- Email: [email protected]
Optimization of machining parameters for improving cutting force and surface roughness in turning of Al6061-TiC in-situ metal matrix composites by using Taguchi method
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 2 (2015) 3075 – 3083
4th International Conference on Materials Processing and Characterization
Optimization of machining parameters for improving cutting force and surface roughness in turning of Al6061-TiC in-situ metal matrix composites by using Taguchi method D. Sai Chaitanya Kishorea, *, K. Prahlada Raob, A. Ramesha b
a Department of Mechanical Engineering, GATES Institute of Technology, Gooty, 515401, Andhra Pradesh, India Department of Mechanical Engineering, Jawaharlal Nehru Technological University, Anantapuramu,515001, Andhra Pradesh, India
Abstract Al6061- TiC composite with 4 wt% TiC was produced by the reaction of halide salt K2TiF6 and C with the molten aluminum. SEM and EDX tests were performed to know the presence of the TiC reinforcement. Vickers micro hardness test was done and find that the hardness of Al6061 was increased by the addition of TiC. Machinability study was performed on the in-situ Al6061TiC MMC to study the effect of cutting speed, feed and depth of cut on cutting force and surface roughness by using Taguchi L27 orthogonal array. ANOVA is performed on the obtained results to investigate the contribution of cutting speed, feed and depth of cut on cutting force and surface roughness. © 2014Elsevier The Authors. Ltd. All rights reserved. © 2015 Ltd. AllElsevier rights reserved. Selection andpeer-review peer-review under responsibility the conference committee members ofInternational the 4th International Selection and under responsibility of theofconference committee members of the 4th conferenceconference on Materialson Materials and Characterization. Processing Processing and Characterization. Keywords: Taguchi; in-situ; TiC; ANOVA; S/N ratio;
1. Introduction There is always a demand to develop new materials to match the developing industrial needs. Composite materials are mostly used in different industrial applications due to its lightweight and high-strength properties. Metal matrix composites (MMC) mostly used in aerospace and automobile applications due to its properties like wear resistant,
* Corresponding author. Tel.: +91-9959545688 E-mail address: [email protected]
2214-7853 © 2015 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the conference committee members of the 4th International conference on Materials Processing and Characterization. doi:10.1016/j.matpr.2015.07.249
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D. Sai Chaitanya Kishore et al. / Materials Today: Proceedings 2 (2015) 3075 – 3083
high hardness, corrosive resistance and better formability. Recently a lot of attention is created towards the TiC reinforced metal matrix composites. The addition of TiC reinforcement to the base material makes the composite operate at high working temperatures. Kaczmar et al. [1] reported that metal matrix composites formed by stir casting, squeeze casting, spray deposition, liquid infiltration, and powder metallurgy. Among these process stir casting process is most economical. The composite prepared by ex-situ method suffers by thermodynamic instability between matrix and reinforcements, thus limiting their ambient and high temperature mechanical properties [2]. Exsitu process possesses drawbacks like agglomeration, poor wetting and heterogeneity in microstructure [3]. Mahamani et al. [4] stated that in-situ composites are having advantages like they are more homogeneous in their microstructure and thermodynamically more stable and they are also have strong interfacial bonding between the reinforcements and the matrix. Sai et al. [5] reported that the hardness of the base material is increased with the increase in TiC wt%. Birol [6] made in-situ Al-TiC composite and investigated that TiC reinforcement particles are created in a large number by the increase in melt temperatures by the addition of halide salt and graphite powder. Yucel Birol [7] reported that salts generated while the formation of Al3Ti particles will clean the surface oxides of the aluminium powders, and Al3Ti particles are gradually replaced by a fine dispersion of TiC particles as soon and as long as solute Ti is made available via the solutionizing of Al3Ti particles over a range of temperatures starting at 8000C. Keshavamurthy et al. [8] fabricated Al2024-TiB2 in-situ composite by liquid metallurgy route using AlTitanium and Al-Boron master alloys. Sai et al [9] investigated that the increase in cutting speed increases the flank wear during turning of Al6061-TiC MMC. Shouvik Ghosh et al. [10] carried out optimization study on wear behaviour of Al-7.5%SiC metal matrix composite by using L-27 orthogonal array. Anandakrishnan et al. [11] did machining investigations on in-situ Al6061-TiB2 composites, and reported that the uniformly distributed fine TiB2 particles will improve the machinability. Senthil et al. [12] did turning investigation on Al-Cu/ TiB2 and found that build-up-edge formation is more in the Al-Cu/ TiB2 than that of the base alloy. Sai et al. [13] reported that the values of cutting force and surface roughness are increased by using uncoated tungsten carbide insert than that of PCD insert while machining Al6061-TiC MMC. Pradeep et al. [14] studied the influences of machining parameters on Al-4.5CuTiC by using cemented carbide inserts, in which TiC reinforcement was produced by the reaction of activated charcoal with titanium. In the present research Al6061-4wt% TiC metal matrix composites were fabricated by in-situ process. Micro hardness tests were performed to know the improvement in hardness of the fabricated Al6061-TiC composite. SEM and EDX tests were performed to know the arrangement and presence of TiC particles. Turning experiments were performed on in-situ synthesised Al6061-4wt% TiC MMC rod by using L-27 orthogonal array. The results were analyzed by using lower the best S/N ratio to optimize the cutting force and surface roughness. ANOVA is performed to investigate the influence of cutting speed, feed and depth of cut on the cutting force and surface roughness. 2. Experimental work 2.1. Fabrication and characterization of in-situ Al6061-4 wt% TiC MMC Al6061-4wt% TiC metal matrix composite is fabricated by flux assisted synthesis, TiC reinforcement is developed within the matrix by using K2TiF6 (Potassium hexafluorotitanate) and C (graphite powder). Al6061 is used as matrix material. The fabrication of Al6061-TiC metal matrix composite is done by using stir casing setup which is shown in Fig. 1. The fabrication of Al6061-TiC metal matrix is done in a batch of 3 Kg. Al6061 is melted in a graphite crucible which is placed in the casting furnace; the premixed K2TiF6 and graphite powder of the measured quantity are preheated in pre-heating furnace. When Al6061 is melted in the casting furnace then the preheated K2TiF6 and graphite powder were added to molten aluminium, and the temperature of casting furnace is maintained as 900 оc, the melting process is carried for 30 minutes. The melt is stirred for the uniform distribution of the reinforcement. While melting the reaction between K2TiF6 and molten aluminium releases Ti, which reacts with graphite powder for the formation of TiC reinforcement. After 30 minutes of melting, the slag is removed from the molten metal, and the molten metal is poured into the cast iron mould. The fabricated composite is subjected to EDX and SEM for to know the characterisation of the manufactured material. EDX and SEM tests are performed on F E I Quanta FEG 200 - High Resolution Scanning Electron Microscope. The prepared test specimens are examined under scanning electron microscopy to ascertain the
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formation of TiC particles and their distribution. Fig.2 shows the SEM image for the 4 wt% TiC, from the SEM image it is identified that the size of the TiC reinforcement is 1 μm or less than 1 μm. Fig. 3 shows the EDX analysis for Al6061-4 wt% TiC composite. From the Fig.3 it is identified that Al6061-4 wt% TiC test specimen consist the elements Al, Ti, C, Fe and Si. Vicker’s micro hardness tests were performed at a load of 300 grams with 15 seconds dwell time. Table.1 displays the results of Vicker’s micro hardness, from these results it was investigated that the micro hardness value was increasing with the increase in wt% of TiC reinforcement.
Fig. 1. Stir casting setup
Fig. 2. SEM image for Al6061-4 wt% TiC
Fig. 3. EDX analysis for Al6061-4 wt% TiC Table 1. Micro hardness Material Trial 1(HV)
Trial 2(HV)
Trial 3(HV)
Average Hardness(HV)
Al6061
54.4
56.0
52.7
54.3
Al6061-4%TiC
60.9
65.4
62.0
62.7
2.2. Turning experiment details Machining experiments are performed on Kirloskar made Turnmaster-35 lathe. The cutting force is measured by Kistler dynamometer (model no 9857B) and charge amplifier model is 5070A. During turning operation, each
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experimental run is performed for one-minute duration. Surface roughness (Ra) is measured by using surface roughness tester made by Mitutoyo (model no SJ-210). TaeguTec make uncoated tungsten carbide tool insert (SNMG120408 MTTT5100) with tool insert holder PSBNR-2525M12 was used for the present investigation. The process parameters with three levels of cutting speed, feed and depth of cut were used for the present study and a list of process parameters were displayed in Table. 2. The setup of lathe and lathe tool dynamometer is shown in Fig.4. All the turning experiments performed in dry cutting condition. Experimental design was planned by using L27 orthogonal array. Table. 2. Process parameters Factor Process parameter
Level 1
Level 2
Level 3
A
Cutting speed(m/min)
40
80
120
B
Feed rate(mm/rev)
0.04
0.1
0.12
C
Depth of cut(mm)
0.5
1
1.5
Table. 3. Experimental results Exp. No
Cutting speed
Feed rate (mm/rev)
Depth of cut(mm)
Cutting force (N)
S/N ratio for cutting force
Ra (μm)
S/N ratio for Ra
1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3
1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
93.18 107.04 175.86 119.65 157.47 234.89 167.62 208.13 273.54 81.31 92.73 146.14 102.21 124.96 191.75 128.06 165.92 241.18 58.41 72.29 124.15 78.94 94.06 170.59 93.76 148.65 214.58
-39.39 -40.59 -44.90 -41.56 -43.94 -47.42 -44.49 -46.37 -48.74 -38.20 -39.34 -43.30 -40.19 -41.94 -45.65 -42.15 -44.40 -47.65 -35.33 -37.18 -41.88 -37.95 -39.47 -44.64 -39.44 -43.44 -46.63
2.274 2.538 2.696 2.561 2.639 2.835 2.816 2.954 3.219 2.068 2.264 2.487 2.258 2.475 2.623 2.592 2.716 2.985 1.852 2.074 2.258 2.136 2.248 2.419 2.427 2.546 2.785
-7.14 -8.09 -8.61 -8.17 -8.43 -9.05 -8.99 -9.41 -10.15 -6.31 -7.10 -7.91 -7.07 -7.87 -8.38 -8.27 -8.68 -9.50 -5.35 -6.34 -7.07 -6.59 -7.04 -7.67 -7.70 -8.12 -8.90
(m/min) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3
3. Results and discussion The turning experiments performed on Al6061 rod to optimize the process parameters for the responses cutting force and surface roughness. The experimental results displayed in Table.3. The obtained results were analysed by using Taguchi’s lower the best signal to noise ratio(S/N ratio). The optimization study is performed by using Minitab16 software. Fig. 5 shows the effect process parameters on the S/N ratios of the cutting force. From the Fig. 5 it is found that higher S/N ratio is achieved at higher cutting speed, lower feed and lower depth of cut. The higher S/N ratio value process parameter combination gives the minimum cutting force, and this combination is A-3, B-1 and C-1.
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Fig. 4. Lathe and lathe tool dynamometer setup
Main Effects Plot for SN ratios of cutting force Data Means
Cutting speed (m/min)
Feed (mm/rev)
-40
Mean of SN ratios
-42 -44 -46 1
2 Depth of cut (mm)
3
1
2
3
1
2
3
-40 -42 -44 -46
Signal-to-noise: Smaller is better Fig. 5. Main effects plot for S/N ratios of cutting force
Table. 4. displays mean values of the S/N ratios of cutting force for all the process parameters at different levels. From the Table. 4. it is identified that depth of cut is having higher delta value and given as rank 1, and later this is followed by the feed and cutting speed respectively. The depth of cut is having highest influence on the S/N ratios of cutting force due to its delta value and rank. Fig. 6 shows the effect of process parameters on surface roughness. From the Fig. 6 and Table. 5. it is observed that the optimum S/N ratio is achieved with the process parameter combination of A-3, B-1 and C-1. From the Table. 5. it is identified that rank 1 is given to the feed, rank 2 is given to the cutting speed and rank 3 is given to the depth of cut respectively. The feed is having highest influence on the S/N ratios of surface roughness due to its delta value and rank, and later this is followed by cutting speed and depth
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of cut respectively. Fig.7 shows the interaction graph for the means of cutting force at different levels of cutting speed, feed and depth of cut, from the graph it is identified that cutting force is less at higher cutting speeds this is because at higher cutting speeds the work past the tool at faster rate. From the graph it is also identified that the cutting force is increasing with the increase in feed and depth of cut. Main Effects Plot for SN ratios of Ra Data Means
Cutting speed (m/min)
-7.0
Feed (mm/rev)
-7.5
Mean of SN ratios
-8.0 -8.5 -9.0 1
2
3
1
2
3
Depth of cut (mm)
-7.0 -7.5 -8.0 -8.5 -9.0 1
2
3
Signal-to-noise: Smaller is better Fig. 6. Main effects plot for S/N ratios of Ra Table. 4. Response table for S/N ratios of cutting force Level A B 1 -44.15 -40.01 2 -42.54 -42.53 3 -40.66 -44.81 3.49 4.80 Delta Rank 3 2 Optimum S/N A-3 B-1 ratio
C -39.85 -41.85 -45.65 5.79 1 C-1
Interaction Plot for Cutting force (N) Data Means
0.04
0.08
0.12
0.5
1.0
1.5 240
160
C utting speed ( m/min)
80 240
160
Feed (mm/r ev)
80
Depth of cut (mm)
Fig. 7. Main effects plot for means of cutting force
Cutting speed (m/min) 40 80 120 Feed (mm/rev ) 0.04 0.08 0.12
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D. Sai Chaitanya Kishore et al. / Materials Today: Proceedings 2 (2015) 3075 – 3083 Table. 5. Response table for S/N ratios of Ra Level A 1 2 3 Delta Rank
-8.671 -7.899 -7.198 1.474
B -7.103 -7.808 -8.858 1.755
C -7.289 -7.896 -8.584 1.295
2
1
3
Optimum S/N ratio
A-3
B-1
C-1
Interaction Plot for Ra (μm) Data Means
0.04
0.08
0.12
0.5
1.0
1.5 3.0
2.5
C utting speed ( m/min)
2.0 3.0
2.5
Feed (mm/r ev)
Cutting speed (m/min) 40 80 120 Feed (mm/rev ) 0.04 0.08 0.12
2.0
Depth of cut (mm)
Fig. 8. Main effects plot for means of Ra Table. 6. ANOVA table for cutting force Source DF A 2 B 2 C 2 A*B 4 A*C 4 B*C 4 Error 8 Total 26
SS 12940.5 26510.4 42407.2 494.0 121.2 1547.1 367.4 84387.9
MS 6470.3 13255.2 21203.6 123.5 30.3 386.8 45.9
F 140.87 288.59 461.65 2.69 0.66 8.42
P 0.000 0.000 0.000 0.109 0.637 0.006
Table. 7. ANOVA table for Ra Source DF A 2 B 2 C 2 A*B 4 A*C 4 B*C 4 Error 8 Total 26
SS 0.79890 1.16459 0.61618 0.00128 0.00148 0.01657 0.00624 2.60524
MS 0.39945 0.58230 0.30809 0.00032 0.00037 0.00414 0.00078
F 511.85 746.15 394.79 0.41 0.47 5.31
P 0.000 0.000 0.000 0.797 0.755 0.022
Fig.8 shows the interaction graph for the means of Ra at different levels of cutting speed, feed and depth of cut, from the graph it is identified that surface roughness is less at higher cutting speed, an increase in cutting speed results lower build-up edge formation, and this gives lower surface roughness values. Fig.8 also shows that Ra is increasing with the increase in feed and depth of cut. ANOVA is performed on the response outputs cutting force and surface roughness for to investigate the influence of process parameters. Table. 6. displays the ANOVA results for cutting force, from the Table. 6 it was identified
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that the F value is high for depth of cut. So the contribution of depth of cut is high for the response cutting force and later this was followed by feed and cutting speed respectively. From the Table. 6. it was observed that the interaction B*C has highest F value, so the contribution of interaction B*C is high on cutting force when compared to other two interactions. The P value of the process parameters A, B and C are less than 0.05, so all the process parameters are significant to obtain the best cutting force values. In the case of interactions the P value of the interactions A*B and A*C are greater than 0.05 so these interactions are not significant, the P value of the interaction B*C is less than 0.05 so this interaction is significant. Table. 7. displays the ANOVA results for Ra, from the Table. 7 it was identified that the F value is high for feed. So the contribution of feed is high for the response Ra and later this was followed by cutting speed and depth of cut respectively. From the Table. 7 it was also identified that the P value of the process parameters A, B and C are less than 0.05, so all the process parameters are significant to obtain the best Ra values. In the case of interactions the P value of the interactions A*B and A*C are greater than 0.05 so these interactions are not significant, the P value of the interaction B*C is less than 0.05 so this interaction is significant. 4. Conclusion In the present research SEM and EDX test were performed on the in-situ fabricated Al6061-4 wt% TiC MMC to investigate the presence and distribution of TiC particles. Vicker’s microhardness test was done and it was identified that the incorporation of TiC particles in the matrix increases the hardness of the base material. Taguchi optimization study is performed on the response cutting force and surface roughness by using lower the best S/N ratio, from the investigations it was identified that the cutting force and surface roughness are low at higher cutting speeds and lower feed and lower depth of cut. ANOVA is performed on the cutting force and surface roughness, by the analysis of ANOVA table it was identified that the contribution of depth of cut is high on the cutting force. In case of surface roughness the contribution of feed is high and later this was followed by cutting speed and depth of cut. Acknowledgements The authors would like to thank to the management of GATES Institute of Technology, Gooty for the encouragement and support. The authors are thankful to Dr. K. Leo Dev Wins, Head, CRDM, Karunya University, Coimbatore, India for accepting our request to carry out this research in their research centre. The authors are also thankful to J. Jones Robin, K.Sivasankar and C.John Kennedy from Deparment of Mechanical Engineering, Karunya University for helping in fabrication and experimental work. The thanks also extend to the Nano technology research center, SRM University and Microlab, Chennai for providing the lab facility. I sincerely thank to my wife D. Srithajani for helping me in preparing this research document. References [1] J. W. Kaczmar, K. Pietrzak, W. Wlosinski, The production and application of metal matrix composite materials., J Mater Process Technology, 2000, 106, 58-67. [2] A. Mahamani, Mechanism of In-situ Reinforcement Formation in Fabrication of AA6061-TiB2 Metal Matrix Composite., Indian foundry journal, 2011, Vol 57, No 3. [3] C. Cui, Y. Shen, F. Meng, Review on Fabrication Methods of In-situ Metal Matrix Composites., Journal of Material Science Technology, 2000, Vol.16, pp.619-626. [4] A. Mahamani, Machinability Study of Al-5Cu-TiB2 In-situ Metal Matrix Composites Fabricated by Flux-assisted Synthesis., Journal of Minerals & Materials Characterization & Engineering, 2011, Vol. 10, No. 13, 1243-1254. [5] D. Sai Chaitanya Kishore, K. Prahlada Rao, A. Mahamani, Fabrication and characterisation of in-situ Al-TiC composite., International journal of mechanical engineering and technology, 2013, volume 4, issue 1, 109-114. [6] Y.Birol, In situ synthesis of Al–TiCp composites by reacting K2TiF6 and particulate graphite in molten aluminium., Journal of Alloys and Compounds, 2008, 454, 110-117. [7] Yucel Birol, Response to thermal exposure of Al/ K2TiF6/C powder blends., Journal of Alloys and Compounds, 2008, 455, 164 -167. [8] R. Keshavamurthy, S.Suhael Ahmed, A.Mudashi Laxman, N.H.Anil Kumar, M.N.Shashidhara, Y.Vimarshan Reddy, Tribological properties of Hot forged Al2024-TiB2 in-situ composite., Advanced Materials Manufacturing & Characterization, 2014, Vol 4, Issue 2, 87-92.
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[9] D. Sai Chaitanya Kishore, K. Prahlada Rao, A. Mahamani, Investigation of cutting force, surface roughness and flank wear in turning of Insitu Al6061-TiC metal matrix composite., Procedia Materials Science, 2014, 6, 1040- 1050. [10] Shouvik Ghosh, Prasanta Sahoo, Goutam Sutradhar, Wear Characteristics Optimization of Al-7.5%Sic Metal Matrix Composite Using Taguchi Method, Advanced Materials Manufacturing & Characterization., 2014, Vol 4, Issue 2, 93-99. [11] V. Anandakrishnan, A. Mahamani, Investigations of flank wear, cutting force, and surface roughness in the machining of Al-6061-TiB2 in situ metal matrix composites produced by flux-assisted synthesis., Int J Adv Manuf Technol, 2011, 55, 65-73. [12] P. Senthil, T. Selvaraj, K. Sivaprasad, Influence of turning parameters on the machinability of homogenized Al-Cu/ TiB2 in situ metal matrix composites., Int J Adv Manuf Technol, 2013, 67, 1589-1596. [13] D. Sai Chaitanya Kishore, K. Prahlada Rao, A. Mahamani, Effect of tooling on cutting force and surface roughness in turning of in-situ Al6061-TiC metal matrix composite., Procedia Materials Science, 2014, 5, 1574- 1583. [14] Pradeep Kumar Jha, Anand Kumar, M. M. Mahapatra, Influence of machining on Al-4.5Cu-TiC In-Situ Metal Matrix composites., Light metals, John Wiley & Sons, 2013, 449-452.
ScienceDirect Materials Today: Proceedings 2 (2015) 3075 – 3083
4th International Conference on Materials Processing and Characterization
Optimization of machining parameters for improving cutting force and surface roughness in turning of Al6061-TiC in-situ metal matrix composites by using Taguchi method D. Sai Chaitanya Kishorea, *, K. Prahlada Raob, A. Ramesha b
a Department of Mechanical Engineering, GATES Institute of Technology, Gooty, 515401, Andhra Pradesh, India Department of Mechanical Engineering, Jawaharlal Nehru Technological University, Anantapuramu,515001, Andhra Pradesh, India
Abstract Al6061- TiC composite with 4 wt% TiC was produced by the reaction of halide salt K2TiF6 and C with the molten aluminum. SEM and EDX tests were performed to know the presence of the TiC reinforcement. Vickers micro hardness test was done and find that the hardness of Al6061 was increased by the addition of TiC. Machinability study was performed on the in-situ Al6061TiC MMC to study the effect of cutting speed, feed and depth of cut on cutting force and surface roughness by using Taguchi L27 orthogonal array. ANOVA is performed on the obtained results to investigate the contribution of cutting speed, feed and depth of cut on cutting force and surface roughness. © 2014Elsevier The Authors. Ltd. All rights reserved. © 2015 Ltd. AllElsevier rights reserved. Selection andpeer-review peer-review under responsibility the conference committee members ofInternational the 4th International Selection and under responsibility of theofconference committee members of the 4th conferenceconference on Materialson Materials and Characterization. Processing Processing and Characterization. Keywords: Taguchi; in-situ; TiC; ANOVA; S/N ratio;
1. Introduction There is always a demand to develop new materials to match the developing industrial needs. Composite materials are mostly used in different industrial applications due to its lightweight and high-strength properties. Metal matrix composites (MMC) mostly used in aerospace and automobile applications due to its properties like wear resistant,
* Corresponding author. Tel.: +91-9959545688 E-mail address: [email protected]
2214-7853 © 2015 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the conference committee members of the 4th International conference on Materials Processing and Characterization. doi:10.1016/j.matpr.2015.07.249
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D. Sai Chaitanya Kishore et al. / Materials Today: Proceedings 2 (2015) 3075 – 3083
high hardness, corrosive resistance and better formability. Recently a lot of attention is created towards the TiC reinforced metal matrix composites. The addition of TiC reinforcement to the base material makes the composite operate at high working temperatures. Kaczmar et al. [1] reported that metal matrix composites formed by stir casting, squeeze casting, spray deposition, liquid infiltration, and powder metallurgy. Among these process stir casting process is most economical. The composite prepared by ex-situ method suffers by thermodynamic instability between matrix and reinforcements, thus limiting their ambient and high temperature mechanical properties [2]. Exsitu process possesses drawbacks like agglomeration, poor wetting and heterogeneity in microstructure [3]. Mahamani et al. [4] stated that in-situ composites are having advantages like they are more homogeneous in their microstructure and thermodynamically more stable and they are also have strong interfacial bonding between the reinforcements and the matrix. Sai et al. [5] reported that the hardness of the base material is increased with the increase in TiC wt%. Birol [6] made in-situ Al-TiC composite and investigated that TiC reinforcement particles are created in a large number by the increase in melt temperatures by the addition of halide salt and graphite powder. Yucel Birol [7] reported that salts generated while the formation of Al3Ti particles will clean the surface oxides of the aluminium powders, and Al3Ti particles are gradually replaced by a fine dispersion of TiC particles as soon and as long as solute Ti is made available via the solutionizing of Al3Ti particles over a range of temperatures starting at 8000C. Keshavamurthy et al. [8] fabricated Al2024-TiB2 in-situ composite by liquid metallurgy route using AlTitanium and Al-Boron master alloys. Sai et al [9] investigated that the increase in cutting speed increases the flank wear during turning of Al6061-TiC MMC. Shouvik Ghosh et al. [10] carried out optimization study on wear behaviour of Al-7.5%SiC metal matrix composite by using L-27 orthogonal array. Anandakrishnan et al. [11] did machining investigations on in-situ Al6061-TiB2 composites, and reported that the uniformly distributed fine TiB2 particles will improve the machinability. Senthil et al. [12] did turning investigation on Al-Cu/ TiB2 and found that build-up-edge formation is more in the Al-Cu/ TiB2 than that of the base alloy. Sai et al. [13] reported that the values of cutting force and surface roughness are increased by using uncoated tungsten carbide insert than that of PCD insert while machining Al6061-TiC MMC. Pradeep et al. [14] studied the influences of machining parameters on Al-4.5CuTiC by using cemented carbide inserts, in which TiC reinforcement was produced by the reaction of activated charcoal with titanium. In the present research Al6061-4wt% TiC metal matrix composites were fabricated by in-situ process. Micro hardness tests were performed to know the improvement in hardness of the fabricated Al6061-TiC composite. SEM and EDX tests were performed to know the arrangement and presence of TiC particles. Turning experiments were performed on in-situ synthesised Al6061-4wt% TiC MMC rod by using L-27 orthogonal array. The results were analyzed by using lower the best S/N ratio to optimize the cutting force and surface roughness. ANOVA is performed to investigate the influence of cutting speed, feed and depth of cut on the cutting force and surface roughness. 2. Experimental work 2.1. Fabrication and characterization of in-situ Al6061-4 wt% TiC MMC Al6061-4wt% TiC metal matrix composite is fabricated by flux assisted synthesis, TiC reinforcement is developed within the matrix by using K2TiF6 (Potassium hexafluorotitanate) and C (graphite powder). Al6061 is used as matrix material. The fabrication of Al6061-TiC metal matrix composite is done by using stir casing setup which is shown in Fig. 1. The fabrication of Al6061-TiC metal matrix is done in a batch of 3 Kg. Al6061 is melted in a graphite crucible which is placed in the casting furnace; the premixed K2TiF6 and graphite powder of the measured quantity are preheated in pre-heating furnace. When Al6061 is melted in the casting furnace then the preheated K2TiF6 and graphite powder were added to molten aluminium, and the temperature of casting furnace is maintained as 900 оc, the melting process is carried for 30 minutes. The melt is stirred for the uniform distribution of the reinforcement. While melting the reaction between K2TiF6 and molten aluminium releases Ti, which reacts with graphite powder for the formation of TiC reinforcement. After 30 minutes of melting, the slag is removed from the molten metal, and the molten metal is poured into the cast iron mould. The fabricated composite is subjected to EDX and SEM for to know the characterisation of the manufactured material. EDX and SEM tests are performed on F E I Quanta FEG 200 - High Resolution Scanning Electron Microscope. The prepared test specimens are examined under scanning electron microscopy to ascertain the
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formation of TiC particles and their distribution. Fig.2 shows the SEM image for the 4 wt% TiC, from the SEM image it is identified that the size of the TiC reinforcement is 1 μm or less than 1 μm. Fig. 3 shows the EDX analysis for Al6061-4 wt% TiC composite. From the Fig.3 it is identified that Al6061-4 wt% TiC test specimen consist the elements Al, Ti, C, Fe and Si. Vicker’s micro hardness tests were performed at a load of 300 grams with 15 seconds dwell time. Table.1 displays the results of Vicker’s micro hardness, from these results it was investigated that the micro hardness value was increasing with the increase in wt% of TiC reinforcement.
Fig. 1. Stir casting setup
Fig. 2. SEM image for Al6061-4 wt% TiC
Fig. 3. EDX analysis for Al6061-4 wt% TiC Table 1. Micro hardness Material Trial 1(HV)
Trial 2(HV)
Trial 3(HV)
Average Hardness(HV)
Al6061
54.4
56.0
52.7
54.3
Al6061-4%TiC
60.9
65.4
62.0
62.7
2.2. Turning experiment details Machining experiments are performed on Kirloskar made Turnmaster-35 lathe. The cutting force is measured by Kistler dynamometer (model no 9857B) and charge amplifier model is 5070A. During turning operation, each
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experimental run is performed for one-minute duration. Surface roughness (Ra) is measured by using surface roughness tester made by Mitutoyo (model no SJ-210). TaeguTec make uncoated tungsten carbide tool insert (SNMG120408 MTTT5100) with tool insert holder PSBNR-2525M12 was used for the present investigation. The process parameters with three levels of cutting speed, feed and depth of cut were used for the present study and a list of process parameters were displayed in Table. 2. The setup of lathe and lathe tool dynamometer is shown in Fig.4. All the turning experiments performed in dry cutting condition. Experimental design was planned by using L27 orthogonal array. Table. 2. Process parameters Factor Process parameter
Level 1
Level 2
Level 3
A
Cutting speed(m/min)
40
80
120
B
Feed rate(mm/rev)
0.04
0.1
0.12
C
Depth of cut(mm)
0.5
1
1.5
Table. 3. Experimental results Exp. No
Cutting speed
Feed rate (mm/rev)
Depth of cut(mm)
Cutting force (N)
S/N ratio for cutting force
Ra (μm)
S/N ratio for Ra
1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3
1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
93.18 107.04 175.86 119.65 157.47 234.89 167.62 208.13 273.54 81.31 92.73 146.14 102.21 124.96 191.75 128.06 165.92 241.18 58.41 72.29 124.15 78.94 94.06 170.59 93.76 148.65 214.58
-39.39 -40.59 -44.90 -41.56 -43.94 -47.42 -44.49 -46.37 -48.74 -38.20 -39.34 -43.30 -40.19 -41.94 -45.65 -42.15 -44.40 -47.65 -35.33 -37.18 -41.88 -37.95 -39.47 -44.64 -39.44 -43.44 -46.63
2.274 2.538 2.696 2.561 2.639 2.835 2.816 2.954 3.219 2.068 2.264 2.487 2.258 2.475 2.623 2.592 2.716 2.985 1.852 2.074 2.258 2.136 2.248 2.419 2.427 2.546 2.785
-7.14 -8.09 -8.61 -8.17 -8.43 -9.05 -8.99 -9.41 -10.15 -6.31 -7.10 -7.91 -7.07 -7.87 -8.38 -8.27 -8.68 -9.50 -5.35 -6.34 -7.07 -6.59 -7.04 -7.67 -7.70 -8.12 -8.90
(m/min) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3
3. Results and discussion The turning experiments performed on Al6061 rod to optimize the process parameters for the responses cutting force and surface roughness. The experimental results displayed in Table.3. The obtained results were analysed by using Taguchi’s lower the best signal to noise ratio(S/N ratio). The optimization study is performed by using Minitab16 software. Fig. 5 shows the effect process parameters on the S/N ratios of the cutting force. From the Fig. 5 it is found that higher S/N ratio is achieved at higher cutting speed, lower feed and lower depth of cut. The higher S/N ratio value process parameter combination gives the minimum cutting force, and this combination is A-3, B-1 and C-1.
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Fig. 4. Lathe and lathe tool dynamometer setup
Main Effects Plot for SN ratios of cutting force Data Means
Cutting speed (m/min)
Feed (mm/rev)
-40
Mean of SN ratios
-42 -44 -46 1
2 Depth of cut (mm)
3
1
2
3
1
2
3
-40 -42 -44 -46
Signal-to-noise: Smaller is better Fig. 5. Main effects plot for S/N ratios of cutting force
Table. 4. displays mean values of the S/N ratios of cutting force for all the process parameters at different levels. From the Table. 4. it is identified that depth of cut is having higher delta value and given as rank 1, and later this is followed by the feed and cutting speed respectively. The depth of cut is having highest influence on the S/N ratios of cutting force due to its delta value and rank. Fig. 6 shows the effect of process parameters on surface roughness. From the Fig. 6 and Table. 5. it is observed that the optimum S/N ratio is achieved with the process parameter combination of A-3, B-1 and C-1. From the Table. 5. it is identified that rank 1 is given to the feed, rank 2 is given to the cutting speed and rank 3 is given to the depth of cut respectively. The feed is having highest influence on the S/N ratios of surface roughness due to its delta value and rank, and later this is followed by cutting speed and depth
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of cut respectively. Fig.7 shows the interaction graph for the means of cutting force at different levels of cutting speed, feed and depth of cut, from the graph it is identified that cutting force is less at higher cutting speeds this is because at higher cutting speeds the work past the tool at faster rate. From the graph it is also identified that the cutting force is increasing with the increase in feed and depth of cut. Main Effects Plot for SN ratios of Ra Data Means
Cutting speed (m/min)
-7.0
Feed (mm/rev)
-7.5
Mean of SN ratios
-8.0 -8.5 -9.0 1
2
3
1
2
3
Depth of cut (mm)
-7.0 -7.5 -8.0 -8.5 -9.0 1
2
3
Signal-to-noise: Smaller is better Fig. 6. Main effects plot for S/N ratios of Ra Table. 4. Response table for S/N ratios of cutting force Level A B 1 -44.15 -40.01 2 -42.54 -42.53 3 -40.66 -44.81 3.49 4.80 Delta Rank 3 2 Optimum S/N A-3 B-1 ratio
C -39.85 -41.85 -45.65 5.79 1 C-1
Interaction Plot for Cutting force (N) Data Means
0.04
0.08
0.12
0.5
1.0
1.5 240
160
C utting speed ( m/min)
80 240
160
Feed (mm/r ev)
80
Depth of cut (mm)
Fig. 7. Main effects plot for means of cutting force
Cutting speed (m/min) 40 80 120 Feed (mm/rev ) 0.04 0.08 0.12
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-8.671 -7.899 -7.198 1.474
B -7.103 -7.808 -8.858 1.755
C -7.289 -7.896 -8.584 1.295
2
1
3
Optimum S/N ratio
A-3
B-1
C-1
Interaction Plot for Ra (μm) Data Means
0.04
0.08
0.12
0.5
1.0
1.5 3.0
2.5
C utting speed ( m/min)
2.0 3.0
2.5
Feed (mm/r ev)
Cutting speed (m/min) 40 80 120 Feed (mm/rev ) 0.04 0.08 0.12
2.0
Depth of cut (mm)
Fig. 8. Main effects plot for means of Ra Table. 6. ANOVA table for cutting force Source DF A 2 B 2 C 2 A*B 4 A*C 4 B*C 4 Error 8 Total 26
SS 12940.5 26510.4 42407.2 494.0 121.2 1547.1 367.4 84387.9
MS 6470.3 13255.2 21203.6 123.5 30.3 386.8 45.9
F 140.87 288.59 461.65 2.69 0.66 8.42
P 0.000 0.000 0.000 0.109 0.637 0.006
Table. 7. ANOVA table for Ra Source DF A 2 B 2 C 2 A*B 4 A*C 4 B*C 4 Error 8 Total 26
SS 0.79890 1.16459 0.61618 0.00128 0.00148 0.01657 0.00624 2.60524
MS 0.39945 0.58230 0.30809 0.00032 0.00037 0.00414 0.00078
F 511.85 746.15 394.79 0.41 0.47 5.31
P 0.000 0.000 0.000 0.797 0.755 0.022
Fig.8 shows the interaction graph for the means of Ra at different levels of cutting speed, feed and depth of cut, from the graph it is identified that surface roughness is less at higher cutting speed, an increase in cutting speed results lower build-up edge formation, and this gives lower surface roughness values. Fig.8 also shows that Ra is increasing with the increase in feed and depth of cut. ANOVA is performed on the response outputs cutting force and surface roughness for to investigate the influence of process parameters. Table. 6. displays the ANOVA results for cutting force, from the Table. 6 it was identified
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that the F value is high for depth of cut. So the contribution of depth of cut is high for the response cutting force and later this was followed by feed and cutting speed respectively. From the Table. 6. it was observed that the interaction B*C has highest F value, so the contribution of interaction B*C is high on cutting force when compared to other two interactions. The P value of the process parameters A, B and C are less than 0.05, so all the process parameters are significant to obtain the best cutting force values. In the case of interactions the P value of the interactions A*B and A*C are greater than 0.05 so these interactions are not significant, the P value of the interaction B*C is less than 0.05 so this interaction is significant. Table. 7. displays the ANOVA results for Ra, from the Table. 7 it was identified that the F value is high for feed. So the contribution of feed is high for the response Ra and later this was followed by cutting speed and depth of cut respectively. From the Table. 7 it was also identified that the P value of the process parameters A, B and C are less than 0.05, so all the process parameters are significant to obtain the best Ra values. In the case of interactions the P value of the interactions A*B and A*C are greater than 0.05 so these interactions are not significant, the P value of the interaction B*C is less than 0.05 so this interaction is significant. 4. Conclusion In the present research SEM and EDX test were performed on the in-situ fabricated Al6061-4 wt% TiC MMC to investigate the presence and distribution of TiC particles. Vicker’s microhardness test was done and it was identified that the incorporation of TiC particles in the matrix increases the hardness of the base material. Taguchi optimization study is performed on the response cutting force and surface roughness by using lower the best S/N ratio, from the investigations it was identified that the cutting force and surface roughness are low at higher cutting speeds and lower feed and lower depth of cut. ANOVA is performed on the cutting force and surface roughness, by the analysis of ANOVA table it was identified that the contribution of depth of cut is high on the cutting force. In case of surface roughness the contribution of feed is high and later this was followed by cutting speed and depth of cut. Acknowledgements The authors would like to thank to the management of GATES Institute of Technology, Gooty for the encouragement and support. The authors are thankful to Dr. K. Leo Dev Wins, Head, CRDM, Karunya University, Coimbatore, India for accepting our request to carry out this research in their research centre. The authors are also thankful to J. Jones Robin, K.Sivasankar and C.John Kennedy from Deparment of Mechanical Engineering, Karunya University for helping in fabrication and experimental work. The thanks also extend to the Nano technology research center, SRM University and Microlab, Chennai for providing the lab facility. I sincerely thank to my wife D. Srithajani for helping me in preparing this research document. References [1] J. W. Kaczmar, K. Pietrzak, W. Wlosinski, The production and application of metal matrix composite materials., J Mater Process Technology, 2000, 106, 58-67. [2] A. Mahamani, Mechanism of In-situ Reinforcement Formation in Fabrication of AA6061-TiB2 Metal Matrix Composite., Indian foundry journal, 2011, Vol 57, No 3. [3] C. Cui, Y. Shen, F. Meng, Review on Fabrication Methods of In-situ Metal Matrix Composites., Journal of Material Science Technology, 2000, Vol.16, pp.619-626. [4] A. Mahamani, Machinability Study of Al-5Cu-TiB2 In-situ Metal Matrix Composites Fabricated by Flux-assisted Synthesis., Journal of Minerals & Materials Characterization & Engineering, 2011, Vol. 10, No. 13, 1243-1254. [5] D. Sai Chaitanya Kishore, K. Prahlada Rao, A. Mahamani, Fabrication and characterisation of in-situ Al-TiC composite., International journal of mechanical engineering and technology, 2013, volume 4, issue 1, 109-114. [6] Y.Birol, In situ synthesis of Al–TiCp composites by reacting K2TiF6 and particulate graphite in molten aluminium., Journal of Alloys and Compounds, 2008, 454, 110-117. [7] Yucel Birol, Response to thermal exposure of Al/ K2TiF6/C powder blends., Journal of Alloys and Compounds, 2008, 455, 164 -167. [8] R. Keshavamurthy, S.Suhael Ahmed, A.Mudashi Laxman, N.H.Anil Kumar, M.N.Shashidhara, Y.Vimarshan Reddy, Tribological properties of Hot forged Al2024-TiB2 in-situ composite., Advanced Materials Manufacturing & Characterization, 2014, Vol 4, Issue 2, 87-92.
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