Analysis on effect of discharge parameters on cylindricity of small holes by orthogonal experiments

In order to control the cylindricity errors of small holes machined by Electrical Discharge Machining (EDM),the relations between the electrical parameters and the cylindricity of small holes was studied by technologic experiments. In the course of studying,a multi-cross section measuring method in a Cartesian coordinate was proposed. The Wire Electrical Discharge Machining(WEDM) was used to cut the processed workpieces in axial and radial directions to obtain the generatrix datum and circle datum of machined small holes,then the characteristic points of two data were measured by an universal tool microscope,and the cylindricity quantitative evaluation of the small holes was realized. Based on the method above,an orthogonal experiment was carried out,and the effect of some main electrical parameters (voltage,current,pulse duration,pulse interval and tool-lifting) on the cylindricity of small holes was studied. The results indicate that the pulse width affects cylindricity most distinctly,the voltage comes second,and the effect of rest parameters show a bit weaker.A sets of discharge parameters are achieved to purchase the least cylindricity error,which are V=110 V,I=0.6 A,ton=150 μs,toff=120 μs and tool-lifting time=1+2 s. In the experiment,a small hole with a average radius of 0.301 84 mm can offer the cylindricity of 0.021 mm,which means the presented method is effective to control the cylindricty of the small holes machined by EDM.