Ram EDM
Ram EDM, or electrical discharge machining, which goes by many names including conventional EDM, sinker EDM and cavity type EDM, produces parts through eroding material in the path of an electrical field using electrical discharges, or sparks that can generate heat anywhere from eight to twenty thousand degrees. Ram EDM is used for more complex geometries where electrodes are used to erode the desired shape into the part or assembly. Industries which commonly use electrical discharge machining include aerospace, medical, tool and die, automobile and military as these applications often require high tolerances and precision components. For extremely high precision requirements, CNC EDM machines are used to guide, monitor and control the electrical discharge machining process, as well as CAD and CAM software to ensure accuracy. Ram type EDM differs from its counterpart wire EDM in terms of the type of electrode used. Consisting of an electrode and a work piece (the material being processed), the electrode is used to generate a series of sparks and is connected to the work piece through a power supply. There is no actual contact between the electrode and the work piece, but rather a conductive path that is established between the electrode and the material. Ram EDM can be applied to hard materials including stainless steel, copper, graphite, and exotic metals that would cause difficulties during conventional machining.
In addition, ram EDM is advantageous due to its ability to create complex and intricate parts with a high degree of accuracy. This process takes place in a bath of dielectric fluid, which prevents premature sparking and flushes away debris, conducts electricity between the electrode and the work piece and then flushes out the melted material. Therefore, while using this process, the work piece is not deformed from any impact as there is no direct contact between the electrode and the material, and likewise the work piece is burr-free after completion and saved from heat damage because very little material-damaging heat is generated during the procedure. Ram EDM has an advantage over wire EDM as well, because ram EDM does not cut all the way through the material, thus producing parts that wire EDM cannot. However, a disadvantage to ram EDM is the additional time and cost necessary to create electrodes. Common plunge EDM electrodes include machined graphite, copper tungsten and brass. Ram EDM is ideal for applications such as injection mold tooling, micro hole drilling, keyways, washers and scientific research apparatus.
