Abstract:
Rasping is the most frequently useful method to disintegrate or to break down the cellular structure of sago pith for mechanical processing. The objective of this study was to investigate the effect of cylinder rotation speed and teeth density on power requirement and specific energy consumption of cylinder type sago rasping machine. In addition, the performance of rasping machine in term of rasping capacity and product’s amounts were also measured. In the experiment, five levels of cylinder rotation speed i.e. 745 rpm, 1490 rpm, 2235 rpm, 2980 rpm and 3725 rpm and three levels of teeth density i.e. 2.2 cm × 4 cm (D1), 2.2 cm × 3 cm (D2), and 2.2 cm × 2 cm (D3) were tested. A torque transducer (torque meter) was used to measure the rasping torque. The torque meter was calibrated before being used. In addition, a strain amplifier was used to amplify the output signal. The power requirement was then calculated. Results showed that the power requirement of the rasping machine increased as the rotating speed of cylinder increased. Likewise, the power required increased with increases of teeth density. The average level of power required at teeth density D1, D2, and D3 ranged from 0.45 to 1.62 kW, 0.46 to 1.62 kW, and 0.54 to 1.62 kW, respectively, when the cylinder rotation speed increased over the full range from 745 to 3725 rpm. The specific energy consumption increased with the increases of both cylinder rotation speed and teeth density. The specific energy consumption at D1, D2, and D3 ranged from 2.08 to 4.92 kWh/ton, 2.67 to 6.53 kW-h/ton, and 3.01 to 9.11 kW-h/ton, respectively, over the range of cylinder speed tested. The lowest levels of power requirement and specific energy consumption were obtained at cylinder rotation speed of 745 rpm for all teeth density.
