Development and Performance Evaluation of a Coffee Cherry Size Grading Machine

The coffee cherry processing industry traditionally relies on the dry method, involving harvesting, drying, and dehulling. Conventional dehulling machines with fixed drum clearances struggle to handle natural size variations, leading to inefficiencies and increased cherry breakage. To address these challenges, an innovative coffee cherry-size grading machine has been developed, utilizing an inclined oscillating sieve technique powered by a diesel engine through a belt drive. Key components include a feeding hopper, reciprocating grading sieve assembly, support frame, and power transmission system. A comprehensive performance evaluation focused on grading efficiency and capacity, exploring various operational parameters: feed rates (5, 10, 15 kg min-1), sieve angles (7˚, 9˚, 11˚), and speeds (80, 140, 200 rpm). Using a split-split-plot block design for data analysis, the study yielded promising results. Maximum grading efficiency of 88.40% was achieved at 15 kg min-1 feed rate, 8 rpm speed, and 7˚ sieve angle, with a capacity of 137.11 kg h-1 and 4.96% sieve clogging rate. ANOVA revealed significant influences of operational speed and sieve inclination angle on performance parameters. These findings offer valuable insights for optimizing coffee cherry processing, potentially enhancing efficiency and quality in the industry.