Showing papers in "Materials and Manufacturing Processes in 2012"

Nano-Cutting Fluid for Enhancement of Metal Cutting Performance

Abstract: Nano-cutting fluids are the mixtures of conventional cutting fluid and nanoparticles. Addition of the nanoparticles can alter wettability, lubricating properties, and convective heat transfer coefficient (cooling properties) of nano-cutting fluids. In the present work, nano-cutting fluid is made by adding 1% Al2O3 nanoparticles to conventional cutting fluid. The wettability characteristic of this nano-cutting fluid on a carbide tool tip is measured using the macroscopic contact angle method. Comparative study of tool wear, cutting force, workpiece surface roughness, and chip thickness among dry machining, machining with conventional cutting fluid as well as nano-cutting fluid has been undertaken. This study clearly reveals that the cutting force, workpiece surface roughness, tool wear, and chip thickness are reduced by the using nano-cutting fluid compared to dry machining and machining with conventional cutting fluid.

Analysis on Drilling of Glass Fiber–Reinforced Polymer (GFRP) Composites Using Grey Relational Analysis

Abstract: Glass fiber–reinforced polymer (GFRP) composite materials are an economic alternative to the engineering materials because of their superior properties. The present work focuses on the use of Grey relational analysis for optimizing the drilling parameters on the surface roughness and the thrust force in the drilling of GFRP composites. Taguchi's L9, 3-level orthogonal array is used for the experimentation. Optimal machining parameters are determined by the Grey relational grade obtained from the Grey relational analysis for multiperformance characteristics. Experimental results show that the machining performance in the composite machining process can be improved at optimal drilling conditions.

Grey Relational Analysis of Micro-EDM Machining of Ti-6Al-4V Alloy

Abstract: In the present work, micro-electric discharge machining (micro-EDM) of Ti-6Al-V alloy with tungsten carbide electrode has been performed. Ti-6Al-4V, which is difficult to machine via conventional machining techniques, however, can be easily machined via EDM machining, with careful selection of machining parameters for getting optimum results. In this study, the effect of various input parameters; current, voltage, frequency, and width, on output parameter viz., metal removal rate (MRR), tool wear rate (TWR), and overcut (OC) are studied. Grey relational analysis and analysis of variance (ANOVA) have been performed to optimize the levels of input parameters.

Mechanical Properties, Corrosion Resistance, and Microstructural Changes during Friction Stir Processing of 5083 Aluminum Rolled Plates

Abstract: Friction stir processing is a solid-state process to modify microstructure and mechanical properties of sheet metals and as-cast materials. In this process, stirring action of the tool causes the material to intense plastic deformation that yields a dynamic recrystallization. In this study, the effect of friction stir processing (FSP) and process parameters on microstructure, mechanical properties, wear resistance, and corrosion behavior of AA5083-O has been investigated. Results show that FSP leads to finer and homogenized grain structure, as well as changes in hardness, corrosion resistance, and wear resistance of the material.

Machining Damage in Edge Trimming of CFRP

Abstract: Conventional machining processes such as turning, milling, drilling, abrasive cutting, and grinding are commonly used to bring composite parts to final shape and assembly requirements. However, due to the layered nature of these materials, their machining may generate undesirable defects such as delamination and high surface roughness. The service life of composite components is believed to be highly dependent on machining quality and damage due to machining may result in scraping expensive parts. In this work, an experimental investigation was conducted to determine the effect of spindle speed, feed rate, and tool condition on machining quality of carbon fiber reinforced polymer (CFRP) composites during edge trimming operation. Machining quality was quantified in terms of average delamination depth and surface roughness. Delaminations were also characterized by their type and frequency of occurrence. It was found that average delamination depth and surface roughness increase with an increase in feed rate...

Performance Evaluation of Electrical Discharge Machining (EDM) Process Using Cryogenically Cooled Electrode

Abstract: This article describes a study on the cooling effect on copper electrode while electrical discharge machining (EDM) M2 grade high speed steel workpiece. To evaluate the machinability, electrode wear ratio (EWR) and surface roughness (SR) were the two responses observed. Discharge current, pulse on time, duty cycle, and gap voltage were the controllable process parameters. It was found that EWR reduced up to 20% by cryogenic cooling of electrode. With electrode cooling, SR was also found to have been reduced after machining. The effect of process parameters on EWR and SR were also analyzed. It was found that for EWR, discharge current, pulse on time, and duty cycle has the most significant effect, while pulse on time and discharge current have the most significant effect on SR. EWR and SR were found to be lower in cryogenic assisted EDM as compared to conventional EDM for the same set of process parameters. The shape of the electrode has also been measured, and it was found that the shape retention was bet...

An Experimental Study on the Depth of Cut of Granite in Abrasive Waterjet Cutting

Abstract: Many studies investigating the cutting performances of waterjets for several kinds of materials such as steel, brass, glass, or aluminium are available. However, there are few studies focused on the rock cutting in the literature. In the present study, therefore, it is aimed at investigating the cuttability of granite by abrasive waterjet. The effect of process parameters and the textural properties of granites on the cut depth and surface quality were investigated. The design philosophy of Taguchi was followed to conduct the experiments. Analysis of variance (ANOVA) was used to evaluate the data obtained statistically. Major significant process factors affecting the cut depth of granite were determined. It was disclosed that the traverse speed was the most significant process parameters affecting the cut depth of granite. Additionally, it was found that the depth of cut and surface quality were strongly affected by the grain size and its boundaries with the grains surrounding. Furthermore, consistent rel...

Some Investigations on High Speed Dry Machining of Aerospace Material Inconel 718 Using Multicoated Carbide Inserts

Abstract: It has been observed that considerable attention has been given to the use of cBN and/or ceramic tools for achieving better performance in the machining of superalloy Inconel 718. However, their cost limits the use in the engineering applications. In this article, the performance of multicoated TiN/TiAlN (PVD) coated and TiN/Al2O3/TiCN (CVD) coated tungsten carbide tools were investigated while high speed turning (HST) of superalloy Inconel 718. The effect of coating materials on cutting force, cutting temperature, vibration, and acoustic emission were recorded, analyzed, and reported. From the experimental results it has been found that TiN/Al2O3/TiCN (CVD) coated tool outperformed the TiN/TiAlN (PVD) coated tool in terms of machinability parameters such as cutting force and cutting temperature. From the fast Fourier transform (FFT) analysis of the vibration signals it was observed that the vibrations were less in case of the CVD coated tool than in case of the PVD coated tool.

Residual Stresses, Surface Roughness, and Tool Wear in Hard Turning: A Comprehensive Review

Abstract: Hard turning is used in the manufacturing industry as an economic alternative to grinding, but the reliability of hard turning processes is often unpredictable. The main factors affecting the reliability of hard turning are surface integrity and tool wear. In the present study, an attempt has been made to investigate the effect of cutting parameters on surface roughness, tool wear, and residual stress distribution in hard turning. This article brings out the comprehensive analysis of the effects of cutting parameters on surface roughness, residual stress, and tool wear.

Effects of Activating Flux on Weld Bead Geometry of Inconel 718 Alloy TIG Welds

Abstract: The purpose of this work is to investigate the effects of activating fluxes and welding parameter to the penetration and depth-to-width ratio (DWR) of weld bead of Inconel 718 alloy welds in the tungsten inert gas (TIG) welding process. In the activating flux with TIG (A-TIG) welding process, the single-component fluxes used in the initial experiment were SiO2, NiO, MoO3, Cr2O3, TiO2, MnO2, ZnO, and MoS2. Based on the higher DWR of weld bead, four fluxes were selected to create six new mixtures using 50% of each original flux. The A-TIG weldment coated 50% SiO2 + 50% MoO3 flux and 75° of electrode tip angle were provided with better welding performance. In addition, the experimental procedure of flux-bounded TIG (FB-TIG) welding with the same welding conditions and flux produced full penetration of weld bead on a 6.35 mm thickness of Inconel 718 alloy plate with single pass weld.

Continuously Tunable and Oriented Nanofiber Direct-Written by Mechano-Electrospinning

Abstract: A mechano-electrospinning method is presented to direct-write oriented nanofiber with high deposition accuracy in continuously tunable manner. This method uses a large nozzle to deposit high-resolution fiber-arrays by near-field localization. Due to the existence of mechanical drawing force, a higher resolution pattern can be direct-written by a lower voltage, which just keeps the Taylor cone stable. Then the fiber is stretched through a moving substrate, by which the deposited fiber can be continuously tuned from 400 nm to 200 nm in a linear relationship. The effects of the speed on the diameter and morphology of fibers are studied, and the analysis of the mechanism of the fiber alignment is given. The positionability and controllability make mechano-electrospinning very different from the traditional electrospinning, which only collects the fibers in the form of nonwoven fabric. In addition, the fibers fabricated by this method can directly deposit over a large flat area in the form of arrays and comple...

Parameter Optimization of Machining Processes Using a New Optimization Algorithm

Abstract: A new advanced algorithm is proposed for the process parameter optimization of machining processes. This algorithm is inspired by the teaching-learning process, and it works on the effect of influence of a teacher on the output of learners in a class. The results obtained by the proposed new algorithm have outperformed the previous results for the considered machining processes.

Machining Efficiency Evaluation of Cryogenically Treated Copper Electrode in Additive Mixed EDM

Abstract: The present experimental investigations have been carried to evaluate machining efficiency with additive powder mixed in dielectric fluid of electrical discharge machining on Inconel 718 with copper and cryogenically treated copper electrodes. Experiments have been conducted to study the effect of input parameters viz. polarity, type of electrode, peak current, pulse on time, duty cycle, gap voltage, retract distance, and concentration of fine graphite powder on machining efficiency. Machining efficiency is evaluated in terms of tool wear rate (TWR) and wear ratio (WR). The optimum factor/level combination of process parameters has been determined by Taguchi's approach treating performance measure as single objective response. Analysis of variance (ANOVA) is employed to indicate the level of significance of machining parameters for TWR and WR. The recommended optimal process input conditions have been verified by conducting confirmation experiments and significant improvement in TWR and WR is observed.

Study of Material Transfer Mechanism in Die Steels Using Powder Mixed Electric Discharge Machining

Abstract: The present article investigates the effect of process parameters and mechanism of material deposition in powder mixed electric discharge machining (PMEDM) on surface properties of EN31, H11, and High Carbon High Chromium (HCHCr) die steel materials. Current, powder, and interaction between workpiece and electrode affected the microhardness significantly. Copper electrode was found best for EN31 and H11 die steel, whereas tungsten-copper electrode was better suited for HCHCr steel to achieve higher microhardness. Graphite powder was found to be more suitable compared to aluminum in improving the microhardness of all three materials. Selected samples were analyzed for X-ray diffraction (XRD) followed by microstructure analysis using a scanning electron microscope (SEM). The results showed significant material transfer from the electrode as well as powder, either in free form and/or in compound form. For maximizing the microhardness of the machined surface, optimum parametric settings were identified for th...

Magnetorheological Ball End Finishing Process

Abstract: Finishing of three-dimensional (3D) surfaces such as grooves, projections, or complex in depth profiles on workpiece surfaces is a challenging task for the many existing advanced fine finishing processes. The advanced fine finishing processes have been developed to precisely control the abrading forces through external magnetic field. The applications of state-of-art finishing processes are limited to specific geometries only such as concave, convex, flat, and aspherical shapes due to restriction on relative movement of finishing medium and workpiece. Many of these processes are incapable of finishing of 3D intricate shaped surfaces. To overcome this problem, a new finishing process for flat as well as 3D surfaces using ball-end magnetorheological (MR) finishing tool is developed for ferromagnetic as well as non-ferromagnetic materials. The smart behavior of MRP fluid is utilized to precisely control the finishing forces and hence the final surface finish. A computer controlled experimental setup is desig...

Investigation on Joining of Aluminum and Mild Steel by Friction Stud Welding

Abstract: Joining of dissimilar metals has various automotive, aerospace, nuclear, chemical, and cryogenic applications. The present study focuses on friction stud welding of aluminum and mild steel. Experiments had been conducted by varying the process parameters and the strength of the friction welded joints was evaluated. Experimental results show that the speed of rotation, friction time, and axial shortening distance have significant effect on the impact strength of the welded joints. The dissipation of frictional heat from the weld center results in temperature gradient across the welded joint, causing different zones with different microstructures. Scanning electron microscope (SEM) micrograph reveals the presence of three distinctive regions in the heat-affected zone, namely, fully plasticized deformed zone, partially deformed zone, and unaffected base metal zone. The microhardness values were measured across the welded joint. At the interfacial region, there is an increased plastic deformation. This is due...

Influence of Tool Pin Profiles on Friction Stir Welding of Copper

Abstract: The influence of tool pin profiles on microstructure and mechanical properties of friction stir welded copper was studied. The different tool pin profiles such as taper cylindrical, taper cylindrical with threaded, triangular, square, pentagonal, and hexagonal having constant shoulder diameters were used to fabricate the joints. Tool rotational speed and traverse speeds were fixed at 900 rpm and 40 mm/min, respectively. The experimental results revealed that the sound defect free joints could be obtained by using six different tool pin profiles and the fracture locations were outside the weld zone on the retreating side. From the investigation it was found that the joints made by using square tool pin profile resulted in better mechanical properties compared to other tool pin profiles which is due to more pulsating actions and with 1.56 dynamic to static volume ratio. The tensile properties of all weld joints showed a relative correspondence to the variation of the hardness in the weld zone. The joint eff...

Nanoparticles: From Theory to Applications

Abstract: The first edition of this book was published in 2004, and after only 6 years, the rapid growth of the field of nanoscience and nanotechnology necessitated a second edition. Such had been the develo...

Review: Thermal Debinding Process in Particulate Materials Processing

Abstract: Developing a rapid and efficient method for removing polymers (termed binders) from a shaped powder component, know as a green body, is important to forming defect-free metal, ceramic, and cermet structures. The rapid growth in powder injection molding to form complex shapes at high precision in large quantities has increased the need for faster, cleaner, and cheaper polymer removal processes. Binder removal using controlled heating of the component in gaseous atmosphere is the most popular method. This thermal debinding or burnout process is a delicate process, since it is easy to crack, blister, slump, or otherwise damage the component with an improperly designed cycle. To avoid these issues, often long heating cycles are used to remove the binder, but with a loss of productivity. Considerable progress has been made over the past several decades in understanding various phenomena during polymer burnout, resulting in substantial reduction in the thermal debinding time. This article provides an overview o...

Formation of Nanocrystalline Tungsten by Selective Laser Melting of Tungsten Powder

Abstract: Nanocrystalline tungsten was obtained by selective laser melting (SLM) in the present work. The microstructures and compositions revealed that the nanocrystalline tungsten could be fabricated via the SLM method using pure tungsten powder. It was found that the produced nanocrystalline tungsten microstructure could be regarded as a resultant of solid forces by laser, which grow along a special crystal surface. The metallurgical mechanisms for the formation of such a novel structure through SLM process were also addressed.

Optimization of Machining Parameters for Surface Roughness and Burr Height in Drilling Hybrid Composites

Abstract: This article focuses on the multiple performance analysis in machining characteristics of drilling hybrid metal matrix composites produced through stir casting route. The desirability function-based approach is employed for the optimization of drilling parameters, namely, spindle speed, feed rate, and wt% of SiC based on the multiple performance characteristics including surface roughness and burr height. Material used for the present investigation is Al 356-aluminum alloy reinforced with silicon carbide of size 25 microns and mica of an average size of 45 microns. Experiments are conducted on a vertical machining center using the Box--Behnken experimental design (BBD) technique. The drilling test is carried out using coated carbide drill of 6 mm diameter. An empirical model has been developed for predicting the surface roughness and burr height in drilling of Al 356/SiC-mica composites. The optimization results showed that the combination of medium spindle speed, low feed rate, and high wt% of SiC is nec...

Optimization of Nd:YAG Laser Parameters for Microdrilling of Alumina with Multiquality Characteristics via Grey–Taguchi Method

Abstract: In laser microdrilling, the formation of taper and the dimension of the heat-affected zone (HAZ) are important attributes that greatly influence the quality of a drilled hole. In this article, an experimental investigation into Nd:YAG laser microdrilling of alumina is carried out to produce desired high-quality microdrill. Four independently controllable process variables viz. lamp current, pulse frequency, air pressure, and pulse width are considered as input parameters, while hole taper and HAZ width are considered the output parameters. The Taguchi method combined with the grey relational analysis is used as a statistical design of experiment technique to set the optimal process parameters. The objective is set to minimize both quality characteristics, simultaneously. Grey relational analysis is applied to convert the multiple quality characteristics to a single performance characteristic, called grey relational grade. Optimal process parameters are then determined by the Taguchi method using grey rela...

Finite Element Analysis of Laser Welding: A State of Art Review

Abstract: As a well-established modern manufacturing process, laser welding is widely adopted in different industry fields to assemble lightweight structures. Major advances have been made in recent years in laser welding. This article reviews the latest development of finite element analysis of laser welding, in terms of process, damage modeling, fatigue behavior, dynamic characteristics, and laser hybrid welding. Some important numerical issues such as materials modeling, meshing procedure, and failure criteria are discussed. Finite element analysis of laser welding will allow many different laser welding processes to be simulated in order to perform a selection of different system parameters before testing, which would be time-consuming or be prohibitively expensive in practice. The main methods used in finite element analysis of laser welding are discussed and illustrated with brief case studies.

Optimization of Correlated Responses of EDM Process

Abstract: Electrical discharge machining (EDM) process has several important performance measures (responses), some of which are correlated. For example, material removal rate (MRR) and electrode wear rate (EWR) are highly correlated. No reported research work on EDM process has taken into consideration the possible correlation between the response variables while determining the optimal process conditions. Thus, the results achieved by the past researchers are often suboptimal. In the recent past, a few multiresponse optimization methods have been proposed that make use of the principal component analysis (PCA) to take into account the possible correlation between the responses. So, ideally, these methods should be more effective for optimizing the EDM process. However, the relative optimization performances of these methods are unknown and therefore, the process engineers may face the difficulty in selecting the most appropriate method for optimizing an EDM process. In this article, two sets of past experimental ...

Assessment of Residual Stresses and Distortion in Stainless Steel Weld Joints

Abstract: Welding introduces significant residual stresses in the welded structure/component due to non-uniform heat distribution during heating and cooling cycle. To control, reduce, or beneficially redistribute the residual stresses in weld joints, the stress distribution needs to be known. In the present study, weld joints of 10 mm thick 316LN stainless steel were made by multi-pass TIG and A-TIG welding processes and their residual stresses distribution and distortion values were measured and compared. While V-groove edge preparation was required for making multi-pass TIG weld joint, square-edge preparation was sufficient for making single pass A-TIG weld joint. Ultrasonic nondestructive technique based on the critically refracted longitudinal waves (LCR waves) has been used for the quantitative surface/sub-surface residual stress measurements in the weld joints. Distortion measurements were carried out before and after welding using height gauge. Peak tensile residual stress and the angular distortion values w...

Influence of Heat Treatment on the Machinability of Titanium Alloys

Abstract: Orthogonal cutting force measurements and single-point tool life tests were conducted in order to analyze the sensitivity to heat treatment on the machinability of three titanium alloys: Ti6Al4V, Ti-5Al-4V-0.6Mo-0.4Fe (TIMETAL® 54M), and Ti6246. The Ti6246 alloy showed the highest tool wear rates and the higher cutting forces in all the heat treatment conditions which could be related to its higher mechanical properties. TIMETAL® 54M alloy, a newly developed alloy with similar mechanical properties to the more commonly used Ti6Al4V, showed the lowest wear rates. Microstructural changes due to heat treatment have some influence in the machinability of the alloys. The β annealed samples of the Ti6Al4V and TIMETAL® 54M alloys, with a very coarse lamellar microstructure, showed considerably shorter tool life and higher cutting forces. The rest of the heat treatments showed no significant influence in the machining behavior of the analyzed alloys as they do not cause important microstructural changes.

Optimization of Machining Parameters in Turning of Titanium (Grade-5) Alloy Using Response Surface Methodology

Abstract: In this study, the performance of polycrystalline diamond (PCD) cutting insert has been described using response surface methodology (RSM) for turning of titanium (Grade-5) alloy. The machining parameters such as cutting speed, feed rate, depth of cut, and approach angle of the cutting edge have been considered in the investigations. The surface roughness and tangential forces are the response variables for investigations. The experimental plan used for four factors at three levels was based on face centered, central composite design (CCD) using RSM. The experimental results obtained indicate that the surface roughness increases with increase in the cutting speed and the feed rate, and decreses with decrese in approach angle and depth of cut, whereas the tangential force increases with increase in approach angle and depth of cut, and decreases with decrease in cutting speed and feed rate.

Study of Crack Formation and Resolidified Layer in EDM Process on T90Mn2W50Cr45 Tool Steel

Abstract: This article is concerned with analysis of crack formation and spherical form of resolidified layer on T90Mn2W50Cr45 tool steel surface, which is processed in electrical discharge machine (EDM). Crack and resolidified layer are examined by scanning electron microscope (SEM) with different magnification. Experiments were conducted on the T90Mn2W50Cr45 tool steel surface for different combination of process parameters like pulse: on time, off time, and current. The crack formation is influenced by the base material (T90Mn2W50Cr45 tool steel) properties, electrode wear, and resolidified layer. SEM with lower magnification will show the crack formation on the surface, while higher magnification will show the structure of the resolidified layer. It was found that the pulse current is directly proportional with resolidified layer thickness and crack density.

Intelligent Modeling and Multiobjective Optimization of Die Sinking Electrochemical Spark Machining Process

Abstract: Die sinking–electrochemical spark machining (DS–ECSM) is one of the hybrid machining processes, combining the features of electrochemical machining (ECM) and electro-discharge machining (EDM), used for machining of nonconducting materials. This article reports an intelligent approach for the modelling of DS–ECSM process using finite element method (FEM) and artificial neural network (ANN) in integrated manner. It primarily comprises development of two models. The first one is the development of a thermal finite element model to estimate the temperature distribution within the heat-affected zone (HAZ) of single spark on the workpiece during DS–ECSM. The estimated temperature field is further post-processed for determination of material removal rate (MRR) and average surface roughness (ASR). The second one is a back propagation neural network (BPNN)-based process model used in a simulation study to find optimal machining parameters. The BPNN model has been trained and tested using the data generated from th...

Study of Coating Thickness of Cold Spray Process Using Taguchi Method

Abstract: In this article, Taguchi design of experiments L 18 orthogonal array have been adopted for making the electro-conductive coatings. Process parameters selected for this study are: substrate material, type of powder feeding arrangement, stagnation gas temperature, stagnation gas pressure, and standoff distance. The response parameter of cold spray coatings produced is measured in terms of coating thickness. The analyses of the raw data and Signal-to-Noise (S/N) ratio of the response parameters have been performed using analysis of variance (ANOVA). The optimum process parameters are predicted on the basis of analyses of the raw data and S/N ratio. The percentage contribution of the various process parameters with reference to coating thickness as response has been predicted. The significant process parameters in decreasing order of their contribution are: standoff distance, stagnation gas temperature, substrate material, stagnation pressure of the carrier gas, and feed arrangement of the powder particles.