The effects of filling level on the milling accuracy of rice in the friction rice mill

The filling levels of rice in friction rice mill is one of the principal factors that determine rice milling quality. Clarifying the influence of filling level on milling accuracy is the key to improve milling quality. In this work, the milling process of particles in mill under different filling levels was examined experimentally and numerically. The effects of filling level on milling degree and milling uniformity were revealed. The results show that with increase of filling level, extra added particles enter originally outer ring afterward mainly inner ring. Particles are subjected to more severe abrasion due to the increase of force and area of milling zone. The tangential dissipated energy of particles increases first then keeps stable. A method which can quantify milling uniformity is established and then applied. Particle rotational kinetic energy directly affects milling uniformity. This study is helpful to provide guidance for parameter selection of similar mills. • Kinematic and dynamic behaviors of particles in friction milling cavity are analyzed. • The effect of filling levels on rice milling accuracy is revealed specifically. • Different flow structure of particles group directly affects the milling accuracy. • A method for quantifying milling uniformity of friction mill is proposed first. • There may be a specific filling level for the best milling performance.