/ EDM Machine-tool related technologies, as tool & mould making engineers are well aware, are continually ONA TWIN HEADS EDM MACHINE BOASTS THE EFFICIENCY OF ILMA PLASTICA In contrast to high speed milling, EDM is often, nowadays, a complementary technology to the HSC. This is confirmed by the Italian mould making company ILMA Plastica, s.r.l. who, thanks to the use of both these technologies, has improved their own efficiency. evolving, to enable manufacturers to become more and more competitive in the market. “A machining workshop from fifty years ago”, says Antonio Caraffini, president of ILMA Plastica, a company specialising in the manufacture of moulds for the automotive industry, “was equipped with machines of a different type: drills, lathes, mills, punchers, copiers, grinders... Over the years, the work performed by some of these machines has disappeared or decreased significantly; at present, the technologies most in evidence in workshops are the high speed milling machine and the EDM”. In fact EDM systems (both wire and die-sinking) have always been one of the fundamental technologies in the manufacture of moulds. In contrast to high speed milling, in recent years this technique has often been able to find its own niche thanks to the notable increase in its performance. “With respect to twenty years ago”, explains Mario Mini- chetti, director general of ONA Italia, “concepts and philo- sophies in the field of erosion, especially die-sinking erosion, have changed completely: in the past the machines worked, in particular, on roughing operations using medium- to large-sized electrodes, discharge control was limited and, therefore, the efficiency and the result were left to the skill of the operator. This process lasted until the end of the nineties. Then the authoritarian arrival on the market of the high speed milling machine led to the slowing down in the development of new solutions as there was no clear idea as to whether HSC technology would completely replace erosion in workshops. However, with time the high speed machine was found to be limited in its applications and to have particularly high management costs. Conse- quently, EDM, boosted by significant developments, began to take on importance again. The innovations have comple- tely transformed this technology, significantly increasing the performance of the installations: firstly, new generators able to improve control of the process automatically and, in parti- cular, with graphite electrodes, guaranteeing the end result without requiring the supervision of operators who are experts in EDM. Another significant aspect are the many technological tables on the numerical control, which are a real help to the user”. 64 /