MACHINABILITY OF PURE METALS BY ELECTRICAL DISCHARGE MACHINING

Electrical discharge machining (EDM) involves the generation of micro-plasmas subjected to high temperature and pressure to promote the material removal. Hence, to understand the material removal mechanism it is of great importance the knowledge of the interaction plasma-solid. Knowing how physical and chemical properties of materials affect heat transfer at the electrode surface, how this eventually affects electrical properties of the plasma channel over the discharge time are key issues to achieve a better understanding of this machining technology. This research attempts to provide some answers to these issues by means of single plasma discharge tests under laboratory-controlled conditions carried out on pure and low-alloyed materials in favour of comprehensiveness and forthcoming numerical modelling. These results demonstrate that material eroded volume is correlated with process operating parameters and that crater morphology has presented a more regular shape in pure metals than in engineering materials. The machinability index of the materials under study has been determined by calculations of the eroded volume and electrical power measures. Further to the low predictability of the models presented in literature, it was also proposed a basic conceptual model referring to the morphology of the eroded craters

Enrolamento filamentar : métodos para obtenção da trajectória do olhal de deposição, com eliminação de colisão

Dissertação apresentada para obtenção do grau de Mestre em Engenharia Estrutural, na Faculdade de Engenharia da Universidade do port