Dry machining characteristics of coated inserts and multi response optimization through DEAR-Taguchi method

The primary intent of the proposed research work is to investigate the effectiveness of the titanium aluminium nitride/tungsten carbide-carbide coated insert during dry turning structural stainless steel. The aim of the study is to simultaneously optimise machining variables like spindle speed, depth of cut and feed for several responses like flank wear, material removal rate and surface roughness. Titanium aluminium nitride/tungsten carbide-carbide is coated on the surface of carbide tool by cathodic arc evaporation method. The characterization studies have been conducted to ensure the existence of coating material. Micro hardness of coated and pure inserts was tested, which confirms that titanium aluminium nitride/tungsten carbide-carbide coated insert possesses 17.43 % augmented hardness over pure inserts. The machining was performed by adopting Taguchi experimental design. A multi-response optimization approach was applied in this study that included ranking methodology based on data development analysis and Taguchi's design. The performance index for multiple responses was measured and mathematically analysed for their effect on processing parameters. The combination of parameter such as spindle speed: 2000 min⁻¹; cutting depth: 0.45 mm and feed rate: 0.16 mm rev⁻¹ was experimental as optimal machining parameters.     

Optimization of cutting power and power efficiency during particleboard helical milling

With the aim of providing scientific guidance for the application of spiral cutters in particleboard machining, this work studied the influence of milling parameters on milling power and power efficiency during helical milling of particleboard. And the response surface methodology was applied to optimize the milling parameters to reduce machining energy consumption and improve energy efficiency. The factors of milling depth, spindle speed and helical angle were selected as input parameters, and the mathematical models between the input parameters and the response parameters were established. Then, the significant influence of each factor and the interaction of two factors were determined by variance analysis, and the change trend of milling power and power efficiency was studied by response surface methodology. Results showed that the milling depth had the greatest impact on milling power and power efficiency, followed by the spindle speed and helical angle. An increase in the milling depth and spindle speed resulted in an increase in milling power and power efficiency, while the increased helical angle resulted in a decrease in milling power and power efficiency. The optimized values of helical angle, spindle speed and milling depth were 54°, 5650 min⁻¹ and 1.3 mm, respectively.     

Optimization of Dry Machining Parameters for High-Purity Graphite in End-Milling Process

The machining factors affecting the tool wear and surface finish produced in the end milling process are generally the cutting speed, the feed rate, the depth of cut, etc. This paper describes a study that identifies the influence of the machining parameters on the groove width and the surface roughness average for the end-milling of high-purity graphite under dry machining conditions. The experiments are based on an orthogonal arrays and grey relational analysis method is then applied to determine an optimal machining parameter setting. The dimensional accuracy of the groove width and the surface roughness average are selected as the quality targets. In this study, the feed rate is the most significant controlled factors for the machining process according to the weighted sum grade of the Δ and the R _a .     

An Experimental Investigation on Ultrasonic Vibration-Assisted Grinding of SiO2f/SiO2 Composites

Fiber-reinforced ceramic matrix composite (FRCMC) have been widely used in aerospace and other high-technology fields due to their excellent mechanical and physical properties. However, FRCMC is a kind of typical material with anisotropic and inhomogeneous structure; thus, it is difficult to guarantee the precision and surface quality using traditional machining. The present paper employed ultrasonic vibration-assisted grinding (UAG) to machine 2.5D woven SiO_2f/SiO₂ composites. By comparing the grinding force, surface microstructure, chip formation, surface topography and surface roughness with and without ultrasonic vibration for the machining of SiO_2f/SiO₂ composites, the feasibility of UAG on FRCMC was investigated experimentally. In addition, the effects of the process parameters (including spindle speed, feed rate, grinding depth, grain mesh size and ultrasonic power) on grinding force and surface roughness were studied through an orthogonal experiment. The research obtained can be a useful technical support for the development of UAG in the machining of FRCMC.     

Experimental investigation and optimization of machining parameters in drilling of fly ash-filled carbon fiber reinforced composites

Particle-filled polymer composites have become attractive because of their wide applications and low cost. Carbon fiber reinforced polymer (CFRP) is well known as a difficult-to-cut material, which has very strong physical and mechanical characteristics. Machining of carbon fiber reinforced composites is essential to have functional upshots, out of which drilling is the key operation needed for fabrication. In this paper Taguchi L₂₇ experimental design is coupled with grey relational analysis (GRA) to optimize the multiple performance characteristics in the drilling of fly ash-filled carbon fiber reinforced composites. Experiments were conducted on a vertical machining center, and Taguchi L₂₇ experimental design was chosen for the experiments. The drilling parameters, namely spindle speed, feed rate, drill diameter and wt% of fly ash, have been optimized based on the multiple performance characteristics including thrust force, surface roughness, and delamination. The GRA with multiple performance characteristics indicates that the wt% of fly ash and drill diameter are the most significant factors that affect the performance. Experimental results have shown that the performance in the drilling process can be improved effectively by using this approach.     

The characteristics of machined surface controlled by multi tip arrayed tool and high speed spindle

In this study, we propose one of the ultra-precision machining methods that can be adapted brittle material as well as soft material by using multi arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because particles of grinding tools are irregular size and material can be fragile. Therefore we were able to design tool paths and machine controlled pattern on surface by multi arrayed diamond tips which has uniform size made in MEMS fabrication and high speed spindle of which maximum speed is about 300,000 rpm. We defined several parameters that can have effect on machining surface. Those are multi array of diamond tips (n * n), speed of the air spindle, and feeding rate. Surface roughness and surface texture can be controlled by those parameters for micro machining.     

Optimization of interior roller burnishing process for improving surface quality

Improving the surface characteristics of roller burnishing processes is one of effective approaches to decrease the machining costs and time. This paper systematically investigates the nonlinear relationships between machining parameters and surface characteristics, including surface roughness (R_a), surface hardness (H), and hardness depth (HD) of the interior roller burnishing using response surface method (RSM) model. Three process parameters considered include spindle speed S, feed rate F, and burnishing depth D. A set of physical experiments was carried out with AISI 1045 steel on a computer numerical control (CNC) milling machine using the roller burnishing tool. The target of the current complex optimization is to enhance the surface hardness and hardness depth, while the surface roughness is considered as the constraint. Finally, an evolutionary algorithm entitled archive-based micro genetic algorithm (AMGA) was used to generate a set of feasible optimal solutions and determine the best machining conditions. The results show that an appropriate trade-off solution can be drawn with regard to the low surface roughness and high the surface hardness as well as hardness depth. Furthermore, the integration of RSM model and AMGA can be considered as a powerful approach for modeling and optimizing interior roller burnishing processes.     

Investigation of machining characteristics in rotary ultrasonic machining of alumina ceramic

Alumina ceramic is well documented as a much-demanded advanced ceramic in the present competitive structure of manufacturing and industrial applications owing to its excellent and superior properties. The current article aimed to experimentally investigate the influence of several process variables, namely: spindle speed, feed rate, coolant pressure, and ultrasonic power, on considered machining characteristics of interest, i.e., chipping size and material removal rate in the rotary ultrasonic machining of alumina ceramic. Response surface methodology has been employed in the form of a central composite rotatable design to design the experiments. Variance analysis testing has also been performed with a view to observing the consequence of the considered parameters. The microstructure of machined rod samples was evaluated and analyzed using a scanning electron microscope. This analysis has revealed and confirmed the presence of plastic deformation that caused removal of material along with brittle fractures in rotary ultrasonic machining of alumina ceramic. The validity and competence of the developed mathematical model have been verified with test results. The multi-response optimization of machining responses (material removal rate and chipping size) has also been attempted by employing a desirability approach, and at an optimized parametric setting the obtained experimental values for material removal rate and chipping size were 0.4166?mm³/s and 0.5134?mm, respectively, with a combined desirability index value of 0.849.     

旋转超声磨削Si3 N4陶瓷用金刚石磨具磨损行为研究

热压烧结Si₃N₄陶瓷材料常应用于航天飞行器中关键耐高温零部件,但由于高硬度和低断裂韧性,其加工效率和加工表面质量难以满足制造需求。为了提高热压烧结Si₃N₄陶瓷旋转超声磨削加工质量,减小由于金刚石磨具磨损带来的加工误差,开展了磨具磨损行为研究。基于热压烧结Si₃N₄陶瓷旋转超声磨削加工实验,分析了金刚石磨具磨损形式;基于回归分析建立了金刚石磨具磨损量数学模型,揭示了加工参数及磨具参数与金刚石磨具磨损量间映射关系;并研究了磨损形式与磨具磨损量及加工表面粗糙度影响规律。结果表明：磨粒磨耗是旋转超声磨削Si₃N₄陶瓷用金刚石磨具最主要磨损形式,比例超过50%;主轴转速和磨粒粒度对磨具磨损量影响最为显著;且磨损量较小时,加工表面粗糙度值反而增加。以上研究可为提高旋转超声磨削Si₃N₄陶瓷加工精度和加工质量提供指导。     

Optimizing Single Point Diamond Turning for Mono-Crystalline Germanium Using Grey Relational Analysis

In this paper the results of an experimental study conducted for precision machining of mono-crystalline germanium with single point diamond turning (SPDT) have been reported. The input parameters include the top rake angle, tool overhang, depth of cut, tool feed rate, and rotational speed of the workpiece. The flat profile is generated on a disk of mono-crystalline germanium possessing three performance characteristics: surface roughness (R_a), profile error (P_t), and waviness error (W_a). The process parameters are optimized to obtain the best surface finish with minimum profile and waviness errors by using the Taguchi method. The grey relational analysis is employed for carrying out multiresponse optimization of performance parameters. The best value of surface finish obtained after multiresponse optimization is 10.7 nm having a profile error and a waviness error of 0.202 µm and 0.046 µm, respectively.     

Influence of input parameters on the near-dry WEDM of Monel alloy

Near-dry wire electrical discharge machining (WEDM) is a modified WEDM process, which has no adverse effects on the environment, in which metal removals have been done with the dielectric medium being used in the form of a mist. As the increase in production by reducing the machining time is a costly affair, the input parameters attract considerable attention for their optimization. The predominant control characteristics in this study are the time-bound material removal and surface quality. The time duration of the electrical pulse on and off, wire feed, air inlet pressure, and water flow rate are the parameters considered for this experimental analysis. In this paper, the optimization techniques such as RSM method and analysis of variance (ANOVA) were used to route the experiments and optimize the responses of near-dry WEDM process for machining the material Monel alloy. A model has been formulated mathematically for the two vital responses needed, under the influence of regression analysis. Additivity test has been performed to validate the mathematical model. The air–water mixture in the form of a mist was used in place of dielectric medium to study the impact on material removal rate (MRR), surface roughness (R_a), and environment. It was observed that a high surface finish could be obtained at 3 bar pressure.     

Studies on Machining Parameters While Milling Particle Reinforced Hybrid (Al6061/Al2O3/Gr) MMC

In this article, response surface methodology has been used for finding the optimal machining parameters values for cutting force, surface roughness, and tool wear while milling aluminum hybrid composites. In order to perform the experiment, various machining parameters such as feed, cutting speed, depth of cut, and weight (wt) fraction of alumina (Al₂O₃) were planned based on face-centered, central composite design. Stir casting method is used to fabricate the composites with various wt fractions (5%, 10%, and 15%) of Al₂O₃. The multiple regression analysis is used to develop mathematical models, and the models are tested using analysis of variance (ANOVA). Evaluation on the effects and interactions of the machining parameters on the cutting force, surface roughness, and tool wear was carried out using ANOVA. The developed models were used for multiple-response optimization by desirability function approach to determine the optimum machining parameters. The optimum machining parameters obtained from the experimental results showed that lower cutting force, surface roughness, and tool wear can be obtained by employing the combination of higher cutting speed, low feed, lower depth of cut, and higher wt fraction of alumina when face milling hybrid composites using polycrystalline diamond insert.     

Investigation of multiple process parameters in abrasive water jet machining of tiles

This paper discusses the optimization of an abrasive water jet machining process with multiple characteristics, using the Taguchi orthogonal array and grey relational analysis (GRA). The machining process variables, such as mesh size, nozzle diameter, abrasive flow rate, water pressure, stand-off distance, and feed rate, were optimized with respect to multiple performance characteristics, namely, the surface roughness and the kerf angle. Experiments were performed using an L₁₈ orthogonal array, and the optimum machining process variables were determined, using GRA. Analysis of variance was used to identify the most significant factor in the machining performance. A confirmatory test was performed to verify the improvement of the performance characteristics. The microstructure of the machined surfaces was also examined by scanning electron microscopy and atomic force microscopy. The results showed that the surface roughness and kerf angle were minimized under optimal machining conditions.     

Cutting Characteristics of Zr-Based Bulk Metallic Glass

Cutting behavior exerts a considerable influence on the fabrication of bulk metallic glass(BMG) components. In this study,the influences of machining parameters(i.e.,depth of cutting,feed rate,and spindle rate) on the turned surface of a Zr-based BMG after observing the 3D morphologies of this surface were characterized.The results showed that the influence of the spindle rate on the surface morphologies is more substantial as compared to the depth of cutting and the feed rate. Nanoscratch tests were conducted to further characterize the separation mechanism of the chips,which revealed that the chips are torn off the surface of a BMG because of inhomogeneous localized maximum shear stress.     

Performance evaluation of Al2O3 nano powder mixed dielectric for electric discharge machining of Inconel 825

Electrical discharge machining (EDM) process is popular for machining conductive and difficult-to-cut materials, but low material removal rate (MRR) and poor surface quality are major limitations of the process. These limitations can be overcome by adding the suitable powder in the dielectric. The powder particles influence electric field intensity during the EDM process which in turn improve its performance. The size (micro to nano) and properties of the mixed powder also influence the machining efficiency. In this regard, the objective of the present work is to study the performance of EDM process for machining Inconel 825 alloy by mixing Al₂O₃ nanopowder in deionized water. The experimental investigation revealed that maximum MRR of 47?mg/min and minimum SR of 1.487?µm, which are 44 and 51% higher in comparison to conventional EDM process, respectively, can be achieved by setting optimal combinations of process parameters. To analyze these observed process behavior, pulse-train data of the spark gap were acquired. The discharge waveform identifies the less arcing phenomenon in the modified EDM process compared to conventional EDM. Further, surface-topography of the machined surface was critically examined by capturing field emission scanning electron microscopy and atomic force microscopy images.     

Effect of deep cryotreated tungsten carbide electrode and SiC powder on EDM performance of AISI 304

Abstract

Powder mixed electric discharge machining (PMEDM) is a further advancement of conventional EDM process in which electrically conductive powder is suspended in the dielectric fluid to enhance the material removal rate (MRR) along with the surface quality. Cryotreatment is introduced in this process for improving the cutting tool properties as well as tool life. In this investigation, EDM is performed for the machining of AISI 304 stainless steel using cryotreated double tempered tungsten carbide electrode when SiC powder is suspended in the kerosene dielectric. The influence of process parameters viz. pulse on time, peak current, duty cycle, gap voltage and powder concentration on tool wear rate (TWR), surface roughness (R_a), and MRR has been studied. Metallographic analysis was carried out for the machined surfaces. By the addition of powder concentration and cryotreated double tempered electrode, significant improvement in the machining efficiency has been found out. When cryotreated electrode used MRR, TWR and R_a decreased by 12%, 24% and 13.3%, respectively and when SiC powder used MRR increased by 23.2%, TWR and R_a decreased by about 25% and 14.2%, respectively.     

Grey-fuzzy algorithm to optimise machining parameters in drilling of hybrid metal matrix composites

Metal matrix composites (MMCs) are difficult to machine due to their abrasive properties. With the projected widespread application of MMCs, it is necessary to develop an appropriate technology for their effective machining. The present investigation focuses on finding the optimal machining parameters setting in drilling of hybrid aluminium metal matrix composites using the grey-fuzzy algorithm. This proposed algorithm, coupling the grey relational analysis with the fuzzy logic, obtains a grey-fuzzy reasoning grade to evaluate the multiple performance characteristics according to the grey relational coefficient of each performance characteristics. The Taguchi method of experimental design is a widely accepted technique used for producing high quality products at low cost, therefore a L₂₇ 3-level orthogonal array is used for the experiments. The optimisation of multiple responses in complex processes is common; therefore, to reduce the degree of uncertainty during the decision making, fuzzy rule-based reasoning is integrated with the Taguchi’s method. The response table, response graph and analysis of variance (ANOVA) are used to find the optimal setting and the influence of machining parameters on the multiple performance characteristics. Experimental results have shown that the required performance characteristics in the drilling process are improved by using this approach.     

Fabrication of damascene Cu wirings using solid acidic catalyst

The copper damascene process is one of the most promising technologies for fabricating Cu wirings for electronic devices such as LSIs. In this research, the fabrication of damascene Cu wirings was conducted using solid acidic catalyst. When a Cu-plated wafer, whose oxide is a basic oxide is dipped into a mixture of oxidizing solution and acidic solution, surface atoms are ionized and etched off into the solution. However, because conventional nonelectrolytic etching does not have a reference surface, it is difficult to utilize for planarization. Therefore, a new nonelectrolytic machining method using a cation-exchange fabric instead of an acidic solution was developed. To be more precise, the planarization of a Cu-plated wafer was carried out by rubbing with the cation-exchange fabric in ozone water. Basically, this method exploits chemical reactions so that the physical properties of the workpiece surface are not deteriorated. Furthermore, this method uses no chemicals except for ozone water, which easily dissociates into water and oxygen molecules; thus, this method is a low-cost, environmentally friendly process. In this paper, as a preliminary experiment, the nonelectrolytic etching of a Cu sample using solutions of O₃ and CO₂ was carried out to inspect the dependence of the etching rate on [O₃] and [H⁺]. The results indicate that the etching rate increased as [O₃] and [H⁺] increased. When [H⁺] was high relative to [O₃], a smooth etch-pit-free surface was achieved. Next, nonelectrolytic etching using a cation-exchange fabric was carried out, and properties similar to those in the case of etching using solutions were obtained. Finally, damascene Cu wirings were fabricated using ozone water and a cation-exchange catalyst.     

Experimental investigation and optimization during the fabrication of arrayed structures using reverse EDM

In recent years, reverse electric discharge machining (R-EDM) has been evolved as a method for the fabrication of arrayed structures for surface texturing which find applications in fabrication of fins and component assembly. In this study, the feasibility of R-EDM process in the fabrication of arrayed features of ?3?mm and height 2?mm on mild steel has been investigated utilizing response surface methodology (RSM)-based experimentation. Influence of control variables such as peak current (I_p), pulse-on time (T_on), and flushing pressure (F_p) on some of the vital geometric characteristics like taper and cylindricity error along with material removal rate (MRR), surface roughness (SR), microhardness, and surface morphology of pillared structure has been investigated. Analysis of variance (ANOVA) results show that I_p has a significant influence followed by T_on on MRR. I_p has a significant contribution toward SR, taper, and cylindricity error. High microhardness was found in heat-affected zone (HAZ). The optimal combination of parameter obtained using principal component analysis (PCA)-based grey relational analysis (GRA) is determined to be I_p?=?10 A, T_on?=?100 μs, and F_p?=?0.3?kg/cm², which was further ascertained using confirmatory test.     

响应曲面法优化超音速等离子喷涂Al2O3-40%TiO2涂层工艺

为获得低孔隙率的Al2O3-40%TiO2(AT40)涂层,采用响应曲面法(RSM)优化超音速等离子喷涂AT40涂层的工艺参数,利用Box-Behnken(BBD)设计分析送粉量、喷涂功率、氩气流量、氢气流量4个主要因素对涂层截面孔隙率的影响规律,利用Design Expert软件设计试验方案,统计分析试验数据,并得到二次多元回归模型.研究表明,在本试验条件下,4种因素对孔隙率影响顺序依次为氩气流量氢气流量喷涂功率送粉量,最优工艺参数为送粉量30 g/min,喷涂功率51.4 kW,氩气流量3.0 m3/h,氢气流量0.45 m3/h,试验测得此时涂层孔隙率为2.74%.