OPTIMIZING GRINDING PARAMETERS FOR SURFACE ROUGHNESS WHEN GRINDING TABLET BY CBN GRINDING WHEEL ON CNC MILLING MACHINE

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 10, Issue 01, January 2019, pp , Article ID: IJMET_10_01_114 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed OPTIMIZING GRINDING PARAMETERS FOR SURFACE ROUGHNESS WHEN GRINDING TABLET BY CBN GRINDING WHEEL ON CNC MILLING MACHINE Le Hong Ky Vinh Long University of Technology Education, Vinh Long, Vietnam Tran Thi Hong Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam Hoang Tien Dung Ha Noi University of Industry, Ha Noi, Vietnam Nguyen Van Tung, Nguyen Thi Thanh Nga, Luu Anh Tung, Vu Ngoc Pi Thai Nguyen University of Technology, Thai Nguyen, Vietnam * Corresponding Author vungocpi@tnut.edu.vn ABSTRACT Surface quality of a workpiece is one of the most important criteria for the evaluation of a grinding process. Surface finish depends on many factors such as grinding and dressing parameters. This paper presents an optimization of grinding parameters when grinding tablet by CBN grinding wheel on CNC milling machine in order to minimize surface roughness. The experiment was conducted with different values of grinding parameters at three levels. Using the Taguchi method, the effect of the grinding parameters i.e., depth of cut, grinding wheel speed, and feed rate on surface roughness was investigated. In addition, the optimal grinding parameters were found at their optimal levels. The predicted surface roughness was therefore determined. Key words: Optimal grinding parameters, surface roughness, CBN grinding wheel, Taguchi method. Cite this Article: Le Hong Ky, Tran Thi Hong, Hoang Tien Dung, Nguyen Van Tung, Nguyen Thi Thanh Nga, Luu Anh Tung, Vu Ngoc Pi, Optimizing Grinding Parameters for Surface Roughness when Grinding Tablet by CBN Grinding Wheel on CNC Milling Machine, International Journal of Mechanical Engineering and Technology (IJMET) 10(1), 2019, pp editor@iaeme.com

2 Le Hong Ky, Tran Thi Hong, Hoang Tien Dung, Nguyen Van Tung, Nguyen Thi Thanh Nga, Luu Anh Tung, Vu Ngoc Pi 1. INTRODUCTION In general, improving the dimensional accuracy and surface quality of a workpiece in a grinding process, many grinding machining parameters could be considered. Analysis of grinding parameters in cylindrical grinding was investigated by designing experiments [1-3]. The influence of dressing parameters in cylindrical grinding was proposed in [4-5]. These researches presented the effect of several important dressing paremters i.e., dressing deep of cut, cross feed rate, drag angle of dresser and number of passes on surface roughness. Lin et al. [6] showed the influence of grinding parameters on surface temperature and burn behavior of the grinding rail. For regarding the optimization in grinding process, Agarwal [7] proposed an optimization of various machining parameters such as depth, table feed, and size and density of grit on the metal removal rate in order to obtain high surface integrity in grinding silicon carbide ceramics. An enumeration method was used to optimize grinding operations based on minimizing grinding time and maximizing the volume of material removed [8]. The optimal grinding operations are material properties, grinding parameters, infeed, workpiece speed, grinding wheel speed, and dress conditions. An optimization of grinding parameters in cylindrical grinding process was investigated in order to minimize surface roughness [9,10]. In this work, the Taguchi technique was used to obtain the optimal grinding parameters. Le et al. [11] was also used Taguchi method for optimizing the dressing parameters such as dressing feed rate, coarse dressing depth, coarse dressing times, fine dressing depth, fine dressing times, and dressing number without depth of cut in order to obtain maximum material removal rate. This study proposes an optimization of grinding parameters for surface roughness when grinding tablet by CBN grinding wheel on CNC milling machine. The important grinding parameters seclected in this work are the depth of cut, grinding wheel speed, and feed rate. The Taguchi technique has been appied in order to determine the optimal grinding parameters leading to minimize surface roughness. Furthermore, the predicted surface roughness was also investigated. 2. EXPRERIMENTAL METHODOLOGY A set of experiments was conducted on the CNC milling machine for grinding by using CBN grinding wheel. The experiment equipment is shown in Table 1. Table 1 Experimental equipment Machine and Equipment Specification CNC milling machine Mitsubishi, Model M-V50C Grinding wheel CBN 325-N75B (Japan) Workpiece material 9CrSi Workpiece dimensions 13x13x30 mm 3 Roughness measurement device Mitutoyo A, SJ-201 The experiments have been conducted on the basis of the Taguchi method in order to design and analyze data of the experiments. For this, the effect of the grinding parameters on the surface roughness when grinding tablet using the CBN grinding wheel on CNC Milling Machine was investigated. The grinding parameters such as the depth of cut, grinding wheel speed and feed rate were selected in the experiments. The ginding parameters and their value range are shown in Table editor@iaeme.com

3 Optimizing Grinding Parameters for Surface Roughness when Grinding Tablet by CBN Grinding Wheel on CNC Milling Machine Table 2. Ginding parameters and their value range Factor Symbol Unit Low High Depth of cut mm Grinding wheel speed r.p.m Feed rate mm/min Table 3. Experiment work Test run No. (mm) (r.p.m) (r.p.m) Fig.1. Experimental setup a) Dressing setup b) Grinding setup c) Schema of grinding Minitab 17 was used to design the experiments with the three grinding parameters. By using Taguchi method, L9 with nine test runs was used for the experiment work as shown in Table 3. For increasing the accuracy of the experiment results, the three grinding parameters and three trials were performed during the experimentation in each test run as shown in Table 4. The total of test runs is 27 for the experimentation. The procedure of the experiment was conducted into three steps as follows: - Step 1: The CBN grinding wheel is dressed by dresser equipment (Figure 1.a) according to the dressing parameters are mm; r.p.m; mm/min. - Step 2: The workpieces are ground (Figure 2b) with schema in Figure 2c and the grinding parameters in Table 2 with the three levels and the three trials editor@iaeme.com

4 Le Hong Ky, Tran Thi Hong, Hoang Tien Dung, Nguyen Van Tung, Nguyen Thi Thanh Nga, Luu Anh Tung, Vu Ngoc Pi - Step 3: The surface roughness of the workpiece was measured by using the roughness measurement device. Table 4 Experiment results Test run No. Ra ( m) Trial 1 Trial 2 Trial 3 Mean S/N RESULT AND DISCUSSION Surface roughness values are obtained from the Mitutoyo surface roughness tester for each experiment. The values of surface roughness in three trial are shown in Table 3. The Taguchi method was used for analyzing the values of surface roughness in order to depict the effect of the grinding parameters on surface roughness and to determine the optimal grinding parameters Effect of the grinding parameters on surface roughness From the analysis of variance - ANOVA, Table 5 presents the effect of the grinding parameters on the surface roughness at three levels. Table 6 and Fig.1 show the effect of the grinding parameters on the surface roughness. It is clearly seen that the depth of cut has the largest effect on the surface roughness. The effect of the grinding wheel speed and feed rate decreases respectively. Table 5. Effect of grinding parameters on surface roughness at different levels Level Delta Rank Fig.1 shows that the surface roughness tremendously increases when the depth of cut increases. The surface roughness obtains the minimum value at 0.02m of the depth of cut. The surface roughness also increases with increase of the grinding wheel speed and the feed rate. Table 6. Results of ANOVA analysis for the surface roughness Source DF Seq SS Adj SS Adj MS F P Residual error Total editor@iaeme.com

5 Optimizing Grinding Parameters for Surface Roughness when Grinding Tablet by CBN Grinding Wheel on CNC Milling Machine Figure 1 Effect of the grinding parameters on surface roughness Ra 3.2. Determination of optimal grinding parameters The Taguchi method uses the term signal-to-noise (S/N) to measure the quality characteristic deviation from the desired value. Thus, based on the maximum S/N ratio, the optimum factors can be determined. Table 7 shows that the effect of the grinding parameters such as the depth of cut, grinding wheel speed, and feed rate on the S/N ratio decreases respectively. It is observed from Table 8 and Fig. 2 that the optimal grinding parameters are obtained in order to achieve the minimum surface roughness. The optimal values of the grinding parameters are,, and. Table 7 Effect of factors on the S/N ratio at their levels Level Delta Rank Table 8. Results of ANOVA analysis for S/N Source DF Seq SS Adj SS Adj MS F P Residual error Total editor@iaeme.com

6 Le Hong Ky, Tran Thi Hong, Hoang Tien Dung, Nguyen Van Tung, Nguyen Thi Thanh Nga, Luu Anh Tung, Vu Ngoc Pi Figure 2 Effect of the grinding parameters on S/N ratio The mean value of optimal surface roughness is determined from the optimum parameters at their optimal levels. As shown in Table 7, level 1 is the optimal level of the three parameters. Thus, the formula for computing the mean value of optimal surface roughness is (1) Where is the mean value of surface roughness at the depth of cut and is the mean value of surface roughness at the grinding wheel speed and is the mean value of surface roughness at the feed rate and is the mean value of surface roughness for all test runs and it can be calculated as (2) Substituting all of the parameters the surface roughness is calculated as. and into Eq. (1), the mean value of To evaluate the appropriateness of the optimum parameters, an experiment was conducted with two replications. The data used in the experiment were: a ed =0.02 mm, R PM = 4000 rpm, Fe= 2500 mm/min. Table 9 shows the values of the surface roughness which was predicted by using the mathematical model and the experiment results. The difference between both values is appropriately 6.6 % of the range. Therefore, this calculation method can be used to accurately predict the surface roughness of the ground parts editor@iaeme.com

7 Optimizing Grinding Parameters for Surface Roughness when Grinding Tablet by CBN Grinding Wheel on CNC Milling Machine Table 9. Comparison results between calculation value and experimental value Optimum parameters Output factors Prediction value Experimental value a ed2, R PM1, F e1 a ed2, R PM1, F e1 Error (%) The surface roughness of part Ra (µm) Signal-to-noise ratio (S/N) CONCLUSIONS In this paper, the proposed designed experiment using Taguchi method with L9 orthogodinal array was carried out to evaluate the effect of the grinding parameters and to find the optimal parameters for surface roughness. The conclusion can be drawn as follows It was found that the depth of cut is the most influencing factor on surface roughness compared with the grinding wheel speed and feed rate. The surface roughness is proportional to all of the grinding parameters. The optimal values of the grinding parameters obtained for surface roughness using Taguchi method of experiment methodology have been found as. ACKNOWLEDGMENTS The work described in this paper was supported by Thai Nguyen University of Technology for a scientific project. REFERENCES [1] Saikat Chatterjee, Ramesh Rudrapati, Pradip Kumar pal, Goutam Nandi, Experiments, analysis and parametric optimization of cylindrical traverse cut grinding of aluminium bronze, Materials Today: Proceedings 5 (2018), p [2] Jae-Seob Kwak, Sung-Bo Sim, Yeong-Deug Jeong, An analysis of grinding power and surface roughness in external cylindrical grinding of hardened SCM440 steel using the response surface method, International Journal of Machine Tools & Manufacture 46 (2006), p [3] Tianyu Yu, Ashraf F. Bastawros, Abhijit Chandra, Experimental and Modeling Characterization of Wear and Life Expectancy of Electroplated CBN Grinding Wheels, International Journal of Machine Tools and Manufacture 121 (2017), p [4] A. Daneshi, N. Jandaghi, T. Tawakoli, Effect of Dressing on Internal Cylindrical Grinding, Procedia CIRP International Conference on High Performance Cutting 14 ( 2014 ), p [5] Dadaso D. Mohite, An Investigation of Effect of Dressing Parameters for Minimum Surface Roughness using CNC Cylindrical Grinding Machine, International Journal of Research in Engineering and Applied Sciences 6 (2016), p [6] B. Lin, K. Zhou, J. Guo, Q.Y. Liu, W.J. Wang, Influence of grinding parameters on surface temperature and burn behaviors of grinding rail, Tribology International 122 (2018), p [7] Sanjay Agarwal, Optimizing machining parameters to combine high productivity with high surface integrity in grinding silicon carbide ceramics, Ceramics International 42(2016), p editor@iaeme.com

8 Le Hong Ky, Tran Thi Hong, Hoang Tien Dung, Nguyen Van Tung, Nguyen Thi Thanh Nga, Luu Anh Tung, Vu Ngoc Pi [8] R. Gupta, K.S. Shishodia, G.S. Sekhon, Optimization of grinding process parameters using enumeration method, Journal of Materials Processing Technology 112 (2001), p [9] Ravi Kumar Panthangi, Vinayak Naduvinamani, Optimization of Surface Roughness in Cylindrical Grinding Process, International Journal of Applied Engineering Research 12 (2017), pp [10] S. Jeevanantham, N.M. Sivaram, D.S. Robinson Smart and S. Nallusamy, Optimization of Internal Grinding Process Parameters on C40E Steel Using Taguchi Technique, International Journal of Applied Engineering Research 12 (2017), pp [11] Le Xuan Hung, Tran Thi Hong, Le Hong Ky, Luu Anh Tung, Nguyen Thi Thanh Nga, Vu Ngọc Pi, Optimum dressing parameters for maximum material removal rate when internal cylindrical drinding using Taguchi method, International Journal of Mechanical Engineering and Technology 9 (2018), pp editor@iaeme.com