Development of micro wire electrical discharge machining platform and its application

A machining platform of micro wire electrical discharge machining (MWEDM) was developed. The key technology of MWEDM mainly includes granite basement, micro energy pulse generator, detection and servo control system, constant tension winding system and V-block guide wire mechanism. Utilizing micro wire electrode with 30μm in diameter, the MWEDM can machine the micro slot with the minimum size of 38μm wide, and the surface roughness is smaller than 0.1μm, the machining precision is less than 0.5μm, the white layer is no more than 2μm with main cut. All kinds of complex micro parts, such as micro gear, micro bearing bracket and micro shaped holes, can also be machined by using this platform.

An experimental investigation of wire electrical discharge machining of hot-pressed boron carbide

The present work discusses the experimental study on wire-cut electric discharge machining of hot-pressed boron carbide.The effects of machining parameters,such as pulse on time(TON),peak current(IP),flushing pressure(FP) and spark voltage on material removal rate(MRR)and surface roughness(R_a) of the material,have been evaluated.These parameters are found to have an effect on the surface integrity of boron carbide machined samples.Wear rate of brass wire increases with rise in input energy in machining of hot-pressed boron carbide.The surfaces of machined samples were examined using scanning electron microscopy(SEM).The influence of machining parameters on mechanism of MRR and R_a was described.It was demonstrated that higher TON and peak current deteriorate the surface finish of boron carbide samples and result in the formation of large craters,debris and micro cracks.The generation of spherical particles was noticed and it was attributed to surface tension of molten material.Macro-ridges were also observed on the surface due to protrusion of molten material at higher discharge energy levels.

CUTTING REGULARITY AND DISCHARGE CHARACTERISTICS BY USING COMPOSITE COOLING LIQUID IN WIRE CUT ELECTRICAL DISCHARGE MACHINE WITH HIGH WIRE TRAVELING SPEED

The analysis of cutting regularity is provided through using and comparing two typical cooling liquids. It is proved that cutting regularity is greatly affected by cooling liquid＇s washing ability. Discharge characteristics and theoretic analysis between two electrodes are also discussed based on discharge waveform. By using composite cooling liquid which has strong washing ability, the efficiency in the first stable cutting phase has reached more than 200 mm^2/min, and the roughness of the surface has reached Ra〈0.8 μm after the fourth cutting with more than 50 mm^2/min average cutting efficiency. It is pointed out that cutting situation of the wire cut electrical discharge machine with high wire traveling speed （HSWEDM） is better than the wire cut electrical discharge machine with low wire traveling speed （LSWEDM） in the condition of improving the cooling liquid washing ability. The machining indices of HSWEDM will be increased remarkably by using the composite cooling liquid.

Analysis of Wire Vibration in Wire Electric Discharge Machining Process

Wire electric discharge machining(WEDM)process is used for precision manufacturing.The accuracy of machining is function of various parameters like current,voltage,wire speed,gap between wire and work piece,wire oscillation,work material,wire material,etc.Once the process parameters are selected,it is important that the wire vibrations are less to obtain a good surface finish.Due to the importance of wire vibration in obtaining the surface finish,it is necessary to study the wire vibration.This paper discusses different models of wire vibration presented in the literature and simulates a closed form solution of wire vibration using MATLAB.The transverse vibration of wire is analysed as forced vibration of moving wire with excitation due to the sparks during machining.The resulting partial differential equation is solved by using finite difference method and vibration is also simulated in the finite element package‘ANSYS’.The wire behaviour is investigated under different operating conditions and results of the two methods are

Electrical discharge machining of 6061 aluminium alloy

The wire electrical discharge machining（EDM） of 6061 aluminium alloy in terms of material removal rate,kerf/slit width,surface finish and wear of electrode wire for different pulse on time and wire tension was studied.Eight experiments were carried out in a wire EDM machine by varying pulse on time and wire tension.It is found that the material removal rate increases with the increase of pulse on time though the wire tension does not affect the material removal rate.It seems that the higher wire tension facilitates steady machining process,which generates low wear in wire electrode and better surface finish.The surface roughness does not change notably with the variation of pulse on time.The appearance of the machined surfaces is very similar under all the machining conditions.The machined surface contains solidified molten material,splash of materials and blisters.The increase of the pulse on time increases the wear of wire electrode due to the increase of heat input.The wear of wire electrode generates tapered slot which has higher kerf width at top side than that at bottom side.The higher electrode wear introduces higher taper.

Wire electric discharge machining characteristics of titanium nickel shape memory alloy

Ti Ni shape memory alloys（SMAs） have been normally used as the competent elements in large part of the industries due to outstanding properties, such as super elasticity and shape memory effects. However, traditional machining of SMAs is quite complex due to these properties. Hence, the wire electric discharge machining（WEDM） characteristics of Ti Ni SMA was studied. The experiments were planned as per L27 orthogonal array to minimize the experiments, each experiment was performed under different conditions of pulse duration, pulse off time, servo voltage, flushing pressure and wire speed. A multi-response optimization method using Taguchi design with utility concept has been proposed for simultaneous optimization. The analysis of means（ANOM） and analysis of variance（ANOVA） on signal to noise（S/N） ratio were performed for determining the optimal parameter levels. Taguchi analysis reveals that a combination of 1 μs pulse duration, 3.8 μs pulse off time, 40 V servo voltage, 1.8×105 Pa flushing pressure and 8 m/min wire speed is beneficial for simultaneously maximizing the material removal rate（MRR） and minimizing the surface roughness. The optimization results of WEDM of Ti Ni SMA also indicate that pulse duration significantly affects the material removal rate and surface roughness. The discharged craters, micro cracks and recast layer were observed on the machined surface at large pulse duration.

Review on non-conventional machining of shape memory alloys

Shape memory alloys （SMAs） are the developing advanced materials due to their versatile specific properties such as pseudoelasticity, shape memory effect （SME）, biocompatibility, high specific strength, high corrosion resistance, high wear resistance and high anti-fatigue property. Therefore, the SMAs are used in many applications such as aerospace, medical and automobile. However, the conventional machining of SMAs causes serious tool wear, time consuming and less dimensional deformity due to severe strain hardening and pseudoelasticity. These materials can be machined using non-conventional methods such as laser machining, water jet machining （WJM） and electrochemical machining （ECM）, but these processes are limited to complexity and mechanical properties of the component. Electrical discharge machining （EDM） and wire EDM （WEDM） show high capability to machine SMAs of complex shapes with precise dimensions. The aim of this work is to present the consolidated references on the machining of SMAs using EDM and WEDM and subsequently identify the research gaps. In support to these research gaps, this work has also evolved the future research directions.

Electrical Discharge Machining of Al2024-65 vol%SiC Composites

In the present work, the wire electrical discharge machining（WEDM） process of the 65 vol% SiCp/2024 Al composite prepared by pressure infiltration methods has been investigated. The microstructure of the machined composite was characterized by scanning electron microscope, the average surface roughness（Ra）, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy（TEM） techniques. Three zones from the surface to the interior（melting zone, heat affected zone and un-affected zone） were found in the machined composites, while the face of SiC particles on the surface toward the outside was ‘‘cut＇＇ to be flat. Increase in Al and Si but decrease in C and O were observed in the core areas of the removed particles. Si phase, which was generated due to the decomposition of SiC, was detected after the WEDM process. The irregular and spherical particles were further observed by TEM. Based on the microstructure observation, it is suggested that the machining mechanism of 65 vol% SiCp/2024 Al composite was the combination of the melting of Al matrix and the decomposition of SiC particles.

FOUR-AXIS WIRE-EDM SIMULATION OF COMPLICATED MODELS

In the verification of wire electrical discharge machining （EDM）, the motion and the performance of the wire-EDM system are analyzed. The maximum inclining angle of the wire is calculated. The relevant judgment methods are used for the collision between the wire, the fixture, and the machining table. In the wire-EDM simulation, the generated solid model can he used to investigate programming results and to check the machining accuracy. The generation algorithm for the solid model in the simulation is solved based on Boolean operations. The wire swept volume for each cutting step is united to form the entire wire swept volume. Through Boolean subtraction between the stock model and the entire wire swept volume, the solid model in the wire-EDM simulation is generated. The method is also suitable for the wire path intersection occurred in cutting cone-shaped models. Finally, experiments are given to prove the method.

Influence of Input Factors on Surface Roughness and Material Removal Speed when Wire-EDM a Hardened SKD11 Steel Curve Profile

The goal of this research is to identify the best set of process machining parameters for wire-EDM(Electrical Discharge Machining)cutting of hardened SKD11 steel when machining a curve profile.The multi-objective function includes reducing surface roughness and increasing MRR(Material Removal Rate).The optimization process is prepared by using Taguchi method coupled Grey Relational Analysis.The obtained results revealed that Toff has the greatest influence on the average grey value(48.30%),followed by the influence of WF(Wire Feed,15.99%),VM(Cutting Voltage,9.33%),SV(Server Voltage,5.05%),Ton(Pulse on Time,1.81%),while SPD(Cutting Speed)has a negligible effect(0.89%).Moreover,using the optimal set of machining parameters generates in surface roughness of 1.25399mm and MRR of 26.5562 mm^(2)/min.The verification experiment and Anderson-Darling method demonstrate the validity of the proposed model,which can be utilized for estimating surface roughness and MRR.

T/CMTBA 1010—2021《数控往复走丝电火花线切割机床性能评价规范》团体标准解读

介绍了《数控往复走丝电火花线切割机床性能评价规范》团体标准的制定背景、目的和主要内容,并在检验项目、关键指标等方面与现行行业标准进行了比对,解读了该团体标准的先进性、科学性和实用性。

基于响应面与狼群算法的电火花线切割加工性能与放电能耗建模及优化

结合电火花线切割加工绿色、精密、高效的发展趋势,提出面向加工性能与放电能耗的电火花线切割加工工艺建模与多目标优化方法。针对电火花线切割加工GH4169高温合金材料开展正交试验设计,以脉冲宽度、放电间隙、管数、加工限速为输入,以放电能耗EEV、表面粗糙度Ra和材料去除率MRR为输出,构建了电火花线切割加工性能与放电能耗多目标优化响应面模型,并采用改进的狼群算法对模型进行优化求解。优化结果与实验结果对比表明,Ra、EEV和MRR的平均误差均不高于10%,且随机优化实验结果优于75%以上的正交试验设计的实验结果,验证了优化模型及求解方法的有效性。

分层供液电火花线切割加工研究

分别采用常规供液和分层供液对缸筒类零件进行电火花线切割加工对比试验。结果表明,分层供液可在火花放电全过程实现电极丝顺向运丝加工,解决了常规供液方式下电极丝逆向运丝导致的缸筒类零件内部供液不足的问题;提高了极间工作液流速与流量,增强了排屑能力,扩大了放电间隙,改善了极间放电条件,从而提高了火花放电效率和稳定性,对工件切割速度的提高和表面加工质量的改善有重要意义。

电火花线切割工艺加工钼铜钨铜载体初探

钼铜钨铜材料的载体,由于孔隙率极低,在热沉制作和电子封装领域应用越来越广泛,但由于载体材料硬度高、厚度尺寸小等特点,传统机械加工方法无法对其进行有效加工。电火花线切割类非接触式特种加工方法为该类材料的顺利加工提供了解决方案。电火花线切割加工技术是一种通过在工具电极与工件之间施加电压,利用两者之间的脉冲性火花放电能量来蚀除工件表面多余的金属,从而使工件得到所需的形状、尺寸精度、表面质量的技术。分析钼铜钨铜材料特性,针对性寻求相应的线切割方案,设计相关加工实验,探究整体工艺方案和工艺参数,加工出符合技术要求的产品。这种加工方式为后续开展钼铜钨铜载体更高效、更高精度的加工提供了宝贵的参考。

金刚石线锯电火花复合切割硬脆半导体的研究进展

太阳能光伏产业和电子工业的迅速发展对使用的晶体硅等硬脆半导体材料的切割提出了更高的要求。为了进一步提高硬脆半导体的切割加工质量和生产效率、降低生产成本,金刚石线锯电火花复合切割技术开始被应用到硬脆半导体的切割中。文章从加工原理、工艺性能和影响因素等方面综述了金刚石线锯电火花复合切割硬脆半导体材料的研究现状,并对后续的发展和研究方向进行了展望。

Machine-vision-based electrode wear analysis for closed loop wire EDM process control

The purpose of this study was to develop a closed-loop machine vision system for wire electrical discharge machining(EDM)process control.Excessive wire wear leading to wire breakage is the primary cause of wire EDM process failures.Such process interruptions are undesirable because they affect cost efficiency,surface quality,and process sustainability.The developed system monitors wire wear using an image-processing algorithm and suggests parametric changes according to the severity of the wire wear.Microscopic images of the wire electrode coming out from the machining zone are fed to the system as raw images.In the proposed method,the images are preprocessed and enhanced to obtain a binary image that is used to compute the wire wear ratio(WWR).The input parameters that are adjusted to recover from the unstable conditions that cause excessive wire wear are pulse off time,servo voltage,and wire feed rate.The algorithm successfully predicted wire breakage events.In addition,the alternative parametric settings proposed by the control algorithm were successful in reducing the wire wear to safe limits,thereby preventing wire breakage interruptions.

基于VC平台实现NC线切割自动编程与加工仿真

电火花线切割加工(WEDM)是机加特种加工的重要构成部分,在航空零件的加工方面应用广泛。针对目前电火花线切割机床自动编程系统操作复杂、绘图功能不全的问题,通过深入分析与研究电火花线切割加工过程,提出一种简单明了的自动编程与仿真加工方案,确定整个数控(NC)线切割仿真加工系统辅助框架和各功能模块,包含各个功能模块的接口。结合COM技术,通过动态链接库DLL完成加工零件图形的输入,并由ActiveX控件技术实现NC代码仿真,利用Access建立整个支撑数据库,实现交互环境下AutoCAD零件图形输入和加工所需的刀位点计算,最终生成后置处理文件及实现全部NC代码的动画仿真,能够辅助提高实际线切割加工的一次成功率,满足实际加工的需要。

Analysis and optimization of sustainable machining of AISI O1 tool steel by the wire-EDM process

Wire electrical discharge machining(wire-EDM)is an energy-intensive process,and its success relies on a correct selection of cutting parameters.It is vital to optimize energy consumption,along with productivity and quality.This experimental study optimized three parameters in wire-EDM:pulse-on time,servo voltage,and voltage concerning machining time,electric power,total energy consumption,surface roughness,and material removal rate.Two different plate thicknesses(15.88 mm and 25.4 mm)were machined.An orthogonal array,signal-to-noise ratio,and means graphs,and an analysis of vari-ance(ANOVA),determine the effects and contribution of cutting parameters on responses.Pulse-on time is the most significant factor for almost all variables,with a percentage of contribution higher than 50%.Multi-objective optimization is conducted to accomplish a concurrent decrease in all variables.A case study is proposed to compute carbon dioxide(CO_(2))tons and electricity cost in wire-EDM,using cutting parameters from multi-objective optimization and starting values commonly employed to cut that tool steel.A sustainable manufacturing approach reduced 5.91%of the electricity cost and CO_(2)tons when machining the thin plate,and these responses were diminished by 14.09%for the thicker plate.Therefore,it is possible to enhance the sustainability of the process without decreasing its productivity and quality.

快走丝线切割机床废钼丝收集装置设计

针对快走丝线切割机床废钼丝徒手收集中普遍存在的废丝收集效率低、中途易脱手、易伤手、易打结而弯曲断丝、散落地上不易找寻和拾取、存储空间大等诸多问题,有针对性地设计了一种便于卸料的废丝收集装置,将废丝收集与卸料合二为一,有效解决了上述问题,提高零件加工的效益。实践证明:利用这种废丝收集装置,废丝收集效率提高67%以上,废丝收集与卸料操作简单方便、稳定可靠。

Optimizing machining parameters of wire-EDM process to cut Al7075/SiCp composites using an integrated statistical approach

Metal matrix composites （MMCs） as advanced materials, while producing the components with high dimensional accuracy and intricate shapes, are more complex and cost effective for machining than conventional alloys. It is due to the presence of discontinuously distributed hard ceramic with the MMCs and involvement of a large number of machining control variables. However, determination of optimal machining conditions helps the process engineer to make the process efficient and effec- tive. In the present investigation a novel hybrid multi-response optimization approach is proposed to derive the economic machining conditions for MMCs. This hybrid approach integrates the concepts of grey relational analysis （GRA）, principal component analysis （PCA） and Taguchi method （TM） to derive the optimal machining conditions. The machining experiments are planned to machine A17075/SiCp MMCs using wire-electrical discharge machining （WEDM） process. SiC particulate size and its weight percentage are explicitly considered here as the process variables along with the WEDM input variables. The derived optimal process responses are confirmed by the experimental validation tests and the results show satisfactory. The practical possibility of the derived optimal machining conditions is also analyzed and presented using scanning electron microscope （SEM） examinations. According to the growing industrial need of making high performance, low cost components, this investigation provides a simple and sequential approach to enhance the WEDM performance while machining MMCs.