Wear is one of the main causes of the material wastage, is an important problem related with industrial components. Friction is the natural phenomenon of resistance to motion between moving surfaces. Zinc based alloys have been proven to be a good bearing material. However, copper based zinc alloy suffer from the low ductility and dimensional instability problems. To eliminate these problems zinc was replaced with aluminium and this resulted in stability of the alloy. As a result of these investigations Al-Zn-Cu-Si alloy have been developed. The wear resistance, tensile strength, hardness of this alloy was much higher than traditional bearing bronze. This can be hence be tested for their tribological applications. The ZA alloys are mainly classified in terms of their higher aluminium content. The numerical digits (8, 12, 27, 40) represent their approximate weight percentage of aluminium. In this study, Al-Zn nonferrous alloy prepared as a higher performance engineering material which is used in industry due to its properties like light weight, high wear resistance, low coefficient of friction, high heat transfer, advantages for same application as that of conventional material this application tries to fulfil by this study.

Here the load, sliding velocity, and time these three parameters have been varied for different experiments in order to examine the effect of different alloying element of Cu, Mn, Si , Al- Zn are studied. The wear mechanism is dependent on following factors- 1. The load on contacting area 2. The Sliding velocity 3. The duration of the sliding 4. The working conditions namely, dry or lubricated 5. Metallurgical structure such as grain structure, hardness. Here the first three parameters have been for material A, material B, material C. Dry working conditions at ambient temperatures have been used and other parameters have been considered constant. The objective will be to generate new performance data which will be useful for the design engineer.

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Tamel savaskan, Ali Pas Hekimoglo, observed that the hardness of the alloys increased consciously with increasing copper content up to 5% and tensile strength also increased with the increasing copper content up to 2%, but beyond this level strength decreased as the copper content increased further [6]. Ahmet Turk, Mehmet Durman, Sabri Kayali found that addition of Manganese over the entire range of concentrations has a successful effect on the alloy hardness. Also, ultimate tensile and 0.2% yield strength of the samples did not change significantly with Manganese addition up to 0.045 weight percentage but decreased gradually with a further increase in Manganese content. On the other hand the creep resistance of the alloy increased with Manganese content up to 0.53% weight .[7] Miroslav Babic, Slobodan Mitrovic, Branislav Jeremic observed the heat treatment resulted in reduction in the tensile strength, hardness and increase in elongation. Both friction and wear characteristics of the heat treated alloy improved over the as cast alloy [8]. Zeki azakh, Temel Savaskan observed that the heat treatment increased the tensile strength and hardness of the alloy. However the friction coefficient increased with the increasing speed after showing a small decrease with it and the temperature of the wear sample increased with both pressure and sliding speed. However the increase in the wear loss with the sliding speed became exponential at pressures above 4 MPa [9]. B. K. Prasad analysed the coMParison of the zinc based alloy of the cast iron on wear performance in similar working conditions with the increasing sliding speed and load, the wear rate of the samples increased [10]. Temel Savkan, Zeki Azakli observed the zinc based alloy in both heat treated and as cast conditions showed higher wear resistance than SAE 65 bronze, especially at the pressures beyond 4 MPa. It was also found that the quench ageing treatment increased the tensile strength and hardness of Zn - 40 Al - 2 Cu-2Si alloy considerably, but only a small improvement was obtained in wear resistance of the alloy after this heat treatment [11].

TAGUCHI DESIGN METHOD

Taguchi method of design was developed by Dr. Genichi Taguchi during the Second World War. During the Second World War due to the scarcity of the resources the need for optimization was at peak. The Taguchi method believes that every problem has easy solutions and that every problem can have linear solutions. The Taguchi method provides set of experiments arranged in arrays such as L9, L18, etc., and input parameters of the experiment. The three levels of parameters were taken as shown in the table 2.

Load (Kg) 3 6 9 liding Velocity (RPM)

200 300 400

Sliding Time (min)

30 60 90

The actual vales calculated for the parameters are shown in the table 3.

Pressure (MPa) 0.374 0.749 1.124 Sliding Velocity(m/s) 1.047 1.570 2.094 Sliding Time (min) 30 60 90

The Taguchi method is applied in following 4 steps, 1. Search for the quality characteristics and design input parameters 2. Design and conduct the experiment 3. Define the output parameters and calculate the same 4. For confirmation of the optimal solution check using the confirmation test. A. Signal-to-Noise Ratio: There are 3 Signal-to-Noise ratios of common interest for optimization (I) Smaller-The-Better: n = -10 Log10 [mean of sum of squares of measured data] (II) Larger-The-Better: n = -10 Log10 [mean of sum squares of reciprocal of measured data]

Gaurav L. Deshpande1*, S. A. Sonawane2, K. V. Nemade3 2

mean)/ Variance]

For the Experimentation the test material was turned in the form of Pin with Diameter of 10 mm and Length 25 mm. Test Parameters used with test Rig are shown in following table 3.Fig 1 and Fig 2 shows the actual photograph of the pin and disc machine and the pin used in the experiment .

The three materials namely A, B, C with the chemical composition are used for the experiment as shown in the table 1.

A Al-25Zn-2.5Cu-0.4Mn-0Si B Al-25Zn-2.5Cu-0.4Mn-

The Design of the standard L9 Orthogonal array is shown in the table 4.

1 0.375 1.047 30 2 0.375 1.57 60 3 0.375 2.094 90 4 0.749 1.047 60 5 0.749 1.57 90 6 0.749 2.094 30 7 1.124 1.047 90

8 1.124 1.57 30 9 1.124 2.094 60

Analysis of S/N ratio: The desirable value for the output characteristics is referred by the term signal in taguchi method whereas the undesirable value is referred as noise. (Standard Deviation) for the output characteristics. To measure the quality characteristic deviating from the desired S/N ratio is used. In S/N ratio S is calculated as S= -10 log (M.S.D.) where, M.S.D. is the mean square deviation for the output characteristic. The M.S.D. for higher-the –better quality characteristic can be expressed Where R = Number of repetitions The experiments were performed on the three different materials and the resultant wear was calculated. The results for Materials A, B, C are shown in the table 5, table 6, table 7 respectively.

1 0.375 1.047 30 91.383 2 0.375 1.57 60 480.617

3 0.375 2.094 90 760.212 4 0.749 1.047 60 289.175 5 0.749 1.57 90 716.76 6 0.749 2.094 30 266.497 7 1.124 1.047 90 712.253 8 1.124 1.57 30 369.465 9 1.124 2.094 60 602.131

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1 0.375 1.047 30 82.64 2 0.375 1.57 60 360.19 3 0.375 2.094 90 550.4 4 0.749 1.047 60 87.624 5 0.749 1.57 90 670.428 6 0.749 2.094 30 257.531 7 1.124 1.047 90 422.047 8 1.124 1.57 30 268.582 9 1.124 2.094 60 591.000

1 0.375 1.047 30 94.601 2 0.375 1.57 60 662.36 3 0.375 2.094 90 781.057 4 0.749 1.047 60 341.244 5 0.749 1.57 90 730.452 6 0.749 2.094 30 325.253 7 1.124 1.047 90 756.094 8 1.124 1.57 30 391.831

Using the analysis of variance (ANOVA) technique, the adequacy of the models is tested. This is statistical tool for testing null hypothesis for experimentation design, where all the variables of the experiment are studied simultaneously so as to check the performance and contribution of the individual input parameter on the optimality of the solution. ANOVA is used to quickly analyse the variances occurred in the experiment with the help of fisher test. This analysis was performed for a level of significance of 5%, i.e. the level of confidence 95%. Manual ANOVA for AZ alloy. The calculations are formulated in the table 8.

P 2 32944.71 16472.35 Pool V 2 57320.95 28660 1.74 T 2 357849.66 178924.80 10.86 Residual 2 447664.42 Total 8 448115.32 The results obtained from the experimentation have been expressed in the form of tribo- graphs shown in the fig 3, fig. 4, fig. 5.

Gaurav L. Deshpande1*, S. A. Sonawane2, K. V. Nemade3 2

From the results of the experimentation and the calculation of the coefficient of friction the results are plotted in the graph fig 6, Fig 7, Fig 8.

Fig.9 Wear Vs Velocity at constant Pressure of 0.375MPa. Fig 10. Wear Vs Velocity at constant Pressure of 0.749 MPa.

The Fig 9, Fig 10, Fig 11 show the variation in the amount of wear with the sliding velocity, at constant pressure and sliding time for all test materials. It is observed that wear of material B is less than material A and material C.

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The Experiments were conducted by varying different parameters such as the pressure, sliding velocity, and sliding time. The materials used were contained silicon 0%, material contained 2.5% silicon, and the material containing 5% silicon. Based on the investigation following conclusions were drawn- 1. The hardness, compressive and tensile strengths of Al-2.5Zn-2Cu-0.4Mn based alloys increased with increasing silicon content, but the trend reversed for one with more than 2.5%Si. Amongst the as cast alloys, the highest wear resistance was obtained with the 2.5% Si alloy. 2. The highest wear resistance was obtained with the 25Zn-2Cu-0.4Mn-2.5Si alloy. 3. The lowest coefficient of friction was obtained with the 25Zn-2Cu-0.4Mn-2.5Si alloy. 4. The wear resistance of Al-25Zn-2Cu-0.4Mn-2.5Si alloy is less.

[1] Bhushan bharat and Gupta B.K.,"Handbook of tribology:Materials, Coating and Surface Treatment",McGraw Hill Inc.,1991,pp.2.1-2.29,5.12-5.76. [2] Burwell J.T.,"Survey of possible wear mechanisms",Wear,Volume 1,pp.119-141. [3] Raymond G.Bayer , "Wear testing ",ASM Handbook:Mechanical testing,ASM International the material information society , Volume 11,1995,pp.600-608. [4] J.F.Archard," Contact and Rubbing of flat surfaces",Journel of Applied Physics, Volume 24 ,August 1953,pp.984-986 . [5] Gencaga Purcek, Temel Savaskan, samuel murphyb, " Dry Sliding Friction and Wear Properties of Znic based alloys ", Wear,Volume 252,2002,pp.894-901. [6] Temel Savaskan, Ali Pas, Hekimoglu,"Effect of Copper content on sliding and wear properties of Monotectioed bas Aluminium Zinc based ZA -8 Alloys ",Tribology International, Volume 37,2004,pp.45-50. [7] Ahmet Truk, Mehmet Durman E.,Sabri Kayli," The effect of Manganese on the microsrcture and mechanical properties of Zinc - Aluminium based ZA-8 Alloys",J.Mater Science, Volume 42,2007,pp.8298-8305. the Sliding wear behavior of ZA 27 Alloy", Tribology International, Volume 43,2010,pp.16-20. [9] Zeki Azakli, Temel Savakasn, "An Examination of Friction and Sliding Wear Properties of Zn-40Al-2Cu-2Si Alloy in case of oil cut off",Tribology International, Volume 41,2008,pp.9-16. [10] B. K. Prasad," Dry Sliding Wear Response of Znic based alloy over a test Speeds and Loads a coMParative study with Cast Iron", Tribology letters,Volume 25,February 2007,pp.25-30. [11] Temel Savaskan, Zeki Azakli,"An Investigation of Lubricated Friction and wear Properties of Zn-40-Al-2Cu-2Si Alloy in coMParison with SAE 65 bearing bronze", Wear, Volume 264,2008,pp.920-928. [12] B.K. Prasad, S. Das, O.P. Modi, A.K. Jha, R.Dasgupta and A.H. Yegneswaran," Wear Response of a Zn-Base Alloy in the Presence of Sic Particle Reinforcement, a coMParative study with a copper - base alloy", Journal of Mechanical Engineering, Volume 8, December 1999,pp.693-700. [13] B.K. Prasad, A.H. Yegneswaran," Influence of the nature of the micro constituents on the Tensile Properties of zinc based alloys and Leaded tin Bronze at different strain rates and tempratures ", Journal of Material Science , Volume 32,1997,pp.1169-1175. [14] B.K. Prasad, A.H. Yegneswaran,"Microsrcture and property Caracterization of a modified zinc based alloy and coMParison with bearing alloys",Journal of mechanical Engineering Volume 7,February 1998,pp.130-135. [15] Yasim Alemdag," Mechanical and Tribological Properties of Al-40Zn-Cu-Alloy",Tribology International, Volume 42, 2009, pp.176-182.

PG Student Government College of Engineering, Aurangabad, India