ENGINEERING STUDIES ON GRADING OF ORANGE

This work was carried out to study some physical and mechanical properties of orange Navel variety, develop, construct and test of small grading machine for horticultural crops suitable for the small Egyptian farms. To evaluate the performance of the modified grading machine, some engineering factors were studied. These factors were feeding conveyor speeds (0.20, 0.25, 0.30 and 0.35 m/s), grading belts speeds (0.30, 0.40, 0.50 and 0.60 m/s) and grading belts at slope angle (zero deg.). Efficiency indicators such as grading efficiency, machine capacity, power and energy requirements and total mechanical damage were measured and calculated. The obtained results can be summarized as follows: Physical properties of Navel orange were 61.5 - 85.6 mm (length), 61.6 - 85.9 mm (width), 114 - 295 g (weight), 130 - 320 mm^3 (volume) and 1.01 (sphericity). The firmness was42.2 N, the rolling angle was 13.12 deg. and the friction angle values were 15 and 11.55 deg. for rubber and metal, respectively. The minimum and maximum grading capacity values were 2.721 t/h and 3.817 t/h at 0.20, 0.30 and 0.35, 0.60 m/s of feeding conveyor and grading belts speeds, respectively for Navel variety. The total mechanical damage values were 0.115% and 0.304% as min. and max., respectively. The minimum machine grading efficiency values were 81.4% and 95.8% as min. and max., respectively. The energy requirements were 7.5 kW.h/t and 0.153kW.h/t for manual and mechanical grading, respectively. The results indicated that fruit feeding conveyor speed (0.20m/s), grading belts speed (0.30 m/s) and zero deg. of grading belts slope angle during grading of orange produced maximum grading efficiency (95.8%) and permissible mechanical damage (0.115%).