E Electrical Discharge Machining (EDM) is a non-conventional process using thermal energy. The cutting process uses the leap of electrical flames to erode the materials. From this cutting process, there will be white layer and HAZ on the surface of the object. White layer or recast layer is shaped from electrical sparks that leaps the gap between electrodes and workpiece that go through vaporization and liquefaction. White coating tends to be harder than the main metal, but it is more fragile. To extend the life of equipments or the product, this white layer must be removed, especially on the use of cyclic load. In this research, the writer want to know the effect of pulse on-time toward the thickness of white layer on SKD 16' steel, the electrode in three layers (copper¬graphite-copper) and petroleum alectriced fluida (kerosene). On the cracking used the pulses on-time variable, are 3, 6, and 9 ps. The sample of SKD 61' steel doing by metalografi, theirithe thickness of white layer in each zone (Lie right, '- 4tre, and left zone) who will measured by image measuremen arison, cutting use a conventional electrode (copper). On the whole pulse on-time the tested (3, 6, and 9 ps) and the depth of cut is 2 mm, cutting with a conventional electrode (copper) longer than using the three-layer electrode. kemudian ketebalan lapisan putih setiap Nora (Dina kanan, tegah, dan kiri) yang akan diukur denglir gan beasis citra. Sebagai pembanding, dilakukan pemotongan dengan menggunakan elektroda konvensional (tembaga). Hasil dari penelitian ini menunjukan bahwa rata-rata perbedaan ketebalan lapisan putih untuk pemotongan tiga lapis relatif Iebih tipis dari pemotongan eletroda konvenisonal.