Frictional properties of selected seeds

The thickness, width, length and weight of five seed species (buckwheat, vetch, pea, lupine and faba bean) and their external friction angle were determined on two types of surfaces - steel and rubber. The experiment was performed with the use of a an inclined plane with an adjustable angle of inclination that measures the angle of external friction and the time taken by seeds to travel a given distance, which supports the determination of the coefficient of kinetic friction. The measured parameters were used to calculate arithmetic and geometric mean diameter, aspect ratio and sphericity index. The dimensions, weight and the calculated indicators of the examined seeds did not significantly affect their coefficients of static and kinetic friction or their coefficients of rolling resistance and rolling friction. The studied parameters were largely influenced by the type of friction surface, and significantly lower average values were reported for steel than rubber. In the studied seed species, the static friction coefficient was determined in the range of 0.187 to 0.582, kinetic friction coefficient - 0.134 to 0.479, rolling resistance coefficient - 0.148 to 0.529 and rolling friction coefficient - 0.29 to 1.80 mm.