AN AUTOMATED CASSAVA PEELING MACHINE

Abstract

Cassava Peeling has been identified as the only un-mechanized unit operation in cassava production which has constituted global challenge in twenty-first century despite an ever-increasing demand for the crop. As at today, cassava peeling is still largely carried out manually. The process is slow, labour intensive and arduous in nature with low productivity. This research work is aimed at identifying crop and machine parameters critical and the effect of these on the performance of an existing automated peeling machine. Physical and mechanical properties of cassava tuber such as tuber length, weight, diameter, surface taper angle, proportion by weight of peel, peel thickness, peel moisture content, peel penetration force and peel shear stress were determined. Effect of crop and machine parameters such as crop variety, weight loaded and machine speed, velocity of conveyance and peeling time at different geographical locations on machine performance evaluation were investigated. TMS 30572 and TMS 4(2)1425 varieties were considered for the experiment while IITA, Ibadan, teaching and research farm, FUTA, Ibilo in Edo State and Awo-mmama in Imo State were selected as farm locations. The tuber length ranges from 125-492 mm, tuber weight ranges from 148-2312 g, proportion by weight of peel ranges from 10.52-20.06%, tuber diameter ranges from 18.86-138.55 mm, peel thickness ranges from 1.22-4.34 mm, surface taper angle ranges from 5.20-24.15o, peel penetration force ranges from 0.13-1.85 N/mm, peel shear stress ranges from 0.65-9.25 N/mm2 and peel moisture content ranges from 70.97-84.65%. The machine was evaluated on the basis of weight classification using variable gear motor at speed; 100, 110, 120, 130 and 140 rpm for smooth-edge cutting tool and 140, 145, 150, 155 and 160 rpm for serrated-edge cutting tool. Two peeling operations were carried out; unit production and mass production. During unit production, 100% peeling efficiency (PE), 1.23% mechanical damage (ME), 0% peel retention (PE) and 98.77% quality performance efficiency (QPE) were achieved at speed 140 rpm during single run. The machine was developed in the Department of Agricultural Engineering, Federal University of Technology, Akure. The peeling principle is by surface traction and impact as the tubers come in contact with the cutting tool. The previous peeling tool was modified and compared. This was aimed at achieving a good tool configuration with effective peel removal from cassava tuber irrespective of the size, shape, variety and orientation. During mass production, weight loaded; 10, 20, 30, 40, and 50 kg for each of the machine speed were considered for both smooth-edge and serrated edge cutting tool. Using smooth-edge cutting tool, PE ranges from 1.09-96.87%, MD ranges from 1.45-14.45%, PR ranges from 3.13-18.91%, QPE ranges from 70.24-96.21% and TC ranges from 339.62-1090.90 kg/h. Optimum performance is achieved at speed 130 rpm. Using serrated-edge cutting tool, PE ranges from 78. 65-91.36%, MD ranges from 5.45-9.32%, PR ranges from 8.64-21.35%, QPE ranges from 71.92-85.04% and TC ranges from 209.30-631.58 kg/h. Optimum performance is achieved at speed 160 rpm. The peeling performance of the machine was analysed theoretically, experimentally and statistically with predictive equations generated and comparison of these were also done. The result of one way analysis of variance shows that crop parameters and machine parameters have no significant difference at significance level > 0.05 for different locations using the same cutting tool. Peeling performance at different locations is significantly influenced by cutting tools, when smooth-edge and serrated-edge cutting tools are compared, there is significant difference in peeling performance at significance level ˂ 0.05. Each of the analysis was modeled and validated. Theoretical analysis was also used as observed to predict experimental and statistical analyses. In the validation of theoretical analysis, as the velocity of conveyance increased from 1.75-2.44 m/s, throughput capacity increased from: 175.31-454.55 kg/h at tuber mass 10 kg; 314.57-740.74 kg/h at 20 kg; 429.01-967.74 kg/h at 30 kg; 534.23-1176.47 kg/h at 40 kg; and 631.65-1351.35 kg/h at 50 kg. Peel removal efficiency decreased from: 84.76-71.11% at tuber mass 10 kg; 82.82-69.34% at 20 kg; 79.94-67.81% at 30 kg; 77.38-66.25% at 40 kg; 76.40-65.77% at 50 kg. As recognized from this research work, there is a linear curve between observation and prediction. The locations of the data point depend on various factors describing the variability in the usage.