Inconel 718 is a representative of high temperature alloy which poses substantial difficulties in machining processes. High strength, high cutting temperature and a subsequent work hardening during machining process adversely affect the cutting force, surface integrity, tool life and chip breakability. The above difficulties have been disproving by employing the Laser Assisted Machining (LAM). LAM is a hybrid technique and used to machining the work-piece with conventional tool after softening it with laser emitted heat. An attempt has been made in the present study for an experimental investigation on the machining attributes of 718 Inconel super alloy during laser assisted machining using uncoated carbide insert. Experimental plan is designed based on Taguchi's L18 mixed orthogonal array of design of experiment. Three response values such as cutting force, surface roughness and tool wear are measured and their effects are studied. The variability due to the machining parameters are dispensed using variance test. Predictive regression equations are developed for the estimation of all the quality characteristics. Also the Pearson correlation coefficient analysis is calculated to analyze the correlation between the input parameters and quality characteristics. Results showed a strong correlation between the feed rate and the cutting force and surface roughness followed by cutting speed. The results obtained from experiments are analyzed to predict the optimal machining conditions using desirability approach. At the optimal laser parameters, the tool life, when laser beam is used, is improved by 9% compared to conventional machining. © 2017 Elsevier Ltd.

Venkatesan K

Department of Design and Automation

School of Mechanical Engineering

Vellore Campus

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Materials Today: Proceedings

This study focused on experimental investigation and optimisation of laser aided hybrid machining of Inconel 718 alloy. Cutting speed, feed rate and laser power are varied each at three levels and total of 27 experiments are conducted. Cutting force, surface roughness and flank wear are measured. The factor effects on each response are analysed using 3D surface plot. The developed regression model shows good degree of fit. From the analysis of variance, the feed rate and laser power are influencing parameters on the cutting force and surface roughness while cutting speed is for tool wear. The optimal process parameter setting using desirability analysis reveals a reduction of cutting force by 50%, surface roughness by 26%, flank wear by 33% and the tool life is extended up to 133% over conventional machining. The segmentation of saw tooth chip is increased which demonstrated the thermal softening effect compared to conventional machining. © 2016 Inderscience Enterprises Ltd.

International Journal of Machining and Machinability of Materials

Optimisation of machining parameters in laser aided hybrid machining of Inconel 718

Laser assisted machining (LAM) is one of the innovative methods to machine difficult to cut materials to obtain maximum benefits of machinability. In this method, the influence of both the laser and cutting parameters affects the quality of machining. Hence it is required to identify the optimal levels of the parameters in order to maximize benefits. The present study focused on optimization of laser beam approach angle, laser power and cutting parameters during LAM of Inconel 718 alloy using chemical vapour deposition (CVD) coated carbide tool. The experimental trials are planned in accordance with central composite design (CCD) in response surface methodology. The ranges for selected parameters are as follows as: cutting speed (50 &lt; Vc &lt; 100 m/min), feed rate (0.05 &lt; f &lt; 0.1 mm/rev), laser power (1.25 &lt; PL &lt; 1.75 kW), and approach angle (60° &lt; θ &lt; 90°). Cutting force and workpiece temperature, the two responses which are measured using Kistler force dynamometer and infra-red pyrometer respectively. The effects of each parameter were analysed using 3D surface plot and analysis of variance (ANOVA). A second order regression equation has been developed and model shows good agreement with experimental and predicted results. Desirability function analysis (DFA) is used to determine the optimal operating conditions. Finally, the results were validated using confirmation experiments. © 2016 Elsevier Ltd.

Measurement

Statistical approach for optimization of influencing parameters in laser assisted machining (LAM) of Inconel alloy

This paper presents a parametric effect, microstructure, micro-hardness and optimization of laser scanning parameters (LSP) on heating experiments during laser assisted machining of Inconel 718 alloy. The laser source used for experiments is a continuous wave Nd:YAG laser with maximum power of 2 kW. The experimental parameters in the present study are cutting speed in the range of 50-100 m/min, feed rate of 0.05-0.1 mm/rev, laser power of 1.25-1.75 kW and approach angle of 60-90°of laser beam axis to tool. The plan of experiments are based on central composite rotatable design L31 (43) orthogonal array. The surface temperature is measured via on-line measurement using infrared pyrometer. Parametric significance on surface temperature is analysed using response surface methodology (RSM), analysis of variance (ANOVA) and 3D surface graphs. The structural change of the material surface is observed using optical microscope and quantitative measurement of heat affected depth that are analysed by Vicker's hardness test. The results indicate that the laser power and approach angle are the most significant parameters to affect the surface temperature. The optimum ranges of laser power and approach angle was identified as 1.25-1.5 kW and 60-65° using overlaid contour plot. The developed second order regression model is found to be in good agreement with experimental values with R2 values of 0.96 and 0.94 respectively for surface temperature and heat affected depth. © 2015 Elsevier Ltd.

Optics & Laser Technology

Parametric modeling and optimization of laser scanning parameters during laser assisted machining of Inconel 718

Hybrid machining is an emerging technique for difficult-to-cut materials to overcome the problems associated with conventional machining (CM). Inconel 718, a super alloy of nickel, is a high-temperature alloy commonly used in aircraft and thermal industries and categorized as one among the difficult-to-cut materials. In this study, the influence of cutting conditions of Inconel 718 alloy during laser-assisted hybrid machining (LAHM) is investigated and the results are compared with CM. During LAHM, the process parameters of cutting speed, feed rate, approach angle, and laser power are varied. The present work is carried out in two phases: (i) determination of effective heat-affected depth (HAD) during laser preheating (using central composite design (CCD) in response surface methodology); (ii) optimization of cutting conditions during machining (using Taguchi's method). Compared with CM, the LAHM shows the following reduction benefits: (i) 33% in feed force (Fx), 42% in thrust force (Fy), and 28% in cutting force; (ii) improved surface finish (surface roughness, Ra) of 28%; and (iii) reduction in tool wear by 50%. The chip morphology reveals the decrease in shear angle and increase in chip thickness during LAHM. No change in the hardness value of the machined surface after LAHM indicates the absence of subsurface damage. © 2016, Copyright © Taylor & Francis Group, LLC.

Materials and Manufacturing Processes

Improvement of Machinability using Laser-Aided Hybrid Machining for Inconel 718 Alloy

High strength alloys such as nickel and titanium and advanced engineering materials such as ceramics, composites are being developed and widely used in aerospace, automotive, medical and nuclear industries due its inherent physical-mechanical properties. However conversion these new materials into engineering products are always associated with machining. The machinability characteristics such as higher cutting force, higher cutting temperature, poor surface integrity and shorter tool life associated with these materials posing many challenges to the researchers, and hence considered as difficult to cut materials. Conventional methods of machining these materials are found to be uneconomical. In recent days, many attempts have been made to improve the machinability of these materials more effectively via use of external energy assisted machining. Among the various external energy assisted machining methods, laser assisted machining (LAM) has received the attention of researchers in the metal cutting domain and a few research was carried during the recent years. This paper is aimed to review and summarize the potential use of LAM for difficult to cut materials, current progress, benefits and challenges in laser assisted machining. In addition an optimization frame work to study the effect of laser parameters and machining process parameters on machinability performance is not reported which is applicable to industrial processes It is concluded that further experimental modeling and empirical techniques are required to create a predictive based models that gives good agreement with reliable experiments, while explaining the effects of many parameters, for machining of these difficult-to-cut materials. © 2014 Published by Elsevier Ltd.

Journal	Data powered by TypesetMaterials Today: Proceedings
Publisher	Data powered by TypesetElsevier BV
ISSN	2214-7853
Open Access	No