| A novel truing and dressing method on superabrasive grinding wheel, namely mist-jetting electrical discharge truing and dressing (MEDD), has been proposed in this paper. MEDD process eliminates vast dielectric liquid and produces less corrosion and pollution to function units in contrast with conventional EDD. It is a green manufacturing technology and has an extensive application prospects on truing/dressing system on-line of precision grinding machine. In this paper, the mechanism of the selective removal of the bond, the transient temperature fields as well as wheel surface profiles and topography control technologies of MEDD process have been systematically studied combining methods of theoretical analysis, FEM numerical simulation and experimental study .It will have an important theoretical value and practical significance not only for the cost reducing and increasing efficiency but also for promoting the development and application of MEDD technology on preparation of superabrasive grinding wheels.The author proposed a complete study on the material removal mechanism of EDM with misted dielectric. The conductance and disruption of misted dielectric are analyzed systematically on the basis of gas medium. Electric field distortion is caused within misted dielectric for the reason that misted dielectric is composed of continuous gas and tiny liquid drops. Consequently, the disruption voltage is about a factor of three than that for gas medium. The material removal mechanism of EMDD process is analyzed on four aspects, which are the disruption of misted dielectric and formation of discharge channel, the conversion of discharge energy, the materials' shoot off and deionization process and a model of single pulse discharge is established. The model shows that the process of material removal for a single pulse discharge includes three stages, ionizing, electrical discharge, and de-ionizing.Conventional EDD technology shows important limitations that it is only applicable to metal-bonded wheels. This paper proposed novel MEDD technology which could truing/dressing non-electrical superabrasive grinding wheels such as resin-bonded diamond wheel and vitrified CBN wheel by means of covering electrical material on the surface of wheel. The principle of removing metal-bond and resin bond during MEDD process is illustrated. The thermal and electrical physical properties differences between bonds and diamond abrasives are analyzed. At the same time, the mechanism of selective removal of the bond and revealing diamond grains is completely clarified on three aspects, which are material science, conduction of heat and electrical discharge machining theory. The calculattion results of temperature distribution indicate that MEDD technology is feasible for metal-bonded and resin-bond superabrasive grinding wheel.Three-dimensional finite element model of transient temperature fields in MEDD process has been built up and relatively comprehensive numerical simulation has been carried out with parametric programming methods. The temperature distribution and variation rules of bronze-bond and diamond grain have been obtained. Simulation results indicated that the maximal temperature of bronze-bond and diamond grains at different layers increase with discharge current. It also reveals that the depth and width of bronze-bond crater increase with the discharge current and pulse duration. However, the maximal temperature of bronze-bond and diamond grains does not increase too much with the growth of pulse duration. At the same time, the maximal temperature of bronze-bond and the depth of molten bronze-bond go down as the speed of grinding wheel increases. The simulation model is benefit to quality forecast, parameter regulation and optimization in the process of truing and dressing bronze-bond diamond grinding wheel. It also helps to avoid that high temperature make diamond grain graphitization or the temperature is not high enough to remove the metal bond well. The simulation model can keep from the blindness to true and dress diamond wheel directly.A series of dressing experiments were carried out on a TROOP434 Die-Sinking Electrical Discharge Machine according to bond selective removal mechanism and temperature fields numerical simulation results. The influence of process parameters including discharge current, pulse duration, speed of wheel, discharge voltage and different dielectric fluid on dressing quality and efficiency was systematically studied with experiments. The condition of the wheel before and after MEDD was analyzed by studying the wheel surface topography. Wheel surface topographies before and after dressing were observed by optical microscope (model: KEYENCE VH-8000 Digital HD); a Dektak 6M profilometer has been used in this work to quantify the grit protrusion before and after dressing. Different dielectric experiments results showed that wheel surface topography with emulsion mist is the best, and that the dressing quality and efficiency of experiments with gas were the worst. Dressing bronze-bond diamond wheel experiments results indicated that discharge current and speed of grinding wheel had direct influence on the wheel surface topography and the performance of diamond grains. As well as, pulse duration had less influence on the wheel surface topography. The experiments results also revealed that discharge current and pulse duration were chief parameters which can affect dressing efficiency, and that discharge voltage had no influence on dressing quality and efficiency.Dressing resin-bond diamond wheel experiments results indicated that the EMDD method proposed in this paper has been applicable to non-electrical bond wheels. Simultaneity, dressing process parameters have the same influence on dressing quality and efficiency as dressing bronze-bond diamond wheel experiments. However, the appropriative discharge current in dressing resin-bond diamond wheel process was much less than one in dressing bronze-bond diamond wheel for the reason that the decomposing point of resin-bond is 200-400℃is less than melting point of bronze-bond. The results of grinding forces measurement showed that the performance of wheel depended on the protrusion height of diamond grain and the number of cutting grains on the wheel surface. The appropriate protrusion height of diamond wheel used in experiments was 35μm～50μm.
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