In-Process Electrical Dressing of Metal-Bonded Diamond Grinding Wheels
A new development of hybrid in-process electrical dressing of metal-bonded diamond grinding wheels is proposed in this paper. The electrical dressing method is used for overcoming the limitations of the conventional dressing methods available in relation to a super-abrasive wheel because of the hardness of its abrasive grains and the durability of its bonding material. The proposed hybrid in-process electrical dressing method consists of electro-discharge and electro-chemical processes and is implemented with twin copper electrodes and alternating power supplies. The results show that with properly maintained process conditions, a better surface finish is produced by the proposed method compared with traditional rotating SiC wheel dressing.
Development of a Simplified Electrochemical Dressing Method with Twin Electrodes
Summary The paper deals with a newly developed method for electrochemical dressing of metal bonded superabrasive wheels. In this method, alternating current derived from a wall outlet via an inexpensive transformer is supplied to a wheel through twin electrodes, hence a troublesome brush and an expensive DC power source are unnecessary. The preprocess dressing of a wheel (d 3 = 200 mm) was accomplished within a few minutes. Inprocess dressing of a wheel resulted in lower grinding force, longer wheel life and higher grinding efficiency in grinding of ceramic materials and hard metals.
Theoretical and Experimental Investigation of the Relative Effects of Spark Erosion and Electrochemical Dissolution in Electrochemical ARC Machining
Electrochemical discharge, or arc, machining (ECAM) is a process combining features of electrochemical (ECM) and electrodischarge (EDM) machining. With the combined process ECM action is assisted by the thermal erosive effect of electrical discharges in the machining gap filled with electrolyte. Machining rates are thereby obtained which can be as much as five and forty times faster than respectively ECM and EDM. The complexity of the process renders difficult any full theoretical treatment. Indeed most work to date has dealt with experimental investigations of this industrially interesting process, particularly for drilling applications. In this paper, some effects of the pulsed voltage and vibrating tool-electrode waveforms are subjected to theoretical analysis. From this treatment, conditions which are favourable to either ECM or sparking can be identified. The effect of the phase-angle between the voltage and vibration waveforms on metal machining rates is also analysed. These results are compared with experimental results, and the influence of the electrical discharges in the electrolyte is shown to become the major factor promoting enhanced rates of metal removal, as both phase-angle and amplitude of vibration increase. Further theoretical and experimental studies deal with the effect of machining voltage and feed-rate, with the sparking element playing an increasing role in raising the metal removal rate, the higher the voltage and the feed-rate used.