The premise of the stable cutting of the wire EDM is to ensure that the wire is continuously cut during the cutting process. The probability of wire breakage increases with the increase of discharge energy and cutting thickness, which is closely related to the ion bombardment, cooling state and residence time of the electrode wire in the discharge channel.
When an emulsion containing about 5% of mechanical oil is used as the working medium, there are two phenomena observed on the surface of the cut workpiece after the CNC EDM wire cut machine is cut: First, the cut specimen is adhered to the substrate, which generally requires It can be separated from the substrate only by force or even knocking; secondly, the surface of the cut specimen is covered with adhesive or even powdery erosion products, which needs to be cleaned with kerosene.
This is mainly due to the high temperature above 10000°C in the discharge channel, the working medium will decompose to generate a large number of polymer compounds, and react with the metal erosion products to generate colloidal or granular substances. These substances will adhere to the slit and mainly accumulate at the exit of the slit, which will seriously affect the removal of the galvanic corrosion products and make it very difficult for fresh working medium to enter the slit.
Since there is no guarantee that there is a continuously updated working medium between the two poles, this will directly affect the continuation of the normal discharge of the CNC EDM wire cut machine, even the discharge in the gap mixed with a large amount of colloidal substances, and even generate arc discharge, which will make the workpiece The surface of the electrode wire cannot be cooled in time, and the insulation state is abnormal, resulting in a reduction in the normal discharge ratio, a reduction in the cutting speed, burns on the surface of the workpiece, serious commutation streaks and deterioration of the processing quality, and damage to the electrode wire, causing wire burning in severe cases. Therefore, the selection of emulsion as the working medium has a great influence on the improvement of the cooling state, deionization and restoration of the insulating state in the inter-electrode channel, and the higher the workpiece, the slower the wire speed, and the longer the electrode wire stays in the processing area. Longer, the probability of broken wire will naturally increase.
It is an inevitable phenomenon that the emulsion decomposes into colloidal or granular substances in the discharge channel, so the use of the emulsion as the working medium will greatly limit the improvement of the cutting process index of the wire EDM machine. The deterioration of the cooling state between the poles, the direct result will lead to a very conservative discharge energy in exchange for non-filament processing.