OPTIMIZATION of BURNISHING PROCESS PARAMETERS on DIFFERENTLY HARDENED 20Mncr5 STEEL

OPTIMIZATION OF BURNISHING PROCESS PARAMETERS ON DIFFERENTLY HARDENED 20MnCr5 STEEL

1HIMANSHU KHANNA, 2HARISH PUNGOTRA, 3SANDEEP GANDOTRA

1M.TECH. STUDENT, BEANT COLLEGE OF ENGINEERING AND TECHNOLOGY GURDASPUR, PUNJAB 2ASSOCIATE PROFESSOR, DEPARTMENT OF MECHANICAL ENGINEERING, BEANT COLLEGE OF ENGINEERING & TECHNOLOGY, GURDASPUR - 143521, PUNJAB, INDIA 3ASSISTANT PROFESSOR, DEPARTMENT OF MECHANICAL ENGINEERING, BEANT COLLEGE OF ENGINEERING & TECHNOLOGY, GURDASPUR - 143521, PUNJAB, INDIA E-mail: [email protected], [email protected], [email protected]

Abstract: Surface finish designates the geometry and microstructural superiority of the machined surface. Different operations such as grinding, lapping, honing, buffing, barrel rolling, polishing, super finishing, and burnishing are required to be performed to achieve the high surface finish. Amongst all, burnishing is a process where the hard roller or a ball tool is engaged to the workpiece to get the better surface finish. In the present study, using Taguchi approach preliminary plan is made for the experimentation then according to it a roller burnishing of the 20MnCr5 workpiece at different input conditions is performed. From the analysis, it is concluded that the hardness of the material is the main contributing factor for burnishing process.

Keywords - Burnishing, Depth of penetration, Feed, Speed, Hardness, Surface roughness.

I. INTRODUCTION Morimoto & Tamamura (1991) compared different types of ball burnishing tools and concluded that the For reliable performance and prolonged life of cemented carbide and silicon nitride ceramic ball-tool contemporary machinery, its components require not tool showed best results regarding surface roughness. only high geometrical and dimensional geometrical Hassan et al. (1996) compared machined and accuracy but also with low surface roughness. The burnished specimens of commercially pure surface roughness has a vital role in functional aluminium and brass material. Surface roughness, features like wear resistance, fatigue strength, hardness, ultimate tensile strength and fatigue corrosion resistance and power loss due to friction. strength before and after burnishing process were Inappropriately, normal machining methods like examined and results showed improvement after turning, milling or even classical grinding cannot burnishing process. Adel Mahmood Hassan (1997) meet this severe condition. Burnishing is a plastic used the simple ball and roller burnishing tools and deformation process used to finish surfaces. studied the effects of the burnishing force; number Burnishing is a cold-working process in which plastic passes on the surface roughness and surface hardness deformation takes place by applying pressure with a on aluminum and brass. Improvements in the surface hard and smooth ball or roller on a metallic surface. roughness and surface hardness were achieved by the Improvements in surface finish, surface hardness, application of both ball and roller burnisher. Hassan wear resistance, fatigue resistance, yield, tensile et al. (1998) examined the surface finish for ball- strength and corrosion resistance can be achieved by burnished brass components using the response the application of this process. As in this process, surface method and established a mathematical model there is no removal of the material from the surface of to burnishing force and the number of tool passes, the workpiece, so burnishing is a chipless finishing with the surface finish. Klocke & Liermann (1998) process. Roller burnishers are mostly used for concluded that the roughness peaks are flattened, and cylindrical surfaces, flat surfaces or to burnish large the quality of the workpiece improved using internal diameters. In roller burnishing a hard roller is hydrostatically borne ceramic ball rolls over the employed to improve surface specifications such as component surface under high pressures. Authors hardness, surface finish and wear resistance of the recommended that the combined hard turning and mechanical components. In Ball burnishing process burnishing provide a manufacturing alternative to hard metallic ball penetrates up to the prescribed grinding and honing operations. Ne´mat & Lyons depth to the pre-machined surface. The workpiece (2000) investigated on ball burnished mild steel and and burnishing tool move in a certain specified aluminum using a purpose-built burnishing tool and. direction, i.e., in the opposite direction or one is The assessed the effects of burnishing feed, force, moving, and other remains stationary. The surface speed and the number of passes on the surface roughness obtained after burnishing depends on the roughness and surface hardness. The experimental depth of penetration, speed, and lubricant used if any. results showed the improvements of 70% in surface

Proceedings of IRF International Conference, 25th February, 2018, Kanyakumari, India 10 Optimization of Burnishing Process Parameters on Differently Hardened 20MnCr5 Steel quality after varying the mix of parameters. M.H. El- machining processes on a brass material on the basis Axir (2000) studied the influence of burnishing of microstructure, circularity and surface roughness. speed, force, feed, and number of passes on both The results showed that burnishing should be surface microhardness and roughness. The preferred to provide the optimum characteristics in relationship between residual stress, burnishing speed hole surfaces subjected to continuous deformation and force was presented for predicting the surface and corrosion. Babu et al., (2012) studied the microhardness and roughness under lubricated influence of various burnishing parameters on the conditions Chen & Shiou (2003) determined the surface characteristics i.e. microhardness and optimal plane ball-burnishing parameters for plastic microstructure, are evaluated, and discussed in the injection molding steel with four burnishing case of EN Series steels (EN 8, EN 24 and EN 31), parameters namely ball burnisher material, speed Alpha-beta brass and Aluminum alloy (AA6061). force and feed using Taguchi’s design of The burnishing parameters considered for studies experiments. Zhang & Lindemann (2005) worked on principally are burnishing speed, burnishing force, roller burnishing and improved the high cycle fatigue burnishing feed and number of passes. Taguchi performance. Authors suggested that roller technique was employed by them to identify the most burnishing is more effective than shot peening in influencing parameters on surface roughness. The enhancing the fatigue life. Hamadache (2006) effort was also made to determine the optimal developed a device for mechanical plastic burnishing parameters and the factors for the deformation of structural Rb40 steel using ball and scientific basis of such optimization. Patel and Patel, roller burnishing. The output parameters were (2013) presented a review of parametric optimization roughness, hardness, and wear resistance and authors of process parameters for roller burnishing process. recommended two number of passes for surface Roller burnishing tool is used to perform burnishing roughness and three passes for hard materials. process using different input and output parameters. Swirad, (2007) experimentally demonstrated the There are many parameters which can be optimized effect of burnishing parameters on steel fatigue for improved performance of surface hardness and strengths with his primary focus on possibilities of surface roughness. It has been used to impart certain sliding burnishing with cylindrical elements made of properties, such as corrosion, friction, wear and diamond composite with ceramic bonding phase. The fatigue resistance. Esme et al., (2013) worked on author identified that a new technology of sliding predictive modeling of ball burnishing process using burnishing with cylindrical elements of the diamond regression analysis and neural network by focusing composite could be used in effortless and easy way on two techniques, namely neural network techniques for smooth machining of various types of material. and regression, for predicting surface roughness in The cylindrical elements are easier to manufacture ball burnishing process. Values of surface roughness and simpler to grind, which reduces the costs of their predicted by the techniques were compared with production, when the contact zone “tool machined experimental values. Also, the effects of the main object” will wear, it can easily grinded in this way it burnishing parameters on surface roughness were was possible to extend its life several dozen times. determined. The surface roughness (Ra) was taken as Babu et al., (2008) worked on effects of internal the response variable, and burnishing force, roller burnishing on surface roughness and surface burnishing speed, the number of passes and feed rate hardness of mild steel.The authors observed that in were taken as input parameters. The relation between internal burnishing process, surface finish and surface the surface roughness and burnishing parameters was roughness of mild steel material increased with found out for measurement of the surface roughness. increase in burnishing speed due to repeated Akkurt et al. (2014) investigated surface finishing of deformation of surface irregularities with increased drilling, turning, reaming, grinding and roller burnishing speed. The surface finish and surface burnishing etc. Different hole surface finishing hardness increase with burnishing speed up to an processes were applied to the samples made of pure optimum value (62m/min)and then decrease when copper and results showed that the roller burnishing speed increases. Prabhu et al., (2010) studied the method gives the best results in terms of mechanical, effect of deep cold rolling and low plasticity metallurgical properties and hole surface quality of burnishing on surface hardness and surface roughness the material. Okada et al. (2015) proposed roller of AISI 4140 steel and focused on the surface burnishing method comprising of both rolling and hardness and surface roughness aspects of AISI 4140 sliding effects on the burnishing simultaneously to work material, using fractional factorial design. They accomplish finish with superior surface. Authors assessed the surface integrity aspects on work compared the processing characteristics method on material, to identify the predominant factors amongst the aluminum-based alloy and carbon steel taking the selected parameters and they found that by using burnishing speed, thrust force, and feed rate as LPB process surface hardness has been improved by process parameters, was also investigated. Naresh et 167% and in DCR process surface hardness has been al., (2016) studied the effect of burnishing process improved by 442%. Ovali & Akkurt (2011) compared parameters like burnishing speed, burnishing the effects of traditional and modern surface condition, depth of penetration, feed and number of

Proceedings of IRF International Conference, 25th February, 2018, Kanyakumari, India 11 Optimization of Burnishing Process Parameters on Differently Hardened 20MnCr5 Steel passes, and investigated on the surface roughness and speed, with 1.5 mm depth of penetration and double hardness of C40E steel. Investigation revealed that pass of tool.from the survey it is concluded that the least surface roughness value of 0.129 μm at wet burnishing of differently hardened 20MnCr5 is topic burnishing condition, 0.06 mm/rev feed, 557 rpm of new research.

II. EXPERIMENTATION In the present research, selected input machining parameters with their designation are listed in Table 1 and Table 2 enlists levels of burnishing parameters and assigned values of burnishing parameters at these levels and their designation for experimental work.

Depth of Burnishing Speed Feed Parameter Hardness Penetration (mm) (RPM) (mm/rev) Symbol A B C D Table 1 Input burnishing parameters

The next is to select an appropriate orthogonal array keeping that total DOF for the array should be greater than or equal to those for the process parameters. L-18 (33 x 21) orthogonal array is selected for the research. This array has four columns and eighteen rows. One burnishing parameter is assigned to each column. Total eighteen rows give the combination of parameters for each set of experiment.

Factor Levels and corresponding values of burnishing Burnishing Parameter Designation parameters (units) Level 1 Level 2 Level3 A Hardness (HB) 155 230 - B Depth of Penetration (mm) 0.10 0.20 0.30 C Burnishing Speed (RPM) 330 440 635 D Feed (mm/rev) 0.10 0.15 0.20 Table 2 Assigned values of input parameters at different levels and their description

The machine used for experimentation is Centre Lathe, HMT, India (Mysore) in Machine Shop of BCET. The raw material 20MnCr5 was received 45 mm in diameter. The rod length is divided into nine equal parts each having an approximate length of 40 mm. The workpiece was turned to a diameter of 42mm. The surface roughness of workpiece was measured before burnishing, at each region with the help of Tally surf roughness tester. To minimize the error, three readings have been taken for each region. Average value of 3 readings was recorded. The specimen was loaded on a lathe machine. The specimen was held between two centers of lathe machine, one center in the headstock and another live center in the tailstock. The roller burnishing tool was fitted in the tool post just like any other cutting tool. The speed and depth of penetration are adjusted on the lathe machine. The roller of the burnishing tool is moved towards the rotating specimen. The roller also starts rotating when it comes in contact with the rotating specimen. Now select the required feed of the tool post with the help of lever provided on a lathe machine. Now burnishing of the specimen will start. Stop the lathe machine after completion of burnishing in one region. So, now by changing the parameters burnishing of the other region was done. Once the burnishing has been done on all the specimens, then it is investigated for output parameters, i.e., the surface roughness (µm) with the help of Tally surf roughness tester.

III. RESULTS AND DISCUSSIONS

Burnishing experiments are performed on 20MnCr5 steel using roller burnishing tool. Different experimental parameter setting and their respective result regarding surface roughness (Ra) are interpreted in Table 3. Taguchi method is used as the design of experiment and results are analyzed by using analysis of variance (ANOVA) using Minitab 16 software.

Speed Depth of Penetration Feed Mean S.No. Hardness (HB) Ra1 Ra2 Ra3 (RPM) (mm) mm/min Ra 1 150 320 0.1 0.1 2.37 2.27 2.13 2.26 2 150 320 0.15 0.2 1.24 1.12 1.03 1.13 3 150 320 0.2 0.3 1.18 1.01 0.89 1.03 4 150 470 0.1 0.1 1.04 0.74 0.47 0.75 5 150 470 0.15 0.2 0.86 0.65 0.4 0.64 6 150 470 0.2 0.3 1.17 0.86 0.63 0.89 7 150 540 0.1 0.2 0.72 0.57 0.39 0.56

Proceedings of IRF International Conference, 25th February, 2018, Kanyakumari, India 12 Optimization of Burnishing Process Parameters on Differently Hardened 20MnCr5 Steel 8 150 540 0.15 0.3 0.68 0.5 0.31 0.5 9 150 540 0.2 0.1 0.53 0.33 0.15 0.34 10 230 320 0.1 0.3 2.42 2.32 2.13 2.29 11 230 320 0.15 0.1 2.26 1.72 1.55 1.84 12 230 320 0.2 0.2 2.73 2.78 2.65 2.72 13 230 470 0.1 0.2 2.83 2.86 2.84 2.84 14 230 470 0.15 0.3 3.8 3.58 3.3 3.56 15 230 470 0.2 0.1 3.7 3.44 3.14 3.43 16 230 540 0.1 0.3 3.35 2.93 2.8 3.03 17 230 540 0.15 0.1 2.19 1.85 1.76 1.93 18 230 540 0.2 0.2 1.56 1.36 1.13 1.35 Table 3

The surface roughness (SR) analyzed using Analysis of the variance in Minitab software. As the minimal value of surface roughness is the requirement in experimentation, so the criterion for evaluation "lower is better" is used. Table 4 summarizes the information of analysis of variance and case statistics for further interpreted in Table 5.

Percentage Source DF Seq SS Adj SS Adj MS F P contribution Hardness 1 12.356 12.356 12.356 31.57 0.03 63.5 Speed 2 1.8199 1.8199 0.9099 2.33 0.301 9.3 Feed 2 0.4703 0.6007 0.3004 0.77 0.566 2.4 Depth of Penetration 2 0.358 0.358 0.179 0.46 0.686 1.8 Hardness*Speed 2 2.1824 2.1824 1.0912 2.79 0.264 11.2 Hardness*Depth of 2 0.2619 0.3699 0.185 0.47 0.679 1.3 Penetration Speed*Depth of 4 1.2398 1.2398 0.3099 0.79 0.624 6.4 Penetration Residual Error 2 0.7827 0.7827 0.3913 4.0

Total 17 19.4709 100.0

Table 4 Analysis of variance for means of SN ratio for SR (Smaller is Better)

ANOVA table for SR indicates that the burnishing feed and depth of penetration are relatively less influencing factors for SR and hardness, speed, and hardness*depth of penetration are the most influencing factors for SR. The percentage contribution for attaining surface finish is described in Figure1.

Percentage Contribution 4% 6% 1% Hardness

11% Speed

Feed 2%

3% Depth of Penetration 64%

9% Hardness*Speed

Hardness*Depth of Penetration

Figure 1 Percentage contribution of process parameters

Proceedings of IRF International Conference, 25th February, 2018, Kanyakumari, India 13 Optimization of Burnishing Process Parameters on Differently Hardened 20MnCr5 Steel Level Hardness Speed Feed Depth of Penetration 1 0.8978 1.8778 1.9544 1.7578 2 2.5548 2.0172 1.6 1.54 3 1.2839 1.6244 1.8811

Delta 1.657 0.7333 0.3544 0.3411 Rank 1 2 3 4 Table 5 Response Table for S/N Ratios (Lower is better)

During the burnishing process, the effect of different parameters like hardness, speed, feed, and depth of penetration on surface roughness is shown in Figure 2 as main effect plot for means and Figure 3 as interaction plot for means.

Main Effects Plot for Means Data Means

Hardness Speed Feed Depth of Penetration 2.75

2.50

2.25 s n a

e 2.00 M

f o 1.75 n a e

M 1.50

1.25

1.00

150 230 320 470 540 0.10 0.15 0.20 0.1 0.2 0.3

Figure 2 Main effects plot for means (Surface Roughness)

Interaction Plot for Means Data Means

320 470 540

3 Hardness 150

2 230 Hardness

3 Speed 320

2 470 Speed 540

3 Depth of Penetration

2 0.1 Depth of Penetration 0.2 0.3 1

150 230 0.1 0.2 0.3

Figure 3 Interaction plot for means (Surface Roughness)

Proceedings of IRF International Conference, 25th February, 2018, Kanyakumari, India 14 Optimization of Burnishing Process Parameters on Differently Hardened 20MnCr5 Steel It is clear from Figure 2 that surface roughness is to 63.5 %, speed is contributing up to 9.3 % minimum at the 1st level of hardness, 3rd level of whereas feed and depth of penetration has the burnishing speed, 2nd level of Burnishing feed and 2nd least contribution in surface roughness of level of depth of penetration. Main effect plots for 20MnCr5 steel. means ratios suggest these levels of the parameters as  The combined effect of hardness and speed is best levels for minimum SR as shown in Table 6. 11.2% significant, speed and depth of penetration is 6.4% whereas hardness and depth of Depth of penetration is 1.3% significant. Factor Hardness Speed Feed Penetration REFERENCE level 1 2 3 4 [1] Morimoto T, Tamamura K. 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Proceedings of IRF International Conference, 25th February, 2018, Kanyakumari, India 15 Optimization of Burnishing Process Parameters on Differently Hardened 20MnCr5 Steel [17] Esme Ugur, Kemal Kulekci Mustafa, Ozgun Sueda, burnishing method with rolling and sliding effects. Kazancoglu Yigit (2013), “Predictive modeling of ball Mechatronics. 2015 Aug 31; 29:110-8. burnishing process”, MP Materials Testing, 3, 187-192. [20] Kumar N , Sachdeva A, Singh L, Tripathi H (2016), [18] AKKURT A, Abdullah KU, ÖZDEMİR A, ŞEKER U. “Experimental investigation of effect of roller burnishing Comparison of hole surface finishing processes with roller process parameters on surface roughness and surface burnishing method applied in copper materials. Gazi hardness of C40E steel”, International Journal Machining University Journal of Science. 2014;27(1):721-34. and Machinability of Materials, 18(1/2), 185-199. [19] Okada M, Suenobu S, Watanabe K, Yamashita Y, Asakawa N. Development and burnishing characteristics of roller

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