EDM Machine Tool Research Articles

A preventive maintenance scheme for rotary ultrasonic vibration EDM machine tool based on PSO under reliability constraints

A preventive maintenance scheme for rotary ultrasonic vibration EDM machine tool based on PSO under reliability constraints

Influence of the punch with concave cutting-edge on the blanking force in micro punching process

Micro blanking machining is a promising manufacture technology to realize mass production of micro parts efficiently. In the process of blanking, the blanking force is significant to the punch, die, and sheet workpiece. In order to investigate the influence of cutting-edge shape of the punch on the micro blanking process, a self-developed micro combined EDM and blanking machine tool is applied in this paper. A punch with concave cutting-edge is capable to be fabricated online through a series of processing based on micro EDM: 3D milling, wire electrical discharge grinding and reverse EDM copy machining techniques. Then the punch and die are accurately matched online due to the preparation of them in the same coordinate system. Micro blanking parts and punching parts with the complex cross-sectional shape is obtained by using the online fabricated punch with flat cutting-edge and concave cutting-edge respectively in the workpiece of stainless steel SUS304 foil. The characteristic of blanking force varying with time indicates that the blanking force is significantly reduced in the case of concave cutting-edge, meanwhile, both blanking parts and punching parts have the high quality.

Effect of electrode material on removal efficiency regarding single discharges in wire EDM

For the precise machining of demanding materials, wire electrical discharge machining (WEDM) is a flexible and often irreplaceable manufacturing process. In order to enhance productivity as the main focus of the wire EDM process, the advancement of the fundamental procedural understanding is of decisive importance. In order to be able to energetically evaluate the removal process, the individual energetic contributors of the process hence the individual discharges need to be understood in terms of their contribution to material removal. In this paper, an experimental setup is presented, which permits the generation of individual discharges on a modern industrial wire EDM machine tool. For three different wire electrodes, the correlation of the discharge energy and the individual removal volume is quantitatively described, showing that coated wires achieve a significantly higher energy-specific removal. Furthermore the removal efficiency is defined as a key figure to transfer the findings to the continuous process and compare theoretical and effective removal rate.

Reliability allocation of rotary ultrasonic vibration-assisted EDM machine tool based on maximum entropy ordered weighted average and constraint under the index of overall cost

In this paper, the reliability allocation and index of overall cost of rotary ultrasonic vibration-assisted EDM machine tool were studied. The failure rate of each module of the rotary ultrasonic vibration-assisted EDM machine tool can be accurately predicted by the maximum entropy ordered weighted average algorithm so that the corrected maintenance cost can be predicted. And effective control of preventive maintenance costs can be achieved by selecting the best maintenance times under the premise of reliability. The cost of corrective maintenance can be reduced by improving modules with a high failure rate, so as to realize the purpose of cost optimization under the premise of determining the maintenance time and reliability. The reliability function of the rotary ultrasonic vibration-assisted EDM machine tool is established according to the series-parallel relationship of each module. The results showed that the reliability of rotary ultrasonic vibration-assisted EDM machine tool is stabler at the non-fixed maintenance period according to the comparison between the non-fixed and the fixed maintenance period.

Optimized Design of Precision EDM Machine Tool based on CAE Simulation and Modal Testing Technology

For precision EDM equipment, in addition to the static stiffness of the body of the machine, the dynamic characteristics of the body and the ambient temperature are also the key factors that affect the machining accuracy of the workpieces. In this paper, through the modal simulation analysis of the machine tool that with the sheet metal shell, the weak points of the EDM machine tool are determined. Through thermal stress simulation analysis, the thermal deformation law of the workpieces mounting table is determined, and a solution to reduce thermal deformation is proposed. Through machine tool ODS (operating deflection shapes) test and analysis, the weak links of the machine tool's body in actual processing are determined. Through the above optimization analysis, the foundation has been laid for improving the dynamic and static accuracy of the precision machine tool. The research method in this paper makes up for the deficiency of the machine tool design method based on static stiffness.

Recent Patents on Control System of EDM Machine Tool

Background: Electrical Discharge Machining (EDM) has widely been used in manufacturing high strength and high hardness of metal material due to the EDM process, which is free from mechanical force. The control system, a core of the EDM machine tool, plays a major role in manufacturing high strength and high hardness metal material in terms of machining efficiency and machining quality of the process of EDM. Thus, more and more attention has been paid to the current trends of the control system of the EDM machine tool. Objective: To meet the increasing requirements of machining quality and machining efficiency in the EDM process, the control system of the EDM machine tool is being improved continuously. Methods: This paper reviews current various representative patents related to the control system of the EDM machine tool. Methods: This paper reviews current various representative patents related to the control system of the EDM machine tool. Results: By summarizing a large number of patents about the control system of the EDM machine tool, the parameter control system, the servo control system and the numerical control system of the EDM machine tool are analyzed, and the development trend of the EDM machine tool control system has been discussed. Conclusion: The optimization of the control system of the EDM machine tool is conducive to increasing machining efficiency and machining quality in the EDM process. More relevant patents will be invented in the future.

Error modeling and accuracy optimization of rotating ultrasonic vibration assisted EDM machine tool

Rotating ultrasonic vibration assisted EDM is a composite machining method that uses EDM to etch a metal surface and adds rotating and ultrasonic vibration. It has high efficiency and a wide range of workpiece materials. Aiming at the structural characteristics of rotary ultrasonic vibration assisted EDM machine tool, the errors caused by the main moving parts of the machine tool were analyzed. The structure relationship is described by multi-body system theory, and the geometric error model is deduced by homogeneous coordinate transformation method. The aim was to improve the overall accuracy, reduce the cost, trace the error source, and get the corresponding relationship between the basic geometric errors and the precision parameters of the related parts. Under the requirement of ensuring the overall accuracy, an optimization function was established that minimizes the cost and relaxes all accuracy parameters to the greatest extent. Finally, MATLAB and its genetic algorithm toolbox was used for analysis. Verification shows that this model can properly reduce the cost on the premise of ensuring the accuracy.

Development of Multi Micro Holes Synchronous Rotating and Vibration EDM Machine Tool

In order to solve the problem of low efficiency of single electrode discharge machining, complex process and limited machining quality of group electrode array hole machining technology in traditional micro EDM machine tools, a multi-micro-hole synchronous rotating and vibration EDM machine tool was developed. The machine tool is composed of a mechanical platform and a control system. It can realize multi-electrode independent micro-energy pulse discharge, real-time detection of each electrode gap state and servo feed adjustment, and synchronous rotation assisted vibration of each electrode. The mechanical platform of the machine tool consists of servo feed mechanism, vibrating mechanism and multi-electrode synchronous rotating mechanism. The structure optimization and stability analysis are carried out by ANSYS finite element analysis software to ensure that the design of each part of the machine tool is reasonable and reliable. The control system is composed of motor control module, servo motion control module and pulse power module. It uses STM32F103RCT6 MCU to detect the machining state in real time and coordinate the work of each module, and uploading the processing data to upper computer. The Experimental tests show that the machine tool has high machining efficiency, stability and precision, and high degree of automation.

Dynamic Performance Analysis of the micro-hole EDM Machine Tool

The EDM machine is special processing machine using the principle of EDM process of conductive materials. By means of modal analysis, ODS (Operational, Deflection, Shapes) analysis and order analysis, the static and dynamic performance parameters of the EDM machine tool are studied. According to the processing requirements, the structure of the machine tool is optimized, and the weak links are strengthened so as to reduce the aperture dispersion of the machined holes. Through the modal test this experiment firstly analyzes the natural frequency, damping ratio and modal shape in each mode of machine tool structure to understanding the characteristics of each order machine main mode. Then, through ODS (Operational Deflection Shapes) test, it analyzes the vibration characteristics of machine tool structure in operation condition. And it also analyzes the relation-shape between the vibration of rotating machinery and the speed of the machine through the order analysis to predict the vibration of actual machine tool structure in a certain band external or internal variety of vibration response. Finally, it makes a comprehensive study on the static and dynamic performance of machine tools, and provides a reference for the design and optimization of structure dynamic strength.

Experimental investigation on precision machining of multiple holes by WEDM on Aluminium-6061 using genetic algorithm

Aluminum base alloys used in aeronautical applications is machined using WEDM to machine complex profiles with good accuracy and minimum taperness. This present investigation explores wire cut EDM machine tool usage for optimization process variables of Aluminium-6061 alloy. A Sequence of experiments are developed to research the process parameters, effects such a pulse on time—TON, wire feed rate—WFR, pulse off time—TOFF and servo voltage control—SVC on dimensional deviation—DD, Taperness, wire wear rate—WWR and metal removal rate—MRR. Trial runs on Al-6061 are conducted by taguchi design of experiments, a regression equation is developed. Genetic algorithm optimization technique is applied to yield global optimum results for optimizing process variables. Finally, comparison done across experimental results to predicted values for effectiveness 95% of confidence level was obtained. The optimum levels for getting minimum taperness is identified for square geometry are pulse on time—103 µs, pulse off time—59.99 µs, wire feed rate—6.45 mm/min and control of speed—92.52%. For circular geometry the identifications are pulse on time—103 µs, pulse off time—59.99 µs, wire feed rate—7.88 mm/min and control of speed—42.34% for optimum response. The optical microscope conformation test has obtained with satisfactory.

Research on Shape Changes in Cylinder Electrodes Incident to Micro-EDM

This paper discusses electrode wear changes under different operating conditions. A series of experiments were designed and conducted using an EDM machine tool with a rectangular pulse power supply. The phenomena of the cylinder electrode shape changes were abstracted from the experiments; the change mechanisms of the end face are discussed and verified by experimental data and interrelated theory. The results disclose that the shape of an electrode is subject to pulse-on time, discharge current density, and electrode polarity.

A look-ahead transition algorithm and jump motion planning in multi-axis EDM for shrouded blisks

Shrouded blisks play a vital role in aero and rocket engines. Multi-axis EDM is regarded as the most commonly used manufacturing method for shrouded blisks. For a linear jump path, the jump motion only needs to consider the starting and end point of the jump and there is no direction change during the jump. However, when dealing with multi-axis jump motions, the path of a jump motion is a curve which is represented by a number of line segments. For this case, the jump speed of an electrode will change abruptly in terms of direction and magnitude during the jump motion. In this paper, multi-axis corner rounding solution (MCRS) is proposed to smooth multi-axis jump paths. Two three-dimensional subspaces, a linear subspace and a rotary subspace, are built to describe six-axis jump paths for a six-axis EDM machine tool. A three-axis jump path smoothing solution can be applied for the subpath in each subspace. By using a bidirectional scanning method as well as an S-shaped profile, the smoothness of the multi-axis feedrate schedule is obtained. Simulation results show that the MCRS achieves a smoother scheduled feedrate profile as well as a higher efficiency. Experimental results show that the machining time can be decreased by 19.68% with the use of the MCRS.

Design of Feed Control System for Micro EDM Machine Tool

This paper designs the closed-loop feedback control system of MEDM, which is based on the motion control card and data acquisition card. To ensure the accuracy of the process, the gap can be regulated through the analysis of discharge condition and the analysis and treatment of the gap voltage, and then a servo control scheme on small holes machining is presented. Through this way, the electrode loss compensation scheme can be solved, which can improve the efficiency and practicality of MEDM.

Development of a TriaxialMicro EDM Machine Tool Based on Programmable Multi-Axes Controller (PMAC)

Based on the research of key technologies for achieving micro EDM process, a triaxialmicro EDM machine tool based on PMAC has been developed. The micro EDM machining tool consists of four parts: triaxial precision motion platform, motion control system, micro-energy pulse generator and CCD microscope imaging system. The hardware and software control system based on industrial control computer and PMAC has been researched. The motion control program and PLC program have been developed for precise controlling the triaxial precision motion platform. The indispensable functions for micro EDM process such as contact perception function for measurement; fast servo control strategy for short circuit and so on has been achieved. Through a number of processing tests, it is proved that the triaxial micro EDM machine tool has the ability for machining micro holes, micro slots and micro structures steadily.

The Optimization of EDM Machining Parameters of Graphite Electrode on BP Neural Network

This paper proposed a machining parameters optimization system of graphite electrode in EDM, which is established on BP neural network. Because BP neural network can approximate any continuous function by random accuracy, it is extensively used in processing technology, for example, the evaluation of the processing parameters, the optimization of machining parameters and processing error prediction, and processing technology effects are eventually predicted. The experiment results show that our system can reflect processing rule of EDM machine tool, and it can successfully predict material remove rate, electrode wear and surface roughness.

Research on Micro EDM Machine Tool for Machining Micro Array Holes

As demands for the micro array holes in modern industry and the characteristics of micro Electrical Discharge Machining (micro EDM), a new type micro EDM machine tool used to machine micro array holes was designed and manufactured. The machine tool contains following systems: the mechanism system, the control system, the pulse generator system and other auxiliary systems. Each system was studied respectively. Base on a large number of experiments, finally, a sample with 256 array holes was processed by the machine tool. The diameter of single hole is 45µm and precision of the holes is ±1µm. The sample has been successfully applied to R & D test of micro nozzle components

Experimental Study of Titanium Alloy Micro-Holes by EDM Fuzzy Control System

Aiming at machining deep micro-holes in titanium alloy, an experimental approach for EDM adopted a fuzzy control system was introduced. The fuzzy control system based on statistics of discharge states, that pulse interval and jumping height as control parameters, was self-developed. The suitable parameter for the deep micro-hole EDM process can be handily adjusted and modified in visual MATLAB fuzzy editor. A lot of experiments for titanium alloy micro-hole machining were performed on the EDM machine tool adopting the fuzzy control system. A titanium alloy deep micro-hole with 80μm in diameter and 15 in the ratio of depth-diameter is obtained. The process and results of experiments show that the process stability and efficiency be improved; due to the fuzzy control system and its suitable control parameters are applied.

Development of Tool Electrode High Frequency Vibration Assisted Micro-Hole EDM Machine for Industry Environment

A new tool electrode high frequency vibration assisted micro-hole EDM machine tool aimed to resolve the problem of machine large quantities micro holes in industry was designed. The machine is mainly composed of main body, electrical control module and assistant mechanisms etc. And drawn tungsten wire was used as the micro tool electrode. A series of experiments were carried out using the micro-hole EDM machine.

The Function Deployment of EDM Machine Tools

This paper addresses the further developing and utilizing about the functions of EDM machine tool on the basis of researching the numerical controls of EDM machine tool itself. Experiments of testing critical gap distances, single pulse discharges and single pulse discharge gap distances have been performed by the machine tool without any extra help of auxiliary instruments or equipments. The measuring accuracy and repeated testing accuracy is the numerically controlled displacement precision of the machine tool itself. The development of this function would have a great impact on enlarging the utilizations of EDM machine tools, on evaluating the behavior of EDM effectively and on designing the jumping displacement of electrodes reasonably.

Experimental and Mechanism Research on EDM Combined with Magnetic Field

The two disadvantages of EDM are the low material removal rate (MRR) and poor surface quality. In this investigation, EDM assisted by magnetic field (MFEDM) has been proposed for the first time to overcome above-mentioned disadvantages. Constant magnetic field was applied to the both sides of discharge channel perpendicularly to form a novel process. In experiment, EDM machine tool D703F was used to machine nonferromagnetic materials. The machining parameters discharge current and pulse duration were chosen to determine the effects on material removal rate and surface roughness.Experiment results indicate that the MRR of the combined machining is 1.2~3 times of EDM’s one. Furthermore, the value of surface roughness is also reduced. Therefore, the introduction of magnetic field to EDM has important academic and practical values to the development of EDM.