrate
S = 0.24(mm/rev) and cutting depth t = 0.35(mm),
Fig. 2, [17]. Programming and simulation of
machining Turbine blades with Matercam software,
machining on Haas VF2 model TRT 160 5-axis CNC
Milling machine corresponding to finishing work.
Some important factors to determine: machining
workpiece, feedrate strategy, order of machining
strategies, cutting mode, cutting tool when
machining. In this operation, simultaneous 5-axis
feedrate paths are used throughout the programming
process. Three steps are performed, including:
Finishing of turbine blades, finishing of cylindrical
surfaces and machining of rounded corners. The
program Gcode is transferred by POSTPROCESSOR
to the CNC machine for processing.
Operation 4: Cutting off the positioning and
clamping is done on a universal lathe.
Fig. 2. Machining turbine blades.
4. Manufacture of turbine blades by 3D
printing method
Turbine blades are manufactured by 3D printing
method using Metal 3D printer HBD-280 series [22]
controlled by Voxeldance additive software (Fig. 3b)
also with AlSi10Mg material. The forming chamber
is initially filled with an inert gas to minimize
oxidation of the AlSi10Mg and then heated to the
optimum forming temperature. A thin layer of metal
Engineering World
DOI:10.37394/232025.2022.4.2
Pham Hoang Anh, Le Hong Ky
E-ISSN: 2692-5079
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Volume 4, 2022
powder is spread on the printing bed and a high-
powered laser scans the cross-section of the part,
fusing the metal particles together and creating the
next layer. When the scanning is complete, the bed
moves down by one layer thickness and the coating
spreads another thin layer of metal powder as shown
in Fig. 3a. The process is repeated until the entire part
is completed. After printing, cleaning and separating
the part from the printing bed, the turbine blade
product is obtained as Fig. 5. Since metal 3D printing
supports are shaped with the same material as the
printed part and are always required to minimize
warping and distortion that can result from high
processing temperatures. When the barrel cools to
room temperature, the excess powder is removed and
the product is heat treated while still attached to the
bed, reducing any residual stress.
a)
b)
Fig. 3. Turbine blade 3D printing process
Fig. 4. Product of turbine blades after 3D printing
5. Results and discussion
After machining the turbine blades on a CNC milling
machine (Fig. 2) and manufacturing it by 3D printing
method (Fig. 3, Fig. 4), similar to the sample part, a
CMM coordinate measuring device and SJ-210
Mitutoyo roughness meter (Fig. 5a, Fig. 5b) are used
to measure diameters (Ø1, Ø2) and surface
roughness.
b)
c)
Fig. 5. Measuring some specifications of 3D
printing product of turbine blades
5.1 Diameter Ø1, Ø2
Measurement results of diameters (Ø1, Ø2) on 3 long
blades with average values (Ø1AvCNC, Ø2AvCNC) and
(Ø1Av3D, Ø2Av3D) corresponding to 2 machining
methods as shown in Tables 3 and 4. The graphs
show the respective values as shown in Fig. 5a, Fig.
5b.
Table. 3. Measurement results of large blade
diameter of turbine blades machined by CNC
milling machine
Measurement
position
Measurement results (mm)
1st time
2nd time
3rd time
ØAvCNC
Ø1
59.981
60.002
59.992
59.9918
Ø2
84.501
84.492
84.592
84.5280
Table. 4. Measurement results of large blade
diameter of turbine blades manufactured by 3D
printing method
Measurement
position
Measurement results (mm)
1st time
2nd time
3rd time
ØAv3D
Ø1
60.0324
60.0050
60.0039
60.0138
Ø2
84.3787
84.4656
84.2545
84.3663
Table. 5. Average diameter error of the 2 machining
methods compared with the model
Measurement
position
Measurement results (mm)
ØAvCNC
Error
ØAv3D
Error
Ø1
59.9918
-0.0081
60.0138
0.0139
Ø2
84.5280
0.0279
84.3663
-0.1338
Table 5 shows that the average diameter size error (Ø1Av3D,
Ø2Av3D) of the 3D printing method is larger than when
machining on a CNC milling machine (Ø1AvCNC, Ø2Av3D).
This error can be overcome when using a metal 3D printer
with higher machining accuracy as well as in calculating
CAD design files that note the shrinkage of the part after
printing and sintering at high temperature.
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5.2 Surface roughness
The results of surface roughness measurement (Ra,
Rz) together with the average values (RzAvCNC,
RaAvCNC) and (RzAv3D, RaAv3D) are as shown in Tables
6, 7. The graph shows the average roughness of 3
times measured on the same surface, the same blade
of the turbine blade machined on a CNC milling
machine (RzAvCNC), 3D printing (RaAv3D) compared to
the sample as shown in Fig. 5.
Table. 6. Surface roughness measurement results of
turbine blades machined on CNC milling machines
1st time
2nd time
3rd time
Overall mean
Ra
Rz
Ra
Rz
Ra
Rz
RaAvCNC
RzAvCNC
1.408
7.420
1.636
6.534
1.656
6.079
1.567
6.678
Table. 7. Surface roughness measurement results of
turbine blades manufactured by 3D printing method
1st time
2nd time
3rd time
Overall
mean
Ra
Rz
Ra
Rz
Ra
Rz
RaAv3D
RzAv3D
3.826
17.570
3.239
17.208
3.577
19.660
3.547
18.146
Fig. 6. Turbine blade surface roughness is machined
on a CNC milling machine, 3D printing compared
to the model
Tables 6, 7 and Fig. 6 show that the Ra surface
roughness of the 3D printing method on the Metal 3D
printer HBD-280 series is larger than that of the
model as well as when it is processed on the Haas
VF2 module TRT 160 5-axis CNC milling machine.
It is completely similar with the measurement value
Rz. This difference can be completely overcome
when machining by sandblasting or using a metal 3D
printer with higher machining accuracy.
4 Conclusion
From the research sample of a compressed turbine
blade in the HX40W turbocharger mechanism, the
ATOS Core 80 scanner with GOM and Geomagic
Design X softwares were used to create CAD data
files for machining programming and 3D printing of
turbine blades. Haas VF2 module TRT 160 5-axis
CNC milling machine and 3D printing on Metal 3D
printer HBD-280 series were used to manufacture
turbine blades with the same material AlSi10Mg.
Research results show that the error of average
diameter and surface roughness of 3D printing
method is larger than that of CNC milling machine.
In which, the surface roughness when machining on
a 5-axis CNC milling machine is smaller than that of
the sample. Although metal 3D printing method is
not expected to replace most traditional
manufacturing methods, its outstanding features are
seen as a breakthrough in the manufacturing industry,
especially for parts with thin walls and complex
geometries, subjected to high-speed working loads,
requiring a combination of good thermal properties
and low weight, such as turbine blades.
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Contribution of individual authors to
the creation of a scientific article
(ghostwriting policy)
Author Contributions:
Pham Hoang Anh has organized and executed The
machining turbine blades on CNC milling machine
and the manufacture of turbine blades by 3D printing
method.
Le Hong Ky was responsible for writing articles and
liaising with the journal.
Creative Commons Attribution License 4.0
(Attribution 4.0 International, CC BY 4.0)
This article is published under the terms of the Creative
Commons Attribution License 4.0
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Engineering World
DOI:10.37394/232025.2022.4.2
Pham Hoang Anh, Le Hong Ky
E-ISSN: 2692-5079
9
Volume 4, 2022