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79:5–2 (2017) 101–104 | www.jurnalteknologi.utm.my | eISSN 2180–3722 |
Jurnal
Teknologi
Full Paper
MECHANICAL PROPERTIES AND CUTTING
PERFORMANCE OF ELECTROLESS TERNARY
NI-W-P COATED CUTTING TOOLS
Mohd Sanusi Abdul Aziza,b*, Bahrin Ikram Redzuwana,
Muhammad Zaimia, Raja Izamshaha, Mohd Shahir Kasima,
Mohd Amran Md Alia, Akira Mizobuchib, Tohru Ishidab
aFaculty of Manufacturing Engineering, Universiti Teknikal
Malaysia Melaka, Melaka, Malaysia
bFaculty of Science and Technology, Tokushima University,
Tokushima, Japan
Article history
Received
30 August 2016
Received in revised form
13 November 2016
Accepted
13 March 2017
*Corresponding author
mohdsanusi@utem.edu.my
Graphical abstract
Abstract
This paper presents a new approach of electroless nickel deposition (END) on cutting tools
as to enhance tool performance. END involves several reactions in aqueous solution and is
performed without using electrical power. The cutting performance of electroless ternary
Ni-W-P alloy-coated cutting tools that were prepared in plating baths with different pH
levels and with the addition of heat treatment was investigated. The cutting tool life was
evaluated during machining on AISI D2 steel followed by measurement of surface
roughness. Experimental results showed that END cutting tools produced from a plating
bath with a pH of 8.5 with heat treatment resulted in the longest tool life, which was 7
minutes 32 seconds, and the lowest surface roughness, which was 0.412 μm. High
deposition rate and high thickness of coating obtained under such pH condition were
found to be the main factors in enhancing tool life. Furthermore, the addition of heat
treatment increases the hardness and improves the coating surface.
Keywords: Electroless nickel deposition (END), electroless ternary N-W-P alloy coating, heat
treatment, tool life, surface roughness
© 2017 Penerbit UTM Press. All rights reserved
1.0 INTRODUCTION
As to survive during challenging market demand, many
manufacturing industries are trying to decrease their
machining costs and improve the quality of machined
parts. There is number of studies that associated with
coating of cutting tool as to prolong the cutter
performance [1-3]. One of the approaches in improving
cutting performance is by depositing a single or multi-
layer of hard material coating on cutting tool substrate
which widely applied on tungsten carbide (WC)[4]. The
coated cutting tool shows lower friction than uncoated
cutting tool hence reduce thermal generation and
cutting force especially at the chip-cutting tool
interface [5]. Physical vapour deposition (PVD) and
chemical vapour deposition (CVD) are two of the well-
known coating techniques that are widely used in
manufacturing coated cutting tools but they are
comparatively expensive to install and require skilled
operators [6].
Normally, the cutting tool was coated by mean of
PVD and CVD. However, electroless nickel deposition
(END) is less to be reported. This coating method
involves several reactions in aqueous solution without
using electrical power [7]. Normally, END process is
performed by depositing a layer of nickel-phosphorus
alloy on a metal, where it depends on sodium
hypophosphite dihydrate (NaH2PO2∙2H2O) as a
reducing agent to react with metal ions for deposition
on metal [7]. END offers advantages over coating
features, such as producing a uniform coating layer,
and its resistance to wear, friction and corrosion, and it
Plating bath of
electroless
ternary Ni-W-P
Uncoated tungsten carbide insert
102 Mohd Sanusi Abdul Aziz et al. / Jurnal Teknologi (Sciences & Engineering) 79:5–2 (2017) 101–104
is also a cost-effective process [8-10]. Moreover, a study
on ternary Ni-W-P alloy in END process showed that it
also can be useful for other mechanical properties of
coatings [11]. Initially, END has been practiced in many
engineering applications such as aerospace,
automotive, chemical and food processing industries
[12] but its implementation on cutting tools is still limited.
Because of the advantages and feasibility of END, it
was recommended to be applied in cutting tool since
the process is simple and can be rebuilt on the worn
area. However, the process requires the inclusion of
heat treatment as to increase the coating hardness as
high as 1100 Hv [13].
This research aims to investigate the cutting
performance of electroless ternary Ni-W-P alloy-coated
cutting tools that were prepared in plating baths with
different pH levels and with the addition of heat
treatment. The cutting performance was evaluated by
machining them on AISI D2 steel followed by
measurement of the tool life and surface roughness of
each cutting tool.
2.0 METHODOLOGY
2.1 Preparation of END Coated Cutting Tool
Figure 1 shows the process of coating cutting tool with
electroless ternary Ni-W-P alloy. A 10 mm diameter of
uncoated tungsten carbide insert (QPMT 10T335 PPEN)
with hardness of 1630 Hv was used as a substrate in the
electroless deposition process. The composition of
plating bath and operating condition are described in
Table 1. The electroless ternary Ni-W-P alloy was
deposited on the tungsten carbide insert in an acidic
plating bath (pH 4.75) or alkaline plating bath (pH 8.50)
for 1 hour at a temperature of 358±2 K. Then, heat
treatment was applied to each ternary nickel alloy for 1
hour at a temperature of 623 K. A total of 4 types of
samples were produced. Table 2 summarizes the
specimens to be analysed on cutting performance.
Figure 1 Electroless deposition process of ternary Ni-W-P alloy
2.2 Evaluation of Cutting Performance
The cutting performance of each sample was
evaluated by performing a cutting process on AISI D2
steel. The cutting parameters to be used in this
experiment are described in Table 3. The machining
experiment was conducted using a CNC milling
machine under dry condition. The tool life of each
cutting tool was determined by measuring flank wear
on cutting edge throughout the experiment. The
process was continued until the flank wear reached 0.3
mm, which is considered as tool failure [14]. The
machining time was recorded as to observe the tool life
under specific cutting condition. As to observe the
relationship between the tool life and surface finish, the
surface roughness of the machined part was measured
by portable surface roughness tester (Mitutoyo Corp.:
Surftest SJ-301).
Table 1 Plating bath composition and condition
Plating Bath Component
Nickel Sulphate Hexahydrate
(NiSO4· 6H2O)
0.10 M
Sodium Hypophosphite Dihydrate
(NaH2PO2· 2H2O)
0.28 M
Trisodium Citrate Dihydrate
(Na3C6H5O7· 2H2O)
0.20 M
Ammonium Sulphate
(NH4)2SO4
0.50 M
Sodium Tungstate Dihydrate
(NaWO4· 2H2O)
0.01 M
Operation Condition
Bath temperature [K]
358±2
Deposition time [s]
3600
Table 2 Samples of END coated tools
Sample Name
Plating
Bath pH
Heat Treatment
Condition
T-pH4.75
4.75
-
T-pH4.75-HT
4.75
623 K for 1 hour
T-pH8.50
8.50
-
T-pH8.50-HT
8.50
623 K for 1 hour
Uncoated (for comparison)
-
-
Table 3 Cutting conditions
Cutting speed v
125 m/min
Feed rate f
0.08 mm/tooth
Axial depth of cut dA
1.5 mm
Radial depth of cut dR
2.5 mm
Workpiece
AISI D2 Steel
Environment
Dry cutting
3.0 RESULTS AND DISCUSSION
3.1 Mechanical Properties
The result of the experiment shows the electroless
ternary Ni-W-P alloy was successfully deposited on the
tungsten carbide inserts in acidic and alkaline plating
baths. Figure 2 shows the cross-sections of both samples
and the coating thickness were measured from the line
scan analysis. The rate of deposition, coating thickness
and hardness of coated tools deposited in acidic and
alkaline plating baths were ranged between 5.6 – 19.6
µm/hr, 10 – 60 µm, 638 – 858 Hv, respectively as shown
in Figure 3. The deposition rate and the coating
thickness were high when the END process was
Uncoated tungsten carbide insert
Plating bath
103 Mohd Sanusi Abdul Aziz et al. / Jurnal Teknologi (Sciences & Engineering) 79:5–2 (2017) 101–104
performed in the alkaline plating bath with 19.6 µm/hr
and 60 µm, respectively. On the other hand, the highest
hardness of 858 Hv was obtained by the tool deposited
in the acidic plating.
Heat treatment was carried out for both conditions. The
hardness after heat treatment was found to be
increased by 10% and this was due to the increment of
crystallinity from the segregation of elements [15].
However, there was no significant change in the
coating thickness after the heat treatment on both
samples.
3.2 Tool Life
Figure 4 shows the tool wear progression for each
coated cutting tool. Each sample was machined until
the tool wear reached 0.3 mm. From the graph, it was
found that the samples produced in the acidic plating
bath, T-pH4.75 and T-pH4.75-HT resulted in shorter tool
life than the uncoated tool by 2 minutes. The sample
produced in the alkaline plating bath without heat
treatment, T-pH8.50 can be last for only about 57
seconds. Coated tool produced in the alkaline plating
bath with heat treatment recorded as the longest tool
life, which was 7 minutes 32 seconds. It shows that the
coated cutting tool improved by about 40% of tool life
compared to the uncoated cutting tool.
Figure 5 shows the comparison of wear rate between
the cutting tool T-pH8.50-HT and other coated carbide
tools which were coated with CVD and PVD. It was
found that PVD has the lowest wear rate followed by T-
pH8.50-HT, CVD and the uncoated tool. Among these
coated tools, PVD has the superior hardness, and as the
previous result indicated that the heat treatment
addition on END coated tool has increased the layer
hardness by about 10%. This result indicated that the
electroless ternary Ni-W-P alloy-coated cutting tool is
competitive with other coating processes.
Figure 4 Tool wear progression of electroless ternary Ni-W-P alloy-coated cutting tool
Figure 2 SEM line scan analysis of cross-section
Figure 3 Hardness, deposition rate and thickness of coatings
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
012345678
Tool wear [mm]
Cutting time [min]
T-pH4.75
T-pH4.75-HT
T-pH8.50
T-pH8.50-HT
Uncoated
Cutting condition:
Cutting speed, v= 125 m/min, Feed rate, f = 0.08 mm/tooth
Axial depth of cut dA= 1.5 mm, Radial depth of cut dR= 2.5 mm
Dry cutting
100 μm100 μm
WNi PCWNi PC
(a) T-pH4.75 (b) T-pH8.50
0
10
20
30
40
50
60
70
0
200
400
600
800
1000
T-pH4.75 T-pH8.50
Deposition rate [µm/hr]
Coating Thinckness [µm]
Hardness [Hv]
104 Mohd Sanusi Abdul Aziz et al. / Jurnal Teknologi (Sciences & Engineering) 79:5–2 (2017) 101–104
Figure 5 Comparison of wear rate
3.3 Surface Roughness
Figure 6 shows the average surface roughness of
electroless ternary Ni-W-P alloy-coated cutting tools
and an uncoated tool. From the graph, it can be seen
that the average surface roughness of the samples
produced in the acidic plating bath, T-pH4.75 and T-
pH4.75-HT, was slightly higher than that of the uncoated
tool, whereas the cutting tool deposited in the alkaline
plating bath without heat treatment, T-pH8.50, had the
highest average surface roughness. Furthermore, T-
pH8.50-HT had the smallest average surface roughness,
which was 0.412 μm. The surface roughness of AISI D2
steel improved by about 27% when machined using a
heat-treated coated tool deposited in a plating bath
with a pH of 8.50. It was understood that the heat
treatment of electroless ternary Ni-W-P alloy deposited
in a plating bath with a pH of 8.50 produced a smoother
surface compared to the previous heat treatment [15].
Figure 6 Average surface roughness of samples.
4.0 CONCLUSION
The cutting performance of electroless ternary Ni-W-P
alloy-coated cutting tools produced in acidic and
alkaline plating baths was experimentally investigated.
The conclusion can be rendered as follows:
1. Electroless ternary Ni-W-P alloy-coated cutting tools
prepared using an alkaline plating bath (pH 8.50)
produced higher coating thickness than tools
prepared in an acidic plating bath (pH 4.75) and the
implementation of heat treatment increased the
hardness by about 10%.
2. Electroless ternary Ni-W-P alloy-coated cutting tools
prepared in a plating bath with a pH of 8.50 with
heat treatment resulted in the highest tool life, which
was 7 minutes 32 seconds. The tool life increased by
about 40% compared to the uncoated cutting tool.
3. Electroless ternary Ni-W-P alloy-coated cutting tools
prepared in a plating bath with a pH of 8.50 of with
heat treatment resulted in the lowest surface
roughness, which was 0.412 μm. This was influenced
by the smoother surface of the coated layer
produced after the heat treatment.
Acknowledgement
The authors are grateful to Universiti Teknikal Malaysia
Melaka for their technical and financial support. This
project is funded by UTeM short term grant (Project No.
PJP/2013/FKP(15B)/S01219).
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0.654 0.666
1.189
0.412
0.566
0
0.2
0.4
0.6
0.8
1
1.2
1.4
T-pH4.75 T-pH4.75-HT T-pH8.50 T-pH8.50-HT Uncoated
Average surface roughness, Ra μm
0.0564
0.0399
0.0506
0.0322
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Uncoated T-pH8.50-HT CVD PVD
Wear rate mm/min
