
Rotary knife cutter is a part of cane chopper machine that mounted on the machine shaft. The number of rotary knife cutter mounted on the machine are 24 pieces that arranged to 6 lines and each line has 4 pieces. Chopper machine is driven by steam turbine, when the engine is operated shaft rotates and rotary knife cutter also rotating because it being tied to the engine shaft. Sugarcane entering through the hopper machine will cut into small parts with a size of 1 - 1.5 cm and further the pieces of cane will be processed on a hammer machine. Rotary knife cutter used in the Sei Semayang and Kualamadu sugar factories is straight shape and sharpened at one end and both sides. Rotary knife cutter materials used are aumtits that imported in the form of plate and manufactured in local workshops. This knife can be used to cut sugar cane upto 60,000 tons, and then be replaced due to wear. In this study resulted four pieces of rotary knife cutter that fabricated by metal casting techniques. Blade material is adopted from the ASSAB, XW-41 standard by modifying the elements molybdenum into three variations. To obtain the actual dimensions used milling and drilling machines. Casting that has been finished on the machine, processed again by heat treatment to a temperature of 10000C and cooled in the air blow to obtain an appropriate hardness. Rotary knife cutter has been tested in the Sei Semayang and Kualamadu sugar factories, from the test results obtained the life time of rotary knife cutter is 175000-210000 tons sugarcane.