of the many machine tool operations available in the shop today, plunge cut edm has become an increasingly useful method of materials fabrication. it is a necessary tool for the research and development type of work performed at the lawrence livermore national laboratory (llnl). with advancing technology, plunge cut edms are more efficient, faster, have greater accuracy and are able to produce better surface finishes. they have been in the past and will continue to be an important part of the production of quality parts in both the precision and nc shop. it should be kept in mind that as a non-traditional machining process, edming is a time consuming process that can be a very expensive method of producing parts. for this reason, it must be used in the most efficient manner in order to make it a cost-effective means of fabrication, although technology has advanced to the point of state-of-the-art equipment, there is currently a void in available technical information needed for use with this process. the type of information sought after concerns the area of electrode/workpiece combinations. this is in reference to the task of choosing the correct electrode material for the specific workpiece material encountered. a brief description of the edm process will help in understanding the electrode/workpiece relationship. 5 figs