International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017
p-ISSN: 2395-0072
www.irjet.net
Study of Surface Roughness measurement in turning of EN 18 steel Ajay Rana Assistant Professor, Dept. of Mechanical Engineering, Universal Group of Institutions, Punjab, India ---------------------------------------------------------------------***--------------------------------------------------------------------2. EXPERIMENTAL PROCEDURE
Abstract – Increasing the productivity with quality is the
main key areas focused in the present scenario of manufacturing. Various techniques have been implemented to improve the machining processes to increase the productivity. And Turning is one of the most important manufacturing techniques because of its simplicity and effectiveness. The main aim of this study is to optimize the understudy parameter specially the surface roughness (Ra) in turning of EN 18 Steel work piece by using three input parameters i.e. spindle speed, feed rate and depth of cut. Experimental work was done using Design Expert 7.0.0 (dx7) software with Central Composite Design (CCD) approach. The input parameters were varied at three different levels. And turning was done using CNC lathe machine and surface roughness was measured with the help of portable Mitotoyo Surftest-4 tester. This study uses Response surface methodology to find the optimum machining parameters to produce minimum surface roughness possible in turning process. Regression Equations were developed for Surface Roughness. Confirmation experiments were conducted in end to validate the results of experimental work. Key Words: HMT HS CNC lathe, EN 18 steel, Response surface methodology (RSM), Surface roughness, CCD central composite design.
1. INTRODUCTION Since ages, Lathe has been revolutionary in industrial sector. Since that time there have been many drastic improvements, whether it is in manufacturing of Lathe machine or is it in processes done on it. The increased demand of manufacturing components of higher accuracy and in large quantities has also added importance to value of Lathe. Nowadays, Lathes have been attached with computers to increase its efficiency to generate parts of higher accuracy in very short span of time. These machines are named as CNC machines, i.e. Computer Numerical Control Machines. These CNC’s help to generate designs of high complexities with ease. In this study, CNC was used namely HMT Stallion HS CNC Lathe Machine to process the workpiece. On the other hand, turning process used in this investigation is one of the most commonly used processes of manufacturing. Whereas, EN 18 is an alloyed medium carbon steel which finds applications in manufacturing of shafts, stressed pins, studs, keys etc. These components are manufactured by process i.e. turning. And Minimizing surface roughness has been the main aim of this study.
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In this study, Design Expert 7.0.0 (dx7) software was used and by using Central Composite Design (CCD) approach the experimental plan was developed for single response optimization. In this study, Response Surface Methodology was used to optimize the Surface Roughness. Response surface methodology (RSM) is a collection of mathematical and statistical techniques used for empirical model building. Where a response of interest is influenced by several variables and the objective is to optimize the response. To find relation between input and response variable, usually first order model is used, as given in equation below
y 0 i xi i i xi i ..... kxi k Where, y is the response understudy, β is regression coefficient and is error. If the result can still be improved, then the Second order model is applied, as given below k
k
i 1
i 1
y 0 i xi ii xi2 ij xi x j i j
The values of regression coefficients are obtained by regression analysis of 23 factorial designs. The experimentation work was conducted using a HMT Stallion CNC lathe machine and Mitotoyo Surftest-4 tester was used to measure the surface roughness. The study used speed, feed and depth of cut as input process parameters varied at three different levels. Design Expert was used for collected data analysis. And overall Desirability was found by numerical optimization. At the end analyzed result was validated by conducting confirmation experiments.
2.1 Workpiece Material In Present work, EN 18 alloyed medium carbon steel is used which is quite responsive to mechanical and heat treatments. This offers more strength and toughness than mild steel. It finds application in automobiles, shafts, pins, couplings, rolls, keys parts. Table 1: Chemical Composition of EN-18 Element
C
Si
Cr
S
P
Mn
Percentage (%)
0.350.45
0.100.35
0.851.15
0.050
0.050
0.600.95
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