ANALYSIS OF SURFACE ROUGHNESS IN CNC TURNING OF ALUMINIUM BASED HYBRID MMC USING RSM Mandeep Singh 1, Shamsher Singh 2 1

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1 ANALYSIS OF SURFACE ROUGHNESS IN CNC TURNING OF ALUMINIUM BASED HYBRID MMC USING RSM Mandeep Singh, Shamsher Singh Assistant Professor, Department of Mechanical Engineering, Om institute of technology and management, Hisar. M.tech scholar, Mechanical Engineering, Om institute of Technology. and management, Hisar 500. Abstract: Metal matrix composites (MMCs) are very advanced materials because they have ability to attain superior strength to cost ratio and strength to weight ratio and mostly used in today s industries.in this study turning of Hybrid Aluminum (Al606) based metal matrix composite with reinforced SiC p 5% and Gr p 5%was done on a CNC turning center using three different carbide tool inserts (TNMG000, TNMG60404 and TNMG60408). Experiments were performed to study how the Surface Roughness is affected in the turning with the variation in the input process parameters. In this study it is observed that all the selected machining parameters have their significant effect on the Surface Roughness. To check the signification of model the ANOVA (Analysis of variance) technique is used.the design matrix and mathematical models were developed by RSM (response surface methodology). Keywords: Hybrid metal matrix composite (HMMC), Surface roughness (SR), CNC Turning, ANOVA and RSM. Introduction: Metal matrix compositions (MMC) have become a leading materials and particles reinforced aluminum MMCs have received considerable attention due to their excellent mechanical properties like high hardness, high tensile strength etc.[].al MMC are significantly important in the various demanding fields of medicine and engineering like aerospace, defense, automobiles, dental and consumer goods.for MMC various techniques are available. Among them stir casting method is generally preferred. Its advantages lie in its simplicity, flexibility and applicability to large quantity of production. It is also attractive because of minimized final cost of the product. It also allows very large sized components to be fabricated []. Greater production cost can be incurred for an improper decision of an operator in turning operation. Thus selection of proper cutting tools and proper input parameters is a very critical and vital task. Therefore a proper estimation of surface roughness is the focus of study for several years. Surface roughness is the indicator of the quality of the machined surfaces and it influences properties such as fatigue strength, wear resistance, wear rate, coefficient of friction, lubrication, and corrosion resistance of the machined parts [4]. There are several factors that need considerable attention, including the difficulty of achieving a uniform distribution of the reinforcement CNC lathe machine is mainly used to machine the materials which are difficult to machine and the materials which have high strength, temperature resistant alloys.. Experimental Work:A series of experiments were performed on Stallion 00HS CNC Lathe machine. Turning is anengineering, machining method in which a cutting tool, typically a tool bit, shows a helical tool ride by moving more or less linearly while the work piece rotates. The tool's axes of movement in a straight line, or they work along few sets of curves or angles, but they are essentially linear in the nonmathematical sense. Usually the term "turning" is composed for the generation of the outer surfaces of this cutting action, whereas this same essential cutting action when applied to the internal surfaces (that is, holes, of one kind or another) is called "boring". Thus the phrase "boring and turning" categorizes the larger family of (essentially similar) processes. The cutting of faces on the workpiece (that is, surfaces straight to its rotating axis) whether with a turning or boring tool, is called "facing". The turning processes are regularly carried out on a lathe, considered to be the original machine tools, such as profiling, taper turning, straight turning or external grooving. The turning processes can produce various shapes of materials such as curved, conical, straight, or grooved work piece. In turning the mostly tool used which is single-point cutting tools. Each group of workpiece materials has a perfect set of tool angles which have been refined through the years... Turning Parameters: There are several parameters of turning process. The parameters have been selected by researchers for their work depends upon the workpiece material, tool size, tool material and working conditions. Major turning parameters that affect the process are: [] Cutting Speed It is the difference between the tool insert and the surface of the work piece. [] Spindle Speed It may be defined as the revolutions of the work piece and the rotational speed of the spindle. [] Feed Rate (Fr = rpm t cl) Fr = feed rate, T = no of teeth on cutter, rpm=calculate speed of the cutter, cl=it is the size of the chip which every tooth of the cutter takes. ISSN Page 4

2 [4] Depth of Cut Volume of the work piece material that can be removed per time unit... Surface Roughness Measurement: Surface roughness is a part of surface texture, and is also referred as simply roughness. The Surface roughness tester is a device for measuring surface roughness (Ra). It is basically the quantified measure of in the direction of the normal vector to the actual surface. The surface is said to be rough, if these deviations are large but if they are small the surface is said to be smooth. It is very important to know the frequency and amplitude of variations to ensure the fit the surface for therequired use. The surface roughness tester modelno ISR-S400 by INSIZE is used.. Design of Experiment RSM (Response Surface Methodlogy):RSM makes it possible to represent independent process parameters in quantitative form as to equation (). Y = f (X, X, X, X 4 )..() Where, Y is the response, f is the response function, and X, X, X, Xn are independent parameters. For predicting the optimal point the quadratic equation model was expressed according to equation ()... () The low and high levels of selected three factors are given in Table. To study out the Percentage adsorption we used standard RSM design called Central Composite design (CCD). Final experiments design matrix was developed by using RSM (Response surface methodology). RSM was applied to optimize the significant parameters of turning where the Surface Roughness is directly affected. In RSM the Central Composite design (CCD) was employed to conduct the experiments and to evaluate the effect of process parameters. RSM combine the mathematical and statistical techniques which are used for improving, developing and examine the processes. It is also used to verify the significant parameters in complex interaction of variables. The main purpose of RSM is created a design for estimating the quadratic model of a process. Mainly steps are performed in RSM approach () designing and experimental work, () analyzed the mathematical models by regression and () optimization. The impartial approach of RSM to diagnosed the optimum process parameters and conditions which fulfill our desire specifications and performances. Table : Machining Parameters and Their Levels Machining parameters Levels Level Level Level Speed (rpm) Feed (mm/rev) DOC (mm/sec) Tool TNMG60408 (-) TNMG000 (0) TNMG60404 () 4. Experimental Setup: The empirical approach of RSM is to calculate the optimum conditions of the process which fulfill our required specifications. The design matrix developed by RSM approach is shown in Table Table : Final Design Matrix with results Run Speed (rpm) Feed (mm/rev) DOC (mm/sec) Tool SR (µm) ISSN Page 44

3 Graphs Generation for SR:One factor graphs are plotted to analyze the variation in the value of SR. Figure shows the main effects graphs for SR. X = A: SPEED X = B: FEED B: FEED = 0.5 C: D.O.C = 0.5 A: SPEED = 800 D: TOOL = 0 C: D.O.C = 0.5 D: TOOL = A: SPEED (a) MRR Analysis with Speed B: FEED (b) MRR Analysis with Feed ISSN Page 45

4 X = C: D.O.C X = D: TOOL A: SPEED = 800 B: FEED = 0.5 D: TOOL = 0 A: SPEED = 800 B: FEED = 0.5 C: D.O.C = C: D.O.C D: TOOL (c) MRR Analysis with DOC (d) MRR Analysis with Tool Figure : Graphs Generation for SR From the above figures it was found that all the input selected process parameters have considerable effect on surface roughness. From figure it was found that the value of the SR of the machined samples deccreases with rise in the value of depth of cut, speed and feed. It was also observed that SR was less in case of TNMG000 tool inserts as compared to the TNMG60408 and TNMG60404 tool inserts. 6. Mathematical Model: The mathematical model for the response (SR) is discussed as follow. This mathematical equation reveals the impact of machining parameters on our desire response (SR). At here the model confirmed the significant effect of depth of cut and tool materials on Surface roughness as compared to other parameters. Surface roughness (SR) (µm) = *A-0.6*B-0.097*C-0.*D-0.4*AB-0.6*AC-0.5*BC-0.09*BD- 0.05*CD-0.8*A *B -0.05*C -0.4*D.(5) R = Table : ANOVA for SR ANOVA for Response Surface Quadratic Model Sum of Mean F p-value Source Squares Df Square Value Prob> F Model Significant A-SPEED Not Significant B-FEED Significant C-D.O.C Significant D-TOOL Not Significant AB Significant AC Significant AD Not Significant BC Significant BD Not Significant CD 5.5E E Not Significant A^ Significant B^ Not Significant C^ Not Significant ISSN Page 46

5 Predicted Externally Studentized Residuals D^ Significant Residual Lack of Fit 5.475E-00.77E not significant checked out by fit summary. If the value of Prob>F in For Confirmation the suitability of the developed models the ANOVA (Analysis of variance) is another technique to check out the second order mathematical models. For the model is less than then it indicate that the model is significant and R is the other one prime coefficient to analyzed the variation of the full scale the performance measure (SR) the quadratic model and reduced scale model to measure the degree of mathematical models were developed shown in Table. fit. To analyze the performances the significant level is Std. Dev. 0.5 R-Squared Mean.4 Adj R-Squared C.V. % 6.79 Pred R-Squared PRESS 0.49 Adeq Precision. The credibility of this developed model was again confirmed by drawing the scatter diagram and the Residual plots graph as shown in Figure and Figure respectively. MRR Color points by value of SR: Predicted vs. Actual MRR Color points by value of SR: Residuals vs. Run Actual Run Number Figure : Scatter Diagram Figure : Residual Plots Graph 7. Conclusion The extensive study carried out during the present work led to following conclusions: Stir casting is a viable option for the preparation of hybrid metal matrix composite and uniform distribution of reinforcements of varying percentage which can be achieved by varying control parameters in stir casting. The selected process parameters for study i.e. speed, feed, depth of cut and tool material have a significant effect in machining of CNC. Speed, Feed and Depth of Cut produced significant effect in surface roughness so selection of the optimum value of these parameters is very important and the characteristic of tool material affect both response parameters differently. Based on design of experiment, minimum surface roughness was found using TNMG60408 and TNMG000 tool bits respectively. The low SR is observed on TNMG000 as compare to TNMG60404 and TNMG60408 tool insert. References: [] PuneetBansal, LokeshUpadhyay, Effect of Turning Parameters on Tool Wear, Surface Roughness and Metal Removal Rate of Alumina Reinforced Aluminum Composite, rd International Conference on Innovations in Automation and Mechatronics Engineering, ICIAME 06, Procedia Technology ( 06 ), pp04 0. [] MehulGosai, Sanket N. Bhavsar, Experimental Study on Temperature Measurement in Turning Operation of Hardened Steel (EN6), rd International Conference on Innovations in Automation and Mechatronics ISSN Page 47

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