Increase In Material Removal Rate Research Articles

Multi Response Optimization of Process Parameters Using Grey Relational Analysis for Turning of Al-6061

Al-6061 is one among the most useful material used in manufacturing of products. The major qualities of Aluminium are reasonably good strength, corrosion resistance and thermal conductivity. These qualities have made it a suitable material for various applications. While manufacturing these products, companies strive for reducing the production cost by increasing Material Removal Rate (MRR). Meanwhile, the quality of surface need to be ensured at an acceptable value. This paper aims at bringing a compromise between high MRR and low surface roughness requirement by applying Grey Relational Analysis (GRA). This article presents the selection of controllable parameters like longitudinal feed, cutting speed and depth of cut to arrive at optimum values of MRR and surface roughness (Ra). The process parameters for experiments were selected based on Taguchi’s L9 array with two replications. Grey relation analysis being most suited method for multi response optimization, the same is adopted for the optimization. The result shows that feed rate is the most significant factor that influences MRR and Surface finish.

Investigation and modelling of hybrid laser-waterjet micromachining of single crystal SiC wafers using response surface methodology

A hybrid laser-waterjet micromachining technology was proposed to implement near damage-free and high-efficient micromachining of thermal-sensitive hard and brittle materials. A new material removal concept was used where a waterjet is applied off-axially to expel the “softened” elemental material by laser radiation and cool the material to eliminate thermal damages during the material removal process. The present study investigates the effect of process parameters and their interaction on the cutting depth, cutting width and the material removal rate in the hybrid laser-waterjet micromachining of single crystal SiC wafers. The analysis of variance (ANOVA) indicates that waterjet inclination angle, waterjet offset distance, nozzle stand-off distance, traverse speed of hybrid cutting head, average laser power and waterjet pressure are the significant terms on cutting depth, cutting width as well as material removal rate. The quadratic backward-eliminated regression models are developed using response surface methodology (RSM). The models show that the material removal ability and the material removal rate increase with the increased average laser power and decrease with the increased nozzle stand-off distance and waterjet pressure. Waterjet offset distance has a knee-point value on the machining results. Cutting depth and width decrease with the increased traverse speed of hybrid cutting head but material removal rate increases with the increased traverse speed when the traverse speed is smaller than a certain value. The turbulent water breaks down the laser optically and weakens its heating ability. The critical waterjet offset distance can also be changed since the interactive effect of the process parameters. The verification results show the models can perform predictions with acceptable errors. Moreover, as compared to laser dry ablation, the photographs of the machined surface and its 3D profile illustrate that hybrid laser-waterjet micromachining can obtain much deeper and wider groove with V-sharp cross-sectional profile. It can significantly reduce or even eliminate thermal damages such as heat-affected zone (HAZ) and re-solidified layer by using the hybrid laser-waterjet micromachining technology.

Study on machining characteristics of micro EDM with high spindle speed using non-contact electric feeding method

In order to improve the efficiency of micro electrical discharge machining (micro EDM), the rotational spindle is widely used at present. Since the EDM technology is invented, the relaxation-type pulse generator, transistor-type pulse generator, or their combinations have been generally used. However, with these pulse generators, it is difficult to supply electrical power to the tool electrode rotating at extremely high speed without causing the vibration and spindle wear due to the contact electric feeding using a brush. So the tool electrode rotating speed is less than thousands of revolutions per minute (rpm) usually. Based on the principle of electrostatic induction, the non-contact electric feeding can be realized in micro EDM. So the rotating speed of the tool electrode can reach high rotating speed. This paper studied the machining characteristics of micro EDM under the high spindle speed up to 60,000 rpm by the machining of micro rods and the micro holes. As a result, the minimum electrode of Φ 2 μm in diameter and 10 μm in length, and the micro rod of Φ 5 μm in diameter and 80 μm in length with a high aspect ratio of 16 were obtained by block electrical discharge grinding (BEDG) method. From the micro hole machining results, it was found that with the increase of the spindle speed, the material removal rate increases, while the electrode wear ratio decreases. Meanwhile, the higher aspect ratio and machining accuracy were realized and the surface roughness was also improved significantly.

Experimental investigation on the suitability of ozonated electrolyte in travelling-wire electrochemical machining

Machining of nickel alloys, particularly Monel 400 alloys, plays an important role in numerous applications of aircraft and marine industries. Machining of these alloys, with complicated shapes, through conventional machine tools is a cumbersome task. Therefore, an experimental research was made to investigate the travelling-wire electrochemical machining (TWECM) characteristics of Monel 400 alloys. TWECM has the benefit of negligible tool wear and stress-free machining. The improper removal of contaminants, mostly oxides on the specimen surface, reduces the performance of TWECM. In this direction, ozonated aqueous NaCl was used as an electrolyte in order to enhance the machining performance of TWECM. The predominant TWECM process parameters i.e. applied voltage (V), electrolyte concentration (EC) and electrolyte flow rate (U) were considered to investigate the performance measures of material removal rate (MRR) and surface roughness (Ra). The microstructure of surface of the Monel 400 alloys specimen machined with TWECM was studied to understand the effect of electrolyte during the machining. Maximum of 90% increase in MRR was observed because of this new electrolyte. The surface roughness was also decreased considerably up to 32%. The contour plots were drawn to study the individual and interactive effect of process parameters on performance measures.

A multi-objective algorithm for optimization of modern machining processes

Multi-objective optimization aspects of four modern machining processes namely wire-electro discharge machining process, laser cutting process, electrochemical machining process and focused ion beam micro-milling process are considered in this work. In WEDM process cutting velocity and surface quality are important objectives which are mutually conflicting in nature. Minimization of kerf taper is vital in the laser cutting process which increases with the increase in material removal rate. The ECM process is characterized by high material removal rate, but poor dimensional accuracy, high tool wear rate and high over cut. FIB micro-milling process is useful in applications where a nano-level surface finish is desired but this process is characterized by a very low material removal rate. All the above mentioned objectives are vital as they closely govern the performance of the machining processes considered in this work. Therefore, the aim of this work is to achieve these objectives through process parameter optimization. In order to handle multiple objectives simultaneously a new posteriori multi-objective optimization algorithm named as multi-objective Jaya (MO-Jaya) algorithm is proposed which can provide multiple optimal solutions in a single simulation run. The regression models for the above mentioned machining processes which were developed by previous researchers are used as fitness function for MO-Jaya algorithm.In the case of WEDM process the optimization problem is an unconstrained, linear and parameter bounded. In the case of laser cutting process the optimization problem is a non-linear, unconstrained, quadratic and parameter bounded. In the ECM process the optimization problem is a non-linear, unconstrained, quadratic and parameter bounded. The second case study of ECM process the optimization problem is a non-linear, constrained, non-quadratic and parameter bounded. In the case of FIB micro-milling process, the optimization problem is a non-linear, unconstrained, quadratic and parameter bounded. In addition, the performance of MO-Jaya algorithm is also tested on a non-linear, non-quadratic unconstrained multi-objective benchmark function of CEC2009. In order to handle the constraints effectively a heuristic approach for handling constraints known as the constrained-dominance concept is used in MO-Jaya algorithm. In order to ensure that the newly generated solutions are within the parameter bounds a parameter-bounding strategy is used in MO-Jaya algorithm. The results of MO-Jaya algorithm are compared with the results of GA, NSGA, NSGA-II, BBO, NSTLBO, PSO, SQP and Monte Carlo simulations. The results have shown the better performance of the proposed algorithm.

Material removal model of ultrasonic elliptical vibration-assisted chemical mechanical polishing for hard and brittle materials

The chemical mechanical polishing (CMP) is widely used to polish hard and brittle materials. However, it is difficult for conventional CMP to achieve high material removal rate (MRR) and high surface quality while polishing of hard and brittle materials such as monocrystalline silicon. Therefore, ultrasonic elliptical vibration (UEV) is employed to aid conventional CMP in our research, which combines the functions of conventional CMP and ultrasonic machining. In the ultrasonic elliptical vibration-aided chemical mechanical polishing (UEV-CMP) experimental setup developed by us, the workpiece attached on the ultrasonic vibrator can vibrate simultaneously in both horizontal and vertical directions during CMP. It is found that the ultrasonic elliptical vibration can effectively increase the MRR while maintaining surface quality in conventional CMP. The possible mechanism in UEV-CMP is firstly analyzed chemically to establish a reasonable material removal rate model. The effects of the ultrasonic elliptical vibration on the interaction among the abrasive particles, polishing pad, and workpiece are investigated to explain why the MRR of UEV-CMP is higher than that of the conventional CMP. A mathematic model, which includes polishing variables such as morphology and material properties of polishing pad; abrasive size; and material properties of particles, frequency, and amplitude of the ultrasonic vibration as well as polishing process parameters, is set up to interpret the increase in MRR for UEV-CMP. The results from the MRR model show that the ultrasonic elliptical vibration can improve material removal by increasing both the chemical reaction efficiency of polishing solution and mechanical impact efficiency of the abrasive particles on the workpiece surface and also by increasing vibration amplitude in vertical direction as the horizontal vibration contributes less towards the increment of MRR. Experiments are conducted for model verification, which should be that the experimental results agree well with model predictions.

Modelling effect of magnetic field on material removal in dry electrical discharge machining

One of the reasons for increased material removal rate in magnetic field assisted dry electrical discharge machining (EDM) is confinement of plasma due to Lorentz forces. This paper presents a mathematical model to evaluate the effect of external magnetic field on crater depth and diameter in single- and multiple-discharge EDM process. The model incorporates three main effects of the magnetic field, which include plasma confinement, mean free path reduction and pulsating magnetic field effects. Upon the application of an external magnetic field, Lorentz forces that are developed across the plasma column confine the plasma column. Also, the magnetic field reduces the mean free path of electrons due to an increase in the plasma pressure and cycloidal path taken by the electrons between the electrodes. As the mean free path of electrons reduces, more ionization occurs in plasma column and eventually an increase in the current density at the inter-electrode gap occurs. The model results for crater depth and its diameter in single discharge dry EDM process show an error of 9%–10% over the respective experimental values.

Influence of Slurry Flow Rate on Material Removal Rate and Topography of Chemical Mechanically Planarized c-Plane (0001) GaN Surface

Chemical mechanical planarization (CMP) processing parameters greatly influence the material removal rate (MRR) and roughness of the processed wafer surface. The slurry flow rates on the polishing pad are likely to alter the polishing performance. Thus, a series of CMP experiments has been performed on c-plane (0001) GaN wafer surfaces with varying slurry flow rates to investigate their effect on the polishing rate and surface planarity for a fixed set of other CMP processing parameters. The slurry flow rate has been varied from 10–50 ml/min during the CMP experiment. An improved MRR (∼228 to 687 nm/h) with decreasing surface roughness has been observed with increasing slurry flow rate from 10–40ml/min. However, at 50 ml/min, a further increase in MRR was observed (904 nm/h) with inferior surface quality. The variation in surface roughness has been studied over varying scan areas and the lowest root-mean-square (rms) surface roughness of ∼1 nm, over a scan area of 5 × 5 μm2, has been achieved at 40 ml/ min slurry flow rate.

Analysis of Material Removal and Surface Characteristics in Machining Multi Walled Carbon Nanotubes Filled Alumina Composites by WEDM Process

The reinforcement of ceramic materials with electrically conductive particles increases the overall conductivity of the ceramic material. This allows the ceramic material to be more readily machined using wire electrical discharge machining process. The current work is an approach to identify the machinability of multi walled carbon nanotubes filled alumina composites in wire electrical discharge machining process. Alumina samples of 5 vol. % and 10 vol. % multi walled carbon nanotubes are machined and analysed for material removal rate and the surface characteristics. An increase in material removal rate is observed with increase in filler concentrations. At the same time, better surface roughness is observed. The surface characteristics of composite alumina are further compared with Monel 400 alloy. It has been observed that spalling action is the dominating material removal mechanism for alumina composites, while melting and evaporation is for the Monel 400 alloy.

Optimum process parameters for efficient and quality thin wall machining using firefly algorithm

The manufacturing requirements of the aerospace industry makes it imperative to use thin wall machining techniques to machine parts that would otherwise have to be assembled from a number of parts. To achieve high productivity, there must be increase in material removal rate, which is constrained by the geometrical accuracy and surface finish requirements. Thus, a compromise must be made between productivity and product quality. This paper presents an optimisation scheme to improve the productivity while keeping the surface finish within acceptable limits during thin-wall machining operations. Initially full factorial experiments were carried out on machining of closed thin walled pocket by varying feed, cutting speed and tool diameter. Surface roughness and material removal values for all experiments were recorded. Analysis of variance was carried out to find out the most significant process parameter. Later firefly algorithm, a nature inspired swarm optimisation technique was employed to obtain the optimum process parameters for desired performance. A confirmation experiment was carried out which indicates an error of 1.27% and 1.03% between predicted and experimental results of surface roughness and material removal rate respectively.

Investigation of Material Removal Rate and Tool Wear Rate on Electrical Discharge Machining of Incoloy 800HT by using Response Surface Methodology

This paper investigates the different machining parameters for the electrical discharge machining (EDM) processes on Incoloy 800HT. A Box-Behnken design of response surface methodology is used to design and analyze the experiments. The experiments intend to study the EDM parameters such as current, voltage and pulse on-time which influences the two major response characteristics namely material removal rate (MRR) and tool wear rate (TWR). The research shows that current is a significant parameter, as if the current increases, there is an increase in material removal rate. Tool wear rate minimizes when the voltage supplied is high. A second order, regression equation using analysis of variance (ANOVA) for each process response is derived which helps in understanding the feasibility and effectiveness of adopted approach. This in turn provides a useful platform to model and optimize MRR and TWR during EDMing Incoloy 800HT.

Process parameter optimization of die-sinking EDM on Titanium grade – V alloy (Ti6Al4V) using full factorial design approach.

EDM is the most versatile and universally accepted modern machining process having vast application in manufacturing industries. The main drawback of this process is lower machining yield and less dimensional control. In this process the machining rate is independent of the work material hardness as the machining is not due to physical contact between work material and tool. The titanium alloy is an important material having vast application in aerospace and other important engineering and bio-medical field. Due to low machining yield and dimensional control, there is an strict requirement for optimizing the governing machining parameters of EDM. In the present study the process parameters of die-sinking EDM was experimentally, optimized by using full factorial technique for machining titanium grade – V alloy. Peak current, gap voltage, pulse on time and dielectric fluid pressure was taken as input control parameter while material removal rate and surface roughness were taken as response parameters. It was found that peak current and gap voltage are the main control parameters for increasing material removal rate. The scanning electron microscope images of the machined surface were analyzed to determine the effect of increasing control parameter on the response output.

Process Design for Rough Machining of Ti6Al4V Integral Components

Titanium materials are used increasingly in the aviation and aerospace industry in place of steel to enable lightweight construction, and manufacturing integral components mainly uses machining processes which involve enormous challenges and high production costs. The aim of the aviation and aerospace industry is to design a suitable process for economically manufacturing integral components. This paper presents associated experimental investigations and a process simulation to design a suitable process. Process improvement is achieved using hybrid machining, based on inductive heating and cryogenic cooling to increase productivity; results show an increased material removal rate and a reduction of tool wear when machining integral titanium components.

Assessing the effects of different dielectrics on environmentally conscious powder-mixed EDM of difficult-to-machine material (WC-Co)

Electrical discharge machining (EDM) is a well-known nontraditional manufacturing process to machine the difficult-to-machine (DTM) materials which have unique hardness properties. Researchers have successfully performed hybridization to improve this process by incorporating powders into the EDM process known as powder-mixed EDM process. This process drastically improves process efficiency by increasing material removal rate, micro-hardness, as well as reducing the tool wear rate and surface roughness. EDM also has some input parameters, including pulse-on time, dielectric levels and its type, current setting, flushing pressure, and so on, which have a significant effect on EDM performance. However, despite their positive influence, investigating the effects of these parameters on environmental conditions is necessary. Most studies demonstrate the use of kerosene oil as dielectric fluid. Nevertheless, in this work, the authors highlight the findings with respect to three different dielectric fluids, including kerosene oil, EDM oil, and distilled water using one-variable-at-a-time approach for machining as well as environmental aspects. The hazard and operability analysis is employed to identify the inherent safety factors associated with powder-mixed EDM of WC-Co.

Comparison of lubrication conditions for grinding of mild steel with electroplated cBN wheel

Grinding low carbon steel with diamond is regarded to be not feasible due to its chemical affinity to iron. A workpiece with comparable low hardness 330 HV30 and low-carbon content is selected. Therefore, cBN is a suitable choice of a superabrasive and thus employed. Its advantages compared to conventional abrasives are higher material removal rate and less wear. The thermal behaviour of the cBN grinding wheel in different environmental conditions is examined. The dry grinding process with a cBN grinding wheel is discussed and compared to wet grinding, grinding with minimum quantity lubrication and CO2 cooling. Increase in material removal rate and low wear rates are targeted. An electroplated, monolayer cBN grinding wheel with open structure design guarantees higher cooling ability and enlarged space for chips. The wear behaviour of the grinding wheel and the thermal damage on the workpiece surface are investigated. Cutting forces and temperatures are measured during the process for different high feed rates and depth of cuts. The thermal damages are evaluated by microscopic texture analysis. Grinding wheel dust contamination and loading connected with a significant temperature increase could be observed under dry environment. Cleaning impact of cooling nozzle on grinding wheel surface led to decreased normal forces and better surface roughness. Cooling impact of minimum quantity lubrication and CO2 cooling appeared less significant than emulsion.

Experimental Investigation of Multiple Quality Characteristics of Laser Beam Machined Surface using Integrated Taguchi and Fuzzy Logic Method

AbstractIn laser cutting, the capability of laser cutting mainly depends on optical and thermal properties of work material. The surface quality and metallurgical properties of the product is most important from the point of laser cutting quality. The present research work explores the modeling and optimization of laser beam cutting process parameters by using hybrid approach of Taguchi based fuzzy logic. The multi-response optimization of process parameters has been done to improve geometrical accuracy by minimizing the kerf width and kerf deviation. The four input parameters power, gas pressure, feed rate, pulse frequency and three output parameters kerf width (KW), kerf deviation (KD) and material removal rate (MRR) have been taken for the experimentation work. The S/N ratios taken for the KW and KD is of the smaller-the-better type and MRR is of the higher the better type. The predicting fuzzy logic model is implemented on Fuzzy Logic Toolbox of MATLAB using Mamdani technique. The fuzzy logic theory has been applied to compute the fuzzy multi-response performance index (FMRPI). This performance index is further used for multi-objective optimization. The selected samples were analyzed using scanning electron microscope. The predicted optimum results have been validated by performing the confirmation tests. The confirmation tests showed the considerable reduction in kerf deviation and increase in material removal rate.

Analysis of the Effect of Ultrasonic Vibrations on the Performance of Microelectrical Discharge Machining of A2 Tool Steel on the Diesel Engine Performance

The application of ultrasonic vibrations to a workpiece or tool is a novel hybrid approach in microelectrical discharge machining. The advantages of this method include effective flushing out of debris, higher machining efficiency and lesser short-circuits during machining. This paper presents a systematic analysis of the influence of kinetic effects of the ultrasonic vibrations on the material removal rate (MRR) and tool electrode wear rate (TWR). The tool wear ratio was estimated for the process at all processing conditions. The maximum variation in tool wear ratio is observed to be 82%. Therefore, MRR and TWR were independently analyzed by using three scientific tools: i) AOM plots, ii) interaction plots and iii) three-dimensional scatter plots. The increase in MRR is 47% corresponding to an increase in the maximum power of vibrations by 30%. The ultrasonic vibrations are found to be very effective at higher machining depths for achieving stable machining conditions. Regression equations were developed for MRR and TWR with capacitance, ultrasonic vibration factor, feed rate and machining time.

Parametric Analysis of Cylindrical Plunge Grinding on Micro-Alloyed Steel Using Taguchi Analysis

In the automotive industry, grinding of round diameters is an important process, to achieve desired tolerances and finish. While the effect of grinding parameters namely cutting velocity, work velocity and infeed (or downfeed) on grinding forces and surface integrity (that includes finish, residual stresses and subsurface damage) have been studied extensively in the literature, the effect on material removal rate (MRR) and dimensional accuracies has been given very limited attention. This work involves the analysis of effect of grinding parameters namely cutting velocity, work speed and infeed on MRR, surface finish (Ra) and dimensional accuracies by performing experiments on micro-alloyed steel bars. A series of cylindrical plunge grinding experiments were performed on round bar using CBN grinding wheel. The results show that, to achieve minimum surface roughness (Ra), infeed is the most influencing input parameter, whereas to achieve maximum MRR, work speed influences the most. An increase in infeed and a reduction in cutting velocity and work speed, leads to an increase in finish on ground surface. Also, an increase in infeed and cutting velocity, and a reduction in work speed results into an increase in MRR. The results show that, dimensional accuracies such as diameter, ovality and taper of ground surfaces have not been affected significantly.

Experimental investigations of gelatin-enabled abrasive water slurry jet machining

This work presents a description of abrasive water-slurry jet machining (AWSJM) to improve machining capabilities of conventional abrasive water jet machine. This work proposes a novel approach of AWSJM, where the conventional abrasive water jet machine (AWJM) is equipped with a liquid (gelatin) polymer solution injection system and a programmable control valve for controlling abrasive flow rate (AFR) and polymer solution flow rate. Parametric study of gelatin enabled AWSJM reveals the improvements in machining performance. Experimental investigations have been performed by varying concentration of the gelatin, pressure of water jet, abrasive flow rate, and abrasive size. The present work identifies the optimal range of process parameters for AWSJM, with natural gelatin as binder, with the response parameters being material removal rate, kerf width, and depth of cut. Gelatin produces a coherent, three-phase, four-content beam of higher kinetic energy in comparison with AWJ and results in increased material removal rate and depth of cut, with reduced kerf width.

Electrochemical Machining – Special Equipment and Applications in Aircraft Industry

AbstractElectrochemical machining is an unique method of shaping in which, for optimal parameters tool has no wear, surface layer properties after machining are similar to the core material and surface quality and accuracy increase together with material removal rate increase. Such advantages of electrochemical machining, besides of some ecological problems, create industry interest in the range of manufacturing elements made of materials with special properties (i.e. turbine blades of flow aircrafts engines). In the paper the nowadays possibilities and recent practical application of electrochemical machining in aircraft have been presented.