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EXPERIMENTAL INVESTIGATION

VIEWS: 4 PAGES: 11

									       INTERNATIONAL Engineering and Technology (IJMET), ISSN
 International Journal of MechanicalJOURNAL OF MECHANICAL 0976 –
 6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), © IAEME
          ENGINEERING AND TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 3, Issue 2, May-August (2012), pp. 189-199
                                                                     IJMET
© IAEME: www.iaeme.com/ijmet.html
Journal Impact Factor (2011): 1.2083 (Calculated by GISI)
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                                                                 ©IAEME



      EXPERIMENTAL INVESTIGATION ON RESPONSES IN
   TURNING OF ALUMINIUM WITH CARBIDE TIPPED TOOL AT
            DIFFERENT COOLANT CONDITIONS
                                    K.Dharma Reddy
                         Research Scholar and Assistant Professor

                                  *Dr.P.Venkataramaiah
                                   Associate Professor

                        Department of Mechanical Engineering
                 Sri Venkateswara University College of Engineering,
                       Tirupati, Andhra Pradesh, India-517502.
 *Corresponding author

 ABSTRACT

         Turning is a widely used metal removal process in manufacturing industry that
 involves generation of high cutting forces and temperature. Lubrication becomes critical
 to minimize the effects of these forces and temperature on life of cutting tool and,
 Surface finish of work. In metal industry, the use of coolant has become more
 problematic in terms of both workpiece quality, employee health and environmental
 pollution. In the present work, chip tool interface temperature was measured for three
 different lubricant conditions such as dry, wet, and Minimum quantity lubrication. Later
 has been proved to be a feasible alternative to the conventional cutting fluid system. In
 the present work 10% boric acid by weight mixed with base oil SAE 40 is used as a
 MQL in turning process. Variations in cutting force, cutting temperature, chip thickness
 and surface roughness are studied under different machining and coolant conditions. The
 results indicate that there is a considerable improvement in machining performance
 under MQL machining compared to dry and wet machining.

 Keywords: Turning ,dry, wet, MQL, Temperature

 1. INTRODUCTION
       A new alternative to traditional use of cutting fluids is Minimum Quantity
 Lubricant (MQL), also known as Near Dry Machining (NDM) or semi-dry machining.
 MQL uses a very small quantity of lubricant delivered precisely to the cutting surface.

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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), © IAEME

Improvements in chip recycling, reduction of electricity consumption, increased tool
life, a "greener” environment, and a decrease of machine maintenance due to
contamination by coolant are very much essential, to the metal cutting industry.
Different work piece materials with different property and microstructure have different
effect on cutting tool performance. No general equation can be available to estimate the
tool life for a given tool grade, cutting condition and work piece material. In this work,
carbides tipped tools are used in machining of Aluminum work piece under Dry, Wet
and MQL conditions. Different researchers investigated the influence of cutting fluid in
cutting of metals is reviewed as follows. Itoigawa, etal [1] are investigated the effects of
MQL in intermittent turning of AL. Liang Liang, etal [2] used the finite difference
solution and an inverse procedure to determine the tool-chip interface temperature.
A.Liljerehn, etal [3] used analytical model for prediction of heat generation in the
primary and secondary deformation zones, results obtained from finite element
simulations are compared with temperatures measured using IR-CCD camera. F.
Akbar,etal [4] investigated the tool-chip interface temperature and Heat Partition in
High-speed Machining. H. Zhao, etal [5] The effects of the heat sink intensity, heat sink
distance from the tool-chip interface, and heat sink area on the tool-chip interface
temperature have been investigated. It was found that the internal cooling with a heat
sink in the cutting tool could greatly affect the tool-chip interface temperature. R.
M'Saoubi, etal[6] found a new method for cutting tool temperature measurement using
ccd infrared technique..Junzhan Hou, etal[7] measured the mean flank temperature
through mounting two K-type thermocouples in work piece of AM50A magnesium
alloy. W.Grzesik,etal [8] A finite difference method was proposed to model the effect
of a variety of tool coatings on the magnitude and distribution of temperatures through
the tool-chip contact region and the coating/substrate boundaries. J.-L. Battaglia etal[9]
The temperature at the tip of a tool used in a turning process are estimated from
temperature measurements in an interior point of the tool insert.J.C.Outeiro, etal[10]
presents the experimental analysis of the temperature distribution in the three-
dimensional cutting process. H. A. Kishawy[11] investigated experimentally the effects
of different process parameters on the cutting edge temperature during high speed
machining of D2 tool steel using polycrystalline cubic boron nitride (PCBN) tools. H. A.
Kishawy, etal[12] investigated the effect of process parameters, tool geometry and edge
preparation on the contact mechanics at the chip/tool interface.Haj Elmoussami[13]
presents an experimental technique for the estimation of the average temperature on the
cutting edge of each insert in a milling tool. Tien-Chien Jen, etal [14] analysed
interrupted cutting tool temperatures. Lorraine Olson etal [15] estimated the tool/chip
interface temperatures for on-line tool monitoring.After the review,this work
concentrated on study of response, like temperature, surface finish and force in turning
of Aluminium of different lubricating conditions.

2. Methodology
2.1 Cutting fluids and lubricants
During the metal cutting process heat is generated due to deformation of the material
ahead of the tool and Friction at the tool point. Heat generated due to friction can readily
be reduced by using a lubricant.In the pursuit of environmental, profit, safety, and
convenience a number of alternatives to traditional machining are currently under
development. Dry machining has been around for as long as traditional machining but
has seen a recent surge in interest as more people are realizing the true cost of cutting
fluid management. There are some alternatives to replace cutting fluids such as dry

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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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machining, minimum quantity lubricant and liquid nitrogen technology.MQL is
alternative to traditional use of cutting fluids. As the name implies MQL uses a very
small quantity of lubricant delivered precisely to the cutting surface. Often the quantity
used is so small that no lubricant is recovered from the piece. Any remaining lubricant
may form a film that protects the piece from oxidation or the lubricant may vaporize
completely due to the heat of the machining process. With the large volumes of cutting
fluid used in traditional machining, misting, skin exposure and fluid contamination are
problems that must be addressed to assure minimal impact on worker health.
             In the present work, boric acid is used as coolant, it is one of the most
popular solid lubricants and has excellent lubrication properties without calling for
expensive disposal techniques. The most important characteristics of boric acid for use
as a lubricant are that it is readily available in cheap and environmentally safe. Several
studies related to the lubrication properties of boric acid are carried out over the past
several decades. This work also focused on the performance of boric acid in high
temperature applications. The studies indicated that boric acid is unique layered inter-
crystalline structure makes it a very promising solid lubricant material because of its
relatively high load carrying capacity and low steady state friction coefficient (0.02).

2.2 MATHEMATICAL MODEL OF SHEAR PLANE TEMPERATURE IN
ORTHOGONAL CUTTING

      In the present work to check the validity of experimental results the following
mathematical model has been used.

       The temperature rise at the shear plane can be approximately estimated by
assuming a thin zone model of metal cutting and by assuming a uniform rise of
temperature all over the shear plane. Losses due to conduction may be taken into
account by multiplying the heat generated with a factor.
Let Es be the energy per unit volume dissipated at the shear plane, then
                                  λ Es
                 θs =                             + θi                     (1.1)

                                 J     Cw
               Where θs = Temperature at shear angle

               θi = Initial temperature of work piece (not consider at primary
zone)
               λ = factor representing the fraction of heat retained by the chip
               J = heat equivalent of mechanical energy = 4.2 N-m/cal
                   = density of work material
               Cw = specific heat of work material
The value of Es is given by
                              Fs.Vs
                  Es =                  N-m/cm³                             (1.2)
                              b.t.v



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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), © IAEME

Where Fs is the shear force in N on the shear plane and Vs is the shear velocity in
m/min, b is the width of cut in mm, t is uncut chip thickness in mm and V is the
cutting velocity in m/min. Otherwise

                                  K cosα
                Es =                             N/mm²                   (1.3)
                                 SinØ cos (Ø – α)


                  K = yield strength of material in N/mm²

                                r cosα                                   (1.4)
                TanØ =
                               1- r sinα
                When it is rake angle of tool (It is considered as10°)


                                  Depth of cut (d)
 Chip thickness ratio (r) =
                                 Chip thickness (tc)




                                                 Cosα
 Shear strain on the shear plane εs =                                     (1.5)
                                           SinØ cos (Ø – α)
Using above models the cutting parameters are calculated as shown in table.8.The
results obtained from mathematical model are compared with experimental
results. (See Table. 8 and figure.10)

3. EXPERIMENTAL WORK

The Experiment is conducted at different conditions like dry, wet and Minimum
lubricant (Boric acid 10% with base oil SAE40) for different cutting speeds. The
cutting temperature, cutting force,chip thickness,surface finish are measured and
recorded. Setup for measuring temperature and cutting force is shown in Fig.1and
fig.2.




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  Fig.1 Experimental setup for measuring         Fig.2 Tool lathe Dynamometer
        chip-tool interface Temperature          measures Cutting force

Table: 1 Experimental conditions


        1 Type of Machine          Lathe full details

        2 Tool used                Carbide insert

        3 Work-piece material Aluminium-6082

        4 Cutting fluid used       Mineral oil and SAE-40

 3.1 Measurement of responses in turning
 (i)Measurement of forces
        The forces acting on the tool have been measured using an Kistler Force
 Dynamometer.The dynamometer senses all the three forces viz. feed
 force(Fx),cutting force(Fy), and thrust force (Fz) generated during the cutting.
 Values of these forces are recorded while turning(Table.7.1,7.2,7.3).
 (ii)Measurement of surace finish
        The surface quality of the machined surface has been measured using
 Mitutoyo surface roughness tester. The tester consists of a flat table, tracer with
 drive unit and recorder. The machined flat surface to be tested was kept on the
 table by adjusting the tracer arm. The stylus traces the machined surface in the
 direction of feed motion. The stylus moves over the surface of work piece for a
 limited length of 0.8mm. The arithmetic mean deviation in micrometers was
 recorded as in Table.6.
 (iii)Measurement of chip thickness
        Chip thickness was measured with out side micrometer, of MITUTOYO
 more precise measuring instrument (Table.5)
 4.Experimental Results
 The experimental values for various parameters are recorded and graphs are
 plotted as follows.




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  International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
  6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), © IAEME

Table 1 Experimental values of temperature
at dry condition. Depth of cut = 1.0mm
            Cutting        Feed          Temperature (°C)
  speed (m/min)(RPM)       Rate
                                          Length of Cut
                         (mm/rev)
                                             (mm)
                                     20     40    60    100
       21 (228)                 1
                                     37     44    58      57
       34 (360)               0.8
                                     45     57    68      78
       42 (450)            0.65
                                     51     64    78      87
       55 (580)               0.4
                                     53     66    85      80
       70 ( 740)              0.2
                                     45     58    68      73
        6 (800)               0.1
                                     43     54    67      76


Table 2 Experimental values of                                           Fig .1 Variation of cutting
temperature at Wet condition                                             Temperature with Length of
                                                                         Cut under dry condition

      Cutting            Feed        Temperature(°C)
                         Rate
   Speed (m/min)                    Length of Cut (mm)
      (RPM)             (mm/rev)
                                    20     40    60    100
      21 (228)             1
                                    29     37    41    45
      34 (360)            0.8
                                    32     36    43    49
      42 (450)            0.65
                                    34     46    40    49
      55 (580)            0.4
                                    34     38    48    52
      70 ( 740)           0.2
                                    28     30    41    45
      76 (800)            0.1
                                    26     28    42    40

Table 3 Experimental values of                                           Fig .2 Variation of cutting
Temperature with temperature in MQL condition.                           Length of Cut under Wet
                                                                                Condition

      Cutting          Feed Rate    Temperature (°C)
 Speed m/min (RPM)     (mm/rev)     Length of Cut(mm)
                                    20     40    60    100
      21 (228)            1
                                    28     30    35    43
      34 (360)            0.8
                                    29     31    38    42
      42 (450)           0.65
                                    33     36    40    39
      55 (580)            0.4
                                    32     35    45    40
     70 ( 740)            0.2
                                    26     29    35    38
      76 (800)            0.1
                                    27     28    33    30

                                                                     Fig. 3 Variation of cutting
                                                                            Temperature with Length of
                                                                            Cut under MQL condition


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  International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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Table 4 Experimental Values of
Temperature at shear Zone for                                                                        Dry
different conditions.
     Cutting            Feed           Average Temperature
                        Rate                   (°C)                                                        Wet
  Speed m/min
     (RPM)          (mm/rev)
                                                           MQL
                                      Dry         Wet
                                                                                                         MQL
                                       49          38       34
     21 (228)             1
     34 (360)            0.8           62          40       35
     42 (450)           0.65           70          42       37
     55 (580)            0.4           71          43       38
 70 (740)                0.2           61          36       32
     6 (800)             0.1           60          34       29

Table 5 Experimental Values of               Fig.4 Variation of cutting Chip thickness
for depth of cut=1mm           Temperature with speed under dry, wet, MQL conditions

   Cutting        Feed                    Average Chip
                  Rate                    Thickness(mm)                                  DRY
 Speed m/min
   (RPM)          (mm/re            Dry           Wet
                                                           MQL                                                   WET
                    v)

   21 (228)         1              0.5674         0.415    0.347
   34 (360)        0.8             0.462          0.343    0.325
   42 (450)        0.65            0.3698         0.475    0.314                                                 MQL
   55 (580)        0.4             0.352          0.355    0.125
   70 ( 740)       0.2             0.514          0.268    0.41
   76 (800)        0.1             0.439          0.387    0.33

Table 6 Experimental values of Surface                               Fig.5 Variation of Chip thickness
Roughness different speeds and feed rates                               with Feed under Dry, wet,
at Dry, Wet and MQL condition.                                                   MQL conditions
Depth of cut = 1.0mm
                                                                                                   MQL
      Cutting              Feed             Surface Roughness                                                    WET
                           Rate                   (µm)
   Speed m/min
   m/min (RPM)           (mm/rev)           Dry     Wet    MQL


      21 (228)                 1            2.6     2.73   2.01

      34 (360)             0.8            1.586     2.23   1.55
                                                                                                            DRY
      42 (450)             0.65             1.2     2.38   1.52

      55 (580)             0.4             1.31     1.68   1.26

      70 ( 740)            0.2             1.22     1.34   1.05

       6 (800)             0.1             0.84     1.09   0.72

                                                                    Fig .6 Variation of Surface Roughness
                                                                          under dry, wet & MQL condition



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  International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
  6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), © IAEME

Table 7.1 Experimental values of
 cutting forces at Dry condition .
Depth of cut = 1.0mm                                                                                     Y
    Cutting       Feed      Feed      Cutting   Thrust
    Speed         Rate      Force      Force    Force
  m/min(RPM)    (rev/min)   X (kgf)   Y (kgf)   Z (kgf)
    21 (228)        1
                              24         31       11.3
    34 (360)       0.8
                              22         30       8.6
    42 (450)      0.65
                                                                                                             X
                             15.6       27.6      7.3
    55 (580)       0.4
                              15        21.6       7

    70 ( 740)      0.2
                             13.6       18.6       6                                                         Z
    76 (800)       0.1
                             10.6       17.3       5


 Table 7.2 Experimental values of cutting                        Fig. 7 Variation of Force with forces
 at Wet condition                                         Feed rate under dry condition
 Depth of cut = 1.0mm
                                                                                           Y
    Cutting       Feed      Feed      Cutting   Thrust
    Speed         Rate      Force      Force    Force
  m/min(RPM)    (rev/min)   X (kgf)   Y (kgf)   Z (kgf)
      21            1
                              23        30        8.6
       34          0.8
                             17.6       29        6.3                                                            X
       42         0.65
                             14.6       22        4.3
       55          0.4
                             14.3      19.3       4                                                                  Z
       70          0.2       13.3      17.3       2.3
       76          0.1
                              9.6      10.6       1.8


  Table 7.3 Experimental values of                         Fig.8 Variation of Force with
  cutting forces MQL condition                                           Feed rate under Wet
                                                                         Condition
  Depth of cut = 1.0mm
    Cutting       Feed      Feed      Cutting   Thrust
    Speed         Rate      Force      Force    Force
  m/min(RPM)    (rev/min)   X (kgf)   Y (kgf)   Z (kgf)
      21            1
                             17.3      29.66      4.3
       34          0.8
                              16       22.33      3.6
       42         0.65
                            13.33       21        3
       55          0.4
                              13        20        2
       70          0.2
                              9.6      16.33      1.6
       76          0.1
                              9.5       14        1.5




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     International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
     6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), © IAEME
                                                                                          Theoretical
                                     Y


                                                                                             Experimental

                                              X


                                              Z



     Fig.9 Variation of Force with                Fig.10 Variation of cutting Temperature
        Feed rate under MQL condition                  at shear zone for different Speeds
                                                       and feeds

     Table 8 Theoretical calculations of temperature for Aluminium
Cutting Speed   Feed Rate     tc          r        tanØ      Ø         Es          εs             θs
m/min(RPM)      (rev/min)    (mm)                                    (N/mm²)                      °C




  21 (228)         1        0.5674       1.762     2.501   68.206     249.84     2.0133          98.43

  34 (360)         0.8       0.462       2.164     3.414   73.674     287.18     2.314          113.14

  42 (450)        0.65      0.3698       2.704     5.02    78.742     343.72     2.769          135.41

  55 (580)         0.4       0.352       2.841     5.522   79.735     358.62     2.889          141.28


  70 ( 740)        0.2       0.514       1.945     2.892   70.925     266.13     2.144          104.85


  76 (800)         0.1       0.439       2.247     3.708   74.907    298.502     2.405           117.6




     5. DISCUSSIONS AND CONCLUSIONS

             Cutting forces, tool temperature, chip formation and surface roughness of work
     piece during machining under the MQL (Boric Acid mixed with SAE oil) are compared
     with dry and wet machining using carbide tipped cutting tool. The experimental results
     reveal that the use of MQL is advantageous over dry and wet machining. This
     lubrication has improved the process performance by reducing the cutting forces and
     temperature. It is due to unique bond characteristics, MQL machining reduces chip
     thickness considerability over dry turning that are favorable for chip formation in
     compare to dry machining. And also the chip-tool interface temperature is reduced
     depending upon the level of process parameters. With increase in speed resulted
     decrease in cutting forces and machined surface temperature. This reduction in
     temperature attribute to higher metal removal rate which carried more heat by chip.


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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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        However, the present work may be extend to address the variability of machining
parameters in attempt to maximize tool life while optimizing the machined surface
quality using mists application. We can also use the analysis of variance (ANOVA) to
check the validity of proposed parameters and also their percentage contributions.
Further, ranges of cutting speed, feeds and depth of cut for machining harder materials
may be investigated using MQL.

Acknowledgements: Authors would like to acknowledge the technical staff and P.G
students E.Madhusudhana Rao, S.Saritha of Mechanical Engineering Department,Sri
Venkateswara University College of Engineering, Tirupati for their help in completing
this research work.

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[3] A. Liljerehn, V. Kalhori, and M. Lundblad, Experimental studies and modeling of
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6340(Print), ISSN 0976 – 6359(Online) Volume 3, Issue 2, May-August (2012), © IAEME

[12] H. A. Kishawya, R. J. Rogers & N. Balihodzic, A numerical investigation of the
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Engineering, Volume 9, Issue 4, 2001, pages 367-388.




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