Influences of Different Contaminations on the Electro-Erosive and the Electrochemical Micro-Machining

The machining processes EDM (Electric Discharge Machining) and ECM (Electrochemical Machining) are predestined for the micro machining and a high process accuracy of the removal processes. The high processing accuracy requires a very low working gap and leads to a high contamination through the removal process. The contamination leads to changes of gap conditions (process stability) which are explained by the electric field in the gap (EDM – electrostatic field and ECM – current density distribution). In the first part, the classification of contamination will be presented according to the state of aggregation and its residence time within the gap. These classifications enable to determine the contamination in predictable conditions or risk conditions, which provide the later selection of the special process regulations. In the second part, the contamination gas bubble for Micro-EDM and μPECMM (pulsed electrochemical micro machining) will be specifically investigated. The ignition conditions through the interaction of the gas bubble and conductive or non-conductive particles are analyzed for the micro-EDM. For the μPECMM, the gas formation in the areas gap-input and gap-output is analyzed in order to decide whether an open or closed gap system must be considered.