Optimization of EN-31 Alloy Steel Metal Removal Rate on Centre Lathe

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 08, 2015 | ISSN (online): 2321-0613

Optimization of EN-31 Alloy Steel Metal Removal Rate on Centre Lathe Vijayesh Rathi1 Jasvinder Kumar2 Gaurav Kochar3 1,2,3 Assistant Professor 1,2,3 Department of Mechanical Engineering 1,2,3 GIMT, Krukshetra (Haryana), India Abstract— The paper presents an experimental study of metal removal rate in turning operation of EN-31 alloy steel with cemented carbide coated tungsten insert tool under different cutting parameters. The cutting parameters namely feed rate, depth of cut and spindle speed were varied to observe the effects on EN-31 alloy steel. The experimental setup includes nine different specimens whose weight was recorded before machining and after machining. Then the depth of cut, feed rate and spindle speed were changed for nine specimens. Then time is noted for each experiment and how much metal is removed during each experiment and in how much time. The main aim of the experiment is to know that at what parameters metal removal rate is maximum.

Key words: EN-31 Alloy Steel Metal, MRR I. INTRODUCTION Metal cutting is one of the vital processes and widely used manufacturing processes in engineering industries. Highly competitive market requires high quality products at minimum cost. Products are manufactured by the transformation of raw materials. To improve productivity with good quality of the machined parts is the main challenges of metal industry; there has been more concern about monitoring all aspects of the machining process. [1, 2] Out of the various parameters which could be considered as the manufacturing goal, the material removal rate (MRR) was considered for the present work as the factor directly affects the cost of machining and the machining hour rate. The machining parameters namely cutting speed, feed rate and depth of cut were considered.

The objective was to find the optimized set of values for maximizing the MRR using Taguchi method.

To select the cutting parameters properly several mathematical models [3] based on statistical regression or neural network techniques have been constructed to establish the relationship between the cutting performance and cutting parameters. Therefore considerable knowledge and experience are required for this approach.

Turning produces three cutting force components,(the main cutting force i.e. thrust force, (FZ), which produces in the cutting speed direction, feed force, (FX), which produces in the feed rate direction and the radial force, (FY), which produces in radial direction and which is normal to the cutting speed).

Carbide cutting tools are very popular in metal cutting industry for the cutting of various hard materials such as, alloy steels, die steels, high speed steels, bearing steels, white cast iron and graphite cast iron. In the past few decades there had been great advancements in the development of these cutting tools. Coating is also used on cutting tools to provide improved lubrication at the tool/chip and tool/work piece interfaces and to reduce friction, and to reduce the temperatures at the cutting edge. During machining, coated carbide tools ensure higher wear resistance, lower heat generation and lower cutting forces,

thus enabling them to perform better at higher cutting conditions than their uncoated counterparts. The use of coated tools are becoming increasingly demanding among the other tool materials. More than 40% of all cutting tools are coated in modern industry today [4, 5].

In order to find the optimized set of input parameters and also to identify the effect of each towards a particular output, researchers have been trying for years together. Meng [6] tried to calculate optimum cutting condition for turning operation using a machining theory.

Researchers [7-12] have tried to optimize the machining parameters using various methods like Genetic Algorithm, simulated annealing method, Multi-Objective Evolutionary Algorithm etc. Bharathi and Baskar reviewed the researches made on optimization techniques for machining using various mathematical models.

The Taguchi method emphasizes over the selection of the most optimal solution (i.e. MRR) over the set of given inputs (i.e. cutting speed, feed rate and depth of cut) with a reduced cost and increased quality. The optimal solution so obtained is least affected by any outside disturbances like the noise or any other environmental conditions [13]. Thus, the modern day approach to find the optimal output over a set of given input can be easily carried out by the use of Taguchi method rather than using any other conventional methods. This method has a wide scope of use varying from the agricultural field to medical field and various fields of Engineering sciences. It has been used by many agricultural scientists to evaluate the production of their crops based on the different sets of inputs like the waterfall level, fertility of the land, types of seeds used and many other factors. It is also used by the weather Department in forecasting of the various environmental conditions. And, in the field of Science and Engineering, it is used for obtaining optimal results based on the various engineering inputs. Thus, the Taguchi approach has a wide variety of applications in the different fields because of its easiness and optimized results [14]. However, even being having a lot of advantages , it suffers from a major disadvantage that the results obtained are only relative to the levels selected and do not exactly indicate the effect of entire range of each parameter on the performance characteristic value. They also do not test the output for all the combinations of input variables as the combination selected here is limited. Moreover, another major disadvantage of the Taguchi method is that it is not a dynamic process i.e. it is not concerned with those variables which discretely or continuously change their values from time to time. Thus, it deals with mostly the static variables i.e. variables whose values are not time dependent.

Moreover, it deals with designing of the quality rather than improving the quality. Because of this, they are applied in the industries at the early stages only [15].

However, despite of all these disadvantages, it is used widely in the different areas very effectively.

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Optimization of EN-31 Alloy Steel Metal Removal Rate on Centre Lathe (IJSRD/Vol. 3/Issue 08/2015/207)

Based on the literature review it was found that the factors that highly influence the process efficiency and output characteristics are spindle speed, feed rate, depth of cut and cutting environment. Experimental works have been carried out on the above mentioned parameters.

II. EXPERIMENTAL SETUP & METHODOLOGY In this study nine specimen of EN 31 alloy steel were used as work material for experimentation on centre lathe machine as shown in figure 1. The chemical composition and mechanical properties of the selected work piece is shown as in table 1 and table 2 respectively.

Cemented carbide coated insert having 0.08 mm nose radius was used as cutting tool as shown in figure 1, which gives high wear resistance and crater resistance required in steel machining. It also offers required chip resistance to give longer tool life. This type of CVD coated insert has well balanced toughness and wear resistance properties, which gives liberty to machine in wide range of application.

C 0.90 - 1.20 Mn 0.30 – 0.75 Si 0.10 – 0.35 S 0.04 P 0.04 Cr 1.00 – 1.60 Table 1: Chemical composition of EN 31 Alloy Steel Bulk Modulus 140 GPa Shear Modulus 80 GPa Elastic Modulus 190 GPa Poison’s ratio 0.30 Hardness Rockwell C 20 Table 2: Mechanical Properties of EN 31 Alloy Steel The machining experiments were carried out on the centre lathe machine (Pac. Turn 360 with maximum 1400 rpm) in dry condition. Spindle speed, feed rate and depth of cut were selected as the machining parameters to analyze their effect on surface roughness and while performing turning operation. A total of 9 experiments were carried out with different combination of the levels of input parameter.

Fig. 1: Experimental Setup with work-piece and coated carbide tool Among them, first three readings were taken with different feed rate and depth of cut keeping spindle speed constant at 165rpm. Another set of three readings were taken with different feed rate and depth of cut keeping spindle speed constant at 330 rpm. Last set of three readings were taken with different depth of cut and feed rate keeping spindle speed 620 rpm constant. The various cutting parameters are shown in table 3.

A. Removal Rate (MRR) The material removal rate (MRR) in turning operations is the volume of material/metal that is removed per unit time in mm/min. for each revolution of the work piece a ring shaped layer of material is removed MRR = (v. f .d ×1000) in mm3 / min

III. RESULT AND DISCUSSION

The experiments have been conducted and values of metal removal rate for different combination of spindle speed (rpm), feed (mm/rev) and depth of cut (mm) have been shown in table 3. It was observed that there was no significant tool wear on flank side as well as on rake face of tool tip during machining on lathe machine with the machining parameters set.

Spindle Weight Weight Experiment Depth of Cut Feed Rate Time Total metal MRR Speed Before After No. mm mm/rev seconds removed gm gm/sec RPM machining machining 1 165 0.2 0.1 700 694 98 6 0.051 2 165 0.5 0.2 672 660 49.30 12 0.243 3 165 1 0.3 700 678 38.15 20 0.524 4 330 0.5 0.1 692 680 49.93 12 0.240 5 330 1 0.2 680 660 25.03 20 0.799 6 330 0.2 0.3 685 680 18.81 5 0.265 7 620 1 0.1 700 680 26.38 20 0.758 8 620 0.2 0.2 676 670 13.51 5 0.370 9 620 0.5 0.3 712 700 9.58 12 1.252 Table 3: Experimental Results Cut with respect to material removal rate (MRR) on Centre IV. CONCLUSION Lathe of En-31 alloy steel using Taguchi method.

The analysis showed that Depth of Cut had the In this paper, a study had been carried out to optimize the most significant effect on MRR followed by feed with an process parameters viz. Cutting Speed, Feed and Depth of

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Optimization of EN-31 Alloy Steel Metal Removal Rate on Centre Lathe (IJSRD/Vol. 3/Issue 08/2015/207)

increase in Depth of Cut MRR increased in the studied range. Optimum cutting parameter combination was found out for maximum MRR and this study may be useful in computer aided process planning.

The maximum material removal of EN-31 alloy steel was done in the experiment 9 where the speed, depth of cut and feed rate are 620 rpm, 0.5 mm and 0.3 mm/ rev respectively.

[14] S. Fraley, M. Oom, B. Terrien, and J. Z. Date, ―Design of Experiments via Taguchi Methods: Orthogonal Arrays, The Michigan Chemical Process Dynamic and Controls Open Text Book, USA, 2006.

[15] Unitek Miyachi Group, ―Welding Material Control‖, Technical Application Brief, 2(1999), pp.1–5

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Technol. 48, 1075–1090, 2010 [10] Datta, R.; Majumder, Optimization of Turning Process parameters Using Multi-Objective Evolutionary Algorithm. 10.1109/CEC.2010.5586296, IEEE 2010 [11] Lan Tian-Syung, Fuzzy Deduction Material Removal Rate Optimization for Computer Numerical Control Turning, DOI : 10.3844/ajassp.2010.1026.1031, American Journal of Applied Sciences, Volume 7, Issue 7, Pages 1026-1031, 2010 [12] Tzeng, C. J., Lin, Y. H., Yang, Y. K., & Jeng, M. C., Optimization of turning operations with multiple performance characteristics using the Taguchi method and Grey relational analysis. Journal of Material Processing Technology, 209, 2753-2759, 2009.

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