This paper proposes the effect of various toolpath methods for semi-finish operation on the machining time when milling 3D surfaces. An optimal selection of toolpath can cause remaking in the advance of time.
Trang 1INFLUENCE OF TOOL PATH STRATEGIES ON MACHINING TIME USING
THE BALL NOSE TOOL WHEN MILLING 3D SURFACES
Nhu Nguyet Vu * , Minh Tuan Ngo, Thuan Nguyen
University of Technology - TNU
ABSTRACT
In machining flexible surfaces, machining processing costs can be reduced by several factors such
as removed material workpieces, the choice of suitable cutting tools, optimal coolant and saving machining time This paper proposes the effect of various toolpath methods for semi-finish operation on the machining time when milling 3D surfaces An optimal selection of toolpath can cause remaking in the advance of time The analysis and comparison of different toolpath strategies in 3D milling are investigated in order to choose the best strategies in different situations The NX software, known as computer- aided manufacturing software, was used to evaluate the different toolpath strategies of three-axis milling The experimental results clearly show the influence of the cutter path strategies on machining times and selecting the optimal strategy was based on a CAM software
Keywords: Tool path strategy, machining time, three- axis milling, 3D surface, CAM software
Received: 29/8/2018; Revised: 13/10/2018; Approved: 28/12/2018
ẢNH HƯỞNG CỦA PHƯƠNG PHÁP CHẠY DAO ĐẾN THỜI GIAN GIA CÔNG
KHI PHAY BỀ MẶT 3D SỬ DỤNG DAO PHAY ĐẦU CẦU
Vũ Như Nguyệt * , Ngô Minh Tuấn, Nguyễn Thuận
Trường Đại học Kỹ thuật Công nghiệp - ĐH Thái Nguyên
TÓM TẮT
Trong gia công các bề mặt phức tạp, chi phí của quá trình gia công có thể giảm bằng vài cách như
là lượng vật liệu phôi được hớt đi, lựa chọn dụng cụ cắt phù hợp, tiết kiệm dung dịch làm mát hay giảm thời gian gia công trên máy công cụ Bài báo này đề cập đến hướng nghiên cứu ảnh hưởng của một số kiểu chạy dao trong khi phay bán tinh bề mặt 3D đến thời gian gia công Việc chọn đường chạy dao tối ưu có thể dẫn đến những lợi ích nhất định cho thời gian gia công Sự phân tích
và so sánh các phương pháp chạy dao khác nhau khi phay mặt cong được đánh giá để chọn cách thức chạy dao tốt nhất trong nghiên cứu này Phần mềm NX, được biết như là phần mềm trợ giúp cho quá trình gia công trên các máy công cụ, được chọn để sử dụng mô phỏng và so sánh sự khác nhau giữa các kiểu đường chạy dao khi lập trình phay 3 trục Kết quả thí nghiệm cũng chỉ rõ ảnh hưởng của cách thức chạy dao đến thời gian gia công cũng như việc chọn được phương pháp gia
công tối ưu trên phần mềm CAM
Từ khóa: Phương thức chạy dao, thời gian gia công, phay 3 trục, mặt cong 3D, phần mềm CAM
Ngày nhận bài: 21/9/2018; Hoàn thiện: 27/10/2018; Duyệt dăng: 28/12/2018
(*) Corresponding author: vunhunguyet@tnut.edu.vn; Tel 0985960902
Trang 2INTRODUCTION
In the milling processes using the CAD/CAM
technology, the selection tool path strategy
extremely affects the quality of machine parts
and the machining time By using a CAM
software, the tool path and the way removing
the material in the milling process can be
simulated Afterwards, having the verified
accuracy as well as the efficiency of the
operations, the CNC program is exported by
input of the milling machine to produce the
parts without confronting any problem of any
kind This, indeed, is another privilege of
using computers in the production process,
i.e., reducing machine time as well as
reducing the production costs The less the
machining time, the cost of products
decreases much
In recent years, several studies have been
conducted in optimizing the machining time
parameters and the tool path strategies In
2016, Mebrahitom A studied the optimizing
the tool path strategies and machining
parameters for milling operations of a
rectangular cavities [1] In 2017, Bagci
analysed the effect of tool path strategies on
dynamic tool deflection, cutting forces,
machining time, effective cutter diameter,
cutter/workpiece engagement area,
instantaneous material removal rate and
machining errors in rough machining of a
sculptured surface [2]
Adriano Fagali de Souza focused on
improvements on the choice of milling
simulations of manufacturing process in CNC
milling machine applying through Mastercam
software (CAD/CAM) were proposed by P
V Savalia and Prof M M Chandrala [4]
The effects of cutter orientation used to
machine curvature surface of thin aluminum
parts (7075) with a 3-axis ball end-milling
were investigated to improve geometric
accuracy, surface integrity, and the most
optimal range of machining forces by B Jabbaripour [5] A computation scheme that generates optimized tool path for five-axis flank milling of ruled surface was studied by Ping-Han Wu [6] H Perez proposed a machining strategy providing a cutting mode for the tool during a particular machining operation, determining the axial and radial depth of cut and the recommended trajectories for the cutting tool [7] It can be seen that, several studies have been investigated to study the tool path strategies However, influence of tool path strategies on machining time using the ball nose tool when milling 3D surfaces has not yet been reported This paper presents the effect of various milling strategies for semi- finish ball end milling computer- mouse surface on the machining time
SIMULATION CUTTING OPERATIONS WITH DIFFERENT TOOL PATH TYPES
IN A CAD/CAM SOFTWARE The models and drawings created by the designer have to undergo other processes to get to the finished product Fig.1 shows the flow chart of the design and manufacturing process using a CAD/CAM software
Figure 1 Design and manufacturing process
using a CAD/CAM software
Trang 3The process widely and commonly used to
generate program codes for CNC machines to
mill the component This technological
development reduces the amount of human
intervention in creating CNC codes After
analyzing the geometry part, parent group
objects are created to store manufacturing
information such as tool data, feed rates, and
tolerances, etc The data is specified in the
parent group object in inherited by operations
that are listed under that particular parent
group object Usually, there are four types of
parent group objects, such as geometry,
method, program and tool Before choosing
operation types, numerous items must be
taken into consideration for achieving the
desired output
In this work, the computer mouse surface is a
complex surface and is designed on NX
software as shown in figure 2 After creating
the machining environment, the tool paths are
created and generated for the cover housing
Most of the CAM systems would provide for
different area clearance options in which the
user can choose considering the type of
geometry In NX software, there are 6 types
of tool path strategies, such as the follow part,
follow periphery, trochoidal, zig and zig zag
The follow part is the most optimal strategy
where the tool path manipulates depending on
the part geometry If there are cores and
cavities in the part, the software will
intelligently consider them to remove the
materials in an optimal way This kind of
treatment is widely used for roughing
operations The follow periphery takes the
path which depends on upon the periphery
profile For example, the outer periphery of
our part is rectangular So the tool path will
be generated such that it gradually cuts the
material from outside to inside with the step
over value This option is mostly used for
projections and cores rather than cavities The
profile takes the cut only along the profile of
the part geometry It is used for
semi-finishing or semi-finishing operations In the
trochoidal method, the cutter is huge and is
used for removing a large amount of material The bulk of material is removed by gradual trochoidal movements The depth of cut will
be very high for this strategy.
Figure 2 The computer mouse surface model in
NX software
Figure 3 The tool path strategies for the
semi-finish milling process in NX software a) Follow part b) Zigzag c)Follow periphery d) Zig
Trang 4The zig takes a linear path in only one
direction of flow In the zig zag method, the
tool takes a zigzag path at every level of
depth It decreases machining time by
reducing amount of air cutting time (idle
running) The climb and conventional cuts
alternate These tool path types were used in
this research In this research, the free-form
model was designed, and the machining
operation was created in NX software as
shown in figure 3 In this figure, the
machining operations were designed with
four tool path types in order to analyze the
influence of the tool path strategies on
machining time
ANALYSIS RESULTS
After conducting simulation for different tool
path types, the values of the machining time
and the length of the NC program were
calculated and recorded Table 2 shows
numerical values of the parameters for each
of these strategies in the experimental tests.
Table 2 The numerical values of the parameters
for each of these strategies in the experimental tests
The results are also shown in figure 4
Regarding the simulated machining times, the
shortest machining time belonged to the
follow periphery strategy was 881 seconds
because this can be found in the lowest
movements of toward the safe level in Z
direction and tool’s idle movement The
longest machining time, that is 218943 seconds
with the zig strategy because of too many the
non-cutting motions of the cutting tool
EXPERIMENTAL WORKS
In this experimental study, the applied milling
tool was a ball nose mill The tool had a
diameter of 8 mm and two insert flutes made
from micro carbide and coated multi-layered
PVD when milling computer mouse surface C45 workpieces material Experimental conditions were presented in table 3 The figure of actual operation of semi- finish mouse computer surface milling in Lab (Figure 5)
Figure 4 The machining time and the length of
NC codes for the semi- finish milling process in
NX software
The experiment was performed in the Laboratory of Thai Nguyen University of Technology
Table 3 Experimental conditions
Cutting tool P3202- WXM25 Design of cutting tool Ball nose mill Tool diameter d (mm) 8 mm
Helix angle λ (◦) 15 Angle of rake γ (◦) −14 Coating Carbide with
multi-layered PVD Workpiece material C45
Hardness (HRC) 40 - 42
Binder
0,42% C; );15 % Si; 0,5% Mn; 0,025% P; 0,025% S; 0,2% Cr Machine tool Mazak VCS 530C Table Right/Left 1300 mm / 51.180 in Table Longitudinal 550 mm / 21.650 in Spindle Taper 40
Maximum Speed 12000 rpm Number of Tools 30 Travel (X Axis) 1050 mm / 41.34 in Travel (Y Axis) 530 mm / 20.87 in Travel (Z Axis) 510 mm / 20.08 in
Trang 5Table 4 Cutting parameters and machining time
Tool
path
strategies
Cutting
speed
(m/
min)
Feed per tooth (mm/
tooth)
Pick feed (mm)
Machining time
Zig 160 0.02 0.05 1h21'15"
Zigzag 160 0.02 0.05 56'09"
Follow
periphery 160 0.02 0.05 55'39"
Follow
part 160 0.02 0.05 1h21'13''
a)
b)
Figure 5 Some images of experiment
a) Mazak VCS 530C b) The part after miling.
CONCLUSION
This study investigated and compared the
effect of three- axis tool path strategies on the
free-form surface as the simulation of
machining operation in NX software Several
remarks can be outlined as follows:
- The optimal tool path strategy for
computer-mouse surface is the follow periphery method
in three- axis milling aided by using NX
software because the length of NC code is the
smallest compared with others
- The simulation shows that the machining
time is speedy at the convex surface for the
semi- finish milling when choosing the follow
periphery method of the toolpath
The experimental work shows that the machining time when milling using follow periphery tool path strategy is the smallest prepared with three different methods, it is mean that the optimal strategy for each geometry model was selected based on simulation in a CAM software
ACKNOWLEDGMENT The work described in this paper has been supported by Thai Nguyen University of Technology for ĐH2016-TN02-09 project
REFERENCES
1 Mebrahitom A., Rizuan D., M Azmir and M Nassif (2016), “Effect of High-speed Milling tool path strategies on the surface roughness of Stavax ESR mold insert machining, 114, pp 012006
2 Bagci, Eyup; Yüncüoğlu, Ercüment U, (2017) The Effects of Milling Strategies on Forces, Material Removal Rate, Tool Deflection, and Surface Errors for the Rough Machining of Complex Surfaces, Vol 63 Issue 11, p643-656 14p
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