Effects of Ultrasonic Vibration and Magnetic Field in Micro-EDM Milling of Nonmagnetic Material

Micro electric discharge milling is acquiring more importance in micro manufacturing because of its unique ability to produce three dimensional micro cavities with high aspect ratio in electrically conductive advanced materials regardless of its mechanical properties. The present study investigates the effects of major micro electric -discharge milling process variables (Voltage (V), Capacitance(C), electrode rotational speed (ERS) and feed rate (FR)) on Ti-6Al-4V. The output performance measures were identified as material removal rate (MRR) and tool wear rate (TWR) to assess the machinability of Ti-6AL-4V. Experiments were designed and carried out based on response surface methodology-Box Behnken statistical design. The most influencing parameters for responses (MRR, TWR) were found to be capacitance and feed rate. At a capacitance of 0.4 µF and feed rate of 18 mm/min, maximum MRR of 0.9756 mg/hr and TWR of 0.6342 mg/hr were observed. Similarly at 0.01 µF and 6mm/min, minimum MRR of 0.2308 mg/hr and TWR of 0.1259 mg/hr were obtained. Downloaded by [UNAM Ciudad Universitaria] at 20:25 25 December 2014 2

Section: Introductionmentioning

confidence: 99%

Experimental Investigations into the Effects of Microelectric-Discharge Milling Process Parameters on Processing Ti–6Al–4V

Kuriachen

Mathew

2014

“…The magnetic pinching force can't be ignored in micro-EDM because the smaller the channel radius is and the bigger current is, the larger the pinching force is [24]. Assume that the plasma channel radius is a, the current density in column is j(r), the magnetic induction intensity is B(r), the pressure distribution is P(r), and μ 0 is the magnetic permeability, then the Maxwell's equations in cylindrical coordinates can be expressed as 0 1 d rB r j r r dr (6) The magnetic field distribution in the plasma can be derived as: …”

Section: Plasma Expand Stagementioning

confidence: 99%

A Study on Plasma Channel Expansion in Micro-EDM

Chu

Zhu

Wang

et al. 2015

Micro-EDM is derived from traditional EDM (electrical discharge machining), and widely used in the micro fabrication field. By using narrow-width pulse power generators, micro-EDM can be applied to machining work with smaller gaps and at low energy levels, which demonstrates a different electro-discharge process and material erosion characteristics, compared with traditional EDM. Through in-depth study on micro-EDM and MHD (magnetic fluid dynamics), a comprehensive plasma model has been established consisting of the breakdown and the expansion stages. In addition, theoretical calculation based on the model is performed, followed by results analysis. Finally, micro-EDM experiments are conducted to verify the feasibility of the model and the correctness of the results analysis.

“…Lu et al [8] conducted a scratch test on KDP crystal and analyzed the friction coefficient and conditions for brittle-ductile removal for KDP crystal in each crystal direction during the scratching process and examined the subsurface damage in each crystal direction. Based on the research results that ultrasonic vibration has a positive effect on the removal of brittle materials, concluded by many researchers [9][10][11][12], we have also performed Vickers indentation tests and nano-scratch tests with a spherical indenter along the 0°, 45° and 90° orientations on the second harmonic generation (SHG) and third harmonic generation (THG) crystal planes of KDP crystal, and determined their mechanical properties, critical loads and depths of the brittle-ductile transition. [13,14] In this paper, we introduced ultrasonic vibrations onto the indenter during the scratching process using a single-point diamond to visualize and analyze the effect of ultrasonic vibration on the material removal characteristics of KDP crystal.…”

Section: Introductionmentioning

confidence: 99%

“…After the coefficient of the critical depth, Ψ, and the modified scratch constant, C, are determined, the critical depth of the brittle-ductile transition during the scratching process can be predicted and used to guide the selection of cutting parameters to optimize the material removal mode.According to a previous study method of indentation test as in reference[10] that we conducted, the mean values of the mechanical properties of the KDP crystal test-pieces for the (001) crystal plane in this experiment are shown inTable 1.…”

mentioning

confidence: 99%

Material Removal Characteristics of KDP Crystal in Ultrasonic Vibration-Assisted Scratch Process

Wang

Feng

et al. 2015

In this paper, the micro-scale removal characteristics of KDP crystal were investigated based on a developed ultrasonic vibration-assisted scratch test apparatus. The common and ultrasonic scratch tests using a Berkovich indenter were conducted in the [210], [110] and [010] crystal directions of the (001) crystal plane. The results showed significant anisotropy in the material removal characteristics for the three directions on the (001) crystal plane of the KDP crystal. The smallest mean friction coefficient and the largest mean critical depth of the brittle-ductile transition were observed in the [110] crystal direction. For the ultrasonic scratch test, the load was relatively small, the removal process was smoother, the scratch debris were small and uniform, and the ductile removal rate was higher than for the common scratch test. The critical depths of the brittle-ductile transition during the common and ultrasonic scratching processes were determined for each crystal direction. Combined with the values of the mechanical properties of KDP crystal that were obtained from the indentation tests, a calculation method for the critical depths of the brittle-ductile transition of KDP crystal during the common and ultrasonic scratch tests was discussed. This method could be used to guide the optimal selection of cutting parameters in practical machining.