T There are various ways in the process of metal formation, which can be done with conventional and non-conventional tooling machines. To produce high precision workpieces with complicated shape and good surface quality, non-conventional machining process is the right choice, and one of them is micro-EDM (electro discharge machining). Micro-EDM is a newly developed method to produce micro parts which in the range of 100 μm - 999 μm. Basically the micro-EDM machine is controlled by a machine and a power supply, during this period sparks will be generated between the electrodes and workpiece materials are immersed in the dielectric liquid. After an electrical spark, it causing the melting material appear outward and leaving a trace of fine craters whose geometric shape depends on the edge of the electrode. To find out the value of the crater, diameter and depth, a surface roughness measuring instrument was used. The data shows the mathematical model that will determine the dimensions of the crater is directly proportional to the current strength, where the discharge current strength makes the diameter and depth of the crater larger.