Action Mechanism And Experimental Study Of PAAS On Small Hole EDM

In this time, as the most major part of the special machining, Electron Discharge Machining(EDM) special machining technology has been discovered and applied in practical engineering in the early days. The hardness of the workpiece is not requested during the EDM machining, neither the process will be accompanied by macroscopic shear stress. Furthermore, Complex shape of the workpiece can be done by EDM. With these advantages, the EDM have not only been an irreplaceable position in the processing field, but also a hot spot of scientific research.As an important branch of EDM technology, small hole EDM machining technology is has the same machining mechanism with general EDM machining,which is corroding the workpiece material to a certain size, shape and surface quality through transient, partical high temperature produced by spark discharge between the electrode and the workpiece. However, there are boundedness in the process: usually, the required hole’s diameter is 0.3-3 mm with the depth to diameter ratio of 20 or higher, which makes small hole EDM have a slower machining speed and a larger electrode relative loss and so on. In this paper, we tried to add dispersant(PAAS) in the working fluid to improve its processingproperties. Based on a lot of analysis, simulation and processing experiment, we find that the concentration of the working fluid has influence on small hole EDM, the main contents are as follows:(1) Based on the application principle of dispersant PAAS in printing,ceramics, paint and other areas, combined with the principle of machining in small hole EDM, we find the machining mechanism of different concentrations of PAAS as working fluid in small hole EDM.(2) Small hole EDM experiments have been done with different concentrations of PAAS as working fluid. The best concentrations of PAAS are obtained corresponding to the different processing requirements. Through experiments, we confirmed that the new working fluid can increase speed,reduce electrode relative loss and increase the maximum processing depth to diameter ratio effectively. Based on the experimental results, the influence of different working fluid on small hole EDM was obtained, in order to verify the mechanism of PAAS as the working fluid during small hole EDM.(3) Small hole EDM is to use an instant high temperature discharge pulses generated on the workpiece for processing, during the processing of experiments we found that with increasing depth of hole machining, carbonization gel would happen to PAAS in the working fluid, and impede the normal processing. In order to alleviate this phenomenon, we tried to use a dispersing working fluid as well as workpiece half immersion during the whole experiments. After simulation, experimentation and analysis, compare with the former process toverify that if the process is feasible.(4) In order to overcome the dispersant PAAS carbonized gel phenomenon hinder the normal experiments problem, another commonly industrial dispersant Etidronic acid(HEDP), which can endure high temperature, was used as new working fluid. Dispersant HEDP with different concentrations as working fluid during small hole EDM experiment. Comparing with PAAS, we can elect a proper working fluid for different processing requirements.