DESIGN OF A VACUUM SEED PLATE BASED ON PHYSICAL AND MECHANICAL PROPERTIES OF MAIZE SEEDS

A vacuum seed plate was designed, developed and evaluated based on physical and mechanical properties for three Egyptian maize seed varieties. The studied properties included seed moisture content, one thousand seed mass, maize seed linear dimensions, geometric mean diameter, the degree of sphericity, coefficient of friction and repose angle. According to the such measured properties, the seed plate dimensions were designed to be 230 mm for outside diameter, 190 mm for pitch circle diameter, 15.1 mm diameter of conical hole edges and 4.0 mm for a hole diameter. A precision vacuum planter was used to evaluate the performance of the developed vacuum seed plate under three different forward speeds 2.7 , 3.6 and 5.6 km/h (0.75, 1.0 and 1.47 m/s), three different hole diameters of 3.5, 4.0, 4.5 mm, the entry cone angle of the hole was 120o and the vacuum pressure was 4 kPa. Results concluded that the vacuum seed plate can be operated successfully at the proper operating parameters of 3.6 km/h forward speed and with a hole diameter of 4.0 mm, At these proper operating parameters, the vacuum metering system having miss indices (0.0%) and multiple indices (5.0 %) with quality of feed index 95 % and 9.91 % precision in spacing (coefficient of variation) with a mean seed spacing of 180.5 mm. The purchase price of the imported vacuum seed plate increased about 83.0 % when compared with that for the developed vacuum seed plate.