One of the two major types of EDM, sinker EDM differs from its counterpart wire EDM in terms of the type of electrode used.
Sinker EDM, which goes by many names including conventional EDM, plunge EDM and ram EDM, produces parts by eroding materials in the path of the EDM tool using electrical discharges, or sparks that can generate heat anywhere from eight to twenty thousand degrees. One of the two major types of EDM, sinker EDM differs from wire EDM in terms of the type of electrode used.
Common sinker EDM electrodes include machined graphite, copper tungsten and brass. Die sinking EDM is ideal for applications such as injection mold tooling, micro hole drilling, keyways, washers and scientific research apparatus. Unlike wire EDM which can only be used in the processing of 2D parts, sinker EDM has the capability of machining 3D pieces. It does not require the pre-drilling of a hole for the electrode and so can be used for more complex geometries.
Consisting of an electrode and a work piece (the material being processed), the EDM electrode is used to generate a series of sparks and is connected to the work piece through a power supply. There is a highly conductive path established between the electrode and the work piece which creates an intense electric field the melts away the material. The electrodes and the work piece do not come into contact with each other; rather the dielectric bath conducts the current to melt away the material and then flushes away the unwanted debris.
Industries commonly served by electrical discharge machining include aerospace, medical, tool and die, automobile and military. One of the biggest advantages to using EDM machining is its ability to create complex and intricate parts with a high degree of accuracy. In CNC EDM processes, CNC machines are used to guide, monitor and control the EDM process, as well as CAD and CAM software. It can be applied to hard materials such as stainless steel, copper, graphite and other metals which are difficult to successfully machine with other conventional methods.
Furthermore, as there is no contact between the machine tools and the work piece, there is less chance for process damage to the part. It is not deformed by impact or by heat, nor are there burrs which need to be removed through secondary machining. Sinker EDM is used for more complex geometries where electrodes are used to erode the desired shape into the part or assembly. Sinker EDM has another advantage over wire EDM in that sinker EDM does not necessarily cut all the way through the material, thus producing parts that wire EDM cannot.