Physical properties of millet

Physical and mechanical properties of millet and other grains and seeds are necessary for the design of equipment to handle, transport, process and store the crop. The physical properties of millet have been evaluated as a function of grain moisture content varying from 5% to 22.5% (db). In this moisture range, grain length, width, thickness and geometric diameter increased from 3.522 to 4.163 mm, 2.735 to 3.211 mm, 2.180 to 2.788 mm, and 2.759 to 3.340 mm, respectively; the grain surface area, volume and sphericity increased from 23.91 to 35.05 mm(2), 8.2 to 14.65 mm(3) and 0.783 to 0.803, respectively; the 1000 seed mass, true density, angle of repose and terminal velocity increased from 14 to 44 gm, 1550 to 1712 kg/m(3), 34.5 degrees to 48.5 degrees and 2.75 to 4.63 m/s, respectively. The sphericity increased slowly with moisture content up to 18% and increased rapidly after that. The coefficient of static friction increased from 0.42 to 0.79, 0.39 to 0.75 and 0.36 to 0.69 for plywood, mild steel and galvanised iron, respectively. Bulk density increased with grain moisture content up to 10% and decreased with moisture content thereafter, while porosity decreased with moisture content up to 7.5% and increased with moisture content thereafter. (C) 2001 Elsevier Science Ltd. All rights reserved.