Process and device for preventing breakage of electrode wire during machining by spark erosion

A device for machining a part by electrical discharge machining using an electrode wire, the device comprising:

• means for holding the electrode wire taut and for driving the electrode wire to translate longitudinally in proximity to said part being machined in a sparking zone,
• a stream of dielectric liquid flowing through the sparking zone between the electrode wire and the part being machined,
• an electrical power source electrically connected between the part being machined and the electrode wire, the power source being capable of generating electrical pulses sufficient to cause sparks in the sparking zone between the electrode wire and the part being machined,
• measuring means for evaluating a quantity of gas bubbles present in the sparking zone between the electrode wire and the part, while the part is being machined, and for delivering a signal to a controller, the signal being representative of said evaluated quantity of gas bubbles,
• wherein the controller includes adapting means for modifying at least one machining parameter, depending on a value of said signal, so as to maintain or return the value of said signal to a suitable range of signal values while the part is being machined,
• wherein the measuring means comprises means for measuring an electrical impedance between the electrode wire and the part being machined, during a time interval between two successive pulses of spark current.