Investigation of rice debranning mechanism based on tribological behaviour between rice grains

Frictional debranning between rice grains is a fragile and energy-consuming process. Understanding the mechanism of this frictional debranning is the key to achieving moderate debranning, yet the mechanisms involved remain poorly understood. In this work, the mechanism of rice grain debranning was investigated through rice milling experiments, SEM analysis of the rice surface, and rice wear experiments. The results showed that the bran layer of rice grains exhibited different removal patterns at different milling pressures. During frictional debranning between rice grains, adhesive wear and bulk stripping of the bran layer occurred. The bran layer of the rice grain initially experiences primary damage due to adhesive wear, followed by bulk stripping at the edges of the existing damage. Pre-milling can effectively improve the debranning efficiency of rice grains. These findings should provide a theoretical reference for the design of grain milling equipment and the process improvement of grain moderate milling.