Higher Machining Rate Research Articles

State of the art in powder-mixed electric discharge machining: A review

Accomplishment of high machining rates along with good surface quality is a major concern in electric discharge machining process. Powder-mixed electric discharge machining in which suitable powder particles are impregnated in dielectric has gone forth as a potential solution to this problem. Nevertheless, challenges such as dielectric circulation, homogeneous blending of the powder particles in the dielectric, debris removal and quantity of the powder material required have to be addressed carefully before implementing this process on a large scale in the manufacturing industry. Extensive research in the field of electric discharge machining using powder-suspended dielectrics has started only in the recent years. In this article, a comprehensive review of the research going on in the field of powder-mixed electric discharge machining is presented. The emphasis is given on powder-mixed electric discharge machining mechanism, influence of powder characteristics and machining parameters on various responses. Some of the major application areas, variants of the basic powder-mixed electric discharge machining process and possibilities of further improvement are also discussed.

Control of Helical Blade Machining in Whirling

Machinings of helical blades have recently been increased with manufacturings of aircrafts and energy facilities. The helical blades have generally machined in ball end millings on the multi-axis machining centers. Because high machining rates and low machining costs have been required for the blade machinings, more effective processes are required to improve the machining performances. This study applies whirling process to the blade machinings. The whirling process is performed in the workpiece and the tool rotations with eccentricity of their centers. A mechanistic model is presented to control the blade shape in the whirling process. Then, the cutting tests were conducted with a turning tool on a turning center. In the presented cutting, the helix angle and the helical orientation are controlled by the feed rate and the ratio of the tool spindle speed to the workpiece one, respectively. The machining errors and the surface finishes were also measured in whirling of the blades. The machining error at the free end of blade is larger than that of the clamping side of blade. The surface finish at the clamping side is worse than that of the free end of blade, which is induced by the vibration of the tool.

Multi-objective Optimization of Electro-chemical Machining by Non-dominated Sorting Genetic Algorithm

Quality of machined surface strongly depend on the selection of optimal parameter settings and type of machining process. Electro-chemical machining (ECM) offers several unique feature, like higher machining rate, better surface finish, and it is suitable for machining a wide range of materials. In this regard, an attempt has been made to develop a mathematical model for responses i.e. metal removal rate (MRR) and surface roughness (SR) through regression analysis for electro-chemical machining on EN 19. And analysis of variance (ANOVA) test is perform to check the aptness of the developed mathematical models. The performance for ECM process is optimized through Non-dominated Sorting Genetic Algorithm-II (NSGA-II) for maximizing the metal removal rate and minimizing the surface roughness. Through this non-dominated optimum parameter settings has been obtained and reported.

Experimental Investigation and Optimization of Micro-EDMing Process for Silicon Substrates

Microelectrical discharge machining of n-type monocrystalline silicon is investigated in this study through a microgrooving process. The pulse duration, pulse frequency, spark current, and gap voltage are varied in the experiments. The groove geometries and roughness are measured together with the material removal rate and electrode wear ratio. The results have shown that a large and deep groove can be made at high machining rate when a high spark energy condition is applied. This can, however, increase the electrode wear ratio as a consequence, making the process inefficient. A multiresponse optimization, using Grey relational analysis, has been applied. The optimum cut result has shown that good cut quality, high material removal rate, and low electrode wear ratio are achievable from this study.

Surface dimple machining in whirling

Structured dimples on product surfaces are required for control of the surface functions such as friction. The dimple machining, therefore, should be performed in large surface areas at high machining rates. This study presents a novel machining to fabricate the dimples on the cylinder surfaces in whirling, which originally machines threads such as ball screws with rotating the workpiece and the tool mounted on a whirling ring. In the presented machining, the circumferential speeds of the workpiece and the tool are controlled so that the tool edge indents on the cylinder surface without cutting in the dimple machining. The configuration in the machining are discussed to characterize the indentation process. A mechanistic model in the dimple machining, then, is presented to control the dimple shapes. The time-series analysis in the indentation process is performed to simulate the dimples for the machining parameters. Some machining examples are shown to verify the high speed dimple machining.

Multi Response Optimization of Powder Mixed Electric Discharge Machining of Aluminum/Alumina Metal Matrix Composite Using Grey Relation Analysis

Electric discharge machining (EDM) is a well-established non-conventional machining process for the machining of electrically conductive and difficult-to-machine materials. But its applications are limited because of slow machining rate and relatively poor surface finish. Powder mixed EDM (PMEDM) is one of the recent advancements in EDM process where the addition of powder particles to the dielectric results in higher machining rate and better surface quality. In this work, Aluminum/Alumina metal matrix composite (MMC), which has many applications in automobile and aero-space industry, was fabricated and machined in EDM by mixing aluminum powder in kerosene dielectric. The effect process parameters (powder concentration, peak current, pulse on time and duty cycle) on two responses namely, material removal rate (MRR) and surface roughness (SR) were measured. A multi response optimization was performed using grey relational analysis (GRA) to find the optimum combination of the process parameters for maximum MRR and minimum SR. The results show that the powder concentration of 6g/L gives the optimum result for the multi responses.

Application of adaptive neuro-fuzzy inference system and cuckoo optimization algorithm for analyzing electro chemical machining process

Electrochemical machining process (ECM) is increasing its importance due to some of the specific advantages which can be exploited during machining operation. The process offers several special privileges such as higher machining rate, better accuracy and control, and wider range of materials that can be machined. Contribution of too many predominate parameters in the process, makes its prediction and selection of optimal values really complex, especially while the process is programmized for machining of hard materials. In the present work in order to investigate effects of electrolyte concentration, electrolyte flow rate, applied voltage and feed rate on material removal rate (MRR) and surface roughness (SR) the adaptive neuro-fuzzy inference systems (ANFIS) have been used for creation predictive models based on experimental observations. Then the ANFIS 3D surfaces have been plotted for analyzing effects of process parameters on MRR and SR. Finally, the cuckoo optimization algorithm (COA) was used for selection solutions in which the process reaches maximum material removal rate and minimum surface roughness simultaneously. Results indicated that the ANFIS technique has superiority in modeling of MRR and SR with high prediction accuracy. Also, results obtained while applying of COA have been compared with those derived from confirmatory experiments which validate the applicability and suitability of the proposed techniques in enhancing the performance of ECM process.

Differential search algorithm-based parametric optimization of electrochemical micromachining processes

Article history: Received June 2 2013 Received in revised format August 15 2013 Accepted August 15 2013 Available online August 19 2013 Electrochemical micromachining (EMM) appears to be a very promising micromachining process for having higher machining rate, better precision and control, reliability, flexibility, environmental acceptability, and capability of machining a wide range of materials. It permits machining of chemically resistant materials, like titanium, copper alloys, super alloys and stainless steel to be used in biomedical, electronic, micro-electromechanical system and nanoelectromechanical system applications. Therefore, the optimal use of an EMM process for achieving enhanced machining rate and improved profile accuracy demands selection of its various machining parameters. Various optimization tools, primarily Derringer’s desirability function approach have been employed by the past researchers for deriving the best parametric settings of EMM processes, which inherently lead to sub-optimal or near optimal solutions. In this paper, an attempt is made to apply an almost new optimization tool, i.e. differential search algorithm (DSA) for parametric optimization of three EMM processes. A comparative study of optimization performance between DSA, genetic algorithm and desirability function approach proves the wide acceptability of DSA as a global optimization tool. © 2013 Growing Science Ltd. All rights reserved

Electrical discharge machining of ceramic matrix composites with ceramic fiber reinforcements

Ceramic matrix composites (CMC) are considered the next generation of advanced materials used in space and aviation due to their high-temperature strength, creep resistance, chemical resistance, low porosity, and low density. However, these materials are difficult to process owing to the large cutting force and high cost on tool consumption. electrical discharge machining (EDM), featured by the negligible machining force and acceptable tooling cost, is a potential nontraditional machining technique for CMC. In this paper, EDM was used to process a new class of advanced CMC, that is, those with continuous ceramic fiber reinforcements. The challenge is its low material removal rate (MRR) due to the low workpiece conductivity and debris evacuation efficiency. Electrode vibration and dielectric deep flushing were used to promote debris evacuation, and an increase of MRR and surface quality without sacrificing tool wear ratio was observed. Gap voltage, peak current, pulse duration, and duty ratio were studied using design of experiments for deeper understanding of the process. The effect of these parameters was investigated, and an analysis of variance was conducted. The optimal condition was also predicted and experimentally validated. It was found that a high gap voltage or low duty ratio leads to a high machining rate due to improved debris evacuation efficiency. The material removal mechanism was found to be cracking due to thermal expansion of the matrix and breakage of the nonconductive fibers.

B25 テクスチヤ表面の高能率切削(OS6 切削加工(1))

simultaneous controlled cutting is presented to fabricate micro-scale textures on surfaces at high machining rates. The surface texture is machined with rotations of the workpiece and the tool on a turning center. The centers of the workpiece rotation and the tool holder rotation are located eccentrically in the process. The periodical circular textures are controlled by 3 parameters: the distance between the centers of the workpiece rotation and the tool holder rotation; the rotation radius of the cutting tool on the tool holder; and the ratio of the tool rotation speed to the workpiece rotation speed. Some surface textures are machined with changing the cutting parameters in the experiments. The cutting force, then, is measured by piezoelectric dynamometers in cutting of a surface texture on an aluminum plate.

Micro Cutting of Glass with Multiedge Tool

Glass cutting with a multiedge tool is presented to machine micro-scale grooves at high machining rates in a planning manner. The critical depth of cut at the ductile-brittle transition was measured to design the edge shape in the glass cutting tests. 13 rectangular edges 2 µm wide and 2 µm high were manufactured on a single crystal diamond tool by the focused ion beam. The cutting tests were conducted on a micro/nano-scale cutting machine, which controls the depth of cut of less than 1 µm. The glass cutting process with the multiedge tool is discussed with measuring the cutting force. The cutting force changes with the cutting mode: sliding/ploughing and cutting. Based on the measured cutting force, the compliance of the machine-tool-workpiece system, the friction coefficient of the tool on the glass surface and the specific cutting force are estimated. Then, 13 grooves 2 µm wide 0.3 µm deep were machined simultaneously in a feed of the multiedge tool. The machining accuracy was verified in optical diffraction tests.

Effects of Wire Surface Roughness on Wire EDM Characteristics

The purpose of this study is to develop a new type of coated wire electrode for fine wire EDM. Piano wire with a very high tensile strength is coated with an electrically conductive brass layer to achieve high-speed and high-precision wire EDM. In our previous papers, using a thin wire of 50μm diameter, the thickness and quality of the brass coating layer were optimized and the effects of the tensile strength of the piano wire used as the core wire on machining characteristics were discussed. In this paper, the effect of surface roughness of the brass wire electrode was experimentally investigated. As a result, it was found that by using wire with relatively large surface roughness, the machining rate increased because of the high discharge frequency. Also, a more uniform distribution of the discharge location was confirmed by high-speed observation of the working gap during the process. In addition, the electrostatic field in the gap between the wire electrode and workpiece surface was analyzed and the reason for the high machining rate in case of the wire with relatively large surface roughness was discussed from the viewpoint of the distribution of electric intensity distribution on the wire surface.

System Design and Low-Speed Kinematics Characteristic Analysis of Electrochemical Micro-Machining Equipment

Electrochemical micro-machining (EMM) appears to be very promising as a future micro-machining technique, since in many areas of applications, it offers many advantages, which include excellent machining precision and control, high machining rate, perfect surface quality and a wide range of materials that can be machined, regardless of their strength and toughness. In the paper, a new style EMM equipment for micro-holes is presented. Double vertical column style structure is chosen as the main mechanical structure of the equipment, which has the advantage of excellent structure rigidity, compact framework dimension as well as good maneuverability and maintainability. In order to verify the reliability of this EMM equipment, some measurement works including static measurements, assembling interferences checking and kinematics simulation have been done. Furthermore, the low-speed kinematics characteristics of the developed EMM equipment are concentrated. The kinematics simulation results indicate that the developed EMM equipment can satisfy the requirements for low-speed motion and anti-interference characteristics of EMM process.

ワイヤ放電加工用高性能ワイヤ電極の開発に関する研究（第３報）―ワイヤ表面の凹凸が放電加工特性に及ぼす影響―

The purpose of this study is to develop a new type of coated wire electrode for fine wire EDM. Piano wire with a very high tensile strength is coated with an electrically conductive brass layer to achieve high-speed and high-precision wire EDM. In our previous papers, using a thin wire of 50μm diameter, the thickness and quality of the brass coating layer were optimized and the effect of the tensile strength of the piano wire used as the core wire was discussed. In this report, the effect of unevenness of the brass wire electrode surface was experimentally investigated. As a result, it was found that by using wire with relatively large surface unevenness, the machining rate increased because of the high discharge frequency. Also, a more uniform distribution of the discharge location was confirmed by high-speed observation of the working gap during the process. In addition, the electrostatic field in the gap between the wire electrode and workpiece surface was analyzed and the reason for the high machining rate for the wire with relatively large surface unevenness was discussed from the viewpoint of the distribution of electric intensity distribution on the wire surface.

Large Scale Laser Microstructuring in the Printing Industry

AbstractApplying lasers in gravure print form fabrication is getting more and more important due to a high machining rate, high spatial resolution and the ability of digital modulation. Direct laser engraving into the metallic surface is the fastest and most versatile process for gravure cylinder imaging (ablation rate up to 1 cm3/min). High power Q‐switch Nd:YAG and fiber lasers up to repetition rates of 100 kHz are used, tuned for high reproducibility and stability. A fast modulation of the laser beam profile for each single pulse allows for optimization of the cell shape to get the best ink transfer interaction on a specific print substrate. Highest screen resolutions are made with single mode cw fiber lasers > 100 W.

Design, Modeling, and Motion Control of the Noncircular Turning Process for Camshaft Machining

This paper presents the design, modeling, and motion control of the noncircular turning process for camshaft machining. The cam profile tracking performance requirements are first characterized to meet industry standards. Based on these requirements, a unique test fixture using state-of-the-art actuation and sensing technologies is designed for the noncircular turning process. Modeling of the electrohydraulic servo valve, actuator, and sensors is conducted based on their frequency responses. Digital motion control that achieves asymptotic cam profile tracking while maintaining system robust stability is designed and implemented on the turning test fixture. Spindle speed can be chosen depending on the required profile tracking accuracy with higher speed rendering higher machining rate for rough turning and lower speed rendering higher accuracy for finish turning. Experimental results of turning a variety of cam profiles show that the tracking error is less than 30μm for spindle speed at 300rpm and is less than 60μm for spindle speed at 600rpm or 1200rpm.

Polishing Characteristics of Silicon Carbide by Plasma Chemical Vaporization Machining

Silicon carbide (SiC) is expected to be a promising semiconductor material for high-temperature, high-frequency, high-power and energy-saving applications. However, it is so hard and so chemically stable that there is no efficient method of machining it without causing damage to the machined surface. Plasma chemical vaporization machining (PCVM) is a gas-phase chemical etching method in which reactive species generated in atmospheric-pressure plasma are used. PCVM has a high removal rate equivalent to those of conventional machining methods such as grinding and lapping, because the radical density in atmospheric-pressure plasma is much higher than that in normal low-pressure plasma. In this paper, the polishing characteristics of silicon carbide by PCVM are described. As a result, a high machining rate (approximately 0.18 mm/min) and a very smooth surface (below 2 nm peak-to-valley in a 500 nm square area) are achieved.

New developments in the process control of the hybrid electro chemical discharge machining (ECDM) process

Electro chemical discharge machining (ECDM) is a hybrid non-conventional manufacturing process which combines the features of electro chemical machining (ECM) and electro discharge machining (EDM). One of the major advantages of ECDM, over ECM or EDM, is that the combined metal removal mechanisms in ECDM, yields a much higher machining rate. This paper presents new developments in process control for the hybrid electro chemical discharge (ECDM) process. The design stages and the implementation issues of a personal computer (PC) based real time controller for the ECDM process is discussed. A system identification experiment was carried out to obtain the dynamics of the system and a process control algorithm was implemented in software form.

A new etchant for the chemical machining of St304

The present work is an investigation aimed at reducing pitting problem and obtaining better surface finish in chemical machining of St304. A new etchant is introduced for chemical machining of St304. Results present good surface finish without any pitting while high machining rate is achieved. The etchant tested in several temperatures and different depths of machining and the results are compared with other etchants, which are introduced in some references [Chemical Milling Nontraditional Machining Process, Machining ASM Handbook, 1994; Chemical Machining, Metals Handbook, vol. 3, Machining, 8th ed., American Society for Metals, Metals Park, OH, pp. 240–248; Fontana, Mars, G., Corrosion Engineering, 30th ed., 1986]. New etchant is a mixture of H 2O+HCl+HNO 3+HF+H 2COOH+TEA. Scan electron microscope (SEM) and roughness tests were employed to observe the surface topography.

A new etchant for the chemical machining of St304

The present work is an investigation aimed at reducing pitting problem and obtaining better surface finish in chemical machining of St304. A new etchant is introduced for chemical machining of St304. Results present good surface finish without any pitting while high machining rate is achieved. The etchant tested in several temperatures and different depths of machining and the results are compared with other etchants, which are introduced in some references [Chemical Milling Nontraditional Machining Process, Machining ASM Handbook, 1994; Chemical Machining, Metals Handbook, vol. 3, Machining, 8th ed., American Society for Metals, Metals Park, OH, pp. 240–248; Fontana, Mars, G., Corrosion Engineering, 30th ed., 1986]. New etchant is a mixture of H2O+HCl+HNO3+HF+H2COOH+TEA. Scan electron microscope (SEM) and roughness tests were employed to observe the surface topography.