Papers by Keyword: Electro Discharge Machining (EDM)

Abstract: EDM; Gap voltage/current; Wavelet analysis; Modulus maxima algorithm Abstract: According to the characteristics of Electrical Discharge Machining Gaps Signal for Non-conductive Engineering Ceramics, the wavelet modulus maxima algroithm was uesed to denoise the gaps voltage/current signal. Compaered the differernt denoising result of different wavelet function, Maxihat wavelet, Meyer wavelet, Daubechies wavelet and Gaussian wavelet, the fitting wavelet function, Gaussian wavelet which used to denoising the EDM Gaps voltage/current signal was found out, and the fitting scales space [-5,+1] and the normalized threshold value interval [0.1,0.3] was determined.

Abstract: This paper deals with EDM characteristics of newly develops electrically conductive ceramics. Titanium boride (TiB2) is widely used as die and mold materials because of its high hardness, high-temperature resistance and so on. The EDM characteristics of the titanium boride, such as electrode wear rate, removal rate and surface roughness were investigated. Experimental results show that EDM with low electrode wear rate is possible when copper electrode is used with positive polarity. The removal rate becomes much higher when graphite electrode is used with negative polarity.

Abstract: Sintered NdFeB magnet is widely used in many areas because of its excellent magnet. This paper studies the effect of ultrasonic vibration of tool on electrical discharge machining of it. Experiments were carried out on self-made equipment and material removal rate(MRR) against pulse-on time, MRR versus peak current and machined surface results with and without ultrasonic employment were analyzed. Results show that MRR of the ultrasonic assisted electro-discharge machining would be up to five times higher than MRR of the conventional EDM for small pulse durations and low discharge currents. The machined surface of US/EDM is finer than EDM because of less arcing and short circuit pulses. There are less cracks on the surface.

Abstract: This paper presents a new kind of multi-axis electro-discharge machining (EDM) computer numerical control (CNC) system which is based on RT-Linux platform. Binary kernel structure of EDM CNC System is proposed to handle real-time task and time-sharing task separately. The system is divided into three parts: CNC kernel module, CNC driver module and CNC user module. CNC kernel module implements CNC control function in of the software system, and implements the move control to the NC machine. CNC driver module is just as device driver level. CNC user module is user manage procedure. The experiment of rimed turbine blisk validates the performance of the system. The performance implied that the system is real-time, stable and reliable.

Abstract: The flow field characteristics have a significant effect on the machining stability in high-speed small hole EDM drilling. Thus, Lagrangian discrete phase model (DPM) has been developed to simulate the gap liquid-solid two-phase flow field. The numerical calculation is based on the standard k-ε turbulent model, and the SIMPLEC algorithm is used in the simulation. All the governing equations are solved by software Fluent 6.2. Through numerical simulation, the pressure distribution, the velocity distribution of the dielectric liquid, traces of debris particles, and the debris particle concentration were obtained. The flow field characteristics under different pressures and drilling depths were obtained through simulations. Finally, experiments were carried out to investigate the effects of the flush velocity at exit obtained through simulation on material removal rate (MRR).

Abstract: The selection of manufacturing conditions is very important in manufacturing processes as these ones determine the material removal rate (MRR) of the so-obtained parts. So in this paper, based on the brief introduction of the experimental principle and the high-speed small hole EDM drilling system, effects of non-electrical parameters on MRR are discussed in detail. The relationships between MRR and these factors are also analyzed. The conclusion can provide an important reference for production in practice.

Abstract: Although various diamond polishing techniques have been studied for many years, no individual method can polish free-standing CVD diamond film with high efficiency and high polishing quality. This paper investigates polishing CVD diamond film by the combination of electro-discharge machining (EDM) and chemical mechanical polishing (CMP). Scanning electro microscopy, Optical microscopy, Energy dispersive X-ray analysis, Talysurf surface profiler and Raman spectroscopy were used to evaluate the surface integrity and quality of diamond film before and after polishing. Based on the experimental results, the material removal during EDM process can be a chemo-mechanical process, including gasification, melting, sputtering, oxidation and graphitization. While in CMP process, diamond was removed under the mechanical and tribochemical interaction. The combination of EDM and CMP has advantages of high efficiency, high polishing quality and low damage. It is suitable to polish large area free-standing CVD diamond film.

Abstract: Advanced engineering ceramics are more and more widely employed in modern industries because of their excellent mechanical properties such as high hardness, high compressive strength, high chemical and abrasive resistance. These properties limited the machining to the insulated ceramics. This paper investigates the electrical discharge machining (EDM) of ZrO2-based ceramics by assisting electrode method. The theory of assisting electrode method is introduced. The machining phenomena under different electrical parameters were studied. The material removal mechanisms change with the increase in the power of single pulse. Some work-pieces have been machined successful through the assisting electrode method.

Abstract: Developed with micro technology, the microelectrode is the key manufacture technique. The micro electrical machining, mainly including micro electrical discharge machining (EDM) and electrochemical machining (ECM), is one of the important technologies of microelectrode fabrication. Firstly, the microelectrode was fabricated with a counter block of EDM while the cylindrical tungsten electrode fed along radius and its axis. Then the fabrication technology of ECM was also introduced. The pulses power supply and the non-passivation electrolyte were used. The cylindrical tungsten electrode also can be served as the probe of the scanning probe microscopy, which fabricated by ECM. Through comparisons, the surface roughness, machining efficiency, and machining capability of the microelectrode fabricated by ECM are better than those of the microelectrode fabricated by EDM, but the shape and the microhardness are worse than those of the microelectrode fabricated by EDM. Both of them can fabricate the cylindrical tungsten microelectrodes with several micrometers diameter.

Abstract: Experiments of combining micro EDM with USM are carried out to enhance the machining ability and flexibility of the micro EDM, improve the machining state, and increase the productivity and aspect ratio of the micro holes. Basing on RC pulse power supply and workpiece vibration, the micro holes are drilled. The results of comparing experiments indicate that in the processes of both micro EDM without USM and micro EDM with USM, the machining velocity and the wear of the electrode increase with the increase of open voltage and loop capacitance. The experiment results of amplitude influencing on the machining process indicate that with the increase of ultrasonic amplitude, the machining velocity heightens and the aspect ratio of the micro holes augments; at the same time, however, the wear of the electrode and the extensive magnitude of the holes increase. Micro holes with some cross-section and accurate profile are drilled steadily.