Electrical Discharge Machining atau EDM merupakan proses permesinan non-konvensional. Sistem kerja EDM dengan memanfaatkan energi panas dari proses loncatan bunga api listrik (spark) akibat adanya perbedaan muatan di antara elektroda dan benda kerja yang terisi cairan dielektrik. EDM sinking secara digunakan untuk memproduksi mold dan dies. Salah satu material yang digunakan dalam industri pembuatan mold adalah AISI P20. Pada proses pembuatan mold menggunakanEDM sinking perlu memperhatikan laju pengerjaan material yang memiliki karakteristik kualitas semakin besar nilainya maka semakin baik. Nilai laju pengerjaan material yang besar dapat meminimalkan biaya produksi. Metode Taguchi digunakan dalam penelitian ini untuk menghasilkan nilai optimal laju pengerjaan material. Desain eksperimen menggunakan orthogonal array L18 untuk mengkombinasikan empat variabel proses yaitu jenis elektroda, gap voltage, on time, dan off time. Berdasarkan hasil analisa setting parameter untuk laju pengerjaan material yang optimal menggunakan tembaga, gap voltage 40 volt, on time 150 μs, dan off time 20 μs.

This research aims to obtain optimal value for the surface roughness of the material AISI P20 on the Electrical Discharge Machining (EDM) Sinking process. In the present research, the Taguchi method is used to investigate the significant influence of process variables on the machining performance and determine the combination of process variables on the EDM process. Orthogonal array L18 (21 × 33) based on the Taguchi method is chosen for the design of experiment. The experiment is replicated twice to finding out the influence of four process variables such as type of electrode, voltage gap, on-time, and off-time on the response performance. Machining performance is evaluated by surface roughness as a response variable that had quality characteristics, smaller is better. These experimental data were analyzed using the Signal-to-noise ratio and Analysis of Variance. The analysis results show that the surface roughness is influenced by the type of electrode and on time. Combination of process variables to obtain optimal surface roughness are using graphite electrodes, and setting values of gap voltage 40 volt, on-time 250 μs, and off-time 20 μs. This combination of process variables can be applied to the manufacturing process using EDM sinking in order to produce a good quality product that determined based on the surface roughness value.