Hans-Peter Schulze

Drilling of Difficult-to-Cut Steel by Electrochemical Discharge Machining

In the case of workpieces made of difficult-to-cut materials, the small-diameter holes (1 mm diameter below) can be obtained by means of various nonconventional machining methods, one of these being the hybrid electrochemical discharge machining (ECDM). In the literature they researched, the authors could not find enough information that would allow them to establish adequate work conditions for the ECDM of small diameter holes by using an electrolyte. The use of a spring in order to obtain the work motion required to drill thin workpieces, and the need to remove the insulating film appearing on the workpiece, including in the last stage of the machining, were considered. The experimental research ended in the development of a power type function, which emphasizes the influence of the electrode tool diameter, of the voltage applied to the electrodes, of the capacity of the electric circuit involved in obtaining the electrical discharges, and of the density of the electrolyte upon the absolute axial wear of the electrode tool.

Measurement equipment for investigation of the influence of viscosity of dielectric working fluids on spark erosion

In the paper functional goals of the measurement equipment for the investigation of electrical discharges in dielectric working fluids are discussed. Electrical discharges take place at electrode distances smaller than 200 /spl mu/m. As an example the influence of the viscosity on the ignition behaviour and on typical phases of the spark erosion are analyzed.

Use of Additional Needle Pulses Using Electrical Discharge Machining

The influence exerted by the longer rectangular pulses with additional Needle Pulses. Needle pulses for the spark erosion are the fundamental of the erosion pulses with pulse durations smaller 1 μs and high current‐rise‐velocity (ramp unit). In this shorter pulse‐duration it is possible to use higher current densities; without composition of the thermal‐affected zones. The technological advantage is a higher productivity because the higher pulse energy and parallel a better quality of the processing area exist; an additional factor for the higher productivity is the smaller number of back‐cuts for the finish quality of the cut.

Machinability of a Stainless Steel by Electrochemical Discharge Microdrilling

Due to the chemical elements included in their structure for ensuring an increased resistance to the environment action, the stainless steels are characterized by a low machinability when classical machining methods are applied. For this reason, sometimes non‐traditional machining methods are applied, one of these being the electrochemical discharge machining. To obtain microholes and to evaluate the machinability by electrochemical discharge microdrilling, test pieces of stainless steel were used for experimental research. The electrolyte was an aqueous solution of sodium silicate with different densities. A complete factorial plan was designed to highlight the influence of some input variables on the sizes of the considered machinability indexes (electrode tool wear, material removal rate, depth of the machined hole). By mathematically processing of experimental data, empirical functions were established both for stainless steel and carbon steel. Graphical representations were used to obtain more sugges...

Change of ignition conditions at the spark erosion process by adding molecules with defined chemical structures to a dielectric fluid

The ignition and breakdown behaviour in spark erosion processes are determined by a large number of different influences. Our paper shows the specific influences of alicyclic and aromatic hydrocarbon molecules, added to an n-alkane base fluid. The aim of our investigations was to find additives which led to modified discharge channels. Also an attempt of an explanation of the test results is presented.