Modelling of ECM and EDM processes

The modelling of ECM and EDM processes requires not one but several models to simulate the different phenomena that occur during machining. This paper reviews the models that have been developed to simulate each of these phenomena, e.g. potential models to calculate the current density distribution in ECM, thermal models for the plasma arc in EDM, moving boundary models to simulate the anodic dissolution in ECM and probabilistic models to determine the discharge location in EDM. In addition to discussing the relative merits of the techniques deployed in these models, the paper describes some salient applications and concludes with desirable future enhancements to these models.     

电火花电解复合加工工作液浓度对电极损耗的影响研究

针对电火花电解复合加工的电极损耗问题,以模具钢为加工对象开展了电火花电解复合加工实验。分析了在不同极性和电极材料条件下,工作液浓度对电极相对损耗、电极形状变化规律及加工精度的影响。结果表明:合理控制工作液浓度能降低电极相对损耗及减小电极形状变化。     

State of the art electrical discharge machining (EDM)

Electrical discharge machining (EDM) is a well-established machining option for manufacturing geometrically complex or hard material parts that are extremely difficult-to-machine by conventional machining processes. The non-contact machining technique has been continuously evolving from a mere tool and die making process to a micro-scale application machining alternative attracting a significant amount of research interests.In recent years, EDM researchers have explored a number of ways to improve the sparking efficiency including some unique experimental concepts that depart from the EDM traditional sparking phenomenon. Despite a range of different approaches, this new research shares the same objectives of achieving more efficient metal removal coupled with a reduction in tool wear and improved surface quality.This paper reviews the research work carried out from the inception to the development of die-sinking EDM within the past decade. It reports on the EDM research relating to improving performance measures, optimising the process variables, monitoring and control the sparking process, simplifying the electrode design and manufacture. A range of EDM applications are highlighted together with the development of hybrid machining processes. The final part of the paper discusses these developments and outlines the trends for future EDM research.     

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。     

齿轮模具电火花展成加工研究

从整体上对齿轮模具电火花展成加工方法进行研究,充分利用电火花加工不受工件硬度限制的优点,结合展成法加工齿轮的强制啮合原理,能均化各齿的加工误差,无轴向进给电火花加工所形成的加工锥度。实验证明,加工的齿轮模具完全能满足使用要求。齿轮模具电火花展成加工是齿轮加工方法的一个创新,对齿轮模具制造具有较大的现实意义。     

A semi-empirical approach for residual stresses in electric discharge machining (EDM)

High residual stresses are developed on the surfaces of electric discharge machined parts. In this study, layer removal method is used to measure the residual stress profile as a function of depth beneath the surface caused by die sinking type EDM. Cracking and its consequences on residual stresses are also studied on samples machined at long pulse durations. A modified empirical equation is developed for scaling residual stresses in machined surfaces with respect to operating conditions. In this model, a unit amplitude shape function representing change in curvature with respect to removal depth is proposed. The proposed form is found to be a special form of a Gauss Distribution. It is the sum of two Gaussian peaks, with the same amplitude and pulse width but opposite center location. The form can be represented by three constant coefficients. These coefficients depend on the released energy by a power function.     

微细阵列方形轴孔的电火花和电化学组合加工工艺研究

对微细阵列轴孔的电火花、电化学组合加工工艺进行了分析和研究.用微细电火花线切割机加工出3×3至10×10系列方形阵列电极,宽度在25～90 μm, 加工中采用降低加工电压、加工电流、进给速度和减小工作液冲击等方法,获得了质量较好的阵列电极,并分别利用微细电化学加工和微细电火花加工两种工艺方法进行阵列孔加工.在加工过程中通过适度间歇抬刀、超声振动、循环流动工作液等方法,较好地解决了微弧放电、排屑、加工区温度过高等加工难题,获得了质量较好的大小在30～100 μm相应的阵列孔,从而实现了微细阵列轴孔的电火花、电化学组合加工,为大规模微细阵列轴孔的加工开辟了高效、可行的新工艺方法.     

模具型腔电火花创成加工无干涉运动轨迹生成研究

针对电火花创成加工具有复杂自由曲面的模具型腔,提出利用简单圆柱形电极在五坐标联动电火花机床上加工自由曲面无干涉电极运动轨迹的生成算法,并对电火花加工过程中的电极损耗进行了补偿,提高了曲面的加工质量和加工精度。     

数控电火花多轴联动斜向加工在模具加工中的应用

介绍了模具加工中运用数控电火花多轴联动斜向加工方法的实例,列出了典型的数控加工程序,并对应用实例的技巧之处作了详细的分析,是模具企业数控电火花加工值得借鉴的加工方法。     

不同电极电火花加工硬质合金的效率研究

通过实验的方式对采用不同电极电火花加工技术加工硬质合金的效率进行了研究。通过调整加工过程中的脉冲宽度和开路电压，变换加工电极，探讨了不同电极材料、开路电压及脉宽加工硬质合金的加工效率的影响.     

混粉电火花加工技术在粗加工中的应用研究

在对混粉电火花加工机理进行系统研究的基础上，对混粉电火花粗加工中的加工效率和加工表面粗糙度进行了实验研究。结果表明，通过合理选择放电参数，混粉电火花加工在相近加工表面粗糙度时，能显著提高加工效率，从而为混粉电火花加工技术在粗加工中应用提供依据。     

电火花加工技术及应用实例

详细介绍了电火花加工技术的有关因素,并列举了应用实例。通过对调整不同加工参数所得的结果进行了总结。     

A simple approach for robust design of high-speed electrical-discharge machining technology

The paper presents a simple approach for optimizing high-speed electrical-discharge machining (EDM). The approach begins with designing the ideal function of an EDM system coupled with Taguchi methods for process optimization. It has been proposed that the ideal function has a linear relationship between the input signal (intended dimension) and the output response (product dimension). This model seeks to develop a robust machining process enabling high precision and accuracy of machining a product.In this study, a two-step optimization strategy has been applied. The first step is to reduce the functional variability of the EDM system to enhance process robustness. The second step is to increase the machining accuracy by adjusting the slope of the best-fit line between the input signals and the output responses. Experimental results have shown that the use of the proposed model is simple, effective, and efficient in the development of robust and high-quality EDM machining processes.     

Micro electrochemical machining for complex internal micro features

In this paper, the application of micro electrochemical machining (ECM) for the micromachining of internal features is investigated. By controlling pulse conditions and machining time, micro features are machined on the side wall of a micro hole. These methods can easily machine a micro hole with larger internal diameters than the entrance diameter, which is very difficult to do by the conventional processes. A micro disk-shaped electrode with an insulating layer on its surface is also introduced to machine microgrooves inside the hole. This method is similar to the turning lathe process. The purpose of this study was to confirm the various possibilities of making complex internal structures in a micro hole by micro ECM.     

精密模具EDM专用补偿软件系统的开发

针对电火花成形加工(SEDM)电极平动的不同类型,提出了电极补偿修正原理,开发了SEDM专用补偿软件系统,并进行了实验验证.实验表明,该系统能有效降低因电极平动所产生的误差,明显提高SEDM加工精度.     

电火花加工工艺参数的优化及其应用

论述了在电火花加工中工艺参数对工艺效果的影响关系和目前常用的工艺参数优化的方法。介绍了KBE技术及其在电火花加工工艺参数优化中的应用前景，提出应用KBE技术将为电火花加工的工艺参数优化提供比较完美的解决方案。     

智能学习型电火花加工工艺决策系统的研究

针对电火花加工工艺的特点，分析了其智能决策系统应具有的特点，进而构筑了具有自学习功能的电火花加工工艺智能决策系统的结构2，详细分析了系统中各模块的功能及相互间的关系。该系统利用多种智能技术来提高电火花加工工艺设计的决策水平，并通过学习机制解决知识获取的瓶颈问题，该系统解决问题的能力将在重复使用过程中不断提高。     

模具企业电火花成型加工误区的分析

列举了模具企业中电火花加工存在的常见误区,针对这些误区进行了技术探讨,对模具企业电火花加工具有指导意义.     

A review on the conventional and micro-electrodischarge machining of tungsten carbide

The capability of machining intricate features with high dimensional accuracy in hard and difficult-to-cut material has made electrodischarge machining (EDM) process as an inevitable and one of the most popular non-conventional machining processes. In recent years, both EDM and micro-EDM processes are being used extensively in the field of mould making, production of dies, cavities and complex 3D structures using difficult-to-cut tungsten carbide and its composites. The objective of this paper is to provide a state of the art in the field of EDM and micro-EDM of tungsten carbide and its composites. The review begins with a brief introduction on the EDM and micro-EDM processes. The research and developments in electrodischarge machining of tungsten carbide are grouped broadly into conventional EDM of tungsten carbide, micro-EDM of tungsten carbide and current research trends in EDM and micro-EDM of tungsten carbide. The problems and challenges in the area of conventional and micro-EDM of tungsten carbide and the importance of compound and hybrid machining processes are discussed. A summary of the future research directions based on the review is presented at the final section.