Erosion Machining Research Articles

Investigation on dry machining of stainless steel 316 using textured tungsten carbide tools

In this research, austenitic stainless steel SS316 material has been machined using textured carbide cutting tools under dry conditions. Micro-textures were made on tool rake face using wire spark erosion machining technology. Effects of three important machining process parameters i.e. cutting speed, depth of cut and feed rate on machinability (MRR, average roughness, and tool wear) of SS316 have been investigated. Taguchi L27 orthogonal array based twenty seven experiments have been carried out by varying machining parameters at three levels. Feed rate has been identified as the most important parameter. Machining parameters have been optimized by grey entropy method to enhance the machinability. Optimal combination of machining parameters i.e. 170 m min−1 cutting speed, 0.5 mm/rev feed rate and 1.5 mm depth of cut produced the best machinability with 3.436 μm average roughness, 105187 mm3 min−1. MRR, and tool wear 234.63 μm. Lastly, a tool wear and chip morphology study have been done where textured tools have been found outperformed plain (Non-textured) tools.

Electrical Discharge Machining Characteristics of ECAP Copper Electrode

Enormous research work has done on the electrode wear in spark erosion machining such as hybrid electrical discharge machining process, introducing various methods such as ultrasonic vibration in electrode, rotating the electrode, developing new electrode material (alloys and composites) and surface coated electrode etc,. Equal Channel Angular pressing is one such technique which makes tool material harder through grain refinement and ultimately enhances the tool life. The work material is AISI H13. For this research work, two copper electrodes are prepared, out of which one copper electrode has undergone equal channel angular pressing process. The most influencing parameters of spark machining like current, pulse on time and pulses off time are chosen for this study. The experiments are conducted using bare copper electrode and equal channel angular pressed copper electrode based on the box Behnken approach. The observations are analyzed for the machining characteristics in terms of rate of machining, rate of tool erosion and surface coarseness. Finally, it is found that ECAP processed copper electrode has lesser wear rate and better surface finish than bare copper electrode.

Effect of ECAP on copper electrode in spark machining

Abstract This paper analyses the behavior of spark erosion machining in terms of output performance such as rate of machining, rate of tool erosion and surface roughness corresponding to the input parameters effect on discharge current, spark existing time and spark absence time with respect to. The experimentation was conducted based on Box-Behnken design using bare electrode and a ECAP processed electrode. The regression models were developed and optimized with Response Surface Methodology. From the analysis, it was concluded that the spark erosion machining quality is significantly high with equal channel angular pressed copper electrode.

Impact Wear Resistance of Nanocomposite Coatings for Aircraft Components

Landing gear is an aircraft component often subjected to wear, fracture, mechanical failure and erosion, principally caused by impact with sand and other small particles. Erosion wear can cause deformation and material removal with consequent efficiency reduction. Coatings can protect stressed structural part and impede the erosion of the metallic components. This work focus on the investigation of the erosion resistance of two ceramic multilayer coatings, AlSiTiN and AlSiCrN, deposited by Physical Vapour Deposition (PVD) on a high speed steel (H11) usually used for landing gear application. Erosion test were carried out with an erosion machine using alumina particles. Powder was directed to the specimens (coatings and substrate) at nominal impingement angles of 90° and 20° with different impact speed (50, 75, 100 and 125 m/s at 90° and 100, 125, 150 and 175 m/s at 20°), at a nozzle-specimen distance of 10 mm. All the tests were performed for two minutes. Hardness and Young's modulus were obtained by nanoindentation, and adhesion between coating and substrate was evaluated by scratch test. Volume lost was measured with Taylor Hobson profiler while cracking behaviour and microstructure modifications were examined with a scanning electron microscope (SEM). AlSiCrN coating significantly enhanced the erosion resistance of H11 substrate, showing higher resistance also with respect to AlSiTiN coating. Indeed, the coating was not completely removed from the surface neither at 90° nor at 20°. The erosion wear rapidly increased by increasing the impact speed in the case of substrate and AlSiTiN, while such parameter was not significantly influent in the case of AlSiCrN. The results suggest that adhesion should play an important role to explain the highest erosion resistance of AlSiCrN coating. Erosion mechanism was principally driven by the intrinsic brittleness of both ceramic coatings.

On wire spark erosion machining induced surface integrity of Ni55.8Ti shape memory alloys

Ni55.8Ti shape memory alloys (SMAs) find applications in different fields of medical and engineering. In every field, surface integrity greatly affects the functional performance of shape memory alloy parts. In the present work, wire spark erosion machining of Ni55.8Ti shape memory alloys has been conducted and surface integrity parameters of the machined specimens have been evaluated. Experiments are designed using Taguchi L16 robust design of experiment technique. Effect of important process parameters, i.e. voltage, pulse-on time and pulse-off time on maximum surface roughness has been studied. Deterioration in surface integrity at various combinations of pulse-on and pulse-of time which produced high discharge energy has been observed. Scanned electron microscopic investigation, energy dispersive spectroscopy and XRD analyses, roughness measurement, and micro-hardness testing results are presented, analyzed and discussed. Optimization of process parameters resulted in surface integrity enhancement with low roughness (Rt – 7.78μm and Ra – 1.45μm) and very thin recast layer (4–6μm) along with minimum subsurface defects.

Smoothed particle hydrodynamics (SPH) simulation of impinging jet flows containing abrasive rigid bodies

A fully Lagrangian model for simulating impinging jet flows containing abrasive particles is established based on smoothed particle hydrodynamics (SPH) method. In the model, both the fluid and the solid are described by SPH, where the jet flow is modeled as the viscous fluid and the metallic target is modeled as the elastic–plastic material. The main novelty of the model is that abrasive particles are explicitly included in the jet flow and modeled as arbitrarily shaped rigid bodies. The interactions among the fluid, solid and abrasives are modeled through suitable techniques that are commonly used in SPH. The simulation of material removal caused by the impact of continuous abrasive-jet flow is conducted as a challenging example to verify the applicability of the model. This new model is attractive for relevant applications, such as solid particle erosion and abrasive water-jet machining. The advantages of the model lie in its conceptual simplicity, straightforward implementation and the relative ease of incorporating new physics.

Wire Spark Erosion Machining of Ni rich NiTi Shape Memory Alloy for Bio-Medical Applications

The application of NiTi shape memory alloys are growing day by day in biomedical industry. These materials present inherent problems when undergoing conventional machining processes during manufacture of bioimplants. Conventional machining processes require high consumption of energy and resources, and assistance of post processing operations to make high quality implants of shape memory alloys. Unlike conventional methods, nonconventional methods are capable to eliminate the need for post processing amongst other advantages and thus prove to be the most economic means of producing biomedical implants. Wire spark erosion machining (also known as Wire Electro Discharge machining i.e. Wire-EDM) is one such nonconventional machining process that has been explored for the machining of biomedical implants by Ni rich NiTi. The present study aims to analyze and optimize the machinability of Ni55.8Ti shape memory alloy during wire electric discharge machining for biomedical applications. The L16 Orthogonal array using Taguchi design of experiments has been employed for this experimental study. The variable input parameters are namely pulse on time, pulse off time, servo voltage and wire feed rate. Machining at optimum parameters produced good surface finish, high material removal rate and excellent surface integrity. In this paper, specifically, the effect of the aforementioned Wire-EDM parameters on cutting rate, process optimization for the highest cutting rate, and surface roughness obtained at optimum parameters are reported. The outcomes encourage exploring wire spark erosion machining of other shape memory alloys for different scientific and industrial applications.

Analysis of micro-rods machined using reverse micro-EDM

In today’s world, microstructures have a wide range of applications in the field of biomedical devices, aerospace engineering, MEMS device elements, etc. In the recent years, reverse micro-electro-discharge machining (R-µEDM) has evolved from µEDM that has become one of the promising technologies to fabricate precise components and microstructures of various shapes with high aspect ratio. In this work, micro-tools (rods) of average size (diameter) 182 µm have been machined using copper sheet from bulk tungsten rod of 800 µm diameter by R-µEDM process. Moreover, Taguchi’s L16 orthogonal array has also been applied for designing the experiments. Feed rate, capacitance and voltage are considered as the parameters of the process. The response parameters such as machining time, erosion rate and dimensional variation have been analyzed in detail for different combinations of the process parameters. It is a well-known fact that the tool wear is the main culprit and responsible for the error in the micro-rods. Dimensional error has been quantified over the entire length of the micro-rods through the measurement process, and the minimum standard deviation is found to be 1.13 µm at a feed rate of 5 µm/s, capacitance of 1000 pF and voltage of 120 V. Further, machining data have been collected in real time and the behavior of machining time with work feed has been studied. In addition to it, a simple analytical model has been developed for calculating the erosion rate and it is seen that voltage produces more effect on erosion rate and machining time than the other parameters. Additionally, using the feed rate, capacitance and voltage at which minimum deviation took place, an array of 4 × 4, i.e., 16 micro-rods with 58 µm diameter and 830 µm length, has been fabricated on the bulk tungsten rod of 800 µm diameter.

Analysis and multi-response optimization of gear quality and surface finish of meso-sized helical and bevel gears manufactured by WSEM process

This paper studies influence of and optimizes pulse-on time, pulse-off time, servo voltage, and feed rate of wire on microgeometry and surface finish of stainless steel meso-helical gears (MHG) and meso-bevel gears (MBG) manufactured by wire spark erosion machining (WSEM) process. Microgeometry of MHG was evaluated in terms of error in total profile and total cumulative pitch and that of MBG in terms of error in single pitch and total cumulative pitch. Average and maximum surface roughness values were used to evaluate their surface finish. Twenty-nine experiments with two replicates were conducted using Box-Behnken approach of response surface methodology thus manufacturing 58 meso-helical gears and 58 meso-bevel gears. It was observed that higher pulse-on time and servo voltage, and lower pulse-off time and feed rate of wire yield poor microgeometry and surface finish of MHG and MBG. Desirability function analysis based multi-response optimization was used to identify optimum WSEM parameters to manufacture the best quality of MHG and MBG. The optimized values of the responses were validated experimentally. It was found that WSEM can attain up to DIN 6 quality in microgeometry of MHG and MBG. SEM micrographs of the best quality MHG and MBG revealed accurate and uniform bore, tooth profile, flank surfaces free from burrs and sharp edges and without any undercut at root. Microstructural examination of these gears showed flank surfaces free from cracks, globules and pores. This study proves that WSEM is economical and technically superior process for near net-shape manufacturing of high quality MHG and MBG.

Application of electric erosion machining for the restoration of splined surfaces

The paper presents an analysis of the possibility of using electric erosive machining when restoring splined surfaces on specialized equipment.

Experimental investigation on surface characteristics in Electrical Discharge Surface Grinding (EDSG) of 6061Al/Al2O3p 10% composite

ABSTRACTThis article reports the results of an experimental study conducted to understand the mechanism of material removal in electrical discharge surface grinding (EDSG) process while machining 6061Al/Al2O3p 10% composite by composite tool electrode. Electrical discharge surface grinding (EDSG) is one of the variants of hybrid machining processes that involve combined operation of conventional grinding and spark erosion machining. In the study the effect of electrical and grinding parameters such as peak current, polarity, pulse-on time, pulse-off time, speed, abrasive particle size (APS) and abrasive particle concentration (APC) has been investigated. Surface characteristics like surface finish, surface topography and recast layer have been studied through scanning electron microscope (SEM) and electrodispersive X-ray spectroscopy (EDS). The experimental results indicate that the effects of peak current, tool polarity, speed and APS are more pronounced as compared to other machining parameters. The outcome of the study further confirms considerable improvement in surface finish at negative tool polarity as compared to the positive polarity of the tool electrode. The results of surface roughness in EDSG have also been compared with EDM. The microstructural and morphological analysis of machined surfaces during EDSG confirmed the effective removal of particulates from the composite workpiece without rupturing the base matrix. The depth of recast layer and heat affected zone is found to be more in case of positive tool polarity as compared to negative tool polarity.

Investigations on the Effect of Tungsten Carbide and Graphite Reinforcements during Spark Erosion Machining of Aluminium Alloy (AA 5052) Hybrid Composite

Reinforcements introduced to metal matrix composites are known for their inherent properties like corrosion resistance, wear resistance and machinability. This study deals with the investigation of the effect of adding tungsten carbide (WC) and graphite (Gr) reinforcements in aluminium alloy (AA 5052) hybrid composite material over the spark erosion machining performance. The composite material was fabricated using stir casting process. The tungsten carbide and graphite particles were introduced in various %-wt combinations to aluminium alloy (AA 5052) as per Taguchi robust experimental design and spark erosion machining was carried out on the composite specimens. Discharge current, voltage and discharge time were chosen as the process parameters and their effect on the output performance was measured using material removal rate (MRR) and average surface roughness (Ra). The optimal set of process parameters and the amount of these particulate reinforcements which either directly or indirectly impact the machining performance were predicted by signal-to-noise ratio analysis and the extent of such impact by each constraint were estimated by employing the analysis of variance (ANOVA). The experimental results showed that the effect of adding WC particles improved the MRR which is proportional to the peak current though surface roughness increases when there is a rise in the peak current at the regions where WC particles are concentrated. Also, compared to tungsten carbide, adding graphite as reinforcement influenced the machining of the composite to a greater extent.

Capabilities evaluation of WSEM, milling and hobbing for meso-gear manufacturing

ABSTRACTThis paper describes manufacturing capabilities evaluation of wire spark erosion machining (WSEM), milling and hobbing to manufacture meso straight bevel gear (MSBG) and meso helical gear (MHG) made of SS 304 using microgeometry, macrogeometry, flank surface topology, surface finish, microstructure, microhardness, manufacturing time and cost, and gear material loss. Experiments were conducted using the parameters of WSEM, milling and hobbing processes optimized through trial experiments. This study reveals that WSEM manufactured MSBG and MHG possess better microgeometry (DIN 5-7), macrogeometry (29, 33, and 46 µm deviation in span, tooth thickness and outside diameter for MHG), topology, higher microhardness, superior microstructure, lower manufacturing time (25 and 20 min, respectively) and cost ($ 4 for both), smaller loss of gear material but poor surface finish (1.07 and 6.60 µm as average and maximum surface roughness for MHG and 1.04 and 6.16 µm for MSBG) than milled MSBG and hobbed MHG. Microstructure study showed presence of burrs and marks of the cutting tool on the flanks of the best quality hobbed MHG and milled MSBG. It proves that WSEM is a superior, economical, material efficient, and environment friendly process to manufacture meso-sized cylindrical and conical gears of higher accuracy and better quality with excellent repeatability.

Productivity Leap

Since August 2017, Exactaform Cutting Tools now occupies one of the UK’s largest cutting tool manufacturing facilities. The state-of-the-art 44,000 ft2 facility is effectively a Vollmer grinding and erosion machine showroom, and its latest investment is setting new standards.

Control of the research stand for electrochemical machining

The paper presents control method of the research process for erosion machining and construction of the stand. The stand has modular design, with separated electrodes drive and machining area, which greatly expands its research capabilities. The stand controller is supplying machining parameters and it consists of a PC program communicating with the PLC I/O modules. This arrangement allows initial referencing of the electrodes before machining and, based on measurements of the electrolyte pressure, on-line control for parameters such as: feed rate of the working electrode, electrode oscillation frequency, synchronization of electrodes oscillation, the inter electrodes gap thickness. Conducting erosion machining experiments on this type of stand allows to verify a mathematical models of the process and lets to develop an active type of on-line control, connecting the theoretical results with measurements of parameters during machining.

Optimization of electric discharge machining parameters on titanium alloy (ti-6al-4v) using Taguchi parametric design and genetic algorithm

The aim of this research work is to analyze the significant of process variables and find the optimum process variables in electric discharge machining (EDM) of Titanium alloy (Ti-6Al-4V) .The variables considered are peak current, pulse-on-time and pulse-off-time where as the responses are Material Removal Rate(MRR) and Surface Roughness(SR). MITSUBISHI EA8 spark erosion machine is employed for this work and copper tungsten electrode of ∅14 mm is used in experimental trials. The experimental runs are done based on Taguchi L27 orthogonal array. The signal-to-noise ratio, the analysis of variance (ANOVA), regression analysis and Genetic algorithm are used to determine the optimal levels of machining parameters on Metal removal rate and Surface roughness. Confirmation tests also done with the optimal levels of machining variables. Comparison of Taguchi’s and Genetic algorithm were employed to analyze the effective optimum value.

Erosion Behaviour of API X100 Pipeline Steel at Various Impact Angles and Particle Speeds

Erosion is the gradual removal of material due to solid particle impingement and results in a failure of pipeline materials. In this study, a series of erosion tests were carried out to investigate the influence of particle speed and impact angle on the erosion mechanism of API X100 pipeline steel. A dry erosion machine was used as the test equipment, while the particle speed ranged from 20 to 80 m/s and impact angles of 30° and 90° were used as test parameters. The eroded API X100 steel surface was characterized using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The weight loss and erosion rate were also investigated. The results showed that at a 90° impact angle, a ploughing mechanism was occurring on the tested specimens, while material removal through low-angle cutting was the dominant mechanism at lower impact angles. Embedment of alumina particles on the target steel surface, micro-cutting, and low-angle cutting were observed at low impact angles. Therefore, the scratches, cuttings, and severe ploughings observed on some failed oil and gas pipelines could be attributed to the erosion mechanism.

Modelling of series of types of automated trenchless works tunneling

Microtunneling is the newest method for making underground installations. Show method is the result of experience and methods applied in other, previous methods of trenchless underground works. It is considered reasonable to elaborate a series of types of construction of tunneling machines, to develop this particular earthworks method. There are many design solutions of machines, but the current goal is to develop non - excavation robotized machine. Erosion machines with main dimensions of the tunnels which are: 1600, 2000, 2500, 3150 are design with use of the computer aided methods. Series of types of construction of tunneling machines creating process was preceded by analysis of current state. The verification of practical methodology of creating the systematic part series was based on the designed erosion machines series of types. There were developed: method of construction similarity of the erosion machines, algorithmic methods of quantitative construction attributes variant analyzes in the I-DEAS advanced graphical program, relational and program parameterization. There manufacturing process of the parts will be created, which allows to verify the technological process on the CNC machines. The models of designed will be modified and the construction will be consulted with erosion machine users and manufacturers like: Tauber Rohrbau GmbH & Co.KG from Minster, OHL ZS a.s. from Brna,. The companies’ acceptance will result in practical verification by JUMARPOL company.

Surface Quality Analysis after EDM Drilling for AA7075

ABSTRACT: Electric Discharge Drill Machine (EDDM) is a spark erosion machining process to generate micro holes in hard to machine and conductive materials. This process is used in space and aerospace, medical and automobile industries. In present research work a brass rod 2 mm diameter was used as a tool electrode. The best parameters such as pulse on-time, Pulse off-time and water pressure were studied for best surface quality. This investigation presents the use of Taguchi approach for better SR in drilling of AA-7075. L27 Taguchi design method was selected for planning of experiments. The optimal levels and the significant drilling parameters on SR were obtained. The optimization results showed that the combination of minimum pulse ontime and maximum pulse offtime gives best SR.

Erosive wear performance of API X42 pipeline steel

The need to transport petroleum products through pipelines has resulted in the increased erosion of the pipeline materials used in the petroleum industry. In this study, dry erosion test was performed using sand blaster erosion machine to investigate the erosive behavior and mechanism relative to API X42 pipeline steel. Different particle velocities in the range of 20 to 80m/s were applied at different test durations, while the incident angle was kept constant. The results showed that the plowing mechanism was prevailing at higher velocity and longer test duration. Plastic deformation, embedment of the erodent particle on the target material surface and plowing were observed at lower velocity. Understanding the transition in the erosion mechanism as the particle velocity increases may be a vital importance to the petroleum industry. This will also aid in the erosion models employed for future erosion analysis.