This research was conducted to determine the effect of working volume, ball mill, and milling time during
milling process. Ball mill with a capacity of 5 kg was used with various ball mill media with diameters of 10 mm, 20
mm, and combined sizes of 10 mm and 20 mm, respectively. The next variation was the working volume starting from
20, 30, 50, and 70% with milling time of 30 and 60 minutes. Corn cob was the material used in this research. The milling
process was carried out at room temperature with an engine speed of 100 Rpm. The working volume produced 70%
smaller powder sizes compared to 20, 30, and 50% working volume for 60-minute milling time; while the working
volume produced 50% smaller powder sizes compared to 20, 30, and 70% working volumes for 30-minute milling time.
For the ball mill variation, a combined ball with diameters of 10 mm and 20 mm was the most effective ball mill at
producing a powder with a small size compared to using only a ball with a diameter of 10 mm and a ball with a diameter
of 20 mm only.