A new method of optimising material removal rate using EDM with copper–tungsten electrodes

Electrical discharge machining (EDM) is widely used in the production of dies. This paper describes an investigation into the optimisation of the process which uses the effect of carbon which has migrated from the dielectric to tungsten–copper electrodes. This work has led to the development of a two-stage EDM machining process where different EDM settings are used for the two stages of the process giving a significantly improved material removal rate for a given tool wear ratio.     

Machining characteristics of magnetic force-assisted EDM

The gap conditions of electrical discharge machining (EDM) would significantly affect the stability of machining progress. Thus, the machining performance would be improved by expelling debris from the machining gap fast and easily. In this investigation, magnetic force was added to a conventional EDM machine to form a novel process of magnetic force-assisted EDM. The beneficial effects of this process were evaluated. The main machining parameters such as peak current and pulse duration were chosen to determine the effects on the machining characteristics in terms of material removal rate (MRR), electrode wear rate (EWR), and surface roughness. The surface integrity was also explored by a scanning electron microscope (SEM) to evaluate the effects of the magnetic force-assisted EDM. As the experimental results suggested that the magnetic force-assisted EDM facilitated the process stability. Moreover, a pertinent EDM process with high efficiency and high quality of machined surface could be accomplished to satisfy modern industrial applications.     

Real-time Tool Wear Compensation in Milling EDM

Accurate machining by milling EDM (i.e. CNC contouring EDM with a rotating cylindrical or tubular electrode) necessitates compensation of the tool electrode wear. Existing anticipated wear compensation is based on off-line tool wear simulation prior to machining. This can be combined with corrections based on periodical measurements of tool length during machining. Anticipated wear compensation involves an important restriction: an exact model of the blank geometry must be available in order to perform the tool wear simulation. This paper presents a new method of wear compensation. On-line estimation of tool wear is used for combining anticipated compensation with real-time compensation. This extends the scope of milling EDM to the machining of blanks of which the exact shape is not known in advance.     

NAK80模具钢混粉电火花加工的实验研究

利用NAK80模具钢作为被加工工件，通过实验和理论分析的方法探索了电火花混粉加工的机理。为加工参数的优化及建立电火花混粉加工专家系统提供了实验依据和技术基础。     

电火花加工工具电极耐电蚀性能的试验研究

电火花成形加工过程中，工具电极的损耗是影响工件几何形状精度的主要因素之一。从工具电极的制作工艺着手，分别利用直流和脉冲电流电铸工具电被，进行了电极放电损耗试验。通过试验和SEM形貌研究分析了工艺参数对电极耐电蚀性能的影响，并用正交试验法优化了工艺参数。结果表明，脉冲电铸铜电极可降低损耗，且在一定工艺条件下脉冲电铸电极具有优异的耐电蚀性能。     

振动辅助液中喷气电火花加工性能研究

提出了振动辅助液中喷气电火花加工方法.该方法通过工件机械振动改善了极间的放电状态,降低了短路率.通过实验研究了机械振动的频率和振幅对液中喷气电火花加工性能的影响,研究了振动辅助作用下电加工参数、气体压力、工具电极转速对加工性能的影响.结果表明,工件的机械振动可有效提高液中喷气电火花加工的材料去除率,改善加工表面质量,而电极损耗几乎为零.     

CPLD在电火花加工脉冲电源设计中的应用

用AHDL语言设计了适用于电火花加工机床脉冲电源的脉冲控制电路。该电路可以和MCU或拨码盘连接，可精密控制脉冲宽度和脉冲间隔，通过对设计项目的编译，综合及对CPLD器件的编程下载，即可硬件实现本文设计。     

数字化控制的电火花加工电源研究

针对电火花加工的特点,分析了关键指标的影响因素和改善的方法,提出了利用单片机控制电火花加工电源的策略。采用先进的开关电源技术和新型的控制电路,通过软件编程。可根据加工工艺的需要,自由设定并产生最合理的加工参数,最终提高产品的精度和加工的效率。     

谐振型电火花加工脉冲电源的研究

分析了限制电火花加工脉冲电源高频化的因素，利用并联谐振软开关技术和高速功率MOSFET器件，设计了一种新型电火花加工脉冲电源，对这种新型电源的工作原理进行了探讨与分析。     

Study on Factors Determining Limits of Minimum Machinable Size in Micro EDM

This paper describes an investigation on factors determining the limits of the minimum machinable diameter of micro rods obtained by micro EDM. Possible factors which influence the limits are discharge crater size, depth of heat affected zone, residual stress, and material micro-structure. In this paper, the influences of residual stress and material micro-structure were especially examined. For the negative effects of residual stress, both residual stress already present prior to machining and residual stress generated by machining itself were investigated using tungsten and cemented tungsten carbide as micro-rod workpiece materials. To determine the effects of material micro-structure, the influence of tungsten carbide grain size on the limits of minimum machinable diameter of cemented tungsten carbide rods was investigated. Comparing the limits between poly-crystal tungsten and mono-crystal tungsten, it was found that micro-machining characteristics were affected significantly by the anisotropy of the mono-crystal tungsten.     

节能型电火花脉冲电源低电极损耗波形控制与工艺研究

分析了电火花加工中存在电极损耗的问题及原因,提出了节能型脉冲电源的低电极损耗波形控制方法,并设计了控制回路。在研制电源的基础上,以铜加工钢材料进行了工艺研究和实验,确定了梯形波电流的初值设定,掌握了二种波形条件下、不同加工规准和关键电参数的影响规律。研究结果为节能型电源实现低电极损耗的粗加工奠定了基础。     

基于非接触给电的高主轴转速微细电火花加工特性研究

在实现非接触给电的微细电火花加工的基础上,分别研究了圆柱电极和削边电极的主轴转速对材料去除率及电极损耗的影响。结果表明:无论是圆柱电极还是削边电极,随着主轴转速的提高,材料去除率增加,电极损耗率降低;且在削边电极的情况下,主轴转速的提高对于材料去除率和电极损耗率的改善更明显。     

日本放电加工的新方法和新技术

综述了日本在放电加工领域的最新研究动态，包括成形放电加工、微细放电加工和线切割放电加工三部分内容。在成形放电加工方面，主要介绍一项新技术——气中放电高速三维空腔铣的原理、实验装置及加工效果；在微细放电加工方面，主要介绍一种新近开发的可同时加工微细轴和微孔的自动微孔加工装置和目前已加工出的微细轴的最小尺寸；在线切割放电加工方面，主要介绍了提高圆角加工精度的新方法、提高放电位置可控性的新方法和新的硅锭切片方法。     

电火花加工脉冲电源人机接口界面设计

利用 12 8× 2 4 0规格点阵式LCD模块设计了电火花加工脉冲电源人机接口界面 ,在汉字提示下能够完成加工尺寸、加工工艺参数设定、加工过程跟踪及设备状态监控等功能 ,使界面变得更为友好 ,大大地提高了脉冲电源的性能。     

The effect in EDM of a dielectric of a urea solution in water on modifying the surface of titanium

This study investigates the influence of the machining characteristics on pure titanium metals using an electrical discharge machining (EDM) with the addition of urea into distilled water. Additionally, the effects of urea addition on surface modification are also discussed. In the experiments, machining parameters such as the dielectric type, peak current and pulse duration were changed to explore their effects on machining performance, including the material removal rate, electrode wear rate and surface roughness. Moreover, the elemental distribution of nitrogen on the machined surface was qualitatively determined by EPMA to assess the effects on surface modification. Micro hardness and wear resistance tests were performed to evaluate the effects of the reinforced surface.Experimental results indicate that the nitrogen element decomposed from the dielectric that contained urea, migrated to the work piece, forming a TiN hard layer, resulting in good wear resistance of the machined surface after EDM.     

加工间隙对电火花加工质量影响的分析

在电火花加工中要降低各种干扰因素的影响,确保加工质量和稳定的加工过程,放电间隙的一致性是非常重要的一个技术指标。详细分析了影响放电间隙状态变化的因素,提出了维持放电间隙大小一致性的相应措施,对进一步改善电火花加工质量具有一定的参考价值。     

Development of ultra-precision machining system with unique wire EDM tool fabrication system for micro/nano-machining

Aiming at quality machining of very hard materials with nanometer level surface quality and 0.1 μm dimensional accuracy, an ultra-precision machining system has been developed. The machine has feed axes accompanied by the counter motion mechanism driven at the center of gravity to eliminate the vibration caused by high acceleration/deceleration. A custom tool fabrication system consists of a 6-axis wire EDM machine and dedicated custom tool CAM system. High quality machining of sophisticated three-dimensional (3D) products made of tungsten carbide has successfully been demonstrated on the developed machine tool with custom-made PCD cutters fabricated by the tool fabrication system.     

A review on current research trends in electrical discharge machining (EDM)

Electrical discharge machining (EDM) is one of the earliest non-traditional machining processes. EDM process is based on thermoelectric energy between the work piece and an electrode. A pulse discharge occurs in a small gap between the work piece and the electrode and removes the unwanted material from the parent metal through melting and vaporising. The electrode and the work piece must have electrical conductivity in order to generate the spark. There are various types of products which can be produced using EDM such as dies and moulds. Parts of aerospace, automotive industry and surgical components can be finished by EDM. This paper reviews the research trends in EDM on ultrasonic vibration, dry EDM machining, EDM with powder additives, EDM in water and modeling technique in predicting EDM performances.     

电火花放电加工间隙状态检测方法综述

间隙状态检测是电火花加工过程中极其重要的一个环节。该文介绍了利用独立式脉冲电源进行电火花加工过程间隙状态检测的常用方法，分析了它们的实现原理与特点。     

Effect of valency on material removal rate in electrochemical machining of aluminium

Material removal rate (MRR) of aluminium work piece has been obtained by electrochemical machining using NaCl electrolyte at different current densities and compared with the theoretical values. It has been observed that resistance of the electrolyte solution decrease sharply with increasing current densities. The over-voltage of the system initially increases and then attains a saturation value with increasing current densities. The material removal rate, determined experimentally, almost corresponds to theoretical value with Al³⁺ state. On the other hand, taking into account over-voltage, MRR comes out be 72%. It appears that removal of a fraction of aluminium occurs in Al⁺ which subsequently gets converted into Al³⁺ through a series chemical reactions. A mechanism of such chemical reactions is proposed.