Experimental Investigation of Hole Diameter in Laser Trepan Drilling of Inconel718 Sheet (original) (raw)
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Modeling and optimization of geometrical characteristics in laser trepan drilling of titanium alloy
Journal of Mechanical Science and Technology, 2016
Laser drilling has become an alternative to drilling precise holes in advanced difficult-to-cut superalloys. Due to better hole quality and capability to generate macro-size holes, laser trepan drilling is becoming more popular as compared with laser percussion drilling. This paper presents a study of laser trepan drilling process performance in terms of geometrical quality characteristics, such as hole taper and circularity for drilling small diameter hole in difficult-to-cut Titanium alloy sheet. Due to involvement of different process parameters such as laser power, pulse width, pulse frequency, workpiece thickness, material composition, cutting speed, stand of distance and assist gas pressure, the laser cutting is a highly nonlinear and complex process. To handle this nonlinearity and complexity, genetic algorithm has been applied for the optimization. We used assist gas pressure, pulse width, pulse frequency and trepanning speed as input process parameters. The effect of significant process parameters on hole characteristics are discussed on the basis of data obtained through a well designed orthogonal array experimental matrix. Reliable empirical models have been developed for different quality characteristics. Improvements of 49% and 8% have been registered in hole taper and circularity, respectively, at optimum level of process parameters.
2019
Inconel-718 is a nickel based super alloy and is extensively in use for working at very high temperature (upto 2000 °C) such as aero engine gas path equipment, nuclear equipment etc. Drilling micro size hole in such material with laser beam has been a proven choice and laser drilling process produces geometrically and dimensionally improved hole. Hole geometrical features can be improved further if laser drilling system operated at optimal input parameter setting. This paper experimentally investigates the behavior of hole geometrical features hole circularity and hole taper in laser trepan drilling of Inconel -718 sheet. Optimal value of laser input parameters for improved hole circularity and reduced hole taper have been suggested with the help of computational intelligence technique particle swarm optimisation. The effect of each laser input parameter on hole quality characteristics are also discussed and demonstrated graphically. Finally the experimental validation of the predic...
Particle Swarm Optimisation of Hole Quality Characteristics in Laser Trepan Drilling of Inconel 718
Defence Science Journal
Inconel-718 is a nickel based super alloy and is extensively in use for working at very high temperature (upto 2000 °C) such as aero engine gas path equipment, nuclear equipment etc. Drilling micro size hole in such material with laser beam has been a proven choice and laser drilling process produces geometrically and dimensionally improved hole. Hole geometrical features can be improved further if laser drilling system operated at optimal input parameter setting. This paper experimentally investigates the behavior of hole geometrical features hole circularity and hole taper in laser trepan drilling of Inconel -718 sheet. Optimal value of laser input parameters for improved hole circularity and reduced hole taper have been suggested with the help of computational intelligence technique particle swarm optimisation. The effect of each laser input parameter on hole quality characteristics are also discussed and demonstrated graphically. Finally the experimental validation of the predic...
Computer-aided genetic algorithm based multi-objective optimization of laser trepan drilling
The laser trepan drilling (LTD) has proven to produce better quality holes in advanced materials as compared with laser percussion drilling (LPD). But due to thermal nature of LTD process, it is rarely possible to completely remove the undesirable effects such as recast layer, heat affected zone and micro cracks. In order to improve the hole quality, these effects are required to be minimized. This research paper presents a computer-aided genetic algorithm-based multi-objective optimization (CGAMO) methodology for simultaneous optimization of multiple quality characteristics. The optimization results of the software CGAMO has been tested and validated by the published literature. Further, CGAMO has been used to simultaneously optimize the recast layer thickness (RLT) at entrance and exit in LTD of nickel based superalloy sheet. The predicted results show minimization of 99.82% and 85.06% in RLT at entrance and exit, respectively. The effect of significant process parameters on RLT has also been discussed.
Experimental study of Hole Taper in Laser Trepan Drilling of Nickel Based Super alloy Sheet
Materials Today: Proceedings, 2018
This research article reports the optimum laser drilling input parameter for getting minimum hole taper and experimentally investigates the behaviour of hole taper in selected laser drilling input parameters on Inconel-718 sheet. Inconel-718 is nickel based super alloy, has diverse application in the field of manufacturing industries, including aerospace, aircraft, automotive, medical equipments, food service equipments and many others. The material is well suited for applications requiring high strength in temperature ranges from cryogenic up to 1400°F. Inconel-718 also exhibits excellent tensile and impact strength. The conventional drilling process faces difficulties to drill quality and precise holes in advanced materials due to its better mechanical properties. Making geometrical better hole is major concerned with conventional drilling process. With the help of Laser drilling process, a geometrically and dimensionally improved hole may be produced. The geometry of hole can be made further better if operating the Laser system at optimum parameters level. In this paper the effects of laser input parameters on hole taper have been investigated and optimal value of input parameters for reduced hole taper has been suggested. The experiments have been conducted by varying one parameter at a time. The experimental data are used to develop the multi regression model for hole taper. A reliable multi regression model is developed for hole taper and modern optimization tool, Genetic algorithm (GA) is used for optimization of the kerf taper. The optimal value of studied laser input parameters such as assist gas pressure, laser Current, stand-off distance, and cutting speed (Trepanning speed) have been suggested for getting lower value of hole taper. Finally, the effects of each laser input parameter of the kerf taper has been discussed.
Experimental investigation on micro drilling of Inconel 718 super alloy
International Journal of Machining and Machinability of Materials, 2018
Drilling is one of the material removal processes which are used in various manufacturing and assembly industries. The current growing and development technology in the drilling process is micro drilling. In this work, micro-holes are drilled on Inconel 718. The effects of various process parameters like feed, spindle speed and cutting tool diameter are used to study the response parameters like machining time, MRR, temperature and thrust force obtained during micro drilling. Experiments are carried out based on Taguchi L27 orthogonal array design using Tungsten carbide drill bit and Inconel 718 as work material. Feed rate is varied from 1 to 3 mm/min, Spindle speed ranges from 16,000 to 26,000 rpm and diameter of the tool also varied from 0.4 mm to 0.8 mm. It is observed that temperature is increasing with increase in speed and feed. When the tool diameter, feed rate and spindle speed increases material removal rate (MRR) also increases. The machining time decreases with increase in feed rate, also the cutting force increase with the increase in tool diameter, feed rate and spindle speed. The optimal combination of the process parameter is found out using grey relational analysis (GRA).
Materials Today: Proceedings, 2018
This paper discusses the effect of laser-assisted process parameters on cutting forces and surface temperature during laser assisted machining (LAM) of Inconel 718. The heat source used for pre-heating the surface is Nd:YAG laser source. Cutting speed, feed rate and laser power are the process parameter assessor for cutting force and cutting temperature. The experiments are planned and results are collected based on Taguchi's L27 orthogonal design. The factor effect on output responses are analysed using a main effect plots (2D) and its significance is perceived from analysis of variance (ANOVA). Results reveal that cutting speed bags a maximum contribution of 56%, followed by cutting speed * feed rate as 24%, feed rate * laser power as 10.5 % and feed rate as 10%. Finally, the benefit of LAM was shown by 55% decrease in feed force (Fx), 50% decrease in thrust force (Fy) and 60% decrease in cutting force (Fz), as compared to those of the conventional machining. Additionally, it is also recommended to employ a work surface temperature in the range of 750˚C-887˚C during LAM of this Inconel 718 alloy to have maximum process benefits. The developed regression model reveals the goodness of fit with experimental data has high determination coefficient i.e. R2 = 0.91 for tangential force and 0.71 for surface temperature.
Infrared Physics & Technology, 2018
Inconel-718 has found high demand in different industries due to their superior mechanical properties. The traditional cutting methods are facing difficulties for cutting these alloys due to their low thermal potential, lower elasticity and high chemical compatibility at inflated temperature. The challenges of machining and/or finishing of unusual shapes and/or sizes in these materials have also faced by traditional machining. Laser beam cutting may be applied for the miniaturization and ultra-precision cutting and/or finishing by appropriate control of different process parameter. This paper present multi-objective optimization the kerf deviation, kerf width and kerf taper in the laser cutting of Incone-718 sheet. The second order regression models have been developed for different quality characteristics by using the experimental data obtained through experimentation. The regression models have been used as objective function for multi-objective optimization based on the hybrid approach of multiple regression analysis and genetic algorithm. The comparison of optimization results to experimental results shows an improvement of 88%, 10.63% and 42.15% in kerf deviation, kerf width and kerf taper, respectively. Finally, the effects of different process parameters on quality characteristics have also been discussed.
Experimental Assessment of Hole Quality and Tool Condition in the Machining of an Aerospace Alloy
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This paper deals with an experimental investigation of hole quality in Al2024-T3, which is one of the aerospace alloys used in aircraft fuselage skin due to its high level of resistance to fatigue crack propagation. The experiments are conducted with 6 mm uncoated carbide and HSS drill bits using a CNC machine under dry conditions and different drilling parameters. The characteristics of the hole quality are investigated in terms of its perpendicularity, cylindricity, circularity and hole size. An ANOVA (analysis of variance) and Pareto charts are used to analyze the effects of the drilling parameters on the hole quality. The hole quality is also assessed using a digital microscope to observe the formation of hole burrs. Moreover, scanning electron microscopy is also used to investigate the inside-hole surface defects. Further investigations are carried out using optical microscopy to inspect the post-drilling tool condition at high drilling parameters. The results show that hole qu...
International Journal of Advanced Manufacturing Technology, 2011
This paper presents a hybrid design strategy for the determination of the optimum laser drilling parameters which simultaneously meets the requirements for seven quality characteristics (responses) of the holes produced during pulsed Nd:YAG laser drilling of a thin sheet of nickel-based superalloy Nimonic 263. The process was designed using two approaches based on the experimental data. In the first approach, the quality losses of seven correlated responses were uncorrelated into a set of components using the principal component analysis; then the grey relational analysis was applied to synthesise components into a synthetic performance measure. Since this approach considered only parameter values used in the experiment, the second approach was developed to find the global optimal parameters solution using an artificial neural network to model the relation between parameters and a synthetic performance measure, and a genetic algorithm to perform a search for the global optimum in a continual multidimensional space. The analysis of the application indicated that the proposed approaches gave a better result, in terms of the optimal parameter settings that yield the maximal synthetic performance measure, than several commonly used methods for multi-response process parameters design. The results demonstrated that the robust Nd:YAG laser drilling of Ni-based superalloy sheets was designed with respect to the requirements for seven quality characteristics of the drilled holes, by using the proposed strategy.