Research on Micro-Size Electrical Discharge Machining Polycrystalline Diamond

2019 ◽  
Vol 943 ◽  
pp. 14-19 ◽  
Author(s):  
Yun Hai Jia ◽  
Jian Mei Guo ◽  
Yan Guo ◽  
Fan Yu
Keyword(s):  
Pulse Duration ◽  
High Efficiency ◽  
Electrical Discharge Machining ◽  
Pulse Discharge ◽  
Cutting Tools ◽  
Polycrystalline Diamond ◽  
Green Manufacturing ◽  
Single Pulse ◽  
Pit Depth ◽  
Thermal Influence

With the demand of modern cutting technology for ‘high efficiency, precise, flexibility and green manufacturing’, polycrystalline diamond materials as cutting tools have been widely used in automobile, aerospace and non-metal processing. Electro-spark erosion is one of the most effective ways to machine polycrystalline diamond materials. Single pulse discharge is one of the research foundations of micro-EDM. Using 2 micron granularity polycrystalline diamond as experiment material, the influence of single pulse discharge technology on the removal efficiency of materials was studied, such as pit radius, pit depth and radius-depth ratio, etc. The experimental results show that, with the extension of the pulse duration, the radius of the discharge pit begins to increase rapidly, then slowly increases, and finally to slow down; while the radius of thermal influence zone increases rapidly and then continues to increase slowly. With the extension of pulse duration, the ratio of pit depth to radius changes within the range of 0.05 ~ 0.25, which shows a downward trend basically.

Research on Micro-Size Electrical Discharge Grinding Polycrystalline Cubic Boron Nitride Based on Single Pulse

2021 ◽  
Vol 1035 ◽  
pp. 778-784
Author(s):  
Yun Hai Jia ◽  
Yan Hua Cia ◽  
Qin Jian Zhang
Keyword(s):  
Boron Nitride ◽  
Pulse Duration ◽  
Electrical Discharge ◽  
High Efficiency ◽  
Pulse Discharge ◽  
Cubic Boron Nitride ◽  
Single Pulse ◽  
Polycrystalline Cubic Boron Nitride ◽  
Corrosion Pit ◽  
Corrosion Pits

Polycrystalline cubic boron nitride (PcBN) was a high temperature and high pressure composite material with high hardness. With its high wear resistance and good chemical stability, it conforms to the basic characteristics of modern advanced cutting technology of "high efficiency, high precision, high efficiency and green". Currently, it was widely used in the field of ferrous metal cutting tools. Electrical discharge grinding was one of the most effective methods for machining polycrystalline cubic boron nitride cutters. It was especially suitable for machining complex shapes and thin edge cutters. Single pulse electrical discharge grinding is the basis of continuous EDG machining and an effective method to study micro-scale electrical discharge grinding. In this study, the morphology of single pulse discharge corrosion pits and the relationship between discharge parameters and material removal rate, such as the deep-diameter ratio of the corrosion pits, the pulse width and the deep-diameter relationship of the corrosion pits, were studied with the polycrystalline cubic boron nitride composite sheet of 2 micron particle size as the test material and the independently developed single pulse discharge power supply as the device. The experimental results show that the radius and heat affected area of the discharge corrosion pit increase rapidly, then slowly, and finally gradually with the extension of pulse duration. The corrosion depth generally varies gently in the range of 0.2 ~ 0.5 micron, and the pulse duration has no obvious effect on the depth of the discharge corrosion pit. With the extension of pulse duration, the ratio of radius to depth of the corrosion pit changed in the range of 13 ~ 20, and the ratio basically declined.

Research on the influence of the discharge breakdown process on the crater formation during EDM

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wenchao Zhang
Keyword(s):  
Mathematical Model ◽  
Discharge Channel ◽  
Electrical Discharge Machining ◽  
Pulse Discharge ◽  
Single Pulse ◽  
Crater Formation ◽  
Content Type ◽  
Breakdown Process ◽  
Positive Ions ◽  
Fluid Coupling

PurposeThis paper aims to study the breakdown, oscillation and vanishing of the discharge channel and its influence on crater formation with simulation and experimental methods. The experiment results verified the effect of the oscillating characteristics of the discharge channel on the shape of the crater.Design/methodology/approachA mathematical model that considers the magnetohydrodynamics (MHD) and the discharge channel oscillation was established. The micro process of discharging based on magnetic-fluid coupling during electrical discharge machining (EDM) was simulated. The breakdown, oscillation and vanishing stage of the discharge channel were analyzed, and the crater after machining was obtained. Finally, a single-pulse discharge experiment during EDM was conducted to verify the simulation model.FindingsDuring the breakdown of the discharge channel, the electrons move towards the center of the discharge channel. The electrons at the end diverge due to the action of water resistance, making the discharge channel appear wide at both ends and narrow in the middle, showing the pinch effect. Due to the mutual attraction of electrons and positive ions in the channel, the transverse oscillation of the discharge channel is shown on the micro level. Therefore, the position of the discharge point on the workpiece changes. The longitudinal oscillation in the discharge channel causes the molten pool on the workpiece to be ejected due to the changing pressure. The experimental results show that the shape of the crater is similar to that in the simulation, which verifies the correctness of the simulation results and also proves that the crater generated by the single pulse discharge is essentially the result of the interaction between transverse wave and longitudinal wave.Originality/valueIn this paper, the simulation of the discharge breakdown process in EDM was carried out, and a new mathematical model that considers the MHD and the discharge channel oscillation was established. Based on the MHD module, the discharge breakdown, oscillation and vanishing stages were simulated, and the velocity field and pressure field in the discharge area were obtained.

Scribing Characteristics of Glass Plate with Ground PCD Scribing Wheel

2018 ◽  
Vol 12 (5) ◽  
pp. 760-766
Author(s):  
Yusuke Akiyama ◽  
Mutsumi Okada ◽  
Hirofumi Suzuki ◽  
Toshio Fukunishi ◽  
Yoshiyuki Asai ◽  
...  
Keyword(s):  
High Efficiency ◽  
Glass Plate ◽  
Cutting Tools ◽  
Polycrystalline Diamond ◽  
Diamond Wheel ◽  
Precision Machining ◽  
Electric Discharge Machining ◽  
Single Crystal Diamond ◽  
Pcd Tools ◽  
Alloy Metal

Polycrystalline diamond (PCD) tools are widely used for cutting tools because PCD has no crystal orientation and is an isotropic material, it is low in cost, and it is easily machined by electric discharge machining. PCD is sintered from diamond abrasives with an alloy metal, such as cobalt, and it is difficult to reduce the surface roughness and the edge accuracy compared with single crystal diamond. In this study, high efficiency and high precision machining of the PCD wheel were investigated. In the experiments, PCD wheels were ground with a diamond wheel, and the effects of the grinding direction and the load on the tool preciseness and the scribing performance were examined.

High-Pressure Synthesis of High-Purity and High-Performance Diamond and cBN Ceramics

2006 ◽  
Vol 45 ◽  
pp. 885-892 ◽  
Author(s):  
Hitoshi Sumiya
Keyword(s):  
High Pressure ◽  
Diffusion Process ◽  
High Purity ◽  
High Performance ◽  
High Efficiency ◽  
Cutting Tools ◽  
Polycrystalline Diamond ◽  
High Hardness ◽  
Secondary Phases ◽  
Fine Grained

High-purity, single-phase polycrystalline diamond and cBN have been successfully synthesized by direct conversion sintering from graphite and hBN, respectively, under static high pressure and high temperature. The high-purity polycrystalline diamond synthesized directly from graphite at ≧15 GPa and 2300-2500 °C has a mixed texture of a homogeneous fine structure (grain size : 10-30 nm, formed in a diffusion process) and a lamellar structure (formed in a martensitic process). The polycrystalline diamond has very high hardness equivalent to or even higher than that of diamond crystal. The high-purity polycrystalline cBN synthesized from high-purity hBN at 7.7 GPa and 2300 °C consists of homogeneous fine-grained particles (<0.5 μm, formed in a diffusion process). The hardness of the fine-grained high-purity polycrystalline cBN is obviously higher than that of single-crystal cBN. The fine microstructure features without any secondary phases and extremely high hardness of the nano-polycrystalline diamond and the fine-grained polycrystalline cBN are promising for applications in next-generation high-precision and high-efficiency cutting tools.

scholarly journals Study on the Discharge Characteristics of Single-Pulse Discharge in Micro-EDM

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 55 ◽  
Author(s):  
Qingyu Liu ◽  
Qinhe Zhang ◽  
Min Zhang ◽  
Fazhan Yang
Keyword(s):  
Electrical Discharge Machining ◽  
Short Pulse ◽  
Pulse Discharge ◽  
Single Pulse ◽  
Energy Utilization ◽  
Utilization Rate ◽  
Micro Edm ◽  
Discharge Characteristics ◽  
Discharge Duration ◽  
Positive Ion

To further study the discharge characteristics and machining mechanism of micro-electrical discharge machining (micro-EDM), the variation trends of the discharge energy and discharge crater size with actual discharge duration are discussed based on single-pulse experiments. The polarity effect of micro-EDM was analyzed according to the motion characteristics of electrons and ions in the discharge plasma channel. The results show that the discharge current and voltage of micro-EDM were independent of the discharge width and open-circuit voltage. The energy utilization rate of the short-pulse discharge was relatively high, and the energy utilization rate decreased gradually as the discharge duration increased. Even if the mass of the positive ion was much larger than that of the electron, the kinetic energy of the positive ion was still less than that of the electron when bombarding the surface of the electrode. The acceleration and speed of electrons were very high, and the number of times that electrons bombarded the surface of positive electrode was more than 600 times that of positive ions bombarding the surface of the negative electrode during the same time.

Nanopatterning on Nano-Polycrystalline Diamond and Cubic Boron Nitride Using Focused Ion Beam and Heat Treatment to Fabricate Textured Cutting Tools

2016 ◽  
Vol 874 ◽  
pp. 543-548 ◽  
Author(s):  
Noritaka Kawasegi ◽  
Kazuma Ozaki ◽  
Noboru Morita ◽  
Kazuhito Nishimura ◽  
Makoto Yamaguchi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Boron Nitride ◽  
Single Crystal ◽  
Focused Ion Beam ◽  
High Efficiency ◽  
Ion Beam ◽  
Cubic Boron Nitride ◽  
Cutting Tools ◽  
Polycrystalline Diamond ◽  
Single Crystal Diamond

Texturing on the surface of cutting tools is an effective method to improve the friction and resultant machining performances of the tool. In this study, to fabricate nanotextures on various tools used for precision cutting, a patterning method on nanopolycrystalline diamond and cubic boron nitride tools was investigated using focused ion beam (FIB) irradiation and heat treatment. Patterning was possible using this method, and the patterning characteristics were different from those of single-crystal diamond. This method was more suitable for cutting tools compared with direct FIB machining because of its high efficiency and significantly low affected layer.

Study on EDM Machining Technics of Polycrystalline Diamond Cutting Tool and PCD Cutting Tool’s Life

2011 ◽  
Vol 268-270 ◽  
pp. 309-315 ◽  
Author(s):  
Yun Hai Jia ◽  
Jian Gang Li ◽  
Xue Jun Lu
Keyword(s):  
Surface Roughness ◽  
Electrical Discharge ◽  
Pulse Width ◽  
Cutting Tool ◽  
Electrical Discharge Machining ◽  
Cutting Tools ◽  
Polycrystalline Diamond ◽  
Machining Parameter ◽  
Diamond Cutting Tool ◽  
The Relationship

The Samples of Polycrystalline Diamond (PCD) Cutting Tool Were Machined by Adjusting the Main Parameters of Electrical Discharge Machining (EDM). after the Machining, the Phases Were Analyzed by X-Ray Diffraction Analyzer and the Surface Layer Microstructure Were Observed by Scanning Electronic Microscope. the Fundamental Component of Machined PCD Cutting Tool Affected Layer Was Obtained and the Reason of Bring Affected Layer Was Analyzed. the Relationship Curves between Pulse Width, Working Electric Current and Depth Affected Layer, Surface Roughness Were Summarized. the Relationship between PCD Cutting Tools that Was Machined by EDM and Cutting Tool Flank Width, Workpiece Surface Roughness Were Analyed.The Results Showed that to Adjust Electical Discharge Machining Parameter, such as Pulse Width and Machining Electric Currents, Can Reduce the Depth of Affect Layer and Extend the Service Life of PCD Cutting Tool.These Researches Provide Valuable Test Reference for Drawing up Electrical Discharge Machining Technics of PCD Cutting Tool and Cutting Tool’s Life.

Shifting Secondary Discharge as the Expulsion Mechanism in EDM

2008 ◽  
Author(s):  
Y. F. Luo ◽  
Jia Tao
Keyword(s):  
Energy Distribution ◽  
Driving Force ◽  
Electrical Discharge ◽  
Metal Removal ◽  
Electrical Discharge Machining ◽  
Pulse Discharge ◽  
Single Pulse ◽  
Complex Surface ◽  
Apparent Difference ◽  
Reversed Polarity

A new understanding of the expulsion mechanism in electrical discharge machining (EDM) is discussed in this investigation. The shifting secondary discharge inside a cathodic root is revealed as the major driving force for metal expulsion in EDM. A typical electrode couple of steel for cathode and copper for anode is used in all the experiments and discussions. Micro graphs of discharge craters are taken from the complex surface directly after a continual discharging process while either normal or reversed polarity is applied. The apparent difference in crater morphologies on anode and cathode indicates the unique expulsion mechanism, namely secondary discharges, which only take place inside the cathodic root. The compliance of secondary discharges with long-disputed phenomena, such as the discrepancy between energy distribution and metal removal, is demonstrated through the applications of the mechanism to the phenomena. The applied methods and results are more realistic since single pulse discharge among other process changes is prohibited. Such a more reliable understanding can correlate the complex metal removal mechanisms to better future process developments.

Modeling and Simulation of Surface Topography Evolution in Electrical Discharge Machining (EDM)

2014 ◽  
Vol 1017 ◽  
pp. 764-769
Author(s):  
Tian Feng Zhou ◽  
Li Zheng Ma ◽  
Zhi Qiang Liang ◽  
Xi Bin Wang
Keyword(s):  
Surface Topography ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Pulse Discharge ◽  
Fem Simulation ◽  
Single Pulse ◽  
Machining Parameters ◽  
Workpiece Material ◽  
Material Erosion ◽  
Gauss Distribution

This paper aims to quantify the effects of the machining condition on the surface topography in electrical discharge machining (EDM), including pulse current, pulse duration and so on. Firstly, the heat source of a single electrical pulse is defined by Gauss distribution, and the thermal effects of machining parameters on the workpiece material erosion are simulated by Finite Element Method (FEM) package ANSYS. Then, the crater size of a single pulse is numerically simulated based on the thermal model of a single pulse discharge. Furthermore, the superposition of multiply craters created by continuous pulse discharges in a random distribution is calculated by MATLAB software program, so that the evolution of the surface topography can be obtained with the combination of FEM simulation and topology calculation. In this way, the surface roughness is quantitatively calculated from the specified EDM parameters.

scholarly journals Impact of Substrate Outgassing on the Growth of Carbon Nanotubes Using the Single-Pulse Discharge Method

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
C. H. Su ◽  
C. H. Huang
Keyword(s):  
Carbon Nanotubes ◽  
Room Temperature ◽  
Electrical Discharge Machining ◽  
Pulse Discharge ◽  
Single Pulse ◽  
Substantial Improvement ◽  
Peak Current ◽  
Electrode Consumption ◽  
Discharge Method ◽  
Better Than

Carbon nanotubes (CNTs) were fabricated in air using the electrical discharge machining method. The main parameters for this process were substrate temperature, peak current (Ip), and pulse duration (τ). The substrate was baked at 50°C and this temperature was maintained for 12 h under vacuum chamber; it was then cooled to room temperature and stored in vacuum for outgassing. During single-pulse discharge in air, the substrate was heated from room temperature to the test temperatures (50 and 70°C). The results indicated that the length, density, and purity of CNTs grown on outgassed substrates were better than those of CNTs grown without outgassing. Additionally, CNTs grown withIp= 3 A andτ= 1200 μs were of better quality than those grown with other combinations of parameters. The size of the discharge pit was effectively reduced by 30% (80 μm). This finding may help in controlling the amount of peak current used during the process, thereby reducing the problems of heat-affected zones and electrode consumption. Consequently, there was substantial improvement in the zonal selectivity and reticular density of the CNTs grown using the single-pulse discharge method.

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