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H.S. Manohar, N.Chikkanna, B.Uma Maheswar Gowd / International Journal of Engineering
Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com
Vol. 2, Issue 5, September- October 2012, pp.1360-1370
Effect of Addition of Nanoclay on Machinability of Al/Nanoclay
Metal Matrix Composites

H.S. Manohar 1, N.Chikkanna 2, B.Uma Maheswar Gowd 3
1
(Asst. Professor, Dept. of Mech. Engg. CMR Institute of Technology- Bangalore-560037).
2
(Principal, Government Engineering College Hoovinahadagali, Bellary-583219)
3
(Rector (I/C) Jawaharlal Nehru Technological University- Anantapur-515002).

ABSTRACT
In this study, machinability test was deeper understanding of the effects of nanoclay
conducted on Al-Nanoclay metal matrix particles on machinability forces and Chip
composites using lathe tool dynamometer. formation with varied machining parameters when
Composites were prepared with aluminium as cutting nanoclay / Al MMC specimens.
the matrix and nanoclay particles with 2, 4, 6
percentage by weight as reinforcement. The II. EXPERIMENTAL DETAILS
effect of clay particles and machining parameters The matrix material used for the MMCs in
such as cutting speed, feed rate and depth of cut this study, Al, has excellent casting properties and
on tangential force and chip formation was reasonable strength. This alloy is best suited for
studied. From the results it is observed that the mass production of lightweight metal castings.
tangential force applied by the tool on MMC, chemical composition of Al6061 shown below
facilitate chip breaking and the generation of
chips significantly depends on feed but almost  Silicon minimum 0.4%, maximum 0.8% by
independent of speed. These results reveal the weight
roles of the nanoclay reinforcement particles on  Iron no minimum, maximum 0.7%
the machinability of MMCs and provide a useful  Copper minimum 0.15%, maximum 0.40%
guide for a better control of their machining  Manganese no minimum, maximum 0.15%
processes.  Magnesium minimum 0.8%, maximum
1.2%
Keywords –Cutting Speed, Chip breaking,  Chromium minimum 0.04%, maximum
Depth of Cut, Feed rate, Machinability 0.35%
 Zinc no minimum, maximum 0.25%
I. INTRODUCTION  Titanium no minimum, maximum 0.15%
Amongst the material variables, the  Other elements no more than 0.05% each,
mechanical properties of fiber and matrix, 0.15% total
particularly the failure strains, interface properties  Remainder Aluminum
and fiber configuration play important role in
determining fracture resistance and damage The nanoclay of 10-60 nm size were used
tolerance of the composites[1-2]. Nanostructure as the reinforcement and the nanoclay content in
materials such as nanocomposites provide the composites was varied from 2 to 6% in steps of
opportunities to explore new fracture behavior and 2% by weight. Liquid metallurgy technique was
functionality beyond those found in conventional used to fabricate the composite materials in which
materials. The presence of small amounts of the clay particles were introduced into the molten
nanoparticles in metal matrix can improve the wear metal pool through a vortex created in the melt by
resistance and hardness of composites. Obviously, the use of an alumina-coated stainless steel stirrer.
the higher the hardness of the material, the more the The coating of alumina on the stirrer is essential to
abrasive wear experienced by the cutting tool in
prevent the migration of ferrous ions from the stirrer
addition. Nevertheless the incorporation of the
material into the molten metal. The depth of
microsize hard particles makes the machining of immersion of the stirrer was about two-thirds the
MMCs difficult [3], and diamond tools are often depth of the molten metal. The stirrer was rotated at
necessary [4]. There have been some investigations
550 rpm. The pre-heated (500 C) nanoclay particles
on the machining of MMCs, dealing with tool wear
were added into the vortex of the liquid melt which
[5], surface / subsurface quality [6] and chip
was degassed using pure nitrogen for about 3 to 4
formation [7]. However until now, no particular
min. The resulting mixture was tilt poured into
work is done exclusively to assess the importance of
preheated permanent moulds.
nanoclay content on the machinability parameters.
The objective of the present research is to gain a

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III. MACHINABILITY TEST
the tangential cutting force and are therefore not
reported.
Fig.2. shows the results for the machining of plain
aluminium at depths of cut of 0.2, 0.5, 0.8 and 1 mm
respectively. It can be seen that there is a general
trend of increase in tangential cutting force with
increase in cutting Speed. The cutting force also
tends to increase as federate or depth of cut is
increased.
The few anomalous cases can be attributed
to experimental error. The same trend can be seen in
Figs.3, 4,and 5 for composites with 2, 4 and 6%
nanoclay reinforcement. i.e tangential cutting force
increases with increase in cutting speed, federate
and depth of cut.
The number of chips produced per gram
when machining the composites under specified
conditions, increases with the increase of amount of
nanoclay in the composites as shown in the Fig. 6
The nanoclay particulate apparently introduces
discontinuities in the material and act as stress
raisers, There by resulting in the frequent fracture of
chips during machining.
The production of small chips is one of the
Fig. 1. Experimental set up criteria of good machinability since very long chips
have a tendency to wrap around the tool at high
Machinability test was carried out by machining speeds limiting the rate of machining; the
turning the specimens in a CNC lathe. The cutting aluminum industry is constantly in need of fast
speeds selected were 200, 315, 400 and 500 rpm. machining alloys.
The depth of cut was 0.2, 0.5, 0.8 and 1 mm and the
feed-rates were 0.1, 0.2, 0.32 and 0.4 mm/rev. The
cutting forces (namely, the tangential, axial and
radial forces) in three perpendicular directions were
measured by means of a computer interfaced
dynamometer on which cutting tool was mounted.
The cutting tool material was high-speed carbide
tool. The tool signature is follows

Brake rake angle 8,
Side rake angle 20.5
End clearance angle 12
Side cutting angle 10
Slide cutting angle 75
End cutting angle 80
Nose radius 1 mm

The number of chips produced per gram of
the material removed was counted.

IV. RESULTS
Because of the large volume of results
obtained, only the values of the tangential cutting
force for various cutting speeds, federates and depth
of cut are presented. The axial and radial cutting
forces were consistently more or less proportional to

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Tangential Force in N

Feed rate in mm/rev
Fig. 2. Typical plot of tangential force vs. feed rate for Al matrix alloy .

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160
140 Depth of cut = 0.2 mm
120
100
80
60
40 Cutting speed in rpm
20 200 315 400 500
0
160 0.1 0.15 0.2 0.25 0.3 0.35 0.4
140 Depth of Cut = 0.5 mm
120
100
80
60
20 200 315 400 500
0
300 0.1 0.15 0.2 0.25 0.3 0.35 0.4
250 Deptha of cut = 0.8 mm

200
150
100
Cutting speed in rpm
50
200 315 400 500
0
0.1 0.15 0.2 0.25 0.3 0.35 0.4

Feed rate in mm/rev
Fig. 3. Typical plot of tangential force vs. feed rate for Al/2% nanoclay

Composites.

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Feed rate in mm/rev
Fig. 4. Typical plot of tangential force vs. feed rate for Al/4% nanoclay

Composites.

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200
Depth of cut = 0.2 mm
150

100

200 315 400 500
0
200 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Depth of Cut = 0.5 mm
150

100


200 315 400 500
0
3000.1 0.15 0.2 0.25 0.3 0.35 0.4
Deptha of cut = 0.8 mm
250
200
150
100
Cutting speed in rpm
50
200 315 400 500
0
0.1 0.15 0.2 0.25 0.3 0.35 0.4

Feed rate in mm/rev

Fig. 5. Typical plot of tangential force vs. feed rate for Al/6% nanoclay composites.

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Fig. 6 Number of chips per gram of nanoclay dispersed in Al MMCs as a
function of speed.

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Table 1. Experimentally obtained machining force (Tangential force) for Al matrix and
Al/nanoclay MMCs

Specimen Al matrix alloy Al/2% nanoclay Al/4% nanoclay Al/6% nanoclay
Feed rate
0.1 0.2 0.32 0.4 0.1 0.2 0.32 0.4 0.1 0.2 0.32 0.4 0.1 0.2 0.32 0.4
mm/sec

Speed,
Dept of cut = 0.2 mm
rpm

200 29 69 78 108 39 78 88 117 42 82 92 125 52 89 98 132

315 39 69 98 128 49 73 113 142 53 78 125 154 62 90 135 164

400 79 88 98 108 81 93 101 112 91 104 125 135 102 113 132 148

500 88 98 103 111 93 103 105 113 97 108 109 119 105 125 148 160


200 39 59 98 122 42 62 102 132 50 84 112 148 62 95 121 170

315 59 88 108 124 62 94 112 132 71 95 120 135 80 102 140 183

400 88 108 112 126 94 112 121 136 101 119 131 145 101 119 131 145

500 108 110 118 134 109 112 121 145 111 121 131 152 125 142 178 188


200 49 88 108 141 52 92 109 145 59 102 112 152 68 103 125 163

315 69 108 125 157 72 108 132 161 74 112 138 178 98 125 141 179

400 108 128 137 154 109 132 143 167 111 138 154 171 123 141 163 178

500 108 128 195 231 112 132 203 245 121 142 204 254 132 154 205 255

Dept of cut = 1 mm

200 88 89 110 117 93 98 121 132 101 102 132 142 111 121 135 154

315 108 119 132 144 115 125 136 154 121 142 158 181 128 154 162 198

400 128 137 225 261 132 145 234 275 142 158 178 270 154 163 197 281

500 147 164 271 318 156 175 284 325 188 195 281 332 198 205 298 354

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Table 2. Number of chips/gram formation during machining of Al matrix and Al/nanoclay
MMCs
Specimen Al matrix alloy Al/2% nanoclay Al/4% nanoclay Al/6% nanoclay
Feed rate 0.1 0.2 0.32 0.4 0.1 0.2 0.32 0.4 0.1 0.2 0.32 0.4 0.1 0.2 0.32 0.4
mm/sec
Speed, Dept of cut = 0.2 mm
rpm

200 222 160 142 59 303 228 202 101 571 421 375 192 756 562 510 298

315 139 106 75 42 252 201 130 87 413 335 209 142 669 551 367 253

400 59 53 48 43 101 91 84 73 136 126 105 92 302 269 230 208

500 33 31 29 26 72 67 65 59 52 47 47 42 248 230 194 163

200 250 201 121 80 342 264 161 109 677 512 384 229 974 693 544 355

315 135 117 95 64 234 199 167 110 362 322 255 190 747 571 416 326

400 69 61 59 48 123 109 101 85 147 132 120 102 296 267 243 206

500 40 35 33 32 92 77 71 69 66 57 52 48 292 276 220 194

200 289 222 181 101 376 282 238 135 695 512 466 270 934 716 590 390

315 170 136 117 75 286 234 192 128 477 370 300 198 730 575 510 400

400 84 75 70 59 151 129 119 98 173 156 140 112 363 332 288 251

500 68 58 38 32 155 129 84 71 110 88 61 52 396 318 239 205
Dept of cut = 1 mm

200 240 226 183 181 342 313 254 241 649 603 466 462 883 774 693 636

315 156 143 129 117 273 241 222 204 485 423 380 324 808 661 628 522

400 142 123 75 70 248 211 131 119 273 180 160 144 573 402 332 314

500 94 80 49 44 206 180 111 99 144 122 84 81 550 463 318 307

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V. DISCUSSION
It has been reported that no specific The nature of the chip formed during machining of
relationship exists between the cutting forces and the composite as well as the matrix alloy changes
cutting speed in the beginning of the machining with extent of the tool wear. When the tool is
process. It was found that the cutting forces sharp, long washer type helical chips are formed,
increase with increasing cutting speed while sometimes accompanied by small amount of
machining the composites. This is due to increase washer type helical chip flow by the tool holder.
in effective area of contact between the tool and the Once the tool starts getting blunt, chip formed
work piece which indirectly increases frictional changes into short washer helical type. It is mainly
forces at the tool-work piece interface [8]. The due to that Al alloy is relatively softer and tends to
variation in the effective contact area at the tool- adhere to the face of the cutting tool during
cutting surface explains the high force components machining. The material begins to pile-up on the
involved in machining. tool resulting in a longer chip [13]. The nanoclay
The test results show that the magnitude reinforcement content in the composite probably
of forces measured during the machining of avoids the occurrence of shearing ahead of the
composite material is more when compared to the cutting tool continuously without fracture and
base alloy. However, the increase in the amount of causes rapture intermittently producing segments of
force is not too high in the case of matrix alloy but chips with smaller lengths. Hence the composite
in the case of particulates reinforced composites it material which produces shorter chips without chip
is very high [9]. The tool life is limited by the breakers is well suited for industrial applications.
amount of wear the tool experiences.
Examination of the wear land on the tool VI. CONCLUSIONS
tip showed significantly scratched grooves parallel  The power consumed for machining the
to the direction of chip flow and work piece composite is higher than that of the
movement. Such grooves are usually found in unreinforced alloy.
Metal Matrix Composites (MMCs) reinforced with  The work required for machining under similar
hard dispersoids like nanoclay and are formed by cutting condition increases for the composite
the mixture of two-body and three-body abrasion when compared to the unreinforced matrix.
between the work piece and the tool which is  Frictional force is seen to increase in the case
mainly due to the hard nature and irregular shape of of the composite and to reduce it cutting
the reinforcement and the loose reinforcement conditions need to be optimized.
found during machining. Since glass short  Shear strain is minimum under the optimized
particulate reinforcement is also a hard cutting condition for the composites.
reinforcement, obviously grooves were found  Material removal rate increases with the depth
parallel to the direction of chip flow [10]. of cut and speed for the composites when
The cutting speed has a more dominant compared to the unreinforced alloy matrix.
influence on the volume of the material removal  Power consumption and tool wear are higher
rate. If maximum cutting time between the tool for composites than that for the matrix alloy.
changes is needed, a lower feed rate is preferable.
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machining of particulate reinforced AUTHORS INFORMATION
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