Machining is an obligatory process to shape and finish the components of desired shape, size, and specific quality. Machining is challenged by the discovery of new generation materials like alloys of different metals, ceramics, composites, etc., which are often categorized as hard-to-machine materials. Comprehensive understanding of cutting mechanisms can help to the development of new cutting tools and innovative machining methods such as hybrid machining (HM), high speed machining (HSM), etc. This chapter presents an overview on materials of hard-to-machine, HSM, and HM processes. The principle of laser-assisted machining (LAM), material removal mechanism in LAM, and the improvement in machinability indices are discussed. Finally, an experimental case study on laser-assisted high speed machining of Inconel 718 alloy and the benefits over conventional machining is reported. © 2020 Elsevier Inc. All rights reserved.

Ramanujam R

Department of Manufacturing Engineering

School of Mechanical Engineering

Vellore Campus

Mr Vignesh M

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

High Speed Machining

Laser-assisted machining (LAM) is a promising solution for all categories of difficult-to-machine materials like ceramics, metals and composites. Inconel 718, a difficult-to-machine material, is used in critical aero engine components. The objective of the study is to investigate its machining characteristics with low-cost cutting inserts using LAM. Therefore, in this paper, the machinability of this alloy has been investigated using physical vapour disposition-coated (TiAlN) carbide inserts in terms of cutting force, surface roughness, flank wear and chip formation in different range of cutting parameters. This investigation shows the improvement in machining performance of about 46, 36, 34, 50 44 and 68% for feed force, thrust force, cutting force, surface roughness and flank wear when compared to conventional machining (CM). For the criteria of benefit comparison, the detailed geometrical characteristic of produced chip and its morphology evaluation have been carried out under microscopic examination. The amplitude of this reduction is due to the maximum undeformed chip thickness of about 170 μm in LAM compared to CM. © 2017, Springer-Verlag London.

The International Journal of Advanced Manufacturing Technology

Investigation of machinability characteristics and chip morphology study in laser-assisted 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

Inconel 718, a nickel based alloys, addressed as difficult to cut material because of hard carbide particle, hardness, work hardening and low thermal conductivity. Improving the machinability characteristics of nickel based alloys is a major anxiety in aircraft, space vehicle and other manufacturing fields. This paper presents an experimental investigation in Laser assisted turning of Inconel 718 to determine the effects of laser cutting parameters on cutting temperature and cutting forces. This nickel alloy has a material hardness at 48 HRC and machined with TICN/Al2O3/TiN tool. This is employed for the manufacture of helicopter rotor blades and cryogenic storage tanks. The experiments were conducted at One-Factor-at-a-Time.The effects of laser cutting parameters, namely cutting speed, feed rate, laser power and laser to work piece angle, on the cutting temperature and cutting force components, are critically analysed and the results are compared with unassisted machining of this alloy. The experiments are conducted by varying the cutting speed at three levels (50, 75, 100 m/min), feed rate (0.05, 0.075 0.1 mm/rev), laser power (1.25 kW, 1.5 kW, 1.75 kW) and at two level laser to work piece angle (60, 75°). At the optimal parametric combinationof laser power 1.5 kW with cutting speed of 75m/min, feed rate of 0.075 mm/min and laser to work piece angle 60°, the benefit of LAM was shown by 18%, 25% and 24% decrease in feed force (Fx), thrust force (Fy) and cutting force (Fz) as compared to those of the conventional machining. Examination of the machined surface hardness profiles showed no change under LAM and conventional machining.

Journal	Data powered by TypesetHigh Speed Machining
Publisher	Data powered by TypesetElsevier
Open Access	No