Study of the Effect of Machining Parameters on the Machining Characteristics in Electrical Discharge Machining of Fe-Mn-Al Alloy

In this work we investigated the electrical discharge machining (EDM) of a Fe-Mn-Al alloy. The surface phenomena caused by EDM were studied in terms of machining parameters. An empirical model of the Fe-Mn-Al alloy was also proposed based on the experimental data. Experimental results indicate that the higher the discharge energy, the faster the machining time. This treatment introduces machining damage in the resolidified surface layer and worsens the surface roughness. The optimum pulse-on duration on the basis of the electrode wear ratio for the copper electrode was about 200 μs. The increase of crater depth with the applied pulsed current and pulse-on duration appears minimal under a small input energy.     

An Experimental Study on Electrical Discharge Machining of Manganese-Zinc Ferrite Magnetic Material

The objective of this research is to investigate the machining characteristics of manganese-zinc (Mn-Zn) ferrite magnetic material using electrical-discharge machining (EDM). The material removal rate, the surface topography, the surface roughness, the recast layer, and the chemical composition of the machined surface were studied in terms of EDM processing variables. Experimental results indicate that the morphology of debris revealed the mechanism of material removal. The surface microgeometry characteristics are not always uniform and homogenous and the EDM process produces much damage on the machined surface. The material removal rate, the surface roughness, and the recast layer are proportional to the applied discharge energy.     

Parametric optimization of multiwalled carbon nanotube-assisted electric discharge machining of Al-10%SiCp metal matrix composite by response surface methodology

The demand for miniaturized products having a glossy surface or nano-level surface is increasing exponentially in automobile, aerospace, biomedical, and semiconductor industries. The mirror-like surface finish has generated a need to develop advanced machining processes. The addition of powder particle into electric discharge machining (EDM) oil is considered a promising technique to achieve surface integrity at the miniaturization level. In this research, the Al–10%SiC_p metal matrix composite (MMC) has been machined after mixing the appropriate amount of multiwalled carbon nanotubes (MWCNTs) into the EDM dielectric fluid. An advanced experimental setup has been designed and fabricated in the laboratory for conducting the experiments. This proposed technology is called nano powder mixed electric discharge machining (NPMEDM). The input parameters of NPMEDM are also optimized using central composite rotatable design (CCRD) based on response surface methodology (RSM) in order to obtain the best surface finish and material removal rate (MRR). The MRR has been increased by 38.22% and surface finish has been improved by 46.06% after mixing the MWCNTs into the EDM dielectric fluid. The results indicate that the combination of parameters A5, B5, C5, and D5 might have produced maximum MRR, whereas A1, B1, C1, and D3 have produced minimum surface roughness (SR).     

Machining Characteristics and Optimization of Machining Parameters of SKH 57 High-Speed Steel Using Electrical-Discharge Machining Based on Taguchi Method

The effects of the machining parameters in electrical-discharge machining (EDM) on the machining characteristics of SKH 57 high-speed steel were investigated. A well-designed experimental scheme was used to reduce the total number of experiments. Parts of the experiment were conducted with the L18 orthogonal array based on the Taguchi method. Moreover, the signal-to-noise ratios associated with the observed values in the experiments were determined by ANOVA and F-test. The significant parameters that critically influenced the machining characteristics were examined, and the optimal combination levels of machining parameters for material removal rate, electrode wear rate, and surface roughness were determined.     

Modeling and simulation of material removal with particulate flows

In this work a multibody collision model, ame-nable to large-scale computation, is developed to simulate material removal with particulate flows. This model is developed by computing momentum exchange to account for different force interactions: (1) particle–particle interaction, (2) particle–fluid interaction, and (3) particle–surface interaction. For the particle-fluid interaction, a velocity field for the fluid is assumed to be known, and the drag force on the particles is computed from this field. In the particle–surface interaction, the Boussinesq solution for a point load on an elastic half-space is used along with the von-Mises yield criterion to determine the amount of material removed. Employing this model, inverse problems are then constructed where combinations of the abrasive particle size, the particle size distribution, the flow velocity, etc., are sought to maximize the efficiency of the process. A genetic algorithm is used to treat this inverse problem, and numerical examples are given to illustrate the overall approach.     

TiBCN陶瓷线切割加工表面质量及蚀除机理

采用硼化法制备的TiBCN导电陶瓷粉末成功热压烧结为块体材料。设置不同电火花线切割加工工艺参数,切割TiBCN块材。通过加工表面质量分析及SEM微观形貌观察,研究了线切割加工表面质量的影响因素及材料蚀除机制。研究结果表明:线切割加工TiBCN陶瓷材料,可以获得质量良好的加工表面,最小表面粗糙度Ra为0.4μm;脉冲电流Ip和脉间ti是影响加工表面质量的主要影响因素;虽然设置长脉宽te有利于提高蚀除效率,但脉间过小,易形成表面裂纹。TiBCN块材线切割加工最佳参数设置范围为:Ip=2~6,te=20~22μs,ti=65~75μs。线切割加工TiBCN陶瓷材料,有三种蚀除机理:剥离、熔融/再凝固、气化蒸发。     

Investigation into the Effect of Voltage Excitation of Pre-Ignition Spark Pulse on the Electro-Discharge Machining (EDM) Process

Studying the variation of the electro-discharge machining (EDM) process outputs due to the change in shape of the generated pulse is one research aspect in the EDM process. In this study, the effects of voltage excitation of the pre-ignition spark pulse on the process outputs material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (Ra) have been investigated. Experiments were designed using design of experiments (DOE), and the results were analyzed using analysis of variance (ANOVA). Based on the results, it has become clear that applying voltage excitation of the pulse produces effective pulses, which in turn lessens EWR, increases MRR, and improves surface quality. Hence, the suitability of this method has been verified for EDM.     

Wear of diamond grinding wheels and material removal rate of silicon nitrides under different machining conditions

Studies have been carried out to determine the influence of depths of cut of diamond grinding wheels on the wear of diamond abrasives and the material removal rate of silicon nitride during single pass grinding. The results suggest that there is an optimum depth of cut, which yields the greatest material removal rate. If the grinding depth is less than this optimum depth of cut, the grinding efficiency is low. If the grinding depth is larger than this optimum depth of cut, premature dulling of the diamond wheel occurs. Furthermore, some of the diamond abrasives break due to grain fracture, and the original sharp diamond abrasives become flat and smooth. As a result, the material removal rate of silicon nitride drastically decreases.